Abstract P2-20-02: Increased Prevalence of HLA-DR3 among Breast Cancer Patients: Implications for Adjuvant Her2/neu Peptide Vaccine Trials

BACKGROUND: HER2/neu is overexpressed in approximately 25% of breast cancer (Bca) patients (pts) and the source of a number of immunogenic HLA class I and II peptides. HLA class II molecules are generally promiscuous in their peptide affinity. Previous studies have shown that HLA-DR3, which has a prevalence of 13% in the population, has a lower binding affinity to multiple HER2/neu peptides. This suggests that pts who are HLA-DR3 positive (DR3+) may respond more poorly to HER2/neu peptide vaccines than HLA-DR3 negative (DR3-). We are conducting clinical trials evaluating HER2/neu-derived peptides GP2, E75, and AE37 administered in the adjuvant setting to prevent disease recurrence in high risk pts. GP2 and E75 are class I peptides. AE37 is the Ii-Key hybrid of HER2/neu:776-790 (AE36), an HLA class II peptide. Here, we report an analysis of DR3 status and response to AE37 vaccination in our trials. METHODS: We enrolled Bca pts rendered disease-free after receiving standard adjuvant therapy. HLA-DR3 status was determined via flow cytometry performed on peripheral blood mononuclear cells. In our phase II trial, pts were randomized to six monthly inoculations of either AE37 with granulocyte-macrophage colony-stimulating factor (GM-CSF) or GM-CSF alone. In vivo immune responses were measured using a delayed-type hypersensitivity immune response (DTH). Ex vivo immune response was measured by vaccine specific proliferative activity of T-lymphocytes using standard 3H-thymidine incorporation proliferation assay and a standard ELISPOT assay measuring peptide specific interferon-γ secreting T-cells.

RESULTS: DR3 status has been determined in 131 pts; 34 (26%) are DR3+, twice the expected (13%). Demographics (age, nodal status, tumor size, HER2 expression) were similar when comparing DR3+ pts to DR3-pts, with the exception that DR3 + pts were less likely to have high grade disease (n=11, 33%) compared to DR3-pts (n=58, 60%, p=0.035). 77 pts (56 DR3-, 21 DR3+) received AE37 ± GM-CSF. Post-vaccination DTH responses were significantly larger in AE37 pts compared to their respective GM-CSF controls (DR3-pts: AE37 40 ± 7 mm, GM-CSF 1 ± 0.5 mm, P<0.00001; DR3+ pts: AE37 39 ± 8 mm, GM-CSF 6 ± 3mm, p=0.002). DTH were similar comparing DR3-and DR3+ pts in both the GM (DR3+ 6 ± 3mm vs DR3-1 ± 0.5 mm, p=NS) and in the AE37 pts (DR3+ 39 ± 8 mm vs DR3-39 ± 7 mm, p =NS). There was a non-statistically significant trend toward increased post vaccination peptide-specific T-cells measured by proliferation and ELISPOT assay when comparing AE37 pts to GM-CSF pts; however, there was no difference in assays comparing DR3+ and DR3-pts.

CONCLUSIONS: We have observed DR3 phenotype in our BCa pts at twice the expected prevalence. DR3+ pts were less likely to have high grade tumors compared to DR3-pts. Despite in vitro studies demonstrating limited binding affinity of DR3 for numerous Her2/neu-derived peptides, our pts demonstrated no statistical difference in the in vivo or ex vivo immunogenic response between DR3+ and DR3-pts to vaccination with AE37 + GM-CSF, suggesting the Ii-key hybrid peptide AE37 may overcome weakly binding MHC II phenotypes. The increased prevalence of DR3 among BCa pts warrants further study.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-20-02.

Multicenter evaluation of an automated assay for troponin I

BACKGROUND

Cardiac troponin I (cTnI) is a powerful tool to aid in the diagnosis of myocardial infarction and cardiac muscle damage. We describe an assay that overcomes problems of early assays that were often affected by cTnI degradation, assay interference, poor sensitivity, and imprecision.

METHODS

The analytical performance of the Access AccuTnI assay (Beckman Coulter) was evaluated at five institutions. Controls, zero calibrator, and diluted patient samples were used to determine precision, detection limit, functional sensitivity, and linearity. The 97.5 and 99 percentiles of a reference population were determined. Common interferents and heterophilic patient samples were tested. Equimolarity was determined by assaying samples with various ratios of free and complexed cTnI. Matched samples drawn into serum, EDTA, lithium heparin, and sodium heparin sample tubes were compared.

