Adult spinal cord stem cells generate neurons after transplantation in the adult dentate gyrus

The adult rat spinal cord contains cells that can proliferate and differentiate into astrocytes and oligodendroglia in situ. Using clonal and subclonal analyses we demonstrate that, in contrast to progenitors isolated from the adult mouse spinal cord with a combination of growth factors, progenitors isolated from the adult rat spinal cord using basic fibroblast growth factor alone display stem cell properties as defined by their multipotentiality and self-renewal. Clonal cultures derived from single founder cells generate neurons, astrocytes, and oligodendrocytes, confirming the multipotent nature of the parent cell. Subcloning analysis showed that after serial passaging, recloning, and expansion, these cells retained multipotentiality, indicating that they are self-renewing. Transplantation of an in vitro-expanded clonal population of cells into the adult rat spinal cord resulted in their differentiation into glial cells only. However, after heterotopic transplantation into the hippocampus, transplanted cells that integrated in the granular cell layer differentiated into cells characteristic of this region, whereas engraftment into other hippocampal regions resulted in the differentiation of cells with astroglial and oligodendroglial phenotypes. The data indicate that clonally expanded, multipotent adult progenitor cells from a non-neurogenic region are not lineage-restricted to their developmental origin but can generate region-specific neurons in vivo when exposed to the appropriate environmental cues.

Fibroblast growth factor-2-producing fibroblasts protect the nigrostriatal dopaminergic system from 6-hydroxydopamine

We tested the hypothesis that fibroblasts, which had been genetically engineered to produce fibroblast growth factor-2 (FGF-2), can protect nigrostriatal dopaminergic neurons. Three groups of rats received either a burr hole only (n=5) or implantation of fibroblasts, which had been genetically engineered to produce beta-galactosidase (beta-gal) (n=8) or FGF-2 (n=8), at two sites in the right striatum. Two weeks later, the animals received an injection of 25 microg of 6-hydroxydopamine hydrobromide (6-OHDA) midway between the two implant sites. The group that received FGF-2-fibroblasts had significantly fewer apomorphine-induced rotations than the groups that received a burr hole only or beta-gal-fibroblasts at weeks 2 and 3 following lesioning with 6-OHDA. Testing for amphetamine-induced rotation revealed a mild reduction in rotation in the beta-gal-fibroblast group compared to the burr hole only group, but a striking attenuation of amphetamine-induced rotation in the FGF-2-fibroblast group. There was also preservation of TH-IR neurons on the lesioned side relative to both control groups. The size of the grafts and the gliosis surrounding the injection sites did not differ between the FGF-2-fibroblast and beta-gal-fibroblast groups. To further characterize the production of FGF-2 by the FGF-2-fibroblasts, we implanted FGF-2-fibroblasts and beta-gal-fibroblast into the striatum of rats but did not lesion the animals with 6-OHDA. The animals were then sacrificed at 1, 2 and 5 weeks following implantation. Prior to implantation the FGF-2 fibroblasts contained 148 ng/mg of FGF-2-immunoreactive (FGF-2-IR) material per mg of protein of cell lysate. After implantation FGF-2-IR material was noted in the grafts of FGF-2-fibroblasts, most conspicuously at 1 and 2 weeks following implantation. We also noted FGF-2-IR material in the nuclei of reactive astrocytes adjacent to the implants, and OX-42-immunoreactive (OX-42-IR) cells adjacent and occasionally within the implants. Our work indicates that fibroblasts genetically engineered to produce FGF-2 and implanted in the striatum can protect the nigrostriatal dopaminergic system and may be useful in the treatment of Parkinson's disease.

FGF-2-responsive neural stem cell proliferation requires CCg, a novel autocrine/paracrine cofactor

We have purified and characterized a factor, from the conditioned medium of neural stem cell cultures, which is required for fibroblast growth factor 2's (FGF-2) mitogenic activity on neural stem cells. This autocrine/paracrine cofactor is a glycosylated form of cystatin C (CCg), whose N-glycosylation is required for its activity. We further demonstrated that, both in vitro and in vivo, neural stem cells undergoing cell division are immunopositive for cystatin C. Finally, we showed in vivo functional activity of CCg by demonstrating that the combined delivery of FGF-2 and CCg to the adult dentate gyrus stimulated neurogenesis. We propose that the process of neurogenesis is controlled by the cooperation between trophic factors and autocrine/paracrine cofactors, of which CCg is a prototype.

