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.     

Neonatal bladder rupture: an unusual complication of umbilical catheterization

Bladder injury in the neonatal period is an exceedingly rare phenomenon that is usually iatrogenic. Bladder rupture as a complication of umbilical catheterization in a newborn with urinary ascites, respiratory distress and hematuria is presented and discussed.     

Neutralizing antibodies from the sera of human immunodeficiency virus type 1-infected individuals bind to monomeric gp120 and oligomeric gp140

Antibodies that neutralize primary isolates of human immunodeficiency virus type 1 (HIV-1) appear during HIV-1 infection but are difficult to elicit by immunization with current vaccine products comprised of monomeric forms of HIV-1 envelope glycoprotein gp120. The limited neutralizing antibody response generated by gp120 vaccine products could be due to the absence or inaccessibility of the relevant epitopes. To determine whether neutralizing antibodies from HIV-1-infected patients bind to epitopes accessible on monomeric gp120 and/or oligomeric gp140 (ogp140), purified total immunoglobulin from the sera of two HIV-1-infected patients as well as pooled HIV immune globulin were selectively depleted of antibodies which bound to immobilized gp120 or ogp140. After passage of each immunoglobulin preparation through the respective columns, antibody titers against gp120 and ogp140 were specifically reduced at least 128-fold. The gp120- and gp140-depleted antibody fraction from each serum displayed reduced neutralization activity against three primary and two T-cell line-adapted (TCLA) HIV-1 isolates. Significant residual neutralizing activity, however, persisted in the depleted sera, indicating additional neutralizing antibody specificities. gp120- and ogp140-specific antibodies eluted from each column neutralized both primary and TCLA viruses. These data demonstrate the presence and accessibility of epitopes on both monomeric gp120 and ogp140 that are specific for antibodies that are capable of neutralizing primary isolates of HIV-1. Thus, the difficulties associated with eliciting neutralizing antibodies by using current monomeric gp120 subunit vaccines may be related less to improper protein structure and more to ineffective immunogen formulation and/or presentation.     

Communication between deaf children and their hearing mothers: the role of language, gesture, and vocalizations

In the present longitudinal study, 20 deaf and 20 hearing children were observed during free play with their hearing mothers when the children were 22 months and 3 years of age. Compared to hearing children, deaf children were severely language delayed, with deaf 3-year-olds using less language (speech or sign) than hearing 22-month-olds. Deaf children communicated primarily through nonlinguistic vocalizations, with increasing use of gesture from 22 months to 3 years of age. Although mothers of deaf children used more visual communication than mothers of hearing children, they still primarily communicated through speech. In addition, deaf children did not visually attend to much of their mothers' communication. Therefore, deaf children received much less communication than hearing children. These results suggest that intervention efforts should be focused on increasing the quantity of perceived linguistic input by the child.     

An evaluation of the effectiveness of competency-based code blue education

Two types of mock code programs were compared. The specific factors investigated were nurse satisfaction, comfort, and retention of knowledge and skills. A sample of 48 nurses initially participated in the mock code program, with 45 nurses participating in the 6-month follow-up evaluation. The study revealed that competency-based and group code blue programs resulted in similar levels of satisfaction, knowledge, and rate of performance of critical elements 6 months after the initial program.     

Effective use of ribonucleotide reductase inhibitors (Didox and Trimidox) alone or in combination with didanosine (ddI) to suppress disease progression and increase survival in murine acquired immunodeficiency syndrome (MAIDS)

Ribonucleotide reductase inhibitors (RRIs) have been recently shown to inhibit retroviral replication. We examined a new series of RRIs, 3,4-dihydroxybenzohydroxamic acid (Didox) and 3,4,5-trihydroxybenzohydroxamidoxime (Trimidox) for their ability to alter disease progression in murine acquired immunodeficiency syndrome (MAIDS), both alone and in combination with 2',3'-dideoxyinosine (ddI). MAIDS disease was induced by inoculation of female C57BL/6 mice with the LP-BM5 murine leukemia virus (MuLV) and disease progression characterized by extensive peripheral lymphadenopathy and splenomegaly. Efficacy of treatment with these drugs was based upon their ability to influence survival and disease pathophysiology by monitoring the development of splenomegaly. Toxicity was determined by changes in body weight, total peripheral white blood cell count and hematocrit. Didox or trimidox monotherapy was associated with increased survival and decreased disease pathophysiology, with no apparent toxicity. Combined with ddI, their ability to reduce development of viral induced splenomegaly was enhanced compared to trimidox, didox or ddI alone. These results demonstrate RRIs have potent activity in reversing the disease manifestations characteristic of MAIDS. Further studies are warranted to determine human clinical efficacy.     

The benefits of atomic resolution

After a long gestation, the elucidation of the crystal structures of proteins at atomic resolution is now maturing. The use of such data for both refinement and structure solution is advancing space. The necessary technology is generally available, in terms of data collection, computing hardware and software. The structures appearing in the literature mainly relate to demonstration projects on native proteins. The importance of these alone is already obvious. Biologically significant results, in terms of ligand complexes and prosthetic groups, are just starting to emerge.     

Relationship of NK3 receptor-immunoreactivity to subpopulations of neurons in rat spinal cord

Exposure to the thiolamine radioprotector N-(2-mercaptoethyl)-1,3-propanediamine (WR-1065) induced apoptosis in the mouse TB8.3 hybridoma after a 60-min (LD50 = 4.5 mM) or during a 20-h (LD50 = 0.15 mM) exposure. In contrast, a 20-h exposure to 17 mM L-cysteine or 10 mM cysteamine was required to induce 50% apoptosis within 20 h. Apoptosis was not induced by either a 60-min or 20-h exposure to 10 mM of the thiazolidine prodrugs ribose-cysteine (RibCys) or ribose-cysteamine (RibCyst). Thiolamine-induced apoptosis appeared to be a p53-independent process since it was induced by WR-1065 exposure in human HL60 cells. Exposure to WR-1065 (4 mM for 15 min) or cysteine (10 mM for 60 min) before and during irradiation protected cells against the induction of both DNA double-strand breaks and apoptosis, while exposure to RibCys (10 mM for 3 h) did not. Treatment with either WR-1065, cysteine, RibCys or RibCyst for 60 min beginning 60 min after irradiation did not affect the level of radiation-induced apoptosis. In contrast, treatment with either cysteine, cysteamine or RibCys for 20 h beginning 60 min after irradiation enhanced radiation-induced apoptosis. Similar experiments could not be conducted with WR-1065 because of its extreme toxicity. Our results indicate that thiolamine enhancement of radiation-induced apoptosis is not involved in their previously reported capacity to reduce radiation-induced mutations.     

Experience in conducting course exams on assignments in test form

Analysis of the results of examinations in oral surgery making use of tests in 319 fourth-year students showed that such a method of assessing students' knowledge is highly objective.