Differentiation of embryonic stem cells to insulin-secreting structures similar to pancreatic islets

Although the source of embryonic stem (ES) cells presents ethical concerns, their use may lead to many clinical benefits if differentiated cell types can be derived from them and used to assemble functional organs. In pancreas, insulin is produced and secreted by specialized structures, islets of Langerhans. Diabetes, which affects 16 million people in the United States, results from abnormal function of pancreatic islets. We have generated cells expressing insulin and other pancreatic endocrine hormones from mouse ES cells. The cells self-assemble to form three-dimensional clusters similar in topology to normal pancreatic islets where pancreatic cell types are in close association with neurons. Glucose triggers insulin release from these cell clusters by mechanisms similar to those employed in vivo. When injected into diabetic mice, the insulin-producing cells undergo rapid vascularization and maintain a clustered, islet-like organization.

Bone marrow cells regenerate infarcted myocardium

Myocardial infarction leads to loss of tissue and impairment of cardiac performance. The remaining myocytes are unable to reconstitute the necrotic tissue, and the post-infarcted heart deteriorates with time. Injury to a target organ is sensed by distant stem cells, which migrate to the site of damage and undergo alternate stem cell differentiation; these events promote structural and functional repair. This high degree of stem cell plasticity prompted us to test whether dead myocardium could be restored by transplanting bone marrow cells in infarcted mice. We sorted lineage-negative (Lin-) bone marrow cells from transgenic mice expressing enhanced green fluorescent protein by fluorescence-activated cell sorting on the basis of c-kit expression. Shortly after coronary ligation, Lin- c-kitPOS cells were injected in the contracting wall bordering the infarct. Here we report that newly formed myocardium occupied 68% of the infarcted portion of the ventricle 9 days after transplanting the bone marrow cells. The developing tissue comprised proliferating myocytes and vascular structures. Our studies indicate that locally delivered bone marrow cells can generate de novo myocardium, ameliorating the outcome of coronary artery disease.

Diabetic retinopathy: effects of national guidelines on the referral, examination and treatment practices of ophthalmologists and optometrists

OBJECTIVE

To investigate the changes in referral, examination and treatment practices for diabetic retinopathy by ophthalmologists and optometrists following the release of national guidelines.

METHODS

A two-page self-administered questionnaire was mailed to all Australian ophthalmologists and a random sample of 500 Australian optometrists prior to and 1 year after release of the National Health and Medical Research Council of Australia (NHMRC) clinical practice guidelines for the management of diabetic retinopathy. The questionnaires elicited information about current practice related to the management of patients with diabetic retinopathy.

RESULTS

Of the 464 contactable ophthalmologists who responded to the baseline survey, 374 (80.6% response) completed the follow-up survey The response rate for the contactable optometrists was 80.1% (310 of 384). There were almost no significant changes in management practices from baseline to follow up. For example, the percentage of ophthalmologists who reported that they were often or almost always confident in detecting moderate retinal thickening near the macula remained nearly identical from baseline to follow up (80.2% vs 79.1 %). The rate was also similar from baseline to follow up for optometrists (31.1% vs 28.8%). The one area in which ophthalmologists reported significant changes in management towards agreement with the NHMRC guidelines was use of angiography; they were less likely to manage their patients this way (20.4% vs 14.2% with laser and 48.9% vs 38.4% without laser for increasing level of severity in clinical signs; both P < 0.05).

CONCLUSIONS

The NHMRC guidelines for diabetic retinopathy have been successfully distributed to ophthalmologists and optometrists in Australia. However, the mere provision of the guidelines has had little impact on management practices. It will be important to determine if ongoing dissemination and implementation strategies not only increase awareness of health-care practitioners to the guidelines, but also change behaviours.