Computerized cochlear implant database system

In an environment of clinical governance with increased demands for accountability it is very important that accurate, reliable and secure data records be maintained for easy retrieval, analysis and presentation when required. A database is a very versatile tool for this purpose. We describe here our experience in designing a database for cochlear implant patients in Cambridge, together with guidance for prospective designers in their chosen sub-specialty.

Cloning and expression of type II collagen mRNA: evaluation as a candidate for canine oculo-skeletal dysplasia

The disease phenotype of oculo-skeletal dysplasia (OSD) detected in Labrador retrievers and Samoyeds shows a large degree of similarity with human Stickler and Kniest dysplasia. Type II collagen (COL2A1) mRNA, which is defective in a larger number of Stickler and Kniest patients, has been cloned and characterized from normal dog. The amino acid sequence of the canine type II procollagen is predicted to contain 1487 residues, with high degree of homology with its human homologue, and maintains all the characteristic structural domains. In addition to cartilage, expression of COL2A1 has also been detected in canine retina and testes. In testes, the N-propeptide region of COL2A1 displayed differential splicing and expressed both splice variants, IIA (with exon 2) and IIB (without exon 2), suggesting the importance of both forms in testis maturation and maintenance. Despite a severe decrease of type II collagen protein in the vitreous of OSD affected Labrador retrievers, COL2A1 gene has been excluded from having any causal association with the disease locus by linkage analysis. Using an intragenic RFLP marker, COL2A1 gene has also been tested as a candidate gene for the non-allelic form of the other canine OSD identified in Samoyeds, and excluded by linkage analysis. Oculo-skeletal dysplastic Labrador retriever and Samoyed provide two animal models for chondrodysplasia with genetic heterogeneity.

Neuronal differentiation and morphological integration of hippocampal progenitor cells transplanted to the retina of immature and mature dystrophic rats

Attempts to repopulate the retina with grafted neurons have been unsuccessful, in large part because donor cells prefer not to integrate with those of the host. Here we describe the first use of neural progenitor cells in the diseased adult retina. Adult rat hippocampal progenitor cells were injected into the eyes of rats with a genetic retinal degeneration. After survival times up to 16 weeks, the retinae of 1-, 4-, and 10-week-old recipients exhibited widespread incorporation of green fluorescent protein-expressing (GFP+) donor cells into the host retina. The 18-week-old recipients showed a similar pattern, but with fewer cells. Grafted cells expressed the mature neuronal markers NF-200, MAP-5, and calbindin. GFP+ cells extended numerous neurites into the host plexiform layers and these processes were intimately associated with synaptophysin+ profiles. GFP+ neurites also extended into the host optic nerve head. These results demonstrate the differentiation of substantial numbers of new neurons within the mature dystrophic retina.

The fate of manuscripts rejected by a general medical journal

PURPOSE

The fate of research manuscripts that have been rejected by medical journals is of interest to authors, editors, and peer reviewers, but previous studies were conducted before the widespread availability of computerized literature searches. We update the previous investigations of the fate of rejected research manuscripts by using an electronic literature search and a larger sample, a longer follow-up, and more descriptive journal indexes.

METHODS

Using a retrospective cohort study design, we examined 350 manuscripts rejected by the Annals of Internal Medicine, a general medical journal, during 1993 and 1994. We assessed the number of manuscripts that were published after initial rejection, time to eventual publication, journal type (general versus specialty), and journal impact factor (higher scores indicated greater impact) and immediacy index.

RESULTS

Of 350 rejected manuscripts, 240 (69%, 95% confidence interval [CI]: 64% to 73%) were eventually published after a mean of 552 days (95% CI: 479 to 544 days, range 121 to 1, 792 days). Of 226 rejected research articles and reviews, 159 (70%, 95% CI: 64% to 76%) were subsequently published in specialty journals. During 1993 and 1994, the mean impact factor for articles published in the Annals was 9.60 (95% CI: 9.56 to 9.64), compared with a mean of 3.09 (95% CI: 2.80 to 3.37) for the journals in which the rejected articles were subsequently published (mean difference 6. 52, 95% CI: 6.24 to 6.81, P < 0.0001). The immediacy index was also lower for these journals. Time to publication had a weak negative correlation with the impact factor of the journal in which the article was published (correlation coefficient -0.15, P = 0.007).

