Mesenchymal chondrosarcoma of the cerebellum

Mesenchymal chondrosarcoma is a rare malignant neoplasm of bone and soft tissues. An unique case is described of an 8-year-old child with a midline cerebellar lesion. Pertinent clinical and radiologic findings along with histopathologic features are described. To our knowledge, this is the first case of mesenchymal chondrosarcoma arising in the cerebellar parenchyma of a child.

Anatomic, histologic, and magnetic resonance imaging abnormalities of the shoulder

Six fresh frozen, human cadaver shoulders were evaluated for gross anatomic, magnetic resonance imaging, and histologic abnormalities. The shoulders underwent routine magnetic resonance imaging with and without intraarticular Gadolinium using a standard surface shoulder coil. The shoulders were dissected in a systematic fashion to yield 18 anatomic specimens from the supraspinatus and infraspinatus tendon as well as the glenoid labrum. These specimens were studied histologically using hematoxylin and eosin and Goldner's trichrome stains. Gross anatomic and magnetic resonance image abnormalities of the rotator cuff corresponded to histologic changes consistent with tendon degeneration. However, there was a poor correlation between gross anatomic, magnetic resonance image, and histologic changes of degeneration in the glenoid labrum. In general, histologic degeneration was more severe than abnormalities seen either grossly or on magnetic resonance images.

The genomic organization of a human creatine transporter (CRTR) gene located in Xq28

During the course of a large-scale sequencing project in Xq28, a human creatine transporter (CRTR) gene was discovered. The gene is located approximately 36 kb centromeric to ALD. The gene contains 13 exons and spans about 8.5 kb of genomic DNA. Since the creatine transporter has a prominent function in muscular physiology, it is a candidate gene for Barth syndrome and infantile cardiomyopathy mapped to Xq28.

Selection for genes encoding secreted proteins and receptors

Extracellular proteins play an essential role in the formation, differentiation, and maintenance of multicellular organisms. Despite that, the systematic identification of genes encoding these proteins has not been possible. We describe here a highly efficient method to isolate genes encoding secreted and membrane-bound proteins by using a single-step selection in yeast. Application of this method, termed signal peptide selection, to various tissues yielded 559 clones that appear to encode known or novel extracellular proteins. These include members of the transforming growth factor and epidermal growth factor protein families, endocrine hormones, tyrosine kinase receptors, serine/threonine kinase receptors, seven transmembrane receptors, cell adhesion molecules, extracellular matrix proteins, plasma proteins, and ion channels. The eventual identification of most, or all, extracellular signaling molecules will advance our understanding of fundamental biological processes and our ability to intervene in disease states.

Characterization of a multicomponent receptor for GDNF

Glial-cell-line-derived neurotrophic factor (GDNF) is a potent survival factor for central and peripheral neurons, and is essential for the development of kidneys and the enteric nervous system. Despite the potential clinical and physiological importance of GDNF, its mechanism of action is unknown. Here we show that physiological responses to GDNF require the presence of a novel glycosyl-phosphatidylinositol (GPI)-linked protein (designated GDNFR-alpha) that is expressed on GDNF-responsive cells and binds GDNF with a high affinity. We further demonstrate that GDNF promotes the formation of a physical complex between GDNFR-alpha and the orphan tyrosin kinase receptor Ret, thereby inducing its tyrosine phosphorylation. These findings support the hypothesis that GDNF uses a multi-subunit receptor system in which GDNFR-alpha and Ret function as the ligand-binding and signalling components, respectively.

Renal and neuronal abnormalities in mice lacking GDNF

Glial cell-line derived neurotrophic factor (GDNF) is a potent survival factor for embryonic midbrain dopaminergic, spinal motor, cranial sensory, sympathetic, and hindbrain noradrenergic neurons, and is available to these cells in vivo. It is therefore considered a physiological trophic factor and a potential therapeutic agent for Parkinson's disease, amyotrophic lateral sclerosis, and Alzheimer's disease. Here we show that at postnatal day 0 (P0), GDNF-deficient mice have deficits in dorsal root ganglion, sympathetic and nodose neurons, but not in hindbrain noradrenergic or midbrain dopaminergic neurons. These mice completely lack the enteric nervous system (ENS), ureters and kidneys. Thus GDNF is important for the development and/or survival of enteric, sympathetic and sensory neurons and the renal system, but is not essential for catecholaminergic neurons in the central nervous system (CNS).

Sequencing the 500-kb GC-rich symbiotic replicon of Rhizobium sp. NGR234 using dye terminators and a thermostable "sequenase": a beginning

Genomes of the soil-borne nitrogen-fixing symbionts of legumes [Azo(Brady)Rhizobium species] typically have GC contents of 59-65 mol%. As a consequence, compressions (up to 400 per cosmid) are common using automated dye primer shotgun sequencing methods. To overcome this difficulty, we have exclusively applied dye terminators in combination with a thermostable "sequenase" for shotgun sequencing GC-rich cosmids from pNGR234a, the 500-kbp symbiotic replicon of Rhizobium sp. NGR234. A thermostable sequenase incorporates dye terminators into DNA more efficiently than Taq DNA polymerase, thus reducing the concentrations needed (20- to 250-fold). Unincorporated dye terminators can simply be removed by ethanol precipitation. Here, we present data of pXB296, one of 23 overlapping cosmids representing pNGR234a. We demonstrate that the greatly reduced number of compressions results in a much faster assembly of cosmid sequence data by comparing assembly of the shotgun data from pXB296 and the data from another pNGR234a cosmid (pXB110) sequenced using dye primer methods. Within the 34,010-bp sequence from pXB296, 28 coding regions were predicted. All of them showed significant homologies to known proteins, including oligopeptide permeases, an essential cluster for nitrogen fixation, and the C4-dicarboxylate transporter DctA.