RESULTS

Total imprecision (CVs) was 4.0-8.8% between 0.40 and 31 microg/L cTnI. The detection limit was <0.01 microg/L. The 97.5 percentile upper reference limit (URL) was 0.03 microg/L (CV = 20%), and the 99 percentile URL was 0.04 microg/L (CV = 14%). Total CVs of 10% and 20% were seen at and above 0.06 and 0.03 microg/L, respectively. The assay was linear to >60 microg/L and not affected by common assay interferents. An equimolar response was observed with free, complexed, phosphorylated, and dephosphorylated forms of cTnI. Results were 4% lower in serum and 14% lower in EDTA plasma than in lithium heparin plasma (P <0.01), independent of cTnI concentration.

CONCLUSION

AccuTnI is a sensitive and precise assay for the measurement of cTnI.

Multicenter Evaluation of an Automated Assay for Troponin I

Background: Cardiac troponin I (cTnI) is a powerful tool to aid in the diagnosis of myocardial infarction and cardiac muscle damage. We describe an assay that overcomes problems of early assays that were often affected by cTnI degradation, assay interference, poor sensitivity, and imprecision.

Methods: The analytical performance of the Access® AccuTnITM assay (Beckman Coulter) was evaluated at five institutions. Controls, zero calibrator, and diluted patient samples were used to determine precision, detection limit, functional sensitivity, and linearity. The 97.5 and 99 percentiles of a reference population were determined. Common interferents and heterophilic patient samples were tested. Equimolarity was determined by assaying samples with various ratios of free and complexed cTnI. Matched samples drawn into serum, EDTA, lithium heparin, and sodium heparin sample tubes were compared.

Results: Total imprecision (CVs) was 4.0–8.8% between 0.40 and 31 μg/L cTnI. The detection limit was &lt;0.01 μg/L. The 97.5 percentile upper reference limit (URL) was 0.03 μg/L (CV = 20%), and the 99 percentile URL was 0.04 μg/L (CV = 14%). Total CVs of 10% and 20% were seen at and above 0.06 and 0.03 μg/L, respectively. The assay was linear to &gt;60 μg/L and not affected by common assay interferents. An equimolar response was observed with free, complexed, phosphorylated, and dephosphorylated forms of cTnI. Results were 4% lower in serum and 14% lower in EDTA plasma than in lithium heparin plasma (P &lt;0.01), independent of cTnI concentration.

Conclusion: AccuTnI is a sensitive and precise assay for the measurement of cTnI.

Visual performance after photorefractive keratectomy with a 6-mm ablation zone

PURPOSE

To prospectively examine the effect of photorefractive keratectomy with a 6-mm ablation zone on best-spectacle-corrected visual performance.

METHODS

A prospective study was conducted of 164 eyes of 164 patients with an average (+/-SD) of -4.02 +/- 1.74 diopters (range, -0.63 to -8.38 diopters spherical equivalent). Best-spectacle-corrected high-contrast and low-contrast visual acuity (18% Weber contrast) was measured with both natural and dilated pupils. Patients were tested preoperatively and at 3, 6, and 12 months after photorefractive keratectomy. Photorefractive keratectomy was performed with an argon fluoride excimer laser. Fifty-five eyes of 55 patients also underwent astigmatic keratotomy.

RESULTS

Twelve months after photorefractive keratectomy, best-spectacle-corrected high-contrast visual acuity with natural pupils showed no significant change from preoperative values; mean (+/-SD) change was 0.004 +/- 0.10 logMAR (t = 0.45, P = .65). Best-spectacle-corrected low-contrast visual acuity with natural pupils was significantly reduced compared to baseline; mean (+/-SD) change was 0.04 +/- 0.13 logMAR (t = 3.3, P = .001). The low-contrast loss was larger (1.5 lines) with dilated pupils; mean (+/-SD) change was 0.13 +/- 0.15 logMAR (t = 9.31, P < .001). Greater losses in dilated low-contrast visual acuity were associated with concurrent astigmatic ketatotomy (t = 2.28, P = .025) and corneal haze of grade 1 or greater (t = 2.71, P = .005).