CONCLUSIONS

The majority of the manuscripts that were rejected from a large general medical journal were eventually published after an average of 18 months. Most were published in specialty journals with lower impact factor and immediacy index ratings.

Genetic characterization of gram-positive homologs of the XerCD site-specific recombinases

Homologs of the XerCD enzymes, which in Escherichia coli have been shown to be responsible for resolving chromosomal multimers prior to chromosome segregation, were identified in the genomes of Staphylococcus aureus and Streptococcus pneumoniae. Phylogenetic and conservation pattern analysis suggests that the S. aureus gene products are orthologs of XerC and D. A S. aureus xerC null mutant displayed in vitro characteristics consistent with the segregation defect reported for E. coli xer mutants, and was found to be attenuated in a murine infection model. Strikingly, the S. aureus xerD gene appears to be absolutely required for viability, and may therefore be the first example of an essential gene of the lambda integrase family. In contrast, phylogenetic and conservation pattern analysis show that the S. pneumoniae gene products are more closely related to phage integrases than to XerCD. S. pneumoniae xer1, 2 and 3 null mutants were each found to be attenuated in a murine infection model, suggesting that they may control processes which affect virulence.

Two distinct mutations cause severe hemophilia B in two unrelated canine pedigrees

The molecular defects causing severe factor IX deficiency were identified in two distinct canine breed-variants. Both defects were associated with an absence of plasma factor IX coagulant activity and antigen. A large deletion mutation was found in 1 breed variant, spanning the entire 5' region of the factor IX gene extending to exon 6. An approximately 5 kb insertion disrupted exon 8 of the second breed-variant. This insertion was associated with alternative splicing between a donor site 5' and acceptor site 3' to the normal exon 8 splice junction, with introduction of a new stop codon. The resultant transcript lacked most of the factor IX catalytic domain and 3' untranslated region. Molecular analyses of canine hemophilia B define an experimental model for study of inhibitor formation and gene therapy strategies, and provide insight into spontaneous mutation mechanisms in the factor IX gene and on the X chromosome of mammalian species.

Further experience with fat graft obliteration of mastoid cavities for cochlear implants

Obliteration of old mastoids and wet middle ears with autologous abdominal fat seems to be a reliable technique to render chronically discharging mastoid cavities or open middle ears dry and closed. This paper is the third in the series and looks at the intermediate results at five years. Of the 16 patients (one bilateral) 94.1 per cent of the ears are still dry and uninfected with closed external meati. Recurrent cholesteatoma was found in two patients at implantation and removed.

Synthesis and release of docosahexaenoic acid by the RPE cells of prcd-affected dogs

PURPOSE

Dogs affected with progressive rod-cone degeneration (prcd) have reduced levels of docosahexaenoic acid (DHA, 22:6n-3) in their plasma and rod photoreceptor outer segments (ROS). Dietary supplementation of DHA has failed to increase the ROS DHA levels to that of unaffected control dogs. The present study was undertaken to test the hypothesis that prcd-affected dogs have a reduced capacity for the synthesis and/or release of DHA in retinal pigment epithelial (RPE) cells.

METHODS

RPE cells (first passage cultures) from prcd-affected and normal dogs were incubated with [3H]eicosapentaenoic acid (EPA, 20:5n-3) for 24 and 72 hours. After incubation, the radiolabeled fatty acids in the cells and media were analyzed.

RESULTS

DHA and all its metabolic intermediates were detected in RPE cells from prcd-affected and normal dogs. No significant difference was found in the amount of products (including DHA) synthesized between normal and affected RPE cells at either time point. In the culture media, RPE cells from prcd-affected dogs released significantly more DHA than cells from normal dogs after 72-hour incubation, but not after 24-hour incubation.

CONCLUSIONS

RPE cells from prcd-affected dogs can synthesize and release DHA at least as efficiently as cells from normal dogs. Therefore, synthesis of DHA from its precursor and its release from RPE cells does not appear to contribute to the reduction in ROS DHA levels found in prcd-affected animals.

Calcium metabolism in pre-eclampsia

OBJECTIVES

To study calcium metabolism in pre-eclampsia and normotensive gravid women.

METHOD

Ten milliliters of heparinized blood samples and 24-h urine samples were collected from 50 pre-eclamptic and 50 normotensive primigravidae. Blood samples were studied for calcium uptake, intracellular calcium level and calcium-dependent adenosine triphosphatase activity of red blood cell ghost. Urinary calcium excretion was estimated from the 24-h urine samples. These values were compared in the two groups.

