Neurofibrillary tangles, amyotrophy and progressive motor disturbance in mice expressing mutant (P301L) tau protein.

Neurofibrillary tangles (NFT) composed of the microtubule-associated protein tau are prominent in Alzheimer disease (AD), Pick disease, progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). Mutations in the gene (Mtapt) encoding tau protein cause frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), thereby proving that tau dysfunction can directly result in neurodegeneration. Expression of human tau containing the most common FTDP-17 mutation (P301L) results in motor and behavioural deficits in transgenic mice, with age- and gene-dose-dependent development of NFT. This phenotype occurred as early as 6.5 months in hemizygous and 4.5 months in homozygous animals. NFT and Pick-body-like neuronal lesions occurred in the amygdala, septal nuclei, pre-optic nuclei, hypothalamus, midbrain, pons, medulla, deep cerebellar nuclei and spinal cord, with tau-immunoreactive pre-tangles in the cortex, hippocampus and basal ganglia. Areas with the most NFT had reactive gliosis. Spinal cord had axonal spheroids, anterior horn cell loss and axonal degeneration in anterior spinal roots. We also saw peripheral neuropathy and skeletal muscle with neurogenic atrophy. Brain and spinal cord contained insoluble tau that co-migrated with insoluble tau from AD and FTDP-17 brains. The phenotype of mice expressing P301L mutant tau mimics features of human tauopathies and provides a model for investigating the pathogenesis of diseases with NFT.

Novel microtubule-associated protein-2 isoform is expressed early in human oligodendrocyte maturation.

We have identified a developmentally regulated, oligodendrocyte-specific protein, designated microtubule-associated protein-2 expressing exon 13 (MAP-2+13), in the human central nervous system (CNS). Monoclonal antibodies directed against MAP-2+13 labeled oligodendrocytes in the white matter of human fetal spinal cord. Double-label immunofluorescence and confocal microscopy, and immunoelectron microscopy localized MAP-2+13 to the soma and extending processes of fetal oligodendrocytes, but not to the myelin sheath. The immunoreactivity was throughout the perikarya. Ultrastructural examination of the fetal myelin sheaths showed them to be thin and not fully compacted, indicating that myelination was in progress. There was no overlap in staining of GFAP+ astrocytes and MAP-2+13+ oligodendrocytes. MAP-2+13 was also expressed in intermediate filament-negative "radial glia" extending from the central canal to the subpial surface. In the mature CNS, MAP-2+13 also marked cells of oligodendroglial morphology, but these cells were rare. These finding demonstrate that in the human CNS, MAP-2+13 is a novel protein transiently expressed in cells of oligodendroglial lineage.

cAMP-dependent protein kinase phosphorylations on tau in Alzheimer's disease.

To elucidate the role cAMP-dependent protein kinase (PKA) phosphorylations on tau play in Alzheimer's disease, we have generated highly specific monoclonal antibodies, CP-3 and PG-5, which recognize the PKA-dependent phosphorylations of ser214 and ser409 in tau respectively. The present study demonstrates by immunohistochemical analysis, CP-3 and PG-5 immunoreactivity with neurofibrillary pathology in both early and advanced Alzheimer's disease, but not in normal brain tissue and demonstrates that cAMP-dependent protein kinase phosphorylations on tau precede or are coincident with the initial appearance of filamentous aggregates of tau. Studies using heat-stable preparations demonstrate that neither site appears to be phosphorylated to any appreciable extent in normal rodent or human brain. Further analysis demonstrates that the beta catalytic subunit of PKA (Cbeta), the beta II regulatory subunit of PKA (RIIbeta), and the 79 kDa A-kinase-anchoring-protein (AKAP79), are tightly associated with the neurofibrillary pathology, positioning cAMP-dependent protein kinase to participate directly in the pathological hyperphosphorylation of tau seen in Alzheimer's disease.