Cardiotrophin-1, a cytokine present in embryonic muscle, supports long-term survival of spinal motoneurons

The muscle-derived factors required for survival of embryonic motoneurons are not clearly identified. Cardiotrophin-1 (CT-1), a cytokine related to ciliary neurotrophic factor (CNTF), is expressed at high levels in embryonic limb bud and is secreted by differentiated myotubes. In vitro, CT-1 kept 43% of purified E14 rat motoneurons alive for 2 weeks (EC50 = 20 pM). In vivo, CT-1 protected neonatal sciatic motoneurons against the effects of axotomy. CT-1 action on motoneurons was inhibited by phosphatidylinositol-specific phospholipase C (PIPLC), suggesting that CT-1 may act through a GPI-linked component. Since no binding of CT-1 to CNTFR alpha was detected, CT-1 may use a novel cytokine receptor alpha subunit. CT-1 may be important in normal motoneuron development and as a potential tool for slowing motoneuron degeneration in human diseases.

Identification of a gene disrupted by a microdeletion in a patient with X-linked retinitis pigmentosa (XLRP)

The gene for the most frequent from of X-linked retinitis pigmentosa (XLRP), RP3, has been assigned by genetic and physical mapping to a segment of less than 1000 kbp, which is flanked by the marker DXS1110 and the ornithine transcarbamylase (OTC) gene. In search of microdeletions, we have screened the DNA of 30 unrelated patients with XLRP by employing a representative set of YAC-derived DNA fragments that were generated by restriction enzyme digestion and PCR amplification. In one of these patients, a 6.4 kbp microdeletion was detected which was not present in the DNA of 444 male controls. A cosmid contig spanning the deletion was constructed and used to isolate cDNAs from retina-specific libraries. Exons corresponding to these expressed sequences as well as other putative exons were identified by sequencing more than 30 kbp of the critical region. So far, no point mutations in these putative exon sequences have been identified.

Genomic Organization of the ATM gene

The ATM gene was recently identified and found to be responsible for the genetic disorder ataxiatelgiectasia. The major ATM transcript is 13 kb. Using long-distance PCR, we determined the genomic structure of this gene and identified all of its exon-intron boundaries. The ATM gene spans approximately 150 kb of genomic DNA and consists of 66 exons. The initiation codon falls within exon 4. The last exon is 3.8 kb and contains the stop codon and a 3'-untranslated region of about 3600 nucleotides.

Transforming growth factor-beta 3, glial cell line-derived neurotrophic factor, and fibroblast growth factor-2, act in different manners to promote motoneuron survival in vitro

Developing chick motoneurons depend on as yet unidentified factors from the periphery and the central nervous system for their survival. Using cultures of purified embryonic motoneurons, we show that basic fibroblast growth factor (FGF-2) or transforming growth factor-beta 3 (TGF beta 3) each have only low survival-promoting activity when tested alone, but act synergistically to keep motoneurons alive for at least 3 days. Glial cell line-derived neurotrophic factor (GDNF), another member of the TGF beta family, was itself sufficient to maintain a population of motoneurons. However, its effect was not significantly increased by the addition of FGF-2. These results suggest that FGF-2, TGF beta 3, and GDNF, which are all present in the environment of developing motoneurons, may act different mechanisms as physiological survival factors for this population of central neurons.

Transition of aortic endothelial cells from resting to migrating cells is associated with three sequential patterns of microfilament organization

The endothelial cell is unique because it must undergo a transition from a resting cell with a cytoskeleton organized for barrier function to one which promotes cell translocation following denuding endothelial injury. Since actin microfilaments are critical for both maintaining the integrity of the resting monolayer and for optimum reendothelialization, we carried out a detailed study of the organization of microfilaments as the cell undergoes the transition from a resting to a translocating cell. We used an in vitro model in which a linear wound was made in a confluent monolayer of porcine aortic endothelial cells. The complex reorganization of actin microfilament bundles following injury and their relationship to microtubules and vinculin was studied in cells at the wound edge using immunofluorescent scanning laser confocal microscopy and time-lapse videomicroscopy. In the resting confluent monolayer, microfilaments were present as a dense peripheral band (DPB) located toward the upper part of the cell and as central microfilament bundles at the substratum. Three distinct stages of microfilament reorganization occurred sequentially during early repair. Stage 1 followed wounding and involved the reduction of the DPBs of microfilaments and associated peripheral cell-cell vinculin plaques. This was associated with rapid forward actin-based lamellipodia extrusions and cell elongation. Low-dose cytochalasin, which did not disrupt the morphology of microfilament bundles, reduced elongation. Stage 2 was characterized by central microfilaments behind the lamellipodia distributed parallel to the wound edge with vinculin plaques at their tips. This was associated with prominent spreading at the front of the cell which enhanced the extent of coverage of the denuded wound area. Stage 3 was characterized by the orientation of central microfilaments perpendicular to the wound edge with vinculin plaques at their tips and was associated with the initiation of cell translocation. There was no specific structural association between central microfilaments and microtubules as the former were toward the substratum while the latter were toward the center and upper part of the cell. Thus, the sequential appearance of three patterns of microfilament distribution define the cytoskeletal events that regulate the reestablishment of endothelial integrity following denuding endothelial injury.

Neurotrophin-4/5 postpones the death of injured spinal motoneurons in newborn rats

We have compared the short- and long-term effects of Neurotrophin-4/5 (NT-4/5) on the survival of spinal motoneurons in neonatal rats. To this aim, the sciatic nerve was cut in newborn rats and NT-4/5 or buffer were applied to the proximal nerve stem in a gelfoam as well as by daily local injection. The number of motoneurons or ventral root fibers was determined 4, 11, and 14 days later. Four days after received NT-4/5 lost only 19% + 2.7% (540 + 81). No systemic effect on the contralateral motoneurons was observed. Surprisingly, 11 and 14 days following the operation, the loss of motoneurons and of ventral root fibers was the same in buffer and NT-4/5 treated animal despite the daily treatment. Thus, although NT-4/5 is a potent survival factor for motoneurons in culture and can transiently prevent the death of motoneurons in vivo, it can not, under these experimental conditions, permanently rescue lesioned motoneurons. These results indicate that other trophic factors or combinations of factors may be required to permanently prevent the death of spinal motoneurons and that the short term survival promoting effects of neurotropic factors in motoneuron lesion models can not be used to predict their therapeutic potential in chronic neurodegenerative disorders.

