A mouse Mecp2-null mutation causes neurological symptoms that mimic Rett syndrome

Rett syndrome (RTT) is an inherited neurodevelopmental disorder of females that occurs once in 10,000-15,000 births. Affected females develop normally for 6-18 months, but then lose voluntary movements, including speech and hand skills. Most RTT patients are heterozygous for mutations in the X-linked gene MECP2 (refs. 3-12), encoding a protein that binds to methylated sites in genomic DNA and facilitates gene silencing. Previous work with Mecp2-null embryonic stem cells indicated that MeCP2 is essential for mouse embryogenesis. Here we generate mice lacking Mecp2 using Cre-loxP technology. Both Mecp2-null mice and mice in which Mecp2 was deleted in brain showed severe neurological symptoms at approximately six weeks of age. Compensation for absence of MeCP2 in other tissues by MeCP1 (refs. 19,20) was not apparent in genetic or biochemical tests. After several months, heterozygous female mice also showed behavioral symptoms. The overlapping delay before symptom onset in humans and mice, despite their profoundly different rates of development, raises the possibility that stability of brain function, not brain development per se, is compromised by the absence of MeCP2.

A "humanized" green fluorescent protein cDNA adapted for high-level expression in mammalian cells

We constructed gfph, a synthetic version of the jellyfish Aequorea victoria green fluorescent protein (gfp) cDNA that is adapted for high-level expression in mammalian cells, especially those of human origin. A total of 92 base substitutions were made in 88 codons in order to change the codon usage within the gfp10 coding sequence so that it was more appropriate for expression in mammalian cells. We also describe a series of versatile recombinant adeno-associated virus and adenovirus vectors for delivery and expression of genes into mammalian cells and, using these vectors, demonstrate the efficient transduction and expression of the gfph gene in the human cell line 293 and also in vivo, within neurosensory cells of guinea pig eye. Cells infected with recombinant adeno-associated virus-GFPH can be readily sorted by fluorescence-activated cell sorting, suggesting that the newly designed gfph gene could be widely used as a reporter in many gene delivery technologies, including human gene therapy.

High-energy particle acceleration in the shell of a supernova remnant

A significant fraction of the energy density of the interstellar medium is in the form of high-energy charged particles (cosmic rays). The origin of these particles remains uncertain. Although it is generally accepted that the only sources capable of supplying the energy required to accelerate the bulk of Galactic cosmic rays are supernova explosions, and even though the mechanism of particle acceleration in expanding supernova remnant (SNR) shocks is thought to be well understood theoretically, unequivocal evidence for the production of high-energy particles in supernova shells has proven remarkably hard to find. Here we report on observations of the SNR RX J1713.7 - 3946 (G347.3 - 0.5), which was discovered by ROSAT in the X-ray spectrum and later claimed as a source of high-energy gamma-rays of TeV energies (1 TeV = 10(12) eV). We present a TeV gamma-ray image of the SNR: the spatially resolved remnant has a shell morphology similar to that seen in X-rays, which demonstrates that very-high-energy particles are accelerated there. The energy spectrum indicates efficient acceleration of charged particles to energies beyond 100 TeV, consistent with current ideas of particle acceleration in young SNR shocks.

Closely related proteins MBD2 and MBD3 play distinctive but interacting roles in mouse development

MBD2 and MBD3 are closely related proteins with consensus methyl-CpG binding domains. MBD2 is a transcriptional repressor that specifically binds to methylated DNA and is a component of the MeCP1 protein complex. In contrast, MBD3 fails to bind methylated DNA in murine cells, and is a component of the Mi-2/NuRD corepressor complex. We show by gene targeting that the two proteins are not functionally redundant in mice, as Mbd3-/- mice die during early embryogenesis, whereas Mbd2-/- mice are viable and fertile. Maternal behavior of Mbd2-/- mice is however defective and, at the molecular level, Mbd2-/- mice lack a component of MeCP1. Mbd2-mutant cells fail to fully silence transcription from exogenous methylated templates, but inappropriate activation of endogenous imprinted genes or retroviral sequences was not detected. Despite their differences, Mbd3 and Mbd2 interact genetically suggesting a functional relationship. Genetic and biochemical data together favor the view that MBD3 is a key component of the Mi-2/NuRD corepressor complex, whereas MBD2 may be one of several factors that can recruit this complex to DNA.

