The human brain age 7-11 years: a volumetric analysis based on magnetic resonance images

Volumetric magnetic resonance image (MRI)-based morphometry was performed on the brains of 30 normal children (15 males and 15 males) with a mean age of 9 years (range 7-11 years). This age range lies in a late but critical phase of brain growth where not volumetric increment will be small but when the details of brain circuity are being fine-tuned to support the operations of the adult brain. The brain at this age is 95% the volume of the adult brain. The brain of the female child is 93% the volume of the male child. For more than 95% of brain structures, the volumetric differences in male and female child brain are uniformly scaled to the volume difference of the total brain in the two sexes. Exceptions to this pattern of uniform scaling are the caudate, hippocampus and pallidum, which are disproportionately larger in female than male child brain, and the amygdala, which is disproportionately smaller in the female child brain. The patterns of uniform scaling are generally sustained during the final volumetric increment in overall brain size between age 7-11 and adulthood. There are exceptions to this uniform scaling of child to adult brain, and certain of these exceptions are sexually dimorphic. Thus, with respect to major brain regions, the cerebellum in the female but not the male child is already at adult volume while the brainstem in both sexes must enlarge more than the brain as a whole. The collective subcortical gray matter structures of the forebrain of the female child are already at their adult volumes. The volumes of these same structures in the male child, by contrast, are greater than their adult volumes and, by implication, must regress in volume before adulthood. The volume of the central white matter, on the other hand, is disproportionately smaller in female than male child brain with respect to the adult volumes of cerebral central white matter. By implication, relative volumetric increase of cerebral central white matter by adulthood must be greater in the female than male brain. The juxtaposed progressive and regressive patterns of growth of brain structures implied by these observations in the human brain have a soundly established precedent in the developing rhesus brain. There is emerging evidence that sexually dimorphic abnormal regulation of these terminal patterns of brain development are associated with gravely disabling human disorders of obscure etiology.     

Adrenal chromaffin cells on microcarriers exhibit enhanced long-term functional effects when implanted into the mammalian brain

Rat adrenal chromaffin cells attached to either collagen-coated dextran (Cytodex 3) or glass bead microcarriers, both of 90-200 microns diameter, were used as dopamine-secreting implants in the caudate-putamen of rats with 6-hydroxydopamine-induced unilateral lesions of the substantia nigra. As controls, beads without cells and cells in suspension alone were implanted. Chromaffin cells adhered to microcarriers reduced apomorphine-induced rotation by 75% in lesioned animals. Animals that were lesioned but not receiving cell implants or receiving beads alone showed no reduction. Animals implanted with cells not attached to beads also showed a reduction in rotation but this effect lasted less than three months. Microcarrier-attached cells, however, maintained their effect in reducing rotation for at least eight months (rotations were reduced from a control mean of 10.9 +/- 1.4 to 3.6 +/- 1.1 turns/min) without any drop-off of the effect. Histological examination showed that eight months post-implant the cells pre-adhered to beads were still present and could be stained by anti-tyrosine hydroxylase antibody. Sections stained with hematoxylin-eosin showed no signs of an inflammatory response. In contrast to beads implanted into the striatum, Cytodex bead implants injected into the lateral ventricle induced a histopathological response appearing to involve the ependyma and choroid plexus. Results suggest that the striatal parenchyma but not the ventricle is amenable to studies using the microcarrier approach to transplantation.     

Biologic glue increases capillary ingrowth after cardiomyoplasty in an ischemic cardiomyopathy model

The authors investigated the multi-step mechanism of healing after cardiomyoplasty, focusing on the process of angiogenesis. The authors contend that enhancement of angiogenesis and prevention of ischemia-reperfusion injuries immediately after muscle mobilization will be effective in improving cardiomyoplasty results. After cardiomyoplasty, autologous biologic glue (ABG) was administered between the latissimus dorsi muscle (LDM) and myocardium. By 2 months, a new pseudo interlayer was present that bridged the gap between the LDM and myocardium. Neovascularization was visible in the form of numerous small capillaries. Marked degeneration of the LDM was noted, possibly caused by muscle ischemia-reperfusion damage after mobilization. Pockets were created of ischemic and nonischemic LDM to test for angiogenesis. One was left free of ABG (control); one received ABG only; one received ABG and pyrrolostatin. Some of the capillaries were large and had erythrocytes inside. biopsy samples showed 9.4 +/- 1.9% of the sample was occupied by blood vessels (compared with 3.6 +/- 0.7% in control muscle). These preliminary studies prove the feasibility of the authors' concept and provide evidence that angiogenesis can accelerate the healing process and provide an organic bridge between the LDM and myocardium after cardiomyoplasty.     

Analysis of linkage between beta-lactoglobulin and J blood group system loci in cattle

Linkage between loci controlling variants of beta-lactoglobulin and blood groups of the J system in cattle was studied by means of stochastic genetic methods reported earlier. The studies were conducted on a herd of Black Pied cattle improved with Holstein sires; population genetic data were analyzed. A plot for lod score was constructed, and point (r - 0.28) and interval estimations of the coefficient of recombination were obtained. The results are in good agreement with earlier reported data on other subjects.     

Is it possible to perform immediate cardiac assist using untrained latissimus dorsi muscle in a work-rest regimen?

The authors investigated what contractile force (CF) could be obtained from unconditioned latissimus dorsi muscle immediately after mobilization and for the 2 week vascular period of recovery. Latissimus dorsi muscle mobilization was performed on seven adult (4 experimental and 3 control) sheep leaving only the pedicle and the peripheral muscle intact. Telectronics stimulators (Myostim 7220; Teletronics Pacing Systems, Inc, Englewood, CO) were implanted. Immediately after mobilization 11-35% of the initial CF was lost. A 30 min fatigue test was performed 1 hr after mobilization (20 g/kg preload, 10 V, 10 Hz, 15 BPM, 6 impulses per burst) using a 1 min work-1 min rest regimen. Two sheep lost 2-12% of initial CF; two increased CF by 14-24%. At the end of the fatigue test, CF consisted of 74-89% of immobilized CF. Electrical stimulation training of the muscle was then initiated with the following regimen in the experimental animals only: 15 BPM, single impulses, 5 V, 10 Hz. Every day the muscle was exercised using a work-rest regimen to mimic cardiac assist, starting with 20 min on day 2, and increasing by 2 min per day until a total of 50 min was reached on day 16. All animals were retested for CF using a 42 min fatigue test on days 6, 11, and 16. On day 6, there was no fatigue evident in the experimental group during the 42 min test. CF after testing was 59-81% (mean 67%) of initial data. In the control group (animals with no electrical stimulation training protocol), CF decreased by 11% (from 64 to 53%). On day 11, there was no fatigue evident in the experimental group; CF in all animals increased by 2-8%. On day 16, there was also no fatigue evident in the experimental group; CF increased by 0-9%. An additional 20 min of continuous contraction (15 BPM) fatigue testing was performed on the muscle without rest between the tests. No fatigue was evident at the end of testing. Light microscopic analysis of latissimus dorsi muscle biopsy specimens taken on the days of testing showed no evidence of necrotic damage. Our investigations suggest that it may be possible to start muscle transformation immediately after mobilization and use the untrained latissimus dorsi muscle for cardiac assist immediately after surgery for short periods.