Altered conformation of recombinant frontotemporal dementia-17 mutant tau proteins.

Recently, a series of both non-coding (intronic) and coding (exonic) mutations in the tau gene have been linked to a family of autosomal dominant dementias referred to as frontotemporal dementia-17. While linkage analysis has demonstrated that these mutations segregate with disease in affected families, it is unclear how mutant tau proteins could lead to the degenerative cascade seen in frontotemporal dementia-17. The present study demonstrates that coding mutations of tau seen in frontotemporal dementia-17 exhibit altered physical and structural characteristics as determined by reverse phase high performance liquid chromatography and circular dichroism spectroscopy. These data suggest that the previously identified mutations in the tau gene seen in frontotemporal dementia-17 are not merely benign polymorphisms, but may have functional consequences for microtubule binding, microtubule polymerization, and the abnormal aggregation of tau seen in a variety of neurodegenerative diseases.

Molecular and functional characteristics of MAP-2a: ability of MAP-2a versus MAP-2b to induce stable microtubules in COS cells.

Microtubule-associated protein-2 (MAP-2) is a prominent cytoskeletal protein in the mammalian nervous system. Two high-molecular-weight (HMW) MAP-2 isoforms, MAP-2a and MAP-2b, are developmentally regulated. MAP-2b is expressed through the life of the neuron, while MAP-2a expression coincides with the time of synaptic formation. MAP-2a and MAP-2b differ in size by approximately 10 kD. Attempts to differentiate MAP-2a from MAP-2b led to the identification of additional exons; exons 7A, 8, 13, and 16. The focus of the present study was to define the complete molecular composition of MAP-2a that was prerequisite for investigating the functional characteristic of the MAP-2a protein. Detailed examination of rat brain mRNA by Northern blot analysis and RT-PCR showed that MAP-2a contains only exon 8 in addition to the exons found in the MAP-2b transcript. Exons 7A, 13, and 16 are not present in the MAP-2a transcript. Antibody generated to exon 8 expressed protein, immunoprecipitated a HMW protein from adult rat brain that co-migrated with MAP-2a and was immunopositive with other MAP-2 antibodies. Comparative transfections of full-length MAP-2a and MAP-2b cDNA into COS-7 cells demonstrated that MAP-2a influenced the microtubule network differently than MAP-2b by inducing rapid and stable microtubule bundle formation even in the presence of nocodazole.

Mediation of NGF signaling by post-translational inhibition of HES-1, a basic helix-loop-helix repressor of neuronal differentiation.

The induction of neurite outgrowth by NGF is a transcription-dependent process in PC12 cells, but the transcription factors that mediate this process are not known. Here we show that the bHLH transcriptional repressor HES-1 is a mediator of this process. Inactivation of endogenous HES-1 by forced expression of a dominant-negative protein induces neurite outgrowth in the absence of NGF and increases response to NGF. In contrast, expression of additional wild-type HES-1 protein represses and delays response to NGF. Endogenous HES-1 DNA-binding activity is post-translationally inhibited during NGF signaling in vivo, and phosphorylation of PKC consensus sites in the HES-1 DNA-binding domain inhibits DNA binding by purified HES-1 in vitro. Mutation of these sites generates a constitutively active protein that strongly and persistently blocks response to NGF. These results suggest that post-translational inhibition of HES-1 is both essential for and partially mediates the induction of neurite outgrowth by NGF signaling.

Post-operative feeding strategies for infants with cleft lip.