Comparison of remifentanil and fentanyl in patients undergoing craniotomy for supratentorial space-occupying lesions

BACKGROUND

Remifentanil hydrochloride is an ultra-short-acting, esterase-metabolized mu-opioid receptor agonist. This study compared the use of remifentanil or fentanyl during elective supratentorial craniotomy for space-occupying lesions.

METHODS

Sixty-three adults gave written informed consent for this prospective, randomized, double-blind, multiple-center trial. Anesthesia was induced with thiopental, pancuronium, nitrous oxide/oxygen, and fentanyl (n = 32; 2 micrograms.kg.-1. min-1) or remifentanil (n = 31; 1 mu.kg-1.min-1). After tracheal intubation, infusion rates were reduced to 0.03 microgram.kg-1.min-1 (fentanyl) or 0.2 microgram.kg-1.min-1 (remifentanil) and then adjusted to maintain anesthesia and stable hemodynamics. Isoflurane was given only after specified infusion rate increases had occurred. At the time of the first burr hole, intracranial pressure was measured in a subset of patients. At bone flap replacement either saline (fentanyl group) or remifentanil (approximately 0.2 microgram.kg-1.min-1) were infused until dressing completion. Hemodynamics and time to recovery were monitored for 60 min. Analgesic requirements and nausea and vomiting were observed for 24 h. Neurological examinations were performed before operation and on postoperative days 1 and 7.

RESULTS

Induction hemodynamics were similar. Systolic blood pressure was greater in the patients receiving fentanyl after tracheal intubation (fentanyl = 127 +/- 18 mmHg; remifentanil = 113 +/- 18 mmHg; P = 0.004). Intracranial pressure (fentanyl = 14 +/- 13 mmHg; remifentanil = 13 +/- 10 mmHg) and cerebral perfusion pressure (fentanyl = 76 +/- 19 mmHg; remifentanil = 78 +/- 14 mmHg) were similar. Isoflurane use was greater in the patients who received fentanyl. Median time to tracheal extubation was similar (fentanyl = 4 min: range = -1 to 40 min; remifentanil = 5 min: range = 1 to 15 min). Seven patients receiving fentanyl and none receiving remifentanil required naloxone. Postoperative systolic blood pressure was greater (fentanyl = 134 +/- 16 mmHg; remifentanil = 147 +/- 15 mmHg; P = 0.001) and analgesics were required earlier in patients receiving remifentanil. Incidences of nausea and vomiting were similar.

CONCLUSIONS

Remifentanil appears to be a reasonable alternative to fentanyl during elective supratentorial craniotomy.

Insulin-like growth factor I acts as an angiogenic agent in rabbit cornea and retina: comparative studies with basic fibroblast growth factor

The release of growth factors from ischaemic retina has been hypothesized as the central stimulus for retinal neovascularization in proliferative diabetic retinopathy. Two of the growth factors implicated are insulin-like growth factor-I and basic fibroblast growth factor. We examined the effect of insulin-like growth factor-I on in vivo neovascularization using the established angiogenic model of the rabbit cornea (n = 30), and also compared the effects of insulin-like growth factor-I and basic fibroblast growth factor using two new in vivo systems. Either supraphysiologic concentrations of each growth factor (600 micrograms) were injected intravitreally into pigmented rabbits (n = 21) or porous polyfluorotetraethylene chambers filled with an emulsion containing collagen and growth factor (500 ng) were placed on the retina surface (n = 8). Our results demonstrate that when insulin-like growth factor-I was implanted together with a slow release carrier into the pocket of the normally avascular cornea, insulin-like growth factor-I (10 micrograms/pellet) induced angiogenesis in all rabbits. This degree of angiogenesis was comparable to that previously shown for basic fibroblast growth factor. For the intravitreal studies, the fibrotic component was greater in the basic fibroblast growth factor injected eyes, whereas the vascular component was accentuated in the eyes injected with insulin-like growth factor-I. Light and electron microscopy demonstrated areas of vascular proliferation in both groups. Porous polyfluorotetraethylene chamber studies with insulin-like growth factor-I and basic fibroblast growth factor demonstrated vascular proliferation in the vicinity of the chamber similar to the intravitreal injected eyes, but to a lesser degree than the injected eyes. Our experiments overall support the angiogenic potential of both insulin-like growth factor-I and basic fibroblast growth factor and support distinct but complimentary roles for each growth factor in the pathogenesis of proliferative diabetic retinopathy.