CONCLUSIONS

Reductions in visual performance occur after photorefractive keratectomy with a 6-mm zone. These changes are greatest for low-contrast visual acuity with dilated pupils. Corneal haze and concurrent astigmatic keratotomy are associated with greater losses in low-contrast visual acuity. Best-spectacle-corrected low-contrast visual acuity is a sensitive measure for evaluating visual performance after refractive surgery.

Nuclear translocation of prolactin: collaboration of tyrosine kinase and protein kinase C activation in rat Nb2 node lymphoma cells

Recent evidence has suggested that prolactin (PRL), internalized by lactogen-dependent Nb2 lymphoma cells, is actively translocated to the nucleus where it binds to PRL receptors. Moreover, the mitogenic action of PRL in these cells has been separately linked to protein tyrosyl phosphorylation and activation of protein kinase C (PKC). Therefore, the coupling of PRL internalization and nuclear translocation to the activation of these signal transduction pathways was investigated. Results from control experiments indicated that 30% of internalized and 5% total cell-associated 125I-rat PRL could be recovered within nuclei obtained from Nb2 cells previously incubated with the radiolabel for 3 h at 37 degrees C. Furthermore, internalized PRL was found to be intact and not associated with any carrier proteins. Addition of tyrosine kinase (TK) antagonists, genistein or tyrphostin, significantly reduced cell surface binding, internalization, and nuclear translocation of 125I-rat PRL. In contrast, neither the level of cell-associated nor internalized hormone differed between cells treated with the PKC antagonists, staurosporine or calphostin C, and control cultures. Instead, PKC inhibition significantly reduced nuclear PRL translocation. The inhibitory effects of the TK and PKC antagonists on PRL internalization and nuclear translocation in intact Nb2 cells were verified by immunofluorescence microscopy in parallel experiments. In other experiments, each of the kinase inhibitors blocked PRL-stimulated Nb2 cell proliferation in a concentration-dependent manner. It is concluded that activated TK and PKC collaborate in the process of PRL internalization and translocation to the nucleus. TK activation may participate in PRL receptor binding or hormone internalization while activation of PKC appears to be required for its nuclear targeting. Since TK and PKC activation are required for lactogen-stimulated Nb2 cell proliferation, we suggest that a component of the mitogenic pathway in these cells is a direct nuclear interaction of PRL.

Normal activity-dependent refinement in a compressed retinotectal projection in goldfish

When the optic nerve in a goldfish is crushed, regenerating fibers can reform a normal retinotopic projection. Two processes are thought to generate this retinotopic order. One is an activity-independent process, presumed to be some form of substrate-directed growth, which generates rough retinotopy as seen in the early formed projection. The other is an activity-dependent process that generates fine retinotopy during a protracted period of refinement. This projection also displays two other behaviors. One is retinotopic plasticity, in which optic fibers can compensate for retinal or tectal ablations by expanding or compressing into the available tectal space while preserving retinotopic order. These plasticities can dramatically alter the scale of the projection. The other behavior is the formation of fixed synaptic sites in tectum. Optic fibers make a characteristic number of synaptic connections in tectum, which is not changed by increasing the number of invading optic fibers. This has been interpreted to mean that fibers compete for limited synaptic sites. How the two processes that generate order, substrate-directed growth, and activity-dependent refinement might each be affected by the expression of retinotopic plasticity and altered synaptic competition is largely unknown. In particular, it is not known how fine retinotopic order (activity-dependent refinement) might be affected by altering the scale of the projection. Would optic fibers from neighboring ganglion cells converge into the same-sized area of tectum, or would they expand or compress in proportion to the altered scale of the overall map? To explore this issue, the posterior half of tectum of goldfish was removed, and the optic nerve was crushed, thereby forcing regenerating fibers to form a compressed retinotopic projection onto the anterior half of tectum. Under these conditions, optic fibers are also forced to compete for half the normal number of synaptic sites. The effect on retinotopy was monitored at various times during regeneration by making a small spot injection of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) into nasal retina corresponding to fibers that would normally terminate in the missing posterior half of tectum. To distinguish between activity-dependent and activity-independent processes, retinal impulse activity was blocked in some animals by repeated intraocular injections of tetrodotoxin. The initial projection was found to be unaffected by impulse activity. Regardless of activity, nasal fibers failed initially to grow to the most posterior available regions, but instead were dispersed across much of the "incorrect" anterior half of tectum at 30 days.(ABSTRACT TRUNCATED AT 400 WORDS)