Theoretical and practical considerations in the psychological and educational assessment of the student with intractable epilepsy: dynamic assessment as an adjunct to static assessment

Assessing the student with intractable epilepsy requires skill not only in evaluating cognitive problems, but also detecting seizures and discovering how to adapt instruction to minimize their negative impact on learning. Ironically, assessment efforts are seen as compromised by the occurrence of seizures during testing, when determining how seizure events may interfere with learning and the instructional modifications that are necessary to cope with them, should be a key part of assessment. A dual approach to assessment is recommended that combines the identification of cognitive deficits with an evaluation of how recurring seizures may prevent the student from engaging in instruction. Without also evaluating the student's response to instruction, teaching to specific cognitive needs is limited by insufficient knowledge about how to keep the student involved in instruction when seizures occur. Static assessment evaluates cognitive functioning at the time of testing, without changing the way that the student learns and responds. By engaging the student in teaching/learning sessions, dynamic assessment explores how the student best learns despite cognitive deficits and the disruptive effect of seizures. This paper includes a description of the authors'experience in using dynamic assessment as an adjunct to static assessment in evaluating a student with intractable epilepsy.

Measurement of CP-violating asymmetries in B0 decays to CP eigenstates

We present measurements of time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurement uses a data sample of 23x10(6) Upsilon(4S)-->BbarB decays collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we find events in which one neutral B meson is fully reconstructed in a CP eigenstate containing charmonium and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the standard model is proportional to sin2beta, is derived from the decay time distributions in such events. The result is sin2beta = 0.34+/-0.20 (stat)+/-0.05 (syst).

Targeted genomic disruption of H-ras and N-ras, individually or in combination, reveals the dispensability of both loci for mouse growth and development

Mammalian cells harbor three highly homologous and widely expressed members of the ras family (H-ras, N-ras, and K-ras), but it remains unclear whether they play specific or overlapping cellular roles. To gain insight into such functional roles, here we generated and analyzed H-ras null mutant mice, which were then also bred with N-ras knockout animals to ascertain the viability and properties of potential double null mutations in both loci. Mating among heterozygous H-ras(+/-) mice produced H-ras(-/-) offspring with a normal Mendelian pattern of inheritance, indicating that the loss of H-ras did not interfere with embryonic and fetal viability in the uterus. Homozygous mutant H-ras(-/-) mice reached sexual maturity at the same age as their littermates, and both males and females were fertile. Characterization of lymphocyte subsets in the spleen and thymus showed no significant differences between wild-type and H-ras(-/-) mice. Analysis of neuronal markers in the brains of knockout and wild-type H-ras mice showed that disruption of this locus did not impair or alter neuronal development. Breeding between our H-ras mutant animals and previously available N-ras null mutants gave rise to viable double knockout (H-ras(-/-)/N-ras(-/-)) offspring expressing only K-ras genes which grew normally, were fertile, and did not show any obvious phenotype. Interestingly, however, lower-than-expected numbers of adult, double knockout animals were consistently obtained in Mendelian crosses between heterozygous N-ras/H-ras mice. Our results indicate that, as for N-ras, H-ras gene function is dispensable for normal mouse development, growth, fertility, and neuronal development. Additionally, of the three ras genes, K-ras appears to be not only essential but also sufficient for normal mouse development.

Do facial averageness and symmetry signal health?

We investigated whether the attractive facial traits of averageness and symmetry signal health, examining two aspects of signalling: whether these traits are perceived as healthy, and whether they provide accurate health information. In Study 1, we used morphing techniques to alter the averageness and symmetry of individual faces. Increases in both traits increased perceived health, and perceived health correlated negatively with rated distinctiveness (a converse measure of averageness) and positively with rated symmetry of the images. In Study 2, we examined whether these traits signal real, as well as perceived, health, in a sample of individuals for whom health scores, based on detailed medical records, were available. Perceived health correlated negatively with distinctiveness and asymmetry, replicating Study 1. Facial distinctiveness ratings of 17-year-olds were associated with poor childhood health in males, and poor current and adolescent health in females, although the last association was only marginally significant. Facial asymmetry of 17-year-olds was not associated with actual health. We discuss the implications of these results for a good genes account of facial preferences.

Diabetes in Victoria, Australia: the Visual Impairment Project

OBJECTIVES

To establish the prevalence and characteristics of self-reported diabetes in a representative sample of Victorian residents aged 40 years and older, and to compare the vision between people with and without self-reported diabetes.