Localization and identification of neuropeptide Y (NPY)-like immunoreactivity in the frog brain

The distribution of neuropeptide Y (NPY) in the central nervous system of the frog Rana ridibunda was determined by immunofluorescence using a highly specific antiserum. NPY-like containing perikarya were localized in the infundibulum, mainly in the ventral and dorsal nuclei of the infundibulum, in the preoptic nucleus, in the posterocentral nucleus of the thalamus, in the anteroventral nucleus of the mesencephalic tegmentum, in the part posterior to the torus semicircularis, and in the mesencephalic cerebellar nucleus. Numerous perikarya were also distributed in all cerebral cortex. Important tracts of immunoreactive fibers were found in the infundibulum, in the preoptic area, in the lateral amygdala, in the habenular region, and in the tectum. The cerebral cortex was also densely innervated by NPY-like immunoreactive fibers. A rich network of fibers was observed in the median eminence coursing towards the pituitary stalk. Scattered fibers were found in all other parts of the brain except in the cerebellum, the nucleus isthmi and the torus semicircularis, where no immunoreactivity could be detected. NPY-immunoreactive fibers were observed at all levels of the spinal cord, with particularly distinct plexus around the ependymal canal and in the distal region of the dorsal horn. At the electron microscope level, NPY containing perikarya and fibers were visualized in the ventral nuclei of the infundibulum, using the peroxidase-antiperoxidase and the immunogold techniques. NPY-like material was stored in dense core vesicles of 100 nm in diameter. A sensitive and specific radioimmunoassay was developed. The detection limit of the assay was 20 fmole/tube. The standard curves of synthetic NPY and the dilution curves for acetic acid extracts of cerebral cortex, infundibulum, preoptic region, and mesencephalon plus thalamus were strictly parallel. The NPY concentrations measured in these regions were (pmole/mg proteins) 163 +/- 8, 233 +/- 16, 151 +/- 12 and 60 +/- 13, respectively. NPY was not detectable in cerebellar extracts. After Sephadex G-50 gel filtration of acetic acid extracts from whole frog brain, NPY-like immunoreactivity eluted in a single peak. Reverse phase high performance liquid chromatography (HPLC) and radioimmunoassay were used to characterize NPY-like peptides in the frog brain. HPLC analysis revealed that infundibulum, preoptic area and telencephalon extracts contained a major peptide bearing NPY-like immunoreactivity. The retention times of frog NPY and synthetic porcine NPY were markedly different. HPLC analysis revealed also the existence, in brain extracts, of several other minor components cross-reacting with NPY antibodies.(ABSTRACT TRUNCATED AT 400 WORDS)

A randomized, double-blind, placebo-controlled study on the effect of conjugated estrogens on skin thickness

OBJECTIVE

Our purpose was to assess the potential benefit of therapy with conjugated estrogens therapy on skin thickness in postmenopausal women.

STUDY DESIGN

Sixty postmenopausal women were randomly allocated to receive conjugated estrogens or placebo treatment for 12 months. Neither participants nor investigators were aware of the group allocation. Skin thickness was measured by ultrasonography at baseline and after 6 to 12 months of treatment. Histologic changes were evaluated by skin biopsy at baseline and after 12 months' treatment. Quality of life and adverse events were recorded at each visit and at the end of treatment.

RESULTS

Treatment with conjugated estrogens for 12 months significantly increases, at the level of the right great trochanter, the thickness of the skin (p < 0.01), as assessed by ultrasonography, and of the dermis (p < 0.05), as assessed by skin biopsy. No statistically significant difference was observed in the control population. Quality of life was reported to be improved (p < 0.05) in women treated with estrogen compared with those in the placebo group.

CONCLUSION

The results may help postmenopausal women to better appraise the benefits of estrogen replacement therapy, and they provide further evidence of the potential of conjugated estrogens in preventing skin aging.