UNLABELLED: Post-operative feeding techniques for infants following primary repair of cleft lip vary considerably. Recommendations range from immediate return to nipple feeding post-operatively to abstinence from nipple feeding for up to 6 weeks. Different surgeons prescribe different post-operative feeding protocols among and within centers. The purposes of this retrospective study (n = 42) were to: (1) identify the specific nonnipple feeding guidelines given to caregivers prior to surgery and the duration for those practices to be used in the post-operative period, (2) describe caregiver compliance, and (3) identify post-operative complications (e.g. dehiscence) related to type and duration of feeding strategies. Feeding guidelines included: nonnipple feeding for 6 weeks (n = 28, 67%), 3 weeks (n = 6, 14%), 2 weeks (n = 6, 14%), and unrestricted return to nipple (n = 2, 5%). Nearly all caregivers (n = 37, 88%) complied with recommendations. The others (n = 5, 12%) returned their infants to nipple feeding sooner than recommended (three in the nonnipple group for 6 weeks, and one each in the other two groups). No medical/surgical complications were related to feeding strategies. CONCLUSION: caregivers typically comply with post-operative feeding recommendations. However, the variability in those recommendations should be reduced with feeding made as easy as possible and not a jeopardy to wound healing.

Thyroid hormone decreases the number of adrenergic cells that develop in neural crest cultures and can inhibit the stimulatory action of retinoic acid.

Environmental cues are known to be important in the migration, survival, and differentiation of neural crest cells and their derivatives. Retinoic acid (RA) can increase the number of adrenergic cells that develop in neural crest cultures in a dose dependent manner. These results with RA prompted us to investigate the effects of other retinoids and other related compounds on neural crest cultures. We have investigated the role of thyroid hormone (T3) in the development of adrenergic cells in quail neural crest cultures. T3 produced a significant decrease in the number of catecholamine-positive cells that developed in neural crest cultures after 7 days in vitro, as compared to untreated controls. The decrease in adrenergic cells produced by T3 was paralleled by a decrease in the number of tyrosine hydroxylase-positive cells, but T3 did not reduce either total or melanocyte cell number. Cultures were sensitive to T3 during the first 5 days in culture and T3 was not cytotoxic to adrenergic cells. The decrease in adrenergic cells seen with T3 was partially reversed by RA suggesting that these two compounds may be working through a common pathway.

An analysis of the effects of retinoic acid and other retinoids on the development of adrenergic cells from the avian neural crest.

In the present work, we have investigated the role of all-trans-retinoic acid (all-trans RA), and several other natural and synthetic retinoids, in the development of adrenergic cells in quail neural crest cultures. Dose response studies using all-trans RA and 13-cis RA revealed a dose-dependent increase in the number of adrenergic cells in neural crest cultures. Similar dose response studies using RA isomers and other natural retinoids did not result in the same increases. In order to determine the receptor mediating the effects of all-trans RA in the neural crest, we tested several synthetic analogs which specifically bind to a particular RA receptor (RAR) subtype. We found that the compound AM 580, which activates the RAR-alpha, produced an increase in adrenergic cells similar to that seen with all-trans RA. The compound TTNPB, which activates all RAR subtypes, also resulted in an increase in adrenergic cells. We conclude that the increase in adrenergic cells seen with all-trans RA is mediated by RAR-alpha and possibly RAR-beta. To further define the actions of all-trans RA on the neural crest we incubated cultures with 5-bromo-2'-deoxyuridine (BrdU) to determine whether all-trans RA could affect the rate of proliferation. The results show that while all-trans RA did not increase the fraction of cells incorporating BrdU into their nuclei at early time points (24 h), it did increase BrdU incorporation by tyrosine hydroxylase (TH) positive cells at 5 days in culture. These findings demonstrate that the increase in adrenergic cells seen with all-trans RA in neural crest cultures is likely due to an increase in the proliferation of cells already expressing TH.

Evidence for a GABAergic projection from the dorsal nucleus of the lateral lemniscus to the inferior colliculus.