Activity-dependent retinotopic refinement in a low-density retinotectal projection in the goldfish: evidence favoring synaptic cooperation over competition

During optic nerve regeneration in goldfish, the label from a small retinal spot injection of WGA-HRP has been previously reported to be initially widely dispersed in the tectum and subsequently to condense into a small patch in the retinotopically appropriate location of tectum. This refinement involves two separate processes: one is activity independent and generates gross retinotopy; the other is activity dependent and mediates the formation of fine retinotopy. Since the number of synapses remains constant during this refinement, one or both of these processes may involve some form of competition for a limited number of synaptic sites. To clarify the role of synaptic competition, we created a low-density retinotectal projection in goldfish by deflecting about 20% of the optic fibers from one tectum into the opposite tectum, which was denervated of all other optic fibers. Under this condition, it was previously shown that less than half the normal density of synapses is formed. If competition for synaptic sites is a requirement of refinement, refinement should be prevented or significantly hindered. To monitor refinement during regeneration, 2 nl spot injections of WGA-HRP were made into the retina at various times after deflection. To distinguish between activity-dependent and activity-independent refinement, retinal impulse activity was blocked in some fish with repeated injections of TTX into the eye for the duration of the experiment. It was found that considerable activity-independent refinement occurred under continuous TTX blockade although the fibers remained more dispersed than in previous TTX studies when normal numbers of fibers were present. Surprisingly, in fish with normal impulse activity, the degree of activity-dependent refinement was almost normal. Labeled fibers condensed into a small area roughly comparable in size to that observed when the full complement of fibers was regenerating into tectum. These results suggest that competition for limited synaptic sites is not essential for activity-dependent refinement, which may, instead, be mediated by a cooperative process that actively promotes convergence. The findings further suggest that if synaptic competition plays a role in this system, it is in regulating activity-independent mechanisms that determine the large-scale distribution of fibers within tectum.

Nuclear co-localization of prolactin and the prolactin receptor in rat Nb2 node lymphoma cells

Previous studies have indicated that prolactin (PRL) interacts with specific, high affinity, immunoreactive binding sites within isolated rat hepatocyte nuclei. Moreover, endogenous PRL appears to be bound to this site. However, it remained important to demonstrate nuclear PRL receptors and hormonal translocation in an intact cell system. Therefore, we sought nuclear translocation of PRL and its receptor in the nucleus of PRL-dependent Nb2 node lymphoma cells. Utilizing immunofluorescence (IF) microscopy, growth-arrested cells were found to constitutively express the PRL receptor in the nucleus and in the membrane/cytosol compartments. Addition of PRL stimulated rapid hormone internalization followed by translocation to the nucleus within 6-12 hrs. The translocation of PRL was found to be reversible and dependent upon ATP. These results indicate that an early event coupled to the mitogenic action of PRL in Nb2 cells is hormone transport to the nucleus during the G1 and S phases of cell cycle. Once in the nucleus, PRL bound to its receptor may directly influence gene transcription.

Short-term dietary copper deficiency does not inhibit angiogenesis in tumours implanted in striated muscle

The effect of dietary copper deficiency on tumour growth, neovascularisation and microvascular integrity was studied in the rat cremaster muscle. Male, weanling Sprague-Dawley rats were fed purified diets which were copper deficient (< 0.5 micrograms g-1 of diet) or copper adequate (5 micrograms g-1 of diet). Seven days after initiation of diets, a chondrosarcoma was implanted in the cremaster muscle of each rat. Five, 10 or 20 days after tumour implantation, rats were anesthetised and their cremasters prepared for observation by intravital microscopy. Intraarterial injection of fluorescein isothiocyanate-conjugated albumin and subsequent observation of fluorescence in the perivascular space indicated no difference in microvascular albumin leakage between the tumour vasculature of copper deficient and copper adequate rats. Neither tumour growth (assessed by wet weight), vascular density (assessed by light microscopy), nor any ultrastructural characteristics of the tumour or its vasculature (assessed by electron microscopy) were affected by copper deficiency. In view of findings by others which indicate changes in tumour characteristics with copper deficiency, we conclude that the copper dependency of tumour growth and vascularisation is a function of the type of tumour, the host tissue, or the conditions of copper depletion.