DESIGN

Cross-sectional survey.

SETTING

Nine randomly selected suburban Melbourne clusters and four randomly selected rural Victorian clusters.

PARTICIPANTS

4,744 subjects (86% participation rate) aged > or = 40 years.

MAIN OUTCOME MEASURES

Subjects answered a detailed questionnaire which provided demographic details, body mass index, and the duration and treatment of any diagnosis of diabetes. Refraction was performed and best-corrected visual acuity was measured.

RESULTS

The prevalence of self-reported diabetes was 5.1%. In a multivariate analysis, self-reported diabetes was positively associated with age (p < 0.01), male sex (p = 0.01), higher body mass index (p = 0.01), Mediterranean ethnicity (p = 0.01), unemployment (p = 0.05) and lack of private health insurance (p < 0.05). People with self-reported diabetes were more likely to have mild or moderate levels of visual impairment than people who reported no previous diagnosis of diabetes (p < 0.01).

CONCLUSIONS

Diabetes in Victoria is more prevalent among men and among people of Mediterranean origin. When planning educational programs and health service delivery, it is also important to consider that, compared with the general population, people with diabetes are less likely to be employed or to have private health insurance, and are more likely to have impaired vision.

Enhanced proliferation, survival, and dopaminergic differentiation of CNS precursors in lowered oxygen

Standard cell culture systems impose environmental oxygen (O(2)) levels of 20%, whereas actual tissue O(2) levels in both developing and adult brain are an order of magnitude lower. To address whether proliferation and differentiation of CNS precursors in vitro are influenced by the O(2) environment, we analyzed embryonic day 12 rat mesencephalic precursor cells in traditional cultures with 20% O(2) and in lowered O(2) (3 +/- 2%). Proliferation was promoted and apoptosis was reduced when cells were grown in lowered O(2), yielding greater numbers of precursors. The differentiation of precursor cells into neurons with specific neurotransmitter phenotypes was also significantly altered. The percentage of neurons of dopaminergic phenotype increased to 56% in lowered O(2) compared with 18% in 20% O(2). Together, the increases in total cell number and percentage of dopaminergic neurons resulted in a ninefold net increase in dopamine neuron yield. Differential gene expression analysis revealed more abundant messages for FGF8, engrailed-1, and erythropoietin in lowered O(2). Erythropoietin supplementation of 20% O(2) cultures partially mimicked increased dopaminergic differentiation characteristic of CNS precursors cultured in lowered O(2). These data demonstrate increased proliferation, reduced cell death, and enhanced dopamine neuron generation in lowered O(2), making this method an important advance in the ex vivo generation of specific neurons for brain repair.

Diabetic retinopathy in Victoria, Australia: the Visual Impairment Project

AIM

To establish the prevalence, severity, and risk factors for diabetic retinopathy in a representative sample of Victorian residents aged 40 years and older.

METHODS

A population based, cluster sampling method was used to recruit 4744 participants (86% participation rate). Nine randomly selected, suburban Melbourne clusters and four randomly selected, rural Victorian clusters were used. Participants provided a detailed medical and personal history and underwent an ocular examination including funduscopy and fundus photography. Rural participants provided a blood sample, from which the glycosylated haemoglobin percentage was measured. The diagnosis of diabetic retinopathy was based on fundus photographs from participants with self reported diabetes.

RESULTS

The prevalence of diabetic retinopathy among people with self reported diabetes was 29. 1%. The prevalence of untreated, vision threatening retinopathy was 2.8%. Retinopathy was positively associated with a longer reported duration of diabetes diagnosis (p<0.01) and with higher fractions of glycosylated haemoglobin (p<0.01). Retinopathy was not significantly associated with age, ethnicity, body mass index, glaucoma, myopia or intake of alcohol, tobacco, or aspirin (all p > 0.05).

CONCLUSIONS

Most people in Victoria with proliferative diabetic retinopathy or clinically significant macular oedema have received laser treatment. There remains however, a small but important group who have not received treatment and whose vision is threatened. People with diabetes should be encouraged to maintain strict glycaemic control and to undergo regular screening to delay or prevent the development of retinopathy.