Malnutrition in hospitalized children with congenital heart disease

OBJECTIVE

To determine the prevalence of malnutrition among hospitalized children with congenital heart disease by age, disease process, and clinical status.

DESIGN

Cross-sectional, retrospective chart review.

SETTING

Pediatric cardiology units at a 150-bed tertiary care teaching hospital in Ann Arbor, Mich.

PATIENTS

Patients (n = 160) were randomly selected from consecutive admissions to the Pediatric Cardiology and Thoracic Surgery Services during a 1-year period.

INTERVENTION

None.

MAIN OUTCOME MEASURES

Acute and chronic malnutrition, assessed by comparing the patients' weight and height with established means.

RESULTS

Acute and chronic malnutrition occurred in 33% and 64% of the patients, respectively. Age, diagnostic category, and symptoms were associated with malnutrition. Eighty percent of infants presented with acute malnutrition compared with 18% of patients of other ages (P < .001). Malnutrition affected 60% of patients with left-to-right shunts, 53% of patients with complex heart disease, and no patients with primary rhythm disturbances. Acute malnutrition affected 11% and chronic malnutrition affected 50% of patients with left-sided heart obstruction. Acute or chronic malnutrition occurred in 70% or more of patients with cyanosis and/or congestive heart failure but in only 30% of patients with neither (P < .001).

CONCLUSION

Malnutrition in hospitalized children with congenital heart disease remains common, highlighting the importance of nutritional screening and intervention.

GDNF is an age-specific survival factor for sensory and autonomic neurons

Glial cell line-derived neurotrophic factor (GDNF) promotes the survival of two populations of CNS neurons: motoneurons and midbrain dopaminergic neurons. To see whether GDNF promotes the survival of PNS neurons, we studied embryonic chicken autonomic and sensory neurons in culture. We show that GDNF promotes the survival of sympathetic, parasympathetic, proprioceptive, enteroceptive, and small and large cutaneous sensory neurons. Whereas sympathetic, parasympathetic, and proprioceptive neurons become less responsive to GDNF with age, enteroceptive and cutaneous sensory neurons become more responsive. GDNF mRNA is expressed in the tissues innervated by these neurons, and developmental changes in its expression in several tissues mirror the changing responses of the innervating neurons to GDNF. These results show that GDNF promotes the survival of multiple PNS and CNS neurons and suggest that GDNF may be important for regulating the survival of various populations of neurons at different stages of their development.

Individualized developmental care for very-low-birth-weight premature infants

Forty very-low-birth-weight neonatal intensive care unit (NICU) infants with birth weights < or = 1,250 g were randomly assigned to treatment or control groups. Behavior of the treatment infants was systematically evaluated, and individualized developmentally oriented care plans were implemented to enhance stability. Treatment babies required fewer days of intermittent mandatory ventilation and continuous positive airway pressure and achieved full enteral feedings sooner. Length of hospital stay and hospital charges were less for treatment than control infants. There were favorable effects on treatment infants' behavioral performance at 42 weeks' postconceptional age. These results support the hypothesis that behaviorally sensitive, developmentally oriented care improves medical and neurodevelopmental outcome in the NICU.

Predictors of 2-year mortality among older male veterans on a geriatric rehabilitation unit

OBJECTIVE

To determine if nutritional parameters and discharge setting are associated with mortality in older male veterans on a Geriatric rehabilitation unit (GRU).

DESIGN

Two-year follow-up of sequential admissions to the GRU who had laboratory studies completed on admission to the acute hospital and on transfer to and discharge from the GRU.

SETTING

University-affiliated VA medical center.

PATIENTS

Eighty-three consecutive older male veterans admitted to the GRU.

MEASUREMENT

Mortality during a period of 2 years post-discharge.

MAIN RESULTS

In a univariate analysis, predictors of mortality were serum albumin level < or = 3.5 g/dL on admission to the GRU (P = .01), moderate or severe Nutritional Status Score (P = .03), discharge to a place other than home (P = .01), and use of antibiotics while on the GRU (P = .05). Discharge albumin remained the single significant predictor of mortality in a multivariate analysis (P = .005).

CONCLUSIONS

Serum albumin is the strongest predictor of 2-year post-hospitalization mortality of older patients cared for on a GRU. Other predictors were presence of infection, Nutritional Status Score of moderate or severe compromise, and discharge to a place other than home.

Immunosuppressive agents and endothelial repair. Prednisolone delays migration and cytoskeletal rearrangement in wounded porcine aortic monolayers

Endothelial denudation at areas of predilection to atherosclerosis is balanced by an active repair process that may be inhibited under conditions of accelerated atherosclerosis. After cardiac transplantation, the accelerated atherosclerotic process that develops may be enhanced by immunosuppressive agents that have nonspecific effects on cell signaling, proliferation, and response to injury. To study subtle effects of cyclosporine A, azathioprine, and 6 alpha-methylprednisolone on normal endothelial repair processes, confluent porcine endothelial monolayers were denuded in the presence of clinically relevant concentrations of these agents. The rate of endothelial wound repair was compared and the effects on cell spreading, proliferation, and the cytoskeleton assessed. 6 alpha-Methylprednisolone at concentrations of 1.25 to 50 mumol/L was associated with a transient 30% to 60% inhibition of endothelial wound repair. This was associated with increased cell size at the wound edge and a delay in centrosomal reorientation toward the wound, without any effect on cell proliferation. Cyclosporine and azathioprine in clinically relevant concentrations did not affect endothelial repair. Thus, corticosteroids transiently inhibit endothelial cytoskeletal alterations that are important in endothelial repair after a denuding injury.