Electron microscope immunocytochemical localization of neuropeptide Y (NPY) in the rat brain

In order to identify the neuronal structures as well as the intracellular organelles which contain the newly discovered brain peptide, neuropeptide Y (NPY), we have localized this peptide by immunoelectron microscopy in brain areas containing high levels of NPY. Ultrastructural studies using both the pre- and post-embedding immunoperoxidase techniques have shown that NPY-like immunoreactivity could be observed in neuronal cell bodies, dendrites and axonal processes. In terminals, the reaction product was associated with the large dense core vesicles. Only a small percentage of the positive terminals were seen making synaptic contacts. These results support the hypothesis that NPY can act as a neurotransmitter or neuromodulator.

The occurrence of serum autoantibodies against enolase in cancer-associated retinopathy

Cancer-associated retinopathy (CAR) is an uncommon paraneoplastic disease in which degeneration of the retina occurs as a remote effect of cancer in a distant part of the body. Immunoreactivity of sera from CAR patients and controls have been analyzed. Immunostaining of human retinal proteins showed that a soluble protein of Mr approximately 46 kDa (p46) is labeled by antibodies from several CAR patients with various types of cancer (lung, breast, bladder, prostate, salivary gland, and gastrointestinal tract cancer and chronic lymphocytic leukemia). These sera did not show reactivity with the 23-kDa protein previously associated with CAR. To identify and further characterize p46, the retinal protein was purified to homogeneity by anion-exchange chromatography and preparative gel electrophoresis. Protein sequence analysis of the peptides from p46 revealed a high homology with human enolase, an important glycolytic enzyme. Although enolase has been previously identified as a product of several types of tumors, and enolase activity has been detected in the sera of some cancer patients, the existence of autoantibodies directed to enolase has not been described. This is the first report of the presence of serum antibodies to retinal enolase in the patients with cancer and the CAR syndrome. When antibodies of specific isotypes (IgG, IgM, and IgA) were measured, IgG1 isotype was dominant. The significance of these antibodies for the disease process is under investigation.

Use of intraosseous infusion in the pediatric trauma patient

Intraosseous infusions (IO) are frequently used for gaining rapid vascular access in critically ill children. Few studies exist evaluating the efficacy of this procedure in the injured child. The objective of this study was to describe one pediatric institution's experience with the procedure of IO in young trauma victims. This study evaluated indications, insertion sites, complications, infused pharmacological agents, age, injury severity, and outcome. Fifteen patients received IO placement for cardiopulmonary arrest, seven for hypovolemic shock, and five for neurological compromise. Patient ages ranged from 3 months to 10 years (mean, 2.9 years). Twenty-nine IO lines were attempted in the tibia and three in the femur. Four of 32 attempts were unsuccessful. Of 32 attempts at IO placement (5 patients received multiple attempts), 15 were started in the prehospital setting and 17 in the emergency department. Multiple resuscitation medications as well as large colloid, crystalloid, and blood boluses were successfully infused. Seven of the 27 patients survived without observed IO-related complications. This study supports the use of IO infusion by prehospital as well as hospital personnel in the initial resuscitation of critically injured children. IO has a been established as a rapid, safe, and simple method of obtaining short term vascular access in both critically ill and injured children. This route deserves primary consideration as an alternate route for fluid resuscitation in pediatric trauma patients regardless of age. IO should be placed without delay when venous access is not rapidly obtainable.(ABSTRACT TRUNCATED AT 250 WORDS)

Blockade of rapid axonal transport. Effect of intraocular pressure elevation in primate optic nerve

After acute intraocular pressure (IOP) elevation, an induced disturbance of rapid axonal transport at the optic nerve head began within three hours at the IOP levels tested. The accumulation of radioactive label at the scleral lamina cribrosa increased with time of IOP elevation. There was a 60% decrease in the amount of transported material in the optic nerve, tract, and lateral geniculate body (LGN). Detailed analysis suggests that this decrease is not due to a simple slowdown of transport, but results from a total block of rapid transport in some axons, with no impairment in other axons. This total blockade of rapid transport by elevated IOP in involved axons differs from the apparent slowdown of transport in experimental papilledema, and the difference may explain the response of ganglion cells to the two conditions.

