Screening for vision-threatening diabetic retinopathy in South India: comparing portable non-mydriatic and standard fundus cameras and clinical exam.

PurposeTo evaluate the sensitivity and specificity of a portable non-mydriatic fundus camera to diagnose vision-threatening diabetic retinopathy (VTDR).Patients and methodsA prospective, single-site, comparative instrument validation study was undertaken at the Aravind Eye Care System. Overall, 155 subjects with and without diabetes were recruited. Images from 275 eyes were obtained with the (1) non-mydriatic Smartscope, (2) mydriatic Smartscope, and (3) mydriatic table-top camera of the macular, nasal, and superotemporal fields. A retina specialist performed a dilated fundus examination (DFE), (reference standard). Two masked retina specialists graded the images. Sensitivity and specificity to detect VTDR with the undilated Smartscope was calculated compared to DFE.ResultsGraders 1 and 2 had a sensitivity of 93% (95% confidence interval (CI): 87-97%) and 88% (95% CI: 81-93%) and a specificity of 84% (95% CI: 77-89%) and 90% (95% CI: 84-94%), respectively, in diagnosing VTDR with the undilated Smartscope compared to DFE. Compared with the dilated Topcon images, graders 1 and 2 had sensitivity of 88% (95% CI: 81-93%) and 82% (95% CI: 73-88%) and specificity of 99% (95% CI: 96-100%) and 99% (95% CI: 95-100%).ConclusionsRemote graders had high sensitivity and specificity in diagnosing VTDR with undilated Smartscope images, suggesting utility where portability is a necessity.

Distinct mechanisms for the induction and maintenance of allograft tolerance with CTLA4-Fc treatment.

A murine CTLA4/Fc gamma2a heavy chain (mCTLA4-Fc) chimeric fusion molecule was used in B6AF1 recipients of BALB/c pancreatic islet allografts to study the induction and maintenance of tolerance following inhibition of the CD28-B7 pathway for T cell activation. Donor-specific tolerance was achieved by administering 100 microg of mCTLA4-Fc on alternate days for 14 days (8 total doses) or a single 500 microg dose of mCTLA4-Fc on day 2 after transplant. Tolerance was mediated by long-lived peripheral lymphocytes and showed features of organ and alloantigen specificity. Whereas tolerance could not be established in allograft recipients receiving simultaneous mCTLA4-Fc and rIL-2, previously tolerant animals did not reject their grafts when given IL-2, suggesting that the induction and maintenance phases of tolerance were distinct and separate. The maintenance of donor-specific tolerance was an active immunologic process that was CD4+ T cell dependent and could be adoptively transferred to naive lymphocytes, but could not be explained by apoptosis or deletion of alloreactive T cells. Although an IL-2-sensitive mechanism such as anergy may contribute toward the induction of tolerance, its maintenance involves active suppression.

A method for preparing chelate-cytokine conjugates with retention of protein structure, biological activity, and pharmacokinetic properties.

The chelating agent diethylenetriaminepentaacetic acid (DTPA) has been conjugated site-specifically to the N-terminus of recombinant human interleukin-2 (rhIL-2) by reaction with DTPA dianhydride at an initial pH of 6.0, thus demonstrating broader application of the conjugation method previously described for the structurally related cytokine rhG-CSF (Ralph et al., 1995). Purity of the DTPA-rhIL-2 conjugate, isolated by cation-exchange FPLC, and chelation of 111In were revealed by cation-exchange HPLC. Purity of the conjugate as well as chelation of radiometal were also demonstrated by SDS-PAGE and TLC, respectively. The stoichiometric molar ratio of DTPA to protein for the conjugate was approximately 1:1 as determined by TLC and mass spectrometry. Localization of the DTPA moiety was resolved by a peptide mapping procedure. The protein retained > 95% secondary structure (alpha helicity) following the conjugation. Addition of metal induced an approximate 22% loss of secondary structure for the conjugate. The in vitro biological activity of the protein was unaffected by the conjugated DTPA, even with chelated metal. Pharmacokinetic analysis of DTPA-conjugated cytokines, following chelated 111In, showed clearance and pharmacokinetic parameter values comparable to those of the corresponding unmodified cytokine. DTPA-conjugated cytokines may prove useful in cytokine research, and furthermore may represent a novel class of molecules for imaging, diagnosing, and/or treatment of malignancies where the cytokine receptor is overexpressed.

In vivo dissolution measurement with indium-111 summation peak ratios.

Dissolution of [111In]labeled tablets was measured in vivo in a totally noninvasive manner by using a modification of the perturbed angular correlation technique known as the summation peak ratio method. This method, which requires the incorporation of only 10-12 microCi into the dosage form, provided reliable dissolution data after oral administration of [111In]lactose tablets. These results were supported by in vitro experiments which demonstrated that the dissolution rate as measured by the summation peak ratio method was in close agreement with the dissolution rate of salicylic acid in a [111In]salicylic acid tablet. The method has the advantages of using only one detector, thereby avoiding the need for complex coincidence counting systems, requiring less radioactivity, and being potentially applicable to a gamma camera imaging system.

Interaction of ethanol with 111In-labelled membranes: evaluation by the perturbed angular correlation-sum peak ratio method.

The interaction of ethanol with erythrocyte ghosts and vesicles composed of brain lipid extracts labelled with indium-111 was studied using the sum peak ratio method of perturbed angular correlation measurements. Membranes from animals that were fed diets containing ethanol for 10 days demonstrated resistance to the decrease in sum peak ratio values observed in control animals. Thus, repeated administration of ethanol induces changes in the properties of biological membranes, possibly by altering phospholipid composition, which is reflected in the anisotropy of membrane-associated 111In-labelled nuclei as measured by sum peak ratios.

Chromosome aberrations acquired in vitro by human B-cell lines. II. Distribution of break points.

Among 165 human B-cell lines examined, 57 were found to have karyotypic abnormalities that involved chromosome breakage. The sites of breakage were identified with quinacrine-, Giemsa-, and reverse-banding techniques, and the distribution of 239 break points was plotted. A pronounced excess of telomeric and, to a lesser extent, centromeric breaks was observed. Chromosomes No. 7, 8, 9, 11, and 14 were involved in structural rearrangements more often and chromosomes No. 2, 5, 10, 20, and X less often than was predicted on the basis of their relative lengths. Lines derived from patients with different categories of disorders varied in the distribution of break points throughout the karyotype. In this sample of cell lines, No. 8q; 14q translocations were found only in cultures derived from patients with Burkitt's lymphoma and were never observed to arise among other Epstein-Barr virus-carrying lines even after several hundred cell generations in vitro. An additional feature, which was evidently restricted to lines derived from leukemia or lymphoma patients, was the presence of interstitial insertion, deletion, or reduplication, particularly involving the long arm of chromosome No. 1.

Chromosome aberrations acquired in vitro by human B-cell lines. I. Gains and losses of material.

Gains and losses of chromosomes or chromosome arms were recorded in 45 of 165 human B-cell lines. Most aberrations were acquired in vitro, and their frequency was related to duration of culture. Gains occurred more frequently than losses and their distribution was nonrandom. Chromosomes most commonly affected were No. 3, 7, 8 (particularly 8q), 9, 12, and 21. Certain differences in the frequency of particular aberrations appeared to be related to the clinical conditions of the patients from whom the lines were derived. The distribution of chromosome gains in this material was correlated with those detected in direct preparations from human tumors.