Management of diabetic retinopathy by Australian ophthalmologists. Working Group on Evaluation of the NHMRC Retinopathy Guideline Distribution. National Health and Medical Research Council

OBJECTIVE

To describe current management practices of diabetic retinopathy used by Australian ophthalmologists.

SETTING

Two-page self-administered questionnaire mailed to 622 ophthalmologists listed with the Royal Australian College of Ophthalmologists.

METHODS

The survey included questions about practice details such as size and location; specialty; current practice with regard to management of patients with diabetes; confidence in screening for diabetic retinopathy; and a number of patient scenarios related to screening, follow-up and treatment of diabetic retinopathy.

RESULTS

Of the 577 eligible ophthalmologists, 475 (82%) completed the questionnaire. They had been practicing ophthalmology between 1 and 50 years (median 16 years) and 89 (19%) indicated that they had a subspecialty interest either in vitreo-retinal surgery or in medical retina. For 145 (30.5%) of the ophthalmologists, at least one of their practices was located in a country area. The estimated percentage of patients with diabetes ranged from 0.1 to 60% (mean = 9.9%). Retinal specialists perform between 0 and 750 macular focal photocoagulation procedures per year (mean = 94) compared with a range of 0-350 for nonretinal specialists (mean = 10.3) (t = 6.1, P < 0.001). The ophthalmologists were presented with a hypothetical patient with cataract requiring surgery and clinically significant macular oedema that would be difficult to treat (but not impossible) because of the cataract. Seventy-seven ophthalmologists (16%) said they would delay the macular laser therapy until after the cataract surgery had been performed. In multivariate logistic regression models, nonretinal specialists were 4.44 times as likely to perform the cataract surgery first (95%CL = 1.57, 12.6) and ophthalmologists who had been in practice more than 15 years were 2.50 times as likely to perform cataract surgery first (95%CL = 1.47, 4.26). There were other examples of practice that differed from the National Health and Medical Research Council (NHMRC) guidelines in patient scenarios. The majority of ophthalmologists (60%) expressed a moderate or strong need to learn more about the management of diabetic retinopathy.

DISCUSSION

The variability in the management of diabetic retinopathy by Australian ophthalmologists and the desire of ophthalmologists to learn more about diabetic retinopathy provide evidence to support the need for the NHMRC Guidelines for Diabetic Retinopathy. These data will be used to evaluate changes in practice as a result of the implementation of the guidelines.

Stem cells and the cellular organization of the brain

The modern field of neuroscience emerged in the hands of neuroanatomists at the end of the last century. They recognized that information flows through arrays of cells and that the structure of the cells shapes the passage of information through the brain. In the middle of this century, the role of ion flux in the movement of information along axons was established. The electron microscope and the microelectrode helped to explain information transfer at the synapse, and study of the modulation of synaptic strength is currently a major area of neuroscience research. The origin of the many types of neuron seen by the early anatomists remains enigmatic, but the solution to this mystery is now emerging. The identification of stem cells and of the mechanisms that control their differentiation into distinct neuron types will contribute to a new understanding of both the origin of neuronal types and neuronal circuits. The current enthusiasm for stem cells is stimulated by interest from both the academic and nonacademic communities. These enthusiasts recognize a simple truth, that the cells are smart; they are the agents that control cell number and type in the brain. They create the structure that generates the higher order brain function. If these premises are true, then in the new century our understanding of the nervous system will be transformed by the facts of stem cell biology. J. Neurosci. Res. 59:298-300, 2000. Published 2000 Wiley-Liss, Inc.

Management of diabetic retinopathy by Australian optometrists. Working Group on Evaluation of NHMRC Retinopathy Guideline Distribution. National Health and Medical Research Council

PURPOSE

To describe current practices related to the management of diabetic retinopathy by Australian optometrists.

SETTING AND METHODS

A two-page self-administered questionnaire was mailed to a random sample of 504 Australian optometrists. The survey included questions about the practice (such as size and location); current practice with regard to management of patients with diabetic retinopathy; barriers to use of dilating drops; and a number of patient scenarios related to screening, follow-up and treatment of diabetic retinopathy.