Treatment of paraneoplastic visual loss with intravenous immunoglobulin: report of 3 cases

BACKGROUND

Paraneoplastic visual loss is an autoimmune disorder believed to be caused by the remote effects of cancer on the retina (cancer-associated retinopathy [CAR]) or optic nerve. Both disorders may result in rapid and complete blindness. Spontaneous recovery of vision has not been reported. The serum of patients with CAR contains autoantibodies against recoverin, enolase, or unidentified retinal proteins. Autopsy examination results of eyes of blind patients with CAR show complete absence of the retinal neurons involved in phototransduction. Corticosteroids and plasmapheresis are the only treatment options previously described.

OBJECTIVE

To treat paraneoplastic visual loss.

DESIGN AND METHODS

Three patients with metastatic cancer developed rapidly progressive loss of vision. The first patient had visual acuity of hand movements in each eye before intravenous immunoglobulin treatment. The second patient had visual acuity of light perception in both eyes. The third patient's visual acuity was 20/400 OD and 20/20 OS. Diagnostic tests included magnetic resonance imaging of the head and cytologic examination of the cerebrospinal fluid to exclude metastasis as the cause of visual loss and then an electroretinogram and serum tests for autoantibodies against retinal antigens to confirm the clinical diagnosis of CAR. Patients 1 and 2 were treated with intravenous immunoglobulin (400 mg/kg per day) for 5 days; however, patient 3 received only a single dose due to adverse effects consisting of shortness of breath and itching.

RESULTS

Within 24 hours of taking the first dose of intravenous immunoglobulin, the visual acuity of patient 1 improved from hand movements only in both eyes to 20/50 OD and 20/200 OS. After the third day of treatment, visual acuity in the left eye further improved to 20/40. Even with the improved acuity, Goldmann visual field perimetry results showed poor responses in both eyes. However, 2 weeks later there was marked visual field improvement, and visual acuity was maintained at 20/50 OD and 20/40 OS. Patient 2 had no improvements and continued to have light perception in both eyes. Patient 3 had improvements in visual field defects but remained 20/400 OD and 20/20 OS.

CONCLUSION

Intravenous immunoglobulin may be another treatment option offered to patients with paraneoplastic visual loss in addition to corticosteroids or plasmapheresis because a review of the medical literature has shown no spontaneous improvements of visual function without treatment.

Reporter expression persists 1 year after adeno-associated virus-mediated gene transfer to the optic nerve

OBJECTIVE

To determine the foci and duration of protein expression following virus-mediated gene transfer to the optic nerve.

METHODS

A cytomegalovirus (CMV) promoter was linked to a lacZ-SV40 polyA reporter gene or a humanized green fluorescent protein (hgfp) reporter gene, then inserted into a bacterial plasmid containing adeno-associated virus (AAV) terminal repeat sequences. The CMV-lacZ or the CMV-hgfp construct were injected into the vitreous cavity of strain-13 guinea pigs. Controls consisted of eyes injected with AAV without the promoter and reporter elements or eyes that received no injections. The eyes and optic nerves were processed for beta-galactosidase immunohistochemistry and hgfp fluorescence analyses. Cellular transduction at the messenger RNA (mRNA) level was evaluated by in situ reverse transcription-polymerase chain reaction.

RESULTS

Weekly fundus photography, done for 1 month, documented the absence of any ocular abnormality due to the viral injections. No in vivo hgfp fluorescence of the retina was visualized. Beta-galactosidase histochemical analysis of eye cups that received the lacZ gene construct showed blue lacZ staining of the optic nerve head at 2 weeks. Light microscopy revealed the blue beta-galactosidase reaction product in fibers, glial cells, and blood vessels of the optic nerve head and retrobulbar nerve. Histochemistry showed absence of beta-galactosidase in the optic nerve at 3 to 12 months, but immunochemistry showed the persistence of beta-galactosidase in fibers, glial cells, and blood vessels as late as 1 year after a single ocular injection. In the retina, histochemical staining showed evidence of lacZ at 3 months, but not later. In situ reverse transcription-polymerase chain reaction revealed brown lacZ mRNA reaction product in ganglion cells of the retina. Control eyes that received AAV without the promoter and reporter elements and the eyes that received no viral injections and were processed for beta-galactosidase showed no reporter gene expression in any ocular tissue or cell type.