Passive immunization of rhesus macaques against SIV infection and disease

To evaluate the role of humoral immunity against simian immunodeficiency virus (SIV), we tested whether passive immunization with plasma from SIVmac251 vaccine-protected or healthy infected animals would protect rhesus monkeys against intravenous infection with ten 50% animal infectious doses of the cell-free homologous virus. The challenge dose of this SIVmac251 virus stock had previously caused persistent infection in all (21 of 21) nonimmunized controls. A plasma pool was obtained from a donor that had been immunized with an inactivated whole SIVmac251 vaccine produced in human T cells. This plasma pool contained low levels of SIVmac binding and neutralizing antibody but had a high titer of antibodies recognizing human cell proteins. Given 4 or 18 hr before intravenous challenge, this plasma completely protected three of eight recipients from infection and delayed virus detection in one recipient. The five unprotected animals had only a transient or undetectable p27 antigenemia and low virus load in their PBMCs, and all survived at least 7 months after infection. By contrast, no protection was observed in 6 monkeys given inactivated, pooled plasma or purified immunoglobulin (Ig) from healthy SIVmac251-infected animals. This plasma pool and the Ig preparation contained high levels of SIV-binding and neutralizing antibody but no reactivity to human cellular components. Five of the six recipients had persistent antigenemia after challenge and four died acutely from simian AIDS in 4-7 months. These studies suggest that passive transfer of antibody to human cellular antigens can confer protection against SIVmac whereas passive transfer of neutralizing antibodies without human cellular antibodies does not protect against the homologous virus and may enhance infection.

Induction of midbrain dopaminergic neurons by Sonic hedgehog

Midbrain dopaminergic neurons, whose loss in adults results in Parkinson's disease, can be specified during embryonic development by a contact-dependent signal from floor plate cells. Here we show that the amino-terminal product of Sonic hedgehog autoproteolysis (SHH-N), an inductive signal expressed by floor plate cells, can induce dopaminergic neurons in vitro. We show further that manipulations to increase the activity of cyclic AMP-dependent protein kinase A, which is known to antagonize hedgehog signaling, can block dopaminergic neuron induction by floor plate cells. Our results and those of other studies indicate that SHH-N can function in a dose-dependent manner to induce different cell types within the neural tube. Our results also provide the basis for a potential cell transplantation therapy for Parkinson's disease.

Exon 2 of the gene for neural cell adhesion molecule L1 is alternatively spliced in B cells

L1CAM is a neural cell adhesion molecule expressed mainly on neurones' cell surface and plays an important role in the developing fetal brain. Recently, we have shown that mutations in the gene encoding L1CAM are responsible for three related neurological disorders including the most common form of inherited hydrocephalus. During our genetic analysis, we have discovered that L1CAM is also expressed on the surface of B cells but that the messenger RNA in this tissue is different to that in brain through alternative splicing of the L1 gene. This indicates that this region of the L1 molecule has a distinct role in brain cells compared to B lymphocytes and confirms its importance in brain development.

Cardiotrophin-1. Biological activities and binding to the leukemia inhibitory factor receptor/gp130 signaling complex

Cardiotrophin-1 (CT-1) is a newly isolated cytokine that was identified based on its ability to induce cardiac myocyte hypertrophy. It is a member of the family of cytokines that includes interleukins-6 and -11, leukemia inhibitory factor (LIF), ciliary neurotrophic factor, and oncostatin M. These cytokines induce a pleiotropic set of growth and differentiation activities via receptors that use a common signaling subunit, gp130. In this work we determine the activity of CT-1 in six in vitro biological assays and examine the composition of its cell surface receptor. We find that CT-1 is inactive in stimulating the growth of the hybridoma cell line, B9 and inhibits the growth of the mouse myeloid leukemia cell line, M1. CT-1 induces a phenotypic switch in rat sympathetic neurons and promotes the survival of rat dopaminergic and chick ciliary neurons. CT-1 also inhibits the differentiation of mouse embryonic stem cells. CT-1 and LIF cross-compete for binding to M1 cells, Kd [CT-1] approximately 0.7 nM, and this binding is inhibited by an anti-gp130 monoclonal antibody. Both ligands can be specifically cross-linked to a protein on M1 cells with the mobility of the LIF receptor (approximately 200 kDa). In addition, CT-1 binds directly to a purified, soluble form of the LIF receptor in solution (Kd approximately 2 nM). These data show that CT-1 has a wide range of hematopoietic, neuronal, and developmental activities and that it can act via the LIF receptor and the gp130 signaling subunit.

Scintigraphic cerebral spinal fluid leak study in a child with recurrent meningitis after resection of a frontal meningocele

An In-111 DTPA cerebrospinal fluid (CSF) leak study was performed on a 3-year-old boy admitted with recurrent meningitis. He was born with a congenital encephalocele that was surgically resected at 7 days-of-age. A residual skull floor defect with a recurrent tumor of the nasal radix was clinically suspected. Computed tomography and MRI scans could not confirm or rule out the presence of a CSF leak. The scintigraphic study clearly demonstrated a leak into the left naris. A large leptomeningeal cyst extending down into the left nares was resected and a defect in the left frontal calvarium, identified as the source of the CSF leak, was repaired at surgery.

Mesencephalic dopaminergic neurons protected by GDNF from axotomy-induced degeneration in the adult brain

Glial-cell-line-derived neurotrophic factor (GDNF) promotes survival of embryonic dopaminergic neurons in culture, and its expression pattern suggests a role as a transient target-derived trophic factor for dopaminergic neurons of the substantia nigra. These neurons participate in the control of motor activity, emotional status and cognition, and they degenerate in Parkinson's disease for unknown reasons. To test whether GDNF has a trophic effect on dopaminergic neurons in the adult brain, we used a rat model in which these neurons are induced to degenerate by transecting their axons within the medial forebrain bundle. We report here that axotomy resulted in loss of half the tyrosine hydroxylase-expressing neurons in the substantia nigra. This loss was largely prevented by repeated injections of GDNF adjacent to the substantia nigra. Our findings suggest that GDNF or related molecules may be useful for the treatment of Parkinson's disease.