The effect of TTX-activity blockade and total darkness on the formation of retinotopy in the goldfish retinotectal projection

In the normal goldfish, neighboring retinal ganglion cells terminate in one small tectal locus to produce the precise retinotopy characteristic of this projection. This can be directly demonstrated by labeling neighboring ganglion cells with small "spot" injections of WGA-HRP, which yield a single small patch of product at the retinotopically appropriate part of the tectum. When the optic nerve is crushed, label from these spot injections was previously found to be widely dispersed during the early phase of regeneration. With time, label subsequently condensed, typically into several discrete patches reminiscent of ocular dominance columns. In this study, we tested whether the formation of these patches required impulse activity by injecting tetrodotoxin (TTX) into the eye during regeneration. We found that impulse blockade completely inhibited the formation of discrete patches while permitting considerable condensation of the label. This implies that these patches are generated by activity but that some map "refinement" utilized cellular processes that are activity independent. This activity-independent condensation progressed at a noticeably slower rate than the equivalent condensation seen with activity, thus suggesting that activity normally participates as a "helper factor," even though it is not strictly required. Since the formation of discrete patches during regeneration provides a sensitive measure of activity-dependent refinement, this was used to further address two controversial questions concerning the role of impulse activity. One is whether there is a chronologically defined critical period for activity-dependent refinement. This was tested by blocking impulse activity for 2 to 4 months, much longer than the activity-dependent refinement is thought to last, and then permitting activity to resume. We found that multiple patches were formed following this period of late activity, thus indicating that synaptic plasticity extends for several months beyond the supposed critical period. The other question was whether spontaneous retinal activity was sufficient for activity-dependent ordering. To test this, fish were kept in constant darkness during optic nerve crush and labelled with retinal spot injections at various times during regeneration. Condensation of label with the final formation of multiple patches formed at about the same time as fish with normal visual experience. This implies that the amount and extent of correlation of spontaneous activity in retina is adequate for driving activity-dependent refinement.

Surface coat material associated with the developing otic placode/vesicle in the chick

Surface coat material (SCM) has been illustrated in association with the apical surfaces of numerous epithelia during morphogenesis. This study investigates the development of a SCM associated with the invaginating otic placode/vesicle in the chick. Glycoconjugate containing SCM was retained by the inclusion of cetylpyridinium chloride (CPC) in the fixative, histochemically visualized by using ruthenium red (RR) staining, and viewed by scanning (SEM) or transmission (TEM) electron microscopy. Initial characterization of the glycoconjugates present in this material was elucidated by using lectins conjugated to fluorescein isothiocyanate. Lectins utilized included concanavalin A (Con A), wheat germ agglutinin (WGA), and soybean agglutinin (SBA). Invagination of the otic placode was apparent as early as stage 12. By stage 15 the vesicle was beginning to separate from the surface ectoderm as evidenced by its aperture, which was altered in shape and reduced in size. All embryos fixed with glutaraldehyde containing either CPC or RR were shown to possess SCM associated with the surface ectoderm, particularly in the area of the otic placode/vesicle. Additional embryos were processed by cryofixation without prior aldehyde fixation; these also exhibited SCM. All lectins labelled the epithelium of the otic placode/vesicle. However, their binding patterns were not identical. The binding of Con A and WGA remained constant over the stages studied, while SBA increased as the otic vesicle developed. The data clearly indicate that otic placode morphogenesis is accompanied by the synthesis of SCM rich in glycoconjugates.

Problems and limitations of ECG baseline estimation and removal using a cubic spline technique during exercise ECG testing: recommendations for proper implementation

One common variety of exercise-induced artifact is baseline wander resulting from movement, respiration, and poor electrode contact. Although filters can be designed to remove much of this baseline variation, they will distort the low-frequency components of the ECG complex, such as the TP-segment, the PR-segment, and, most problematically, the ST-segment. The ST-segment is the most diagnostically relevant measure of the ECG taken during exercise. While linear baseline interpolation and removal may be adequate at lower heart rates, they also will introduce significant distortions. This is particularly evident when excessive nonlinear wander is present, as seen at higher heart rates and respiration rates. A nonlinear, third-order, polynomial estimator of baseline wander, known as the cubic spline, has been used for nearly 15 years. It is a very robust technique applied to exercise ECG recordings. Since the cubic spline is not a filter and use an a priori knowledge of the shape of the ECG signal, it estimates the true baseline and avoids distortion better. The more common implementations of this technique use relatively short ECG recordings. With the advent of increasing power in computerized ECG systems, the implementation of the cubic spline algorithm for removing baseline wander in continuous, longer-duration ECG records and in real-time processing is being attempted. However, the correct application of the cubic spline to continuous recordings is not straightforward and involves a number of previously unforeseen difficulties. The accuracy and resolution of both floating point and integer operations is critical during long-term application of the cubic spline function.(ABSTRACT TRUNCATED AT 250 WORDS)