This study attempts to determine whether the pathways from the guinea pig dorsal nucleus of the lateral lemniscus (DNLL) to the inferior colliculus (IC) use gamma-aminobutyric acid (GABA) as a transmitter. Injections of kainic acid (KA) were used to destroy neurons in the left DNLL. Two to 4 days after the injection, Nissl-stained sections through the lesion site showed destruction of the DNLL neurons. The lesions varied in size; 12-100% of the DNLL neurons were destroyed on the injected side without damage to the ipsilateral IC. Two to 4 days after the injection, the electrically evoked, Ca(2+)-dependent release and high-affinity uptake of [3H]GABA were measured in dissected pieces of the left and right IC. These activities were compared with those in the IC taken from unlesioned controls and from sham controls, which received injections of saline instead of KA. Each IC was divided into a dorsal piece, which contained the dorsal cortex and dorsomedial nucleus, and a ventral piece, which contained the central and lateral nuclei. Lesions of the left DNLL depressed the release and uptake of [3H]GABA in the ventral pieces of the IC, but there was a greater depression in the ventral IC contralateral to the lesioned DNLL. There were good correlations between the percentage of neuronal loss in the left DNLL and deficits in [3H]GABA release and uptake activities in the ipsi- and contralateral ventral IC. By contrast, there was no depression of [3H]GABA release and uptake in the dorsal pieces of the IC. The localization of the deficits in release and uptake appears to match the distribution of the synaptic endings of the DNLL pathways in the IC. This correspondence associates GABA release and uptake activities with the DNLL projections to the IC and, therefore, suggests that GABA may be a transmitter of these pathways. The release and uptake of [14C]glycine was also measured to determine whether glycine might be a transmitter of the DNLL pathways to the IC. Lesions of the left DNLL failed to alter the Ca(2+)-dependent release or the uptake of [14C]-glycine, suggesting that DNLL neurons are unlikely to use this compound as a transmitter.

Are modified radical mastectomies done for T1 breast cancers because of surgeon's advice or patient's choice?

Clinical trials show that T1 breast cancers are equally well treated with breast-conserving surgery as with modified radical mastectomy. However, the Colorado Central Cancer Registry indicates that, for the past 5 years, the majority of women (72%) with T1 breast cancer in Colorado have undergone modified radical mastectomies. A questionnaire was sent to 175 general surgeons to determine the reasons for the high number of modified radical mastectomies still being performed. The results indicate that one group of surgeons (34% of those responding) believes each type of surgery has equal survival rates but unknowingly influences the patient to choose modified radical mastectomy, with a subtly biased presentation. Education of both surgeons and patients is needed to increase the number of patients with T1 breast lesions who can benefit from breast-conserving therapy.

A correlation for heat transfer coefficients in food extruders.

A dimensionless correlation of heat transfer coefficient for heat flow between the extruder barrel wall and extrudate is presented. The standard error of estimate of the correlation is 12.4%. The correlation is useful for the design and scale-up of food extruders and the design of associated temperature control systems.

The vulnerable child syndrome: fact and theory.

Studies which have evaluated parent-child relationships following a life-threatening event indicate that parents and children have subsequent interactional difficulties. This study sampled a group of 17 mothers who gave birth to a low birth weight infant (mean weight 1260 grams) and compared them to 17 mothers of normal infants matched for age, education and marital status. The mothers were studied at the infant's adjusted chronological age of 12 to 18 months. At that time all infants were developing normally as determined by the Denver Prescreening Questionnaire. The results indicated that mothers of low birth weight infants did not demonstrate any greater degree of depression or over-protection than their matched controls. The findings of this preliminary study suggest the need for reassessing the relationship between prematurity and other life-threatening events and the psychological sequelae associated with the vulnerable child syndrome. Previous studies are reviewed, and their methodologies are discussed.

Simplified models for estimating isothermal operating characteristics of food extruders.

A model of isothermal food extruder performance is described. Inferences about alternative extruder screw designs and their performance are drawn from the model. The model suggests that thread depth or diameter compression screws are superior in performance to a pitch compression screw. The advantage gained from using diameter compression screws is paid for with significantly higher rates of energy dissipation. The use of the model to characterize screws having both a compression zone and metering zone is described.