Control of neuronal diversity by the floor plate: contact-mediated induction of midbrain dopaminergic neurons

The notochord and floor plate contribute to patterning the ventral neural tube in part by expressing a diffusible factor that induces motoneurons. To determine the mechanisms that direct the development of other classes of ventral neurons, we studied the development of dopaminergic neurons that reside near motoneurons in the ventral midbrain. We provide evidence that dopaminergic neurons develop in the vicinity of the floor plate and that they can be specified by the floor plate in vitro and in vivo. Unlike motoneurons, efficient induction of dopaminergic neurons requires contact with floor plate cells. These results suggest that neuronal diversification along the dorsal-ventral axis may be achieved partly through the concerted action of diffusible and contact-dependent signals from a single organizing center, the floor plate.

Formulation and characterization of dry mixes based on dehydrated fresh high-lysine corn

Fresh sweet corn pulp from high-lysine corn was dehydrated in a drum-dryer and utilized in the formulation of creamy instant soups. Studied formulas contained 27.5 to 67% dehydrated high-lysine corn pulp. The sensory profiles of the formulas improved with increasing proportion of dehydrated fresh corn pulp. Formula with 27.5% fresh corn pulp was rated lowest by the tasters on the basis of poor appearance, low characteristic fresh corn flavor and low overall impression. Formulas with 60 and 67% corn pulp rated highest in sensory quality and were nutritionally adequate. The PER for these formulas did not differ from casein control diet but nitrogen absorption and nitrogen retention was inferior for the formulas protein as compared to casein.

Neurons from mouse embryos with a null mutation in the tumour suppressor gene p53 undergo normal cell death in the absence of neurotrophins

Cell death plays an important role in regulating cell numbers in a wide variety of tissues during development and throughout life. Cell death can be triggered by changes in the levels of hormones and growth factors and is regulated by the expression of the tumour suppressor gene p53 in many cells. To determine if p53 plays a role in neuronal death resulting from neurotrophin deprivation, we studied the survival of neurons obtained from normal mouse embryos and embryos with a null mutation in the p53 gene. Embryonic sensory and sympathetic neurons from mutant embryos survived in response to the appropriate neurotrophin and died normally in the absence of neurotrophins. These results indicate that neurotrophin-deprived neurons die by a p53-independent pathway.

GDNF: a potent survival factor for motoneurons present in peripheral nerve and muscle

For survival, embryonic motoneurons in vertebrates depend on as yet undefined neurotrophic factors present in the limb bud. Members of the neurotrophin family are currently the best candidates for such neurotrophic factors, but inactivation of their receptor genes leads to only partial loss of motoneurons, which suggests that other factors are involved. Glial cell line-derived neurotrophic factor (GDNF), originally identified as a trophic factor specific for dopaminergic neurons, was found to be 75-fold more potent than the neurotrophins in supporting the survival of purified embryonic rat motoneurons in culture. GDNF messenger RNA was found in the immediate vicinity of motoneurons during the period of cell death in development. In vivo, GDNF rescues and prevents the atrophy of facial motoneurons that have been deprived of target-derived survival factors by axotomy. GDNF may therefore be a physiological trophic factor for spinal motoneurons. Its potency and specificity in vitro and in vivo also make it a good candidate for treatment of motoneuron disease.

TGF beta 2 and TGF beta 3 are potent survival factors for midbrain dopaminergic neurons

The vertebrate ventral midbrain contains 3-4 x 10(4) dopaminergic neurons that influence motor activity, emotional behavior, and cognition. Recently, glial cell line-derived neurotrophic factor (GDNF) was shown to be a potent survival factor for these dopaminergic neurons in culture. However, many midbrain dopaminergic neurons project to targets that do not express GDNF. We report here that transforming growth factors (TGFs) TGF beta 2 and TGF beta 3, which are distantly related to GDNF, also prevent the death of cultured rat embryonic midbrain dopaminergic neurons at picomolar concentrations. Furthermore, we find that TGF beta 2, TGF beta 3, and GDNF are expressed sequentially as local and target-derived trophic factors and that subpopulations of dopaminergic neurons projecting to distinct targets have access to only one of these factors. These findings are consistent with the idea that GDNF, TGF beta 2, and TGF beta 3 are physiological survival factors for developing midbrain dopaminergic neurons and may have applications as therapeutics for Parkinson's disease, a neurodegenerative disorder of dopaminergic neurons.

Masson's hemangioma of spinal meninges causing cord compression with paraplegia

Masson's hemangioma is a rare benign pathological entity. A unique case is reported of a 42 year old man with a spinal epidural mass who developed acute cord compression resulting in sudden onset of paraplegia. Histological examination of the resected mass revealed a cystic vascular lesion associated with papillary endothelial cell proliferation, and overlying thrombosis, consistent with Masson's hemangioma. Clinicoradiological correlation is also presented.

X-linked spastic paraplegia (SPG1), MASA syndrome and X-linked hydrocephalus result from mutations in the L1 gene

X-linked hydrocephalus, spastic paraplegia type I and MASA syndrome are related disorders with loci in subchromosomal region Xq28. We have previously shown that X-linked hydrocephalus is caused by mutations in the gene for neural cell adhesion molecule L1 (L1CAM), an axonal glycoprotein involved in neuronal migration and differentiation. Here we report mutations of the L1 gene in MASA syndrome and SPG1, in addition to HSAS families. Two of the HSAS mutations would abolish cell surface expression of L1 and represent the first functional null mutations in this disorder. Our results indicate that these three syndromes from part of a clinical spectrum resulting from a heterogeneous group of mutations in the L1 gene.