CONCLUSIONS

Viral-mediated gene transfer can be successfully accomplished in the optic nerve. Further evaluation is needed to determine whether the level of protein expression at 1 year after injection, which is clearly reduced relative to shorter postinjection time, is sufficient for therapeutic purposes.

CLINICAL RELEVANCE

We have previously shown that gene therapy with catalase suppressed experimental optic neuritis at 1 month after injection. Viral-mediated gene transfer may be a powerful technique for the treatment of optic neuropathies, particularly for recurrences of optic neuritis, if long-term expression of transduced protein can be demonstrated in the optic nerve.

DNA sequence and analysis of human chromosome 9

Chromosome 9 is highly structurally polymorphic. It contains the largest autosomal block of heterochromatin, which is heteromorphic in 6-8% of humans, whereas pericentric inversions occur in more than 1% of the population. The finished euchromatic sequence of chromosome 9 comprises 109,044,351 base pairs and represents >99.6% of the region. Analysis of the sequence reveals many intra- and interchromosomal duplications, including segmental duplications adjacent to both the centromere and the large heterochromatic block. We have annotated 1,149 genes, including genes implicated in male-to-female sex reversal, cancer and neurodegenerative disease, and 426 pseudogenes. The chromosome contains the largest interferon gene cluster in the human genome. There is also a region of exceptionally high gene and G + C content including genes paralogous to those in the major histocompatibility complex. We have also detected recently duplicated genes that exhibit different rates of sequence divergence, presumably reflecting natural selection.

Acellular Dermal Allograft for Ventral Hernia Repair in the Compromised Surgical Field

A ventral hernia and a contaminated surgical field are a difficult surgical combination. We hypothesize that acellular human dermis (AHD) can be a suitable biological tissue alternative in the repair of a ventral hernia. The study involved a retrospective review of the use of AHD in the repair of ventral hernia from 2001–2004. Inclusion criteria included a ventral hernia repair in a clean-contaminated (CC) or contaminated-dirty (CD) surgical field. The primary outcome of the study was wound infection and mesh removal. Patients were stratified into CC and CD, and management of a wound infection [medically managed (MM) or surgically managed (SM)]. Seventy-five patients met the study criteria. The most common comorbidity was hypertension (45.3%). There was one death in the study (from multiple organ dysfunction syndrome). The overall wound infection rate was 33.3 per cent: 11 MM (14.7%) and 14 SM (18.7%). The average length of stay was 16.7 days (±20.8) with a mean follow-up of 275 (±209) days. Subgroup analysis: CC (n = 64) had 9 wound infections that were MM (14.1%) and 12 wound infections that were SM (18.8%); CD (n = 11) had 2 wound infections that were MM (18.2%) and 2 wound infections that were SM (18.2%). Five of 14 SM (35.7%) wound infections required removal of the mesh. Wound infection in the contaminated surgical field occurred 33.3 per cent of the time. Some (18.7%) of the cases required SM management, and 35.7 per cent of these required removal of the AHD.

Delivery of DNA into mammalian cells by receptor-mediated endocytosis and gene therapy

The correction of genetically based disorders by the introduction of a therapeutic genetic construct into the appropriate cell type ("gene therapy"), has become a distinct possibility in recent years. In order for gene therapy to be a practical alternative to more conventional pharmaceutical approaches to treatment, it must be administrable in vivo. This demands that a system be developed that can specifically target the DNA to the desired cell type once introduced into the patient. Among the procedures that are currently being pursued, the delivery of DNA to cells by receptor mediated endocytosis (RME), comes closest to fulfilling this crucial requirement. The natural physiological process of RME can be exploited to deliver genetic material to cells. An antibody or ligand to a cell surface receptor that is known to undergo endocytosis, is complexed with DNA through a covalently linked polycationic adjunct (e.g., polylysine, protamines). Such complexes retain their binding specificity to the cell surface and are taken up into the cell where they enter the endosomal compartment via normal endocytotic processes. In addition, steps must be taken to avoid degradation of the DNA within the endosome-lysosome. Cells can be treated with the lysosomatropic agent chloroquine during the transfection procedure. Alternatively, the components of viruses that enter cells by endocysis and possess an endosomal "break out" capacity can be used. Replication defective adenovirus coupled to the ligand-DNA complex gives transfection efficiencies of virtually 100% on tissue culture cells in vitro. Synthetic peptides that mimic the membrane fusing region of influenza virus hemagglutinin, have also been successfully used as part of the ligand-DNA complex to bring about endosomal escape. Preliminary studies have demonstrated the potential of this method to specifically target DNA to the cell type of choice in vivo. Delivery of genes by receptor-mediated endocytosis offers the greatest hope that gene therapy can be an inexpensive, easily applicable, widespread technology.

