Optometric manpower in the Commonwealth of Puerto Rico: estimates and projections, 1982-2025

BACKGROUND: The 1982 study investigated the potential impact of the IAUPR School of Optometry on the adequacy of supply of optometrists in Puerto Rico for the years of 1980-2000. This article is designed to: (1) update the 1982 study; (2) appraise the accuracy of the 1982 projections; (3) re-evaluate the status of optometric manpower in Puerto Rico through the year 2025; and (4) provide the School of Optometry with information necessary to make informed judgments about future enrollments. METHODS: Estimates of supply are based on data from the Colegio de Optometras de Puerto Rico, the Sección de Oftalmología de la Asociación Médica de Puerto Rico, and the enrollment and graduation registries from the School of Optometry. Requirements are based on estimates of annual effective demand, provider-to-population ratios, per capita demand, and optometric productivity. RESULTS: Optometrists comprised 52.2% of Puerto Rico's actively practicing vision care manpower in 1995, with a mean optometrist-to-population ratio of 8.2 per 100,000. The number ranged from 28 in Mayagüez to 107 in San Juan. Under different assumptions regarding supply, productivity, and demand, surpluses and deficits are estimated and projected for the years 1995 to 2025. CONCLUSIONS: Depending on the assumptions used, an undersupply or an oversupply of optometrists may be found in Puerto Rico, currently and in the future. Projections of supply and demand predict a considerable range--from a surplus of 961 optometrists to a deficit of 2,085 optometrists in the year 2025.     

Clinical and molecular characterization of a Brazilian patient with Pit-1 deficiency

We studied a 14 year-old girl with extreme short stature (-9.5 SDS), normal psychomotor development and signs of progressive hypothyroidism. Basal IGF-I and T4 were low. Serum GH was low after insulin-induced hypoglycemia and GH-releasing hormone administration. Both TSH and prolactin were low and did not rise after TRH administration. Gonadotropins were normal and cortisol levels were elevated. In contrast, DHEA-S levels were low and she did not develop pubic hair until 26 years of age, compatible with deficiency of a putative pituitary adrenal androgen stimulating hormone. Pituitary size was reduced on magnetic resonance imaging. Sequencing of the Pit-1 gene revealed a heterozygous C to T transition in codon 271 resulting in substitution of tryptophane for a highly conserved arginine. Her parents were homozygous normal for this locus indicating a de novo mutation with dominant expression. Genetic and phenotypic heterogeneity of patients with Pit-1 gene mutations, particularly the R271W mutation, may reveal further information about the nature of genetic silencing, imprinting, and epigenetic inheritance. The relationship of Pit-1 deficiency to abnormal adrenal secretion remains to be elucidated.     

Exploring Prostate Cancer Genome Reveals Simultaneous Losses of PTEN,FAS and PAPSS2 in Patients with PSA Recurrence after Radical Prostatectomy

The multifocal nature of prostate cancer (PCa) creates a challenge to patients’ outcome prediction and their clinical management. An approach that scrutinizes every cancer focus is needed in order to generate a comprehensive evaluation of the disease, and by correlating to patients’ clinico-pathological information, specific prognostic biomarker can be identified. Our study utilized the Affymetrix SNP 6.0 Genome-wide assay to investigate forty-three fresh frozen PCa tissue foci from twenty-three patients. With a long clinical follow-up period that ranged from 2.0–9.7 (mean 5.4) years, copy number variation (CNV) data was evaluated for association with patients’ PSA status during follow-up. From our results, the loss of unique genes on 10q23.31 and 10q23.2–10q23.31 were identified to be significantly associated to PSA recurrence (p < 0.05). The implication of PTEN and FAS loss (10q23.31) support previous reports due to their critical roles in prostate carcinogenesis. Furthermore, we hypothesize that the PAPSS2 gene (10q23.2–10q23.31) may be functionally relevant in post-operative PSA recurrence because of its reported role in androgen biosynthesis. It is suggestive that the loss of the susceptible region on chromosome 10q, which implicates PTEN, FAS and PAPSS2 may serve as genetic predictors of PSA recurrence after radical prostatectomy.     

Epindolidiones—Versatile and Stable Hydrogen‐Bonded Pigments for Organic Field‐Effect Transistors and Light‐Emitting Diodes

Hydrogen‐bonded pigments are remarkably stable high‐crystal lattice energy organic solids. Here a lesser‐known family of compounds, the epindolidiones, which demonstrates electronic transport with extraordinary stability, even in highly demanding aqueous environments, is reported. Hole mobilities in the range 0.05–1 cm² V^–1 s^–1 can be achieved, with lower electron mobilities of up to 0.1 cm² V^–1 s^–1. To help understand charge transport in epindolidiones, X‐ray diffraction is used to solve the crystal structure of 2,8‐difluoroepindolidione and 2,8‐dichloroepindolidione. Both derivatives crystallize with a linear‐chain H‐bonding lattice featuring two‐dimensional π–π stacking. Powder diffraction indicates that the unsubstituted epindolidione has very similar crystallinity. All types of epindolidiones measured here display strong low‐energy optical emission originating from excimeric states, which coexists with higher‐energy fluorescence. This can be exploited in light‐emitting diodes, which show the same hybrid singlet and low‐energy excimer electroluminescence. Low‐voltage FETs are fabricated with epindolidione, which operate reliably under repeated cyclic tests in different ionic solutions within the pH range 3–10 without degradation. Finally, in order to overcome the insolubility of epindolidiones in organic solvents, a chemical procedure is devised to allow solution‐processing via the introduction of suitable thermolabile solubilizing groups. This work shows the versatile potential of epindolidione pigments for electronics applications.     