Extension of incomplete cDNAs (ESTs) by biotin/streptavidin-mediated walking using the polymerase chain reaction

In the last 2 years thousands of new partial cDNAs or expressed sequence tags (ESTs) have been identified by single pass sequencing methods. It is expected that this number will further increase in order to help to isolate all human genes. However, the scientific value of partial cDNA fragments is limited unless they are used as tools for isolating and sequencing their full length parent molecules. Conventional library screening methods are tedious and not very effective in achieving this goal. We present a modified PCR technique which allows rapid isolation of the ends of partial cDNA fragments in vitro using a biotin/streptavidin capture procedure. Our method has several advantages over the RACE technique, is very specific, and allows to frequently sequence the final product directly without subcloning. We also show that cDNA walks can be obtained from partial sequences as short as 26 bp.

Neurotrophin 4/5 is a trophic factor for mammalian facial motor neurons

The survival of developing motor neurons depends on factors secreted from skeletal muscles and from cells within the central nervous system. Although several members of the nerve growth factor protein family [neurotrophins (NTs)] are able to maintain developing rat motor neurons in vitro, only the brain-derived neurotrophic factor has been shown to have significant effects on the survival of motor neurons in vivo. In the present study, we demonstrate that NT-4/5 also prevents injury-induced death of facial motor neurons in neonatal rats. Furthermore, facial motor neurons express a functional receptor for NT-4/5, whereas mRNA-encoding NT-4/5 can be detected in their environment throughout embryonic and postnatal life. Thus, both NT-4/5 and brain-derived neurotrophic factor may be physiological survival factors for facial motor neurons and may serve as therapeutic agents for motor neuron disease.

Neurotrophin 3 stimulates the differentiation of motoneurons from avian neural tube progenitor cells

Neurotrophin 3 (NT-3) promotes differentiation of neural tube progenitors into motoneurons expressing the BEN/SC1 and islet-1 epitopes. A 1.75- to 6.7-fold increase in BEN-positive motoneurons was obtained when quail neural tube cells were cultured with NT-3 at 0.1-10 ng/ml, respectively. In contrast, the overall number of cells, as well as the proportion of motoneurons that developed from cycling precursors, did not change. Addition of NT-3 at 1 ng/ml to cells obtained from ventral half-neural tubes promoted a 2.5-fold stimulation in motoneuron number, confirming the specificity of the effect. Moreover, NT-3 had no significant effect on survival of differentiated avian motoneurons. The distribution of trkC mRNA, which encodes the high-affinity receptor for NT-3, is consistent with these findings. trkC expression is homogeneous in the embryonic day 2 (E2) neural tube, becomes restricted to the mantle layer on E3, where differentiation occurs, and disappears from the ventral third of the E4-E5 spinal cord right before the onset of normal motoneuron death. These results suggest that NT-3 and trkC regulate early neurogenesis in the avian central nervous system.

Regulation of neurotrophin receptor expression during embryonic and postnatal development

Members of the NGF family of proteins act as neurotrophic agents for defined populations of peripheral and central neurons during embryonic and postnatal development. We have studied the presence of receptors for brain-derived neurotrophic factor (BDNF) and neurotrophin-3 and -4/5 (NT-3, NT-4/5) by cross-linking radioiodinated neurotrophins to specific cell surface receptors. We have identified neurotrophin receptors representing full-length TrkB and TrkC and their truncated forms (lacking a functional cytoplasmic kinase domain) in neuronal as well as in non-neuronal tissues. During chicken embryonic and early postnatal brain development, expression of full-length TrkB and TrkC proteins preceded the onset of the truncated forms of these receptors. A similar pattern was also observed in mouse embryonic and early postnatal brain. The relative levels of neurotrophin receptors in the basal forebrain and in the hippocampus did not change significantly with age in mice. High levels of receptors for the three neurotrophins were detected in the nigrostriatal system. Full-length TrkB and TrkC receptors were found in chicken and rat embryonic ventral spinal cord, as well as on purified motoneurons. Again, truncated TrkB appeared significantly later than the full-length form on spinal motoneurons. In chicken embryonic retina and optic tectum we detected full-length TrkB and TrkC; however, the optic tectum also expressed large amounts of the truncated form of TrkB. TrkC but not TrkB was detected in chicken embryonic skeletal muscle, suggesting that NT-3 may have a novel function in this tissue. The presence of neurotrophin receptors in a wide variety of embryonic and postnatal tissues underlines the significant role of BDNF, NT-3, and NT-4/5 in embryonic and postnatal development. The regulation of the ratio of full-length versus truncated neurotrophin receptors may play an important role in the development, maturation, and maintenance of various neuronal networks.

The pediatric nurse practitioner as case manager in the delivery of services to children with heart disease

Today's health care environment prompted implementation of a case management model by pediatric nurse practitioner clinical nurse specialists to promote the organization of resources for optimal care of children with heart disease. Evaluation of this pilot program suggests that achievement of expected outcomes within an appropriate length of stay was facilitated, that parents were ready for discharge, and that readmissions were infrequent. In addition, patient and system variances resulting in delay of discharge and discharge preparation needs were identified. The pediatric nurse practitioner as case manager may have a significant impact on the quality and cost of care for hospitalized children.

