Postnatal development of the hamster coclea. I. Growth of hair cells and the organ of Corti

A morphometric analysis of the developing organ of Corti and its component hair cells was carried out in an age-graded series of Syrian golden hamsters with the aid of scanning electron microscopy. The purpose was to establish a quantitative framework that would provide insight into the rules and principles by which the mammalian cochlea attains its adult proportions. This study examined postnatal development at two day intervals from birth to 22 days after birth. Our analysis included measures of cochlear length and hair cell numbers as well as measures of hair cell sizes in each of five sectors along the cochlear spiral. Our results demonstrate several principles of cochlear development: (1) The full two and one-fourths turns seen in the adult cochlea are already present at birth, but the cochlea continues to elongate for the next 10–12 days. (2) Development of hair cells in the apex generally lags behind that in the base. Whereas the stereocilia and apical margins of hair cells are clearly defined in the basal turn, they become well defined in the apex only postnatally. (3) Growth in cochlear length occurs mainly by increases in cell size rather than in cell numbers; although hair cells do increase in numbers during the first 4 days of cochlear growth, this increase involves addition of hair cells only to preexisting regions of the cochlear apex. Moreover, the full complement of hair cells is established 6 days before the full size of the cochlea is attained; in contrast, hair cell growth occurs at all positions along the cochlear spiral and spans the entire period of cochlear elongation. (4) The period of hair cell growth exceeds the period of organ of Corti growth and appears to be possible by decreases in intercellular spacing, primarily in the apical region of the cochlea; inner and outer hair cell growth was complete between 16 and 18 days after birth. (5) Inner and outer hair cell neighbors remain virtually constant at different ages indicating that the spatial relationships between the two hair cell populations is preserved as the cochlea grows. (6) Comparison with previous developmental studies of auditory function in the hamster reveals that the age of 16 days after birth, when hair cells attain their mature sizes, coincides with the onset of brainstem auditory evoked responses. Growth of hair cell somas alone, however, cannot explain either the subsequent maturation of evoked potential thresholds or changes in frequency representation in the developing cochlea. © Wiley-Liss, Inc.     

Normalized protein catabolic rate versus serum albumin as a nutrition status marker in pediatric patients receiving hemodialysis.

BACKGROUND: Protein-energy malnutrition occurs commonly in patients receiving hemodialysis (HD). Although serum albumin (sAlb) is recommended to monitor nutrition status in patients receiving HD, many processes unrelated to nutrition status can affect albumin concentrations. METHODS: We previously showed normalized protein catabolic rate (nPCR) to be superior to sAlb to reflect improvement in nutrition status in pediatric patients receiving maintenance HD after treatment with intradialytic parenteral nutrition for severe protein-energy malnutrition. We now compare nPCR and sAlb as nutrition status markers for pediatric patients on HD irrespective of current nutrition status. RESULTS: Forty-four patients comprising 840 months of HD provision were assessed. nPCR was higher for younger patients. Mean nPCR values were significantly lower for adolescent patients with persistent weight loss of at least 2% for at least 3 consecutive months versus patients without persistent weight loss (1.03 +/- 0.29 g/kg/d vs. 1.15 +/- 0.27 g/kg/d, P < .002), and the odds for developing persistent weight loss were four times greater for adolescent patients with nPCR less than 1 g/kg/d. No association between nPCR and weight loss was observed for younger patients. Mean sAlb levels were greater than 4 g/dL for all patient age groups and did not demonstrate a clinically significant difference between patients with or without weight loss. CONCLUSION: We suggest that nPCR may be useful for monthly nutrition status in adolescent patients receiving maintenance HD and that adolescents with nPCR less than 1 g/kg/d may be at increased risk for subsequent weight loss.     