Sequences flanking the centromere of human chromosome 10 are a complex patchwork of arm-specific sequences, stable duplications and unstable sequences with homologies to telomeric and other centromeric locations

Little is known about sequence organization close to human centromeres, despite empirical and theoretical data which suggest that it may be unusual. Here we present maps which physically define large sequence duplications flanking the centromeric satellites of human chromosome 10, together with a fluorescence in situ hybridization (FISH) analysis of pericentromeric sequence stability. Our results indicate that the duplications on each chromosome arm are organized into two blocks of approximately 250 and 150 kb separated by approximately 300 kb of non-duplicated DNA. The larger proximal blocks, containing ZNF11A, ZNF33A and ZNF37A (10p11) and ZNF11B, ZNF33B and ZNF37B (10q11), are inverted. However, the smaller distal blocks, containing D10S141A (10p11) and D10S141B (10q11), are not. A primate FISH analysis indicates that these loci were duplicated before the divergence of orang-utans from other Great Apes, that a cytogenetically cryptic pericentric inversion may have been involved in the formation of the flanking duplications and that they have undergone further rearrangement in other primate species. More surprising is the fact that sequences across the entire pericentromeric region appear to have undergone unprecedented levels of duplication, transposition, inversion and either deletion or sequence divergence in all primate species analysed. Extrapolating our data to the whole genome suggests that a minimum of 50 Mb of DNA in centromere-proximal regions is subject to an elevated level of mechanistically diverse sequence rearrangements compared with the bulk of genomic DNA.

Are Five-View Plain Films of the Cervical Spine Unreliable? A Prospective Evaluation in Blunt Trauma Patients with Altered Mental Status

OBJECTIVES

Clearing the cervical spine in a time-sensitive fashion is difficult. We hypothesized that admission computed tomographic scan of the occiput to T1 (CTS) with multiplanar reformatted images will replace five-view (odontoid, anteroposterior, lateral, and oblique) plain films of the cervical spine (CSX) in the initial evaluation of blunt trauma patients with altered mental status.

METHODS

Between January and July 2001, all patients aged 16 years or older with altered mental status undergoing both CTS and CSX were prospectively entered into the study group. Attending physician interpretation defined the presence of cervical spine injury. Unstable fractures were defined as requiring surgical or halo stabilization.

RESULTS

One thousand six patients met study criteria. One hundred sixteen patients had 172 cervical spine injuries (CSIs) (fracture and subluxation). CSX missed 90 of 172 (52.3%) CSIs in 65 of 172 (56.0%) patients. Anatomically, CSX failed to identify 14 of 15 occipital fractures (93.3%), 17 of 36 (47.2%) C1-3 fractures, and 59 of 121 (48.8%) C4-T1 CSIs. CSX failed to identify 5 of 29 (17.2%) patients with unstable CSIs. CTS failed to diagnose 3 of 172 (1.7%) CSIs that were stable (spinous process fractures at C6-7). Two patients exhibited spinal cord injury without radiologic abnormality missed by both modalities. CTS had a sensitivity of 97.4%, a specificity of 100%, a prevalence of 11.5%, a positive predictive value of 100%, and a negative predictive value of 99.7%. CSX had a sensitivity of 44.0%, a specificity of 100%, a prevalence of 11.5%, a positive predictive value of 100%, and a negative predictive value of 93.2%.

CONCLUSION

CTS outperformed five-view CSX in a group of patients with altered mental status or distracting injuries. Five-view CSX failed to diagnose 52.3% of cervical spine fractures identified by CTS. Five-view CSX failed to diagnose five patients with unstable cervical fractures and failed to identify 93.3% of patients with occipital condyle fractures.