Improving results with first-stage palliation for hypoplastic left heart syndrome

Between January 1990 and February 1993, 73 patients underwent first-stage reconstruction for hypoplastic left heart syndrome at the University of Michigan Medical Center. During this period, surgical reconstruction remained essentially constant and consisted of a pulmonary artery-to-aorta anastomosis with allograft augmentation of the ascending, transverse, and proximal descending aorta, restriction of pulmonary blood flow with a polytetrafluoroethylene shunt from the innominate artery to the central pulmonary artery confluence, and atrial septectomy. Hospital survival was 62 of 73 patients, 85% (70% confidence limits: 80% to 89%). These results stand in marked contrast to those obtained during the earlier years of our experience from 1986 to 1989 when only 21 of 50 patients (42%, 70% confidence limits: 35% to 49%) survived (p = 0.001). Among the most recent group of patients, only 2 of 7 patients older than 1 month of age at operation survived, whereas 60 of 66 (91%, 70% confidence limits: 87% to 94%) patients younger than 1 month of age survived (p = 0.0001). Anatomic subtype and ascending aortic diameter were not predictive of survival. Actuarial survivals for those patients younger than 1 month of age at the first-stage operation, including hospital deaths and subsequent operative procedures, were 81%, 74%, and 74% at 6 months, 1 year, and 2 years, respectively. These results indicate that survival for patients after first-stage reconstruction for hypoplastic left heart syndrome has significantly improved in recent years. Older age was a strong risk factor, with a hospital survival of 91% for those patients undergoing first-stage palliation within the first month of life. These data have important implications for the type of operative intervention and its timing.

Passive immunization of macaques against SIV infection

Passive immunization with plasma from an inactivated-whole SIVmac vaccine protected monkey conferred complete or partial protection to rhesus macaques challenged intravenously 4 or 18 hours later with 10 AID50 of homologous cell-free virus. In contrast, passive immunization with inactivated plasma or purified immunoglobulin (Ig) from SIVmac infected asymptomatic monkeys failed to protect any recipients similarly challenged and may have enhanced infection and accelerated disease. Administered 24 hours post challenge, anti-SIV Ig may also have enhanced the infection.

Neurotrophin-4/5 is a survival factor for embryonic midbrain dopaminergic neurons in enriched cultures

Parkinson's disease is a prevalent neurological disease characterized by profound and incapacitating movement disorders. A common pathology in Parkinson's patients is degeneration of substantia nigra dopaminergic neurons that innervate the striatum and a corresponding decrease in striatal dopamine content. We now report that NT-4/5 can prevent the death of rat embryonic substantia nigra dopaminergic neurons in low density, enriched, primary cultures. Furthermore, these neurons express messenger RNA encoding the trkB receptor for NT-4/5 and transcripts for NT-4/5 are present in their environment. In addition, we demonstrate that NT-4/5 protects embryonic dopaminergic neurons from the toxic effects of the neurotoxin MPP+. Thus, NT-4/5 could be a physiological survival factor for midbrain dopaminergic neurons and may be useful as a therapeutic agent for Parkinson's disease.

Neurotrophin-3 affects proliferation and differentiation of distinct neural crest cells and is present in the early neural tube of avian embryos

Neurotrophin-3 is mitogenic for cultured quail neural crest cells (Kalcheim et al., 1992, Proc. Natl. Acad. Sci. USA 89:1661-1665). We now report that neurotrophin-3 also influences the survival and/or differentiation of a subset of postmitotic neural crest precursors into neurons, provided these progenitors are grown on a cellular substrate. When cultured for 1 day on monolayers of NT-3-producing, chinese hamster ovary cells, 59% of the neural crest clusters growing on the transfected line revealed the presence of intense neuronal outgrowth, compared to 25% of that in controls. Moreover, dissociated neural crest cells grown for 20 h on top of mesodermal cells in the presence of various concentrations of purified recombinant neurotrophin-3 displayed a dose-dependent increase in neuronal number. Localization experiments using specific polyclonal antibodies, revealed that neurotrophin-3 is confined to neuroepithelial cells of quail neural tubes in situ on E2 and E3, and to E2 neural tubes grown in culture for 24 h. At this stage, neural crest cells and somites were negative. At later stages, staining was likewise apparent in peripheral nerves and dorsal root ganglia. We, therefore, propose that NT-3, a factor that is expressed in the early avian central nervous system, has multiple effects both on the proliferation and differentiation of distinct neural crest cells, which depend on the state of commitment of the responsive progenitors.

Neurotrophin-4/5 is a mammalian-specific survival factor for distinct populations of sensory neurons

We have studied the effect of human recombinant neurotrophin-4/5 (NT-4/5) on the survival of developing PNS neurons from embryonic mice and chickens. NT-4/5 transiently supported mouse NGF-dependent trigeminal and jugular neurons at early stages of target field innervation and mouse brain-derived neurotrophic factor (BDNF)-dependent no-dose neurons during the phase of naturally occurring cell death. NT-4/5 was as potent as BDNF in supporting the survival of these neuronal populations. Surprisingly, NT-4/5 was 3 orders of magnitude less potent than BDNF as a survival factor for early chick dorsomedial trigeminal sensory neurons and did not support the survival of chick BDNF-dependent trigeminal mesencephalic or ventrolateral trigeminal sensory neurons at any of the developmental stages tested. Thus, NT-4/5 is a survival factor for certain embryonic mouse cranial sensory neurons. It is the first species-specific neurotrophin to be identified and it can discriminate at high concentrations between different BDNF-responsive chick neurons.

Results of a policy of primary repair of truncus arteriosus in the neonate

Although the early mortality for repair of truncus arteriosus has decreased in the modern era, routine correction in the neonate has not been widely adopted. To assess the results of our protocol of early repair, we reviewed 46 neonates and infants undergoing repair of truncus arteriosus at the University of Michigan Medical Center from January 1986 to January 1992. Their ages ranged from 1 day to 7 months (median 13 days) and weights from 1.8 kg to 5.4 kg (mean 3.1 kg). Repair was performed beyond the first month of life in only 8 patients, because of late referral in 7 and severe noncardiac problems in 1. Associated cardiac anomalies were frequently encountered, the most common being interrupted aortic arch (n = 5), nonconfluent pulmonary arteries (n = 4), hypoplastic pulmonary arteries (n = 4), and major coronary artery anomalies (n = 3). Truncal valve replacement was performed in 5 patients with severe regurgitation, 3 of whom also had truncal valve systolic pressure gradients of 30 mm Hg or more. The truncal valve was replaced with a mechanical prosthesis in 2 patients and with a cryopreserved homograft in 3 patients. Right ventricle-pulmonary artery continuity was established with a homograft in 41 patients (range 8 mm to 15 mm), a valved heterograft conduit in 4 (range 12 mm to 14 mm), and a nonvalved polytetrafluoroethylene tube in the remaining patient (8 mm). There were 5 hospital deaths (11%, 70% confidence limits 7% to 17%). Multivariate and univariate analyses failed to demonstrate a relationship between hospital mortality and age, weight, or associated cardiac anomalies. Only 1 death occurred among 9 patients with interrupted aortic arch or nonconfluent pulmonary arteries. Hospital survivors were followed-up from 3 months to 6.3 years (mean 3 +/- 0.4 years). Late noncardiac deaths occurred in 3 patients, all within 4 months after the operation. Actuarial survival was 81% +/- 6% at 90 days and beyond. Despite the prevalence of major associated conditions, early repair has resulted in excellent survival. We continue to recommend repair promptly after presentation, optimally within the first month of life.