RESULTS

Completed questionnaires were returned by 407 of the 473 eligible optometrists (86%). They had been practising optometry between 1 and 50 years (median 14). Of the 243 optometrists who provided details about the location of their practices, 145 (37%) had at least one of their practices in a rural area. The estimated percentage of patients with diagnosed diabetes ranged from 0.5 to 40% (median = 5.0%). Three-hundred and twenty-two optometrists (79%) reported that they would often or almost always ask new patients over the age of 40 whether they have diabetes. The majority of optometrists (n = 387, 95%) would often or almost always ask their new patients with diabetes about their control of blood glucose levels and the majority of optometrists (n = 330, 81%) would often or almost always tell their patients with diabetes about the importance of strict glucose control in delaying retinopathy. The most common barrier to dilated ophthalmoscopy was patients not wanting to be dilated, with 38.1% of optometrists reporting this to be a moderate or major barrier. The next most common barrier was fear of precipitating angle closure glaucoma; 17.1% of optometrists reported this to be a moderate or major barrier

CONCLUSION

The National Health and Medical Research Council (NHMRC) guidelines for the management of diabetic retinopathy are timely in relation to the expressed desire of Australian optometrists to learn more about management of diabetic retinopathy These data will be used prospectively to assess changes in management of patients with diabetic retinopathy as a result of the release of the NHMRC guidelines.

Antisense methods for discrimination of phenotypic properties of closely related gene products: Jun kinase family

Methods for the selection and characterization of antisense oligonucleotides for specifically eliminating closely related gene family members are available. High-throughput semiautomated methods using 96-well plate formats and array technology and improved assays are under active development that will streamline many steps and will likely merge. Second-generation 20-mer antisense phosphorothioate oligonucleotides containing 2'-methoxyethyl groups at the first and last 6 nucleotides with improved nuclease resistance and RNA affinity are becoming available.

Isolated connection of the right superior caval vein to the left atrium: non-invasive neonatal diagnosis

Isolated anomalous drainage of the right superior caval vein to the left atrium is a very rare cause of cyanosis in the newborn. Herein, the cross-sectional echocardiography and colour Doppler findings of this malformation are described.

The Jun kinase 2 isoform is preferentially required for epidermal growth factor-induced transformation of human A549 lung carcinoma cells

We have previously found that epidermal growth factor (EGF) mediates growth through the Jun N-terminal kinase/stress-activated kinase (JNK/SAPK) pathway in A549 human lung carcinoma cells. As observed here, EGF treatment also greatly enhances the tumorigenicity of A549 cells, suggesting an important role for JNK in cancer cell growth (F. Bost, R. McKay, N. Dean, and D. Mercola, J. Biol. Chem. 272:33422-33429, 1997). Several isoforms families of JNK, JNK1, JNK2, and JNK3, have been isolated; they arise from alternative splicing of three different genes and have distinct substrate binding properties. Here we have used specific phosphorothioate oligonucleotides targeted against the two major isoforms, JNK1 and JNK2, to discriminate their roles in EGF-induced transformation. Multiple antisense sequences have been screened, and two high-affinity and specific candidates have been identified. Antisense JNK1 eliminated steady-state mRNA and JNK1 protein expression with a 50% effective concentration (EC50) of <0.1 microM but did not alter JNK2 mRNA or protein levels. Conversely, antisense JNK2 specifically eliminated JNK2 steady-state mRNA and protein expression with an EC50 of 0.1 microM. Antisense JNK1 and antisense JNK2 inhibited by 40 and 70%, respectively, EGF-induced total JNK activity, whereas sense and scrambled-sequence control oligonucleotides had no effect. The elimination of mRNA, protein, and JNK activities lasted 48 and 72 h following a single Lipofectin treatment with antisense JNK1 and JNK2, respectively, indicating sufficient duration for examining the impact of specific elimination on the phenotype. Direct proliferation assays demonstrated that antisense JNK2 inhibited EGF-induced doubling of growth as well as the combination of active antisense oligonucleotides did. EGF treatment also induced colony formation in soft agar. This effect was completely inhibited by antisense JNK2 and combined-antisense treatment but not altered by antisense JNK1 alone. These results show that EGF doubles the proliferation (growth in soft agar as well as tumorigenicity in athymic mice) of A549 lung carcinoma cells and that the JNK2 isoform but not JNK1 is utilized for mediating the effects of EGF. This study represents the first demonstration of a cellular phenotype regulated by a JNK isoform family, JNK2.