A real-time data-logger system using an optical disk WORM for archiving continuous 12-lead ECG data during exercise testing

An exercise ECG analysis program was developed over 15 years on a number of mainframes, minicomputers and, most recently, microcomputer-based systems. It has been rehosted into both Motorola MC68000 and Intel 80286 microprocessor-based development systems and is currently used with a removable 200 Mbyte optical disk (Write-Once-Read-Many, WORM) based data-logger system that can record and store all 12 leads simultaneously and continuously for an entire exercise test (up to 38 minutes). Data is acquired with 12-bit A/D resolution at 500 samples/sec. All ECG data and patient information are archived on the optical disk for later off-line recall and analysis on a PC or real-time replay through a D/A converter. Recorded ECG signals are at patient levels so they can be replayed through the patient cable box on any commercial system. Current development includes both simultaneous on-line processing and storage of 12-lead ECG data and off-line processing and development performed on the long-term, continuous ECG data being archived on optical disk. Patient medical histories and clinical information are separately entered into an applications database, where ECG measures and test results are later included. This new optical disk based exercise ECG database contains more than 600 complete exercise tests and is projected to increase to nearly 3,000 within 2 years.

Effect of histamine on cardiac sarcolemmal calcium binding as indicated by use of ionic lanthanum

To determine whether the inotropic effect of histamine might be associated with enhanced calcium binding to the sarcolemmal-glycocalyx complex, the effect of histamine on lanthanum binding to the cell membrane in the presence of verapamil was assessed. Rabbit hearts were perfused firstly with histamine, secondly with histamine and verapamil, and subsequently with histamine in the presence of lanthanum and verapamil. Subsequent transmission electron microscopy showed the presence of bound lanthanum on both the cellular surface and cytoplasmic vesicles of most cardiac myocytes, which is in contrast to the absence of lanthanum binding that occurs in the presence of verapamil alone. Furthermore, this histamine mediated enhancement of lanthanum binding is not affected by the H1 antagonist diphenhydramine but is reduced by the H2 antagonist cimetidine. This visual evidence of an apparent enhancement of lanthanum binding under histamine and subsequent attenuation with cimetidine supports the hypothesis that histamine may exert its positive inotropic effect by causing increased calcium binding to the sarcolemmal-glycocalyx complex of cardiac muscle and that the effect is mediated at least in part by H2 receptors.

Histamine induced alteration of calcium binding to microvascular endothelium as indicated by use of ionic lanthanum

To determine whether histamine's effect on microvascular permeability might be associated with altered calcium binding, the influence of histamine on lanthanum binding to vascular endothelium was assessed in the presence of verapamil. Isolated rabbit hearts were perfused firstly with histamine, secondly with histamine and verapamil, and subsequently with histamine in the presence of lanthanum and verapamil. Examination by transmission electron microscopy showed that 92% of microvessels examined contained bound lanthanum on plasma membranes, plasmalemmal vesicles, or endothelial clefts of vascular endothelium, or all three, in both atria and ventricles, which is in contrast to the low proportion (4%) of microvessels containing bound lanthanum found in the presence of verapamil alone. The enhancement of lanthanum binding was reduced by both H1 and H2 receptor antagonists. This evidence supports the hypothesis that the increase in vascular permeability with histamine may be associated with increased calcium binding to vascular endothelial membranes and that both H1 and H2 receptors play a part in this activity.