Selective dry etching of (Sc2O3)x(Ga2O3)1−x gate dielectrics and surface passivation films on GaN

(Sc₂O₃)_x(Ga₂O₃)_1?x films grown by molecular beam epitaxy show promise for use as surface passivation layers and gate dielectrics on GaN-based high electron mobility transistors. Completely selective, low-damage, dry etching of (Sc₂O₃)_x(Ga₂O₃)_1?x films with respect to GaN can be achieved with low-power inductively coupled plasmas of CH₄/H₂/Ar with etch rates in the range 200–300 Å/min. The incident ion energies are of order 100 eV, and no roughening of the underlying GaN was observed under these conditions. Similar etch rates were obtained with Cl₂/Ar discharges under the same conditions, but GaN showed rates almost an order of magnitude higher.     

Extracellular glucose concentrations in the rat hippocampus measured by zero-net-flux: effects of microdialysis flow rate, strain, and age

The concentration of glucose in the brain's extracellular fluid remains controversial, with recent estimates and measurements ranging from 0.35 to 3.3 mM. In the present experiments, we used the method of zeronet-flux microdialysis to determine glucose concentration in the hippocampal extracellular fluid of awake, freely moving rats. In addition, the point of zero-net-flux was measured across variations in flow rate to confirm that the results for glucose measurement were robust to such variations. In 3-month-old male Sprague-Dawley rats, the concentration of glucose in the hippocampal extracellular fluid was found to be 1.00 +/- 0.05 mM, which did not vary with changes in flow rate. Three-month-old and 24-month-old Fischer-344 rats both showed a significantly higher hippocampal extracellular fluid glucose concentration, at 1.24 +/- 0.07 and 1.21 +/- 0.04 mM, respectively; there was no significant difference between the two age groups. The present data demonstrate variation in extracellular brain glucose concentration between rat strains. When taken together with previous data showing a striatal extracellular glucose concentration on the order of 0.5 mM, the data also demonstrate variation in extracellular glucose between brain regions. Traditional models of brain glucose transport and distribution, in which extracellular concentration is assumed to be constant, may require revision.     

Internet mapping for dissemination of statistical information

City and regional administrations find increasing interest in providing mapping services to their customers: citizens, businesses, non-governmental organizations, etc. The paper discusses possible architectures of implementing such services on the Internet, and then describes our own system, Descartes, in more detail. Descartes can be used in client–server mode, where the interactive client interface can be downloaded as a Java applet. Descartes is particularly suited for Web-based analysis and publication of geo-referenced statistical data. The functionality and user interface of Descartes is illustrated by some example applications of the cities of Bonn and Tilburg and of the UK Census of Population.     

Annealing and Measurement Temperature Dependence of W<Subscript>2</Subscript>B- and W<Subscript>2</Subscript>B<Subscript>5</Subscript>-Based Rectifying Contacts to <Emphasis Type="Italic">p</Emphasis>-GaN

Schottky contact formation on p-GaN using W₂B/Pt/Au and W₂B₅/Pt/Au metallization schemes was investigated using x-ray photoelectron spectroscopy (XPS), current-voltage (I-V), and Auger electron spectroscopy measurements. The Schottky barrier height (SBH) determined from XPS is 2.71 eV and 2.87 eV for as-deposited W₂B- and W₂B₅-based contacts, respectively. By comparison, fitting of the I-V curves using the thermionic field emission model gives unphysical SBHs > 4 eV due to the presence of an interfacial layer acting as an additional barrier to carrier transport. Upon annealing to ∼600–700°C, the diodes show slight deterioration in rectifying behavior due to the onset of metallurgical reactions with the GaN. The experimental dependence of the reverse leakage current on bias and measurement temperature is inconsistent with both thermionic emission and thermionic field emission models, suggesting that leakage must originate from other mechanisms such as surface leakage or generation in the depletion layer through deep-level defects.     

Identification of thyroid hormone transporters

Thyroid hormone action and metabolism are intracellular events that require transport of the hormone across the plasma membrane. We tested the possible involvement of the Na+/taurocholate cotransporting polypeptide (Ntcp) and organic anion transporting polypeptide (oatp1) in the hepatic uptake of the prohormone T4, the active hormone T3, and the metabolites rT3 and 3,3'-T2. Xenopus laevis oocytes were injected with 2.3 ng Ntcp or oatp1 cRNA and, after 2-3 days, incubated for 1 h at 25 degrees C with usually 0.1 microM 125I-labeled ligand. Uninjected oocytes showed marked uptake of iodothyronines and this was further increased by Ntcp and oatp1 cRNA, i.e., 1.9- and 2.8-fold for T4, 1.7- and 1.7-fold for T3, 1.8- and 6.0-fold for rT3, and 1.3- and 1.4-fold for 3,3'-T2, respectively. Mostly due to much lower uptake by uninjected oocytes, Ntcp and oatp1 cRNA induced larger, 12- to 76-fold increases in uptake of iodothyronine sulfates. The Ntcp cRNA-induced iodothyronine uptake was completely inhibited in Na+-deplete medium, whereas the oatp1 cRNA-induced uptake was not affected. These results suggest that hepatic uptake of thyroid hormones and their metabolites is mediated at least in part by Ntcp and oatp1.