Plasticity and stem cells in the vertebrate nervous system

How and when do vertebrate neural precursor cells choose their fates? While some studies suggest a series of commitments on the road to fate choice, many recent experiments indicate that precursor fate choices can often be changed. Additionally, the identification of common gene control mechanisms in precursors suggest that these cells share fundamental properties throughout development.

Resolution of the heterogeneous fluorescence in multi-tryptophan proteins: ascorbate oxidase

Ascorbate oxidase is a copper-containing enzyme which catalyzes a redox reaction between vitamin C and molecular oxygen. The protein, which shows a complex tertiary structure, is an homodimer of monomers, each containing three domains and 14 tryptophan residues. Recently, we have demonstrated by spectroscopic and ultracentrifugation techniques the existence of a stable dimeric intermediate along the unfolding pathway of this enzyme [Mei, G., Di Venere, A., Buganza, M., Vecchini, P., Rosato, N. & Finazzi Agrò, A. (1997) Biochemistry 36, 10917-10922]. In this study, the steady-state and dynamic fluorescence features of ascorbate oxidase have been exploited in order to find a way of monitoring the individual subsystems of the protein. The fluorescence intensity and anisotropy upon excitation at 295 nm are extremely sensitive functions of the emission wavelength, indicating a great heterogeneity of the system. The emission decay collected through a cut-off filter can be analyzed in terms of two continuous distributions of lifetimes. Using a monochromator in emission or an optical multichannel analyzer, the two distributions may be attributed to distinct components of the fluorescence spectrum. Differential quenching by cesium chloride also confirmed that the several tryptophan residues present in the protein structure may be grouped into two main classes, each with a different environment. Once the complex fluorescence decay of ascorbate oxidase was analyzed and resolved, a comparison with the crystallographic data allowed a first, approximate attribution of the protein spectroscopic properties to some of the tryptophan residues. This might provide a powerful tool of investigation about the role of definite segments of the protein in its three-dimensional structure and catalytic activity. Furthermore, the methodology set up for ascorbate oxidase can be usefully extended to other multitryptophan proteins.

Stem cells and neurogenesis in the adult brain

A new interest in replacing neurons lost to trauma or disease has been generated by findings that challenge the traditional view of the static (irreparable) adult brain. The discovery of stem cells and neurogenesis in the adult central nervous system is responsible for much of this interest.

Open-heart correction of tetralogy of Fallot in an acyanotic dog

Tetralogy of Fallot was diagnosed in an acyanotic 11-month-old dog. Predicted pressure gradient across the pulmonic valve, as assessed by use of continuous wave Doppler echocardiography, was 94.5 mm Hg. Bidirectional shunting was identified by means of selective angiography. Open-heart correction was performed, using a transatrial approach with limited ventriculotomy and cardiopulmonary bypass. The hypertrophied infundibulum was resected, the ventricular septal defect was closed primarily, and a transannular pericardial patch graft was applied. Pressure gradients across the pulmonic valve were 52.9 and 22.8 mm Hg 2 weeks and 4 months after surgery, respectively. Advances in cardiopulmonary bypass, anesthetic management, and use of the transatrial approach may improve the success of open-heart correction of tetralogy of Fallot in dogs.

Report of two sibs with Knobloch syndrome (encephalocoele and viteroretinal degeneration) and other anomalies

We report on two sibs with high myopia, vitreoretinal degeneration (VRD), and occipital encephalocoele or scalp lesion. We review the literature on Knobloch syndrome, discuss possible causes, and suggest a possible involvement of mesoderm in the morphogenesis. One case presents with very early onset of severe eye disease, whereas the other is notable for the very mild scalp defect. In addition, both appear to have an unusual pulmonary lymphatic condition.