RESULTS

The mean gestational age at recruitment was similar in both the groups. The mean maternal age was 24.28 +/- 2.41 years in pre-eclamptic and 23.48 +/- 4.16 years in normotensive women. In pre-eclampsia 24-h urinary calcium excretion (71.20 +/- 22.95 mg/day) and calcium-dependent ATPase activity (10.78 +/- 2.40 nmol/Pi/mg protein/min) was significantly lower compared to normotensive primigravidae (calcium excretion = 189.24 +/- 57.06 mg/day; Ca2+-dependent ATPase = 12.64 +/- 2.42 nmolPi/mg /protein per min; P < 0.001). Intracellular calcium levels and calcium uptake at 10 min by red blood cells were significantly higher in pre-eclampsia (P < 0.05). Calcium uptake by red blood cells at 20 and 30 min was similar in both groups.

CONCLUSION

Pre-eclampsia is associated with increased levels of intracellular calcium, decreased calcium-dependent ATPase activity of erythrocytes and hypocalciuria.

Rapidly invading sebaceous carcinoma of the external auditory canal

A very rare case of a sebaceous carcinoma of the external auditory canal with basal cell differentiation is presented. Fewer than 400 cases affecting any part of the body have so far been reported and of that only seven cases have been known to involve the external auditory canal. The clinical features, pathology and treatment are described and the relevant literature has been reviewed.

Patient-controlled antiemesis: a randomized, double-blind comparison of two doses of propofol versus placebo

BACKGROUND

The role of propofol for the management of postoperative nausea and vomiting (PONV) is not well established. This study determines the efficacy of small doses of propofol administered by patient-controlled device for the treatment of PONV.

METHODS

Patients presenting for ambulatory surgery received a standardized general anesthetic. Those who experienced significant nausea or emesis within 1 h of arrival in the recovery room were randomized to receive repeated doses of propofol 20 mg (P-20), propofol 40 mg (P-40), or intralipid (placebo) on demand. Study medications (in equal volumes) were administered with a patient-controlled delivery device for 2 h. A lockout interval of 5 min between doses was used. The following parameters were assessed: nausea, vomiting, rescue antiemetic use, recovery profile, study drug administration history, and satisfaction with treatment.

RESULTS

Sixty-nine patients participated in the study. Patient demographics were similar. The average nausea score for a patient in the P-20 and P-40 groups was 25% and 29% less, respectively, compared with placebo during the study period (P < 0.05). This difference was apparent 15 min after initiation of therapy. More placebo patients vomited (P-20, 12%; P-40, 23%; placebo, 56%; P = 0.003) and needed rescue antiemetics (P-20, 17%; P-40, 23%; placebo, 70%; P = 0.001) compared with treatment groups. Sedation scores were similar between groups. Propofol-treated patients had shorter stays in the post-anesthesia care unit (PACU; P-20, 131+/-35 min [mean +/- SD]; P-40, 141+/-34 min; placebo, 191+/-92 min; P = 0.005) and higher satisfaction with their control of PONV than placebo (P < 0.01).

CONCLUSIONS

Propofol is effective in managing PONV with shorter PACU stay and great degree of patient satisfaction. There were two episodes of oversedation in the P-40 group. Hence, propofol at a demand dose of 20 mg seems more appropriate.

Evaluation of the APOH gene as a positional candidate for prcd in dogs

PURPOSE

Progressive rod-cone degeneration (prcd) is an autosomal recessive retinal degeneration of dogs characterized by abnormalities in lipid metabolism. It has recently been mapped to the centromeric region of canine chromosome 9, homologous to human 17q, which contains the apolipoprotein H (apoH, protein; APOH, gene) gene involved in lipid metabolism and regulation of triglycerides. The present study was undertaken to evaluate APOH as a positional candidate for prcd.

METHODS

Expression of APOH in the retina was examined by reverse transcription-polymerase chain reaction (RT-PCR) and by immunocytochemistry in normal and prcd-affected dogs. The level of apoH in the plasma was determined by western blot analysis. Intragenic polymorphic markers were identified and typed in the prcd pedigree. Canine-rodent hybrid cell lines were analyzed to detect canine APOH.