Hyperbaric oxygen in the treatment of radiation-induced optic neuropathy

Four patients with radiation-induced optic neuropathies were treated with hyperbaric oxygen. They had received radiation therapy for treatment of pituitary tumors, reticulum cell sarcoma, and meningioma. Two presented with amaurosis fugax before the onset of unilateral visual loss and began hyperbaria within 72 hours after development of unilateral optic neuropathy. Both had return of visual function to baseline levels. The others initiated treatment two to six weeks after visual loss occurred in the second eye and had no significant improvement of vision. Treatment consisted of daily administration of 100% oxygen under 2.8 atmospheres of pressure for 14-28 days. There were no medical complications of hyperbaria. While hyperbaric oxygen is effective in the treatment of radiation-induced optic neuropathy, it must be instituted within several days of deterioration in vision for restoration of baseline function.

Development of intracerebral dopaminergic grafts: a combined immunohistochemical and autoradiographic study of its time course and environmental influences

The aim of the study was to obtain a description of some aspects of the development of intracerebral dopaminergic grafts, namely, the time course of the glial reaction and its relation to cell division on one hand, and the development of graft-originated innervation and its dependence on adequate matching of the implanted neurons and target site on the other hand. Cell suspensions obtained from the mesencephalon or hypothalamus of embryonic day (ED) 14 rat embryos were implanted into the striatum or lateral hypothalamus of adult rats following the destruction of the nigrostriatal system of the hosts. Animals were sacrificed at different postimplantation times, and the development of the graft was followed by immunohistochemistry by using antisera directed against tyrosine hydroxylase (TH) or glial fibrillary acidic protein (GFA). Furthermore, the existence of cell division at various times following implantation was examined by performing autoradiography on immunostained sections after prior intraventricular administration of 3H-thymidine to the host. The first stage of the development of intracerebral grafts was characterized by the existence of intense cell division within the grafted tissue, lasting about 2 weeks, and also in the host tissue surrounding the graft, lasting only about 6 days. The cell division in the host tissue was paralleled by the existence of a strong glial reaction which, however, did not extend into the graft itself. Glial reaction in the host tissue gradually decreased at later times and disappeared by 4 weeks postimplantation without leaving behind a noticeable glial scar. The graft itself was, however, transiently filled with a population of reactive astroglial cells between 3 and 6 weeks postimplantation. Within grafts of mesencephalic tissue located in the striatum TH-positive neurons were distributed evenly at short times postimplantation (2-6 days). At later time a compartmentation could be observed, with TH-positive neurons being aligned along the graft-host interface or clustered within the graft itself. Innervation of the host tissue by TH-positive fibers increased between 1 and 6 weeks postimplantation. On the other hand, no compartmentation and reinnervation of surrounding host tissue was observed for intrahypothalamic grafts of mesencephalic tissue or intrastriatal grafts of hypothalamic tissue. This last observation indicates that adequate matching of implanted neurons and target tissue plays an important role in the development of intracerebral dopaminergic grafts.

Identification of a second category of alpha-melanocyte-stimulating hormone (alpha-MSH) neurons in the rat hypothalamus

An immunocytochemical localization of alpha-melanocyte-stimulating hormone (alpha-MSH) as well as ACTH and a fragment (16K) of the common precursor of ACTH and beta-lipotropin (beta-LPH) was performed in rat brain. Two different groups of neuronal cell bodies showing alpha-MSH-like immunoreactivity (alpha-MSH-LI) were observed in the hypothalamus. One group of neurons located in the arcuate nucleus was shown to contain not only alpha-MSH-LI, but also ACTH and the 16K fragment. A second category of alpha-MSH-LI-containing neurons was characterized by the complete absence of staining for ACTH and 16K fragment. These neurons were mainly located in the dorsal-lateral portion of the hypothalamus. Immunoelectron microscopy showed that immunostaining for alpha-MSH was restricted to dense core vesicles in the positive perikarya. Nerve fibers staining for alpha-MSH (but not for ACTH and 16K fragment) were also observed outside the ACTH-beta-LPH pathway, especially in the cortex, caudate-putamen nucleus and hippocampus. These findings strongly suggest the presence of two different neuronal systems reacting with antibodies to alpha-MSH.