Surface coat material associated with the cells of the developing lens vesicle in the chick embryo

Ruthenium red (RR) and cetylpyridinium chloride (CPC) were used to demonstrate the distribution of cell surface coat material (SCM) on the free epithelial surface of the developing lens vesicle in stages 14-17 (50-64 hours) chick embryos. Observations were made by light microscopy and transmission. (TEM) and scanning (SEM) electron microscopy. A progressive increase in SCM is observed on cellular apices within the epithelium of the lens vesicle by means of RR staining, particularly at the margins of the aperture which are the sites of presumptive fusion. In contrast, a relatively thin layer of SCM persist on the adjacent surface ectoderm. Ruthenium red-positive SCM extends across the aperture of the lens vesicle prior to initial contact between the advancing epithelial surfaces. The presence of abundant SCM is interpreted as a possible significant prerequisite to invagination and to epithelial adhesion and fusion prior to detachment of the lens from surface ectoderm. When CPC is added to the fixative, a flocculent precipitate over the aperture of the lens vesicle and an associated band of modified surface ectoderm which extends ventrally from its lower margin are observed. The modified ectoderm and associated SCM likely represent a presumptive region of active coordinated cellular migration.

The case for self-insurance

Faced with escalating costs for primary professional liability insurance, many hospitals are considering self-insuring at least part of their professional liability risk. Self-insurance offers advantages over commercial insurance in several areas. The most important corollary of self-insurance from the perspective of the board is the need for more intimate involvement in the quality of medical practice in the institution.

Morphogenesis of rod cells in the retina of the albino rat: a scanning electron microscopic study

This study presents scanning electron microscopic (SEM) observations of topographical changes that occur during morphogenesis of rod cells in the albino rat. Correlative transmission electron microscopy (TEM) was also utilized. Albino rats ranging in age from birth to three weeks were used for the study. Tissues were prepared by conventional methods for SEM and TEM. At birth, numerous irregularly arranged inner segments extend from the external surface of the sensory retina. They are spherical, smooth surfaced and possess a randomly oriented cilium. The internal morphology of these immature inner segments is comparable to that observed in other vertebrate species. Statistical analysis reveals a rapid increse in the number of rod cells during the first week. This period is characterized by the elongation of inner segments and their associated cilia. Microvilli project from the apices of Müller cells, but not from adjacent inner segments. By day 5, cilia occasionally display small bulbous outer segments. They are more numerous by day 8 and are usually eccentrically positioned at the tips of cilia. By day 11, outer segments are abundant and frequently obscure from view the underlying inner segments and associated cilia. Elongated cylindrical outer segments are present within the posterior retina at the end of the second week. However, rod cell morphogenesis lags in the peripheral retina. Topographical variations between developing photoreceptor cells in mammalian and non-mammalian retinas are discussed.

Development of Bruch's membrane in the chick: an electron microscopic study

The development of fibrous connective tissue in Bruch's membrane within the choroid of chronologically staged chick embryos was observed by means of transmission electron microscopy. The appearance of these connective tissue elements follows an orderly developmental sequence. The first component of Bruch's membrane to appear is a continuous basal lamina at the basal surface of the presumptive retinal pigment epithelium (RPE) at 21/2 days. Microfibrils and associated amorphous material are present in the adjacent connective tissue space. A discontinuous inner collagenous layer is observed at the basal aspect of the RPE during the fourth day. A definitive elastic layer is present during the ninth day and becomes more apparent following subsequent stages of development. An outer collagenous layer begins development during the tenth and twelfth days. Collagenous fibrils average 37 nm in diameter and display axial periodicity measuring 46 nm between major periods. These measurements increase with age as do the number of collagenous fibrils. Only isolated patches of basal lamina are observed in association with the choriocapillary endothelium by the twentieth day.

Scanning electron microscopy of developing photoreceptors in the chick retina

Photoreceptor morphogenesis in the sensory retina of chicks of 2 to 20 days incubation age was studied by scanning electron microscopy (SEM) and correlative transmission electron microscopy (TEM). At 9.5 days spherical inner segments extend into the subretinal space (optic ventricle). They are randomly arranged with chiefly smooth surfaces and contain centrioles, polyribosomes and microtubules. Microvilli project primarily from Müller cells. By the twelfth day immature ellipsoid and myoid regions have formed. Microvilli are abundant on the lateral surfaces of inner segments and extend over the entire spherical surface by the fifteenth day. Occasional cilia with surrounding depressions at their bases were also observed. Inner segments are more symmetrically arranged due to close proximity of photoreceptor cells. Inner segments elongate during the sixteenth day; many display a transitional ovoid form. Microvilli become less numerous but some persist as calycal processes. By the eighteenth day, conical shaped outer segments appear. Thereafter, all photoreceptor cells are comparable to those in the mature retina. Abundant microvilli on the external surface of the sensory retina suggest a supportive role in supplying adequate nutrition