The rat trkC locus encodes multiple neurogenic receptors that exhibit differential response to neurotrophin-3 in PC12 cells

Members of the Trk tyrosine kinase family have recently been identified as functional receptors of the NGF family of neurotrophins. Here we show the rat trkC locus to be complex, encoding at least four distinct polypeptides. Three of the encoded polypeptides are full-length receptor tyrosine kinases that differ by novel amino acid insertions in the kinase domain. A fourth protein is a truncated receptor that lacks the catalytic domain. Tyrosine phosphorylation, cross-linking, and ligand binding assays indicate that TrkC receptors interact with NT-3 and not with the related neurotrophins NGF, BDNF, xNT-4, or hNT-5. Furthermore, high and low affinity NT-3-binding sites are associated with the TrkC receptors. Stable and transient expression of TrkC receptors in PC12 cells indicates that the neurite outgrowth response elicited by NT-3 is dramatic in receptors lacking the novel kinase insert (gp150trkC) but absent in receptors containing the 14 amino acid insert in the kinase domain (gp150trkC14). These data suggest that the trkC locus encodes receptors that may be capable of mediating different biological responses within the cell. This could have important implications in understanding the role of neurotrophins in the development of the vertebrate nervous system.

A randomized controlled trial of the efficacy, safety and cost of a single-use myocardial bioptome

A randomized single-blind study was performed comparing a reusable 8 French bioptome with a single-use 7 French bioptome in a consecutive series of 63 myocardial biopsy procedures performed during follow-up of cardiac transplant patients. Safety, efficacy and cost were compared between 30 procedures performed with the single-use bioptome (Group I) and 33 procedures performed with the reusable bioptome (Group II). The two instruments were found equally efficient in obtaining adequate biopsy samples (69% of attempts for both instruments). The average specimen weight was not significantly different (Group I 2.5+/-1.3 mg, Group II 2.7+/-1.1 mg) despite different nominal jaw sizes. There was no significant difference in the incidence of incompletely cut specimens (Group I 13%, Group II 7%) and there were no complications in either group. The cost of the two instruments was, as expected, markedly different with an estimated average per-use cost of $250.00 for the single-use bioptome and $35.89 for the reusable instrument. In this small study, a single-use 7 French myocardial bioptome was found to be an acceptable substitute for the larger, reusable instrument with no decrement in specimen size. The substantial cost differential is noteworthy, although the maintenance required by the reusable instrument can present a formidable challenge.

Nonciliated cells of the rat efferent ducts endocytose testicular sulfated glycoprotein-1 (SGP-1) and synthesize SGP-1 derived saposins

Sertoli cell sulfated glycoprotein-1 (SGP-1) is a heavily glycosylated and sulfated 70 kDa protein that is secreted into the lumen of the seminiferous tubule where it binds to spermatozoa. Recent light and electron microscope immunocytochemistry has suggested that the testicular SGP-1 detaches from the surface of spermatozoa in the lumen of the efferent ducts to be endocytosed within the endocytic apparatus of the epithelial nonciliated cells. The finding of SGP-1 mRNA together with anti-SGP-1 immunogold labeling of the lysosomal compartment suggest that these cells synthesize an efferent duct form of SGP-1. In the present study, a number of different experimental approaches (ligation, tunicamycin treatment and a combination of both) in combination with quantitative electron microscope immunogold labeling and Western blot analysis were performed in order to test this hypothesis. The number of gold particles and the profile area of the early (endosomes, pale multivesicular bodies) and late (dense multivesicular bodies, secondary lysosomes) endocytic apparatus were estimated in each of the experimental groups and expressed as the number of gold particles per micron 2 (labeling densities). The data revealed that ligation produced a significant reduction of anti-SGP-1 immunogold labeling of the early endocytic apparatus but not of the late endocytic apparatus. Tunicamycin treatment on the other hand produced a significant reduction of immunogold labeling of both the early and late endocytic apparatus. The combination of both treatments resulted in a more effective reduction of the labeling densities of these two endocytic compartments. These results thus indicate that the nonciliated cells of the efferent ducts are involved both in the endocytosis of the Sertoli-derived SGP-1 and in the synthesis of an efferent duct form of SGP-1 that is targeted from the Golgi apparatus to secondary lysosomes after its glycosylation. In order to determine the biosynthetic pathway of SGP-1 within the efferent ducts, an I.V. injection of 35S-cysteine followed by immunoprecipitation and SDS-PAGE revealed that SGP-1 was initially biosynthesized as a 55 kDa protein. This protein appears to be post-translationally modified to a 65 kDa form after 1 hour, which preceded the appearance of the 70 kDa form, and smaller peptides of about 15 kDa characteristic of saposins after 3-4 hours. Western blot analysis of ligated efferent ducts showed an increase in the biosynthesis of the 70 kDa form of SGP-1 when compared to untreated controls, however, it has yet to be established if this protein is secreted or retained in an intracellular compartment.(ABSTRACT TRUNCATED AT 400 WORDS)