RESULTS

ApoH has been localized to the photoreceptor outer segment layer by immunocytochemistry. Its expression in the retina of normal and prcd-affected dogs was confirmed by RT-PCR. The levels of antihuman apoH cross-reacting material in plasma were similar in all dogs, regardless of disease status. Finally, linkage analysis of the APOH gene with the disease locus in the prcd pedigree detected 3 recombinants among 70 informative offsprings (lod score 15.09 at 0 = 4.3 centimorgan [cM]).

CONCLUSIONS

APOH is expressed in the retina and tightly linked to the prcd locus. However, despite its potential role in phenotypes of abnormal lipid metabolism associated with prcd, the gene has been excluded as a primary candidate for prcd by linkage analysis.

Biochemical basis of the beta-glucuronidase gene defect causing canine mucopolysaccharidosis VII

Mucopolysaccharidosis type VII (MPS VII), or Sly syndrome, is an autosomal recessive lysosomal storage disorder resulting from the deficiency in the activity of the enzyme beta-glucuronidase (GUSB). To characterize the biochemical and molecular defect in GUSB-deficient MPS VII dogs, we have measured lysosomal enzyme activities, analyzed distribution of glycosaminoglycans (GAGs), and estimated the size and abundance of the GUSB gene product at the mRNA and protein level in normal, homozygous affected, and heterozygous carrier retinal pigment epithelium (RPE) samples. Compared to normal, only 2-5% and 40-60% of GUSB activity was detected in the affected and the carrier samples, respectively. The decrease in GUSB activity resulted in storage of GAGs predominantly heparan sulfate and chondroitin sulfate. A slight increase in storage of GAGs was also observed in the carrier sample. Northern blot analysis of affected and carrier RPE samples detected a 2.4 kb GUSB transcript similar in size and abundance to that of normal controls. In western blot analysis using anti-human GUSB antibody, three bands of size 78, 56, and 38 kDa were detected in normal samples, which were present at lower intensity in the carrier RPE samples and absent in the MPS VII-affected RPE samples. These results suggest that the mutant GUSB gene causes a posttranscriptional defect and produces an unstable protein.

Bilateral and multicystic major salivary gland disease: a rare presentation of primary Sjögren's syndrome

We present a case of a 15-year-old girl with bilateral parotid and sub-mandibular salivary gland enlargement as the sole presentation of primary Sjögren's syndrome. The clinical, radiological, immunological and pathological features have been discussed. The relevant literature has been reviewed. To our knowledge this is the only reported case of Sjögren's syndrome presenting as multicystic disease with bilateral major salivary gland involvement.

The Scheibe cochlea deformity with macrocephaly: a case for single channel implantation

An 11-year-old congenitally deaf child with bilateral primitive common cavity (Scheibe type) cochleosaccular dysplasia and benign familial macrocephaly was implanted with an extracochlear single channel device with an ear level speech processor. This paper describes the assessment, findings, dilemmas in decision making, surgical procedure and the favourable outcome after implanting. The relevant literature has been reviewed and our case is presented for the unusual combination of features.

The implementation of prompted retinal screening for diabetic eye disease by accredited optometrists in an inner-city district of North London: a quality of care study

Diabetic retinopathy remains the most common cause of blindness in people of working age but the provision of high quality eye screening for diabetic patients is still erratic in many health districts in the UK. National consensus guidelines recommend comprehensive population coverage, high sensitivity (>80%), high specificity (>95%), agreed clinical criteria, referral procedures and centralized data collection to facilitate audit. This study looks at the effectiveness of implementing a prompted recall programme for retinal screening in an inner-city district of North London. The scheme uses trained, accredited optometrists to screen patients with diabetes who are looked after in the community by their general practitioner. During the first 17 months of the scheme, 63 optometrists attended training and gained accreditation. Of the 666 patients recruited, 645 were scheduled for screening and 536 (83%) attended. Fourteen per cent of patients screened were found to have background retinopathy and 2.3% sight-threatening eye disease. In two audits, carried out 15 months apart in a random sample of GP practices, the incidence of recorded dilated fundoscopy increased from 48% at baseline to 56%, an increase of 8% (95% CIs 2%-14%). For referable eye disease, the sensitivity of this screening technique was 100%, the specificity 94% (95% CIs 90%-98%), the positive predictive value 79% (95% CIs 72%-86%) and the negative predictive value 100%. The administrative cost per case screened was Pound Sterling 12.60 (excluding clinical costs and any additional optometry payment).