Care of the child in a body cast

Caring for a child in a body cast is a stressful situation for most families and many families state they do not receive adequate information on how to care for their child. This paper presents a comprehensive guide on caring for a child in a body cast. It examines the physical care issues, transportation and cast care. An instrument for assessing the family’s ability to cope with caring for a child in a body cast is described, and further resources for parents and nurses are presented.     

Prognostic factors in surgically resected N2 non-small cell lung cancer: the importance of patterns of mediastinal lymph nodes metastases.

OBJECTIVE: Patients with non-small cell lung cancer (NSCLC) with metastases to ipsilateral mediastinal lymph nodes (N2) are an heterogeneous group of patients as regard to prognosis and treatment. Indication and timing of surgery remain controversial. The present study investigates the prognostic factors, in order to identify homogenous subgroups of patients. METHODS: Histologically proven N2-NSCLC patients, who underwent a complete surgical resection were retrospectively reviewed. Clinical and pathological features were reported and analyzed, and survival study was performed. RESULTS: One hundred eighty-three patients were analyzed. Overall 1.3 and 5 years survival rates were, respectively, 70, 35 and 20%, with a median survival time of 24 months. Univariate analysis showed a significant better prognosis for: incidental N2 respect to clinical N2 (5-years 35.4 vs 17.4%); single level lymph node involvement respect to multiple levels (5-years 23.8 vs 14.7%); metastases to superior mediastinal or aortic nodes respect to lower mediastinal nodes (5-years 32 and 24.3 vs 16.3%); right upper lobe tumors with superior mediastinal nodes and left upper lobe tumors with aortic nodes respect to lower lobes tumors with lower mediastinal nodes (5-years 31.8 and 26.9 vs 15.7%). Skip metastases had not a significant survival advantage respect to continuous lymphatic spread. N2 clinical status, the number of levels involved and the two specific patterns of lymphatic spread resulted significant prognostic factors at multivariate analysis. CONCLUSIONS: Clinical N2 status, number of lymph nodes levels involved and specific patterns of lymphatic spread identify homogenous subgroups of patients that can be proposed for different therapeutic strategies.     

Alternative brain organization after prenatal cerebral injury: convergent fMRI and cognitive data.

The current study presents both longitudinal behavioral data and functional activation data documenting the effects of early focal brain injury on the development of spatial analytic processing in two children, one with prenatal left hemisphere (LH) injury and one with right hemisphere (RH) injury. A substantial body of evidence has shown that adults and children with early, lateralized brain injury show evidence of spatial analytic deficits. LH injury compromises the ability to encode the parts of a spatial pattern, while RH injury impairs pattern integration. The two children described in this report show patterns of deficit consistent with the site of their injury. In the current study, their longitudinal behavioral data spanning the age range from preschool to adolescence are presented in conjunction with data from a functional magnetic resonance imaging (fMRI) study of spatial processing. The activation results provide evidence that alternative profiles of neural organization can arise following early focal brain injury, and document where in the brain spatial functions are carried out when regions that normally mediate them are damaged. In addition, the coupling of the activation with the behavioral data allows us to go beyond the simple mapping of functional sites, to ask questions about how those sites may have come to mediate the spatial functions.     

The onset of tense marking in children at risk for specific language impairment.

PURPOSE: The purpose of this study was to develop and evaluate measures reflecting the onset of tense marking for children between the ages of 2;0 (years;months) and 3;0. METHOD: The validity of 4 cumulative measures of tense marker emergence and productivity was evaluated relative to existing measures of early grammatical development in a sample of 20 children followed longitudinally. Fourteen children were at risk for specific language impairment (AR-SLI group), and 6 children had low average language abilities (LA group). RESULTS: All measures of onset were highly correlated with the traditional measures; however, children's progress toward mastery of grammatical tense marking was best explained by the productivity of their tense marking systems. Finally, the onset measures imposing productivity requirements best differentiated children in the LA group from those in the AR-SLI group. CONCLUSIONS: The clinical implications for using the late onset of tense marking to improve the early identification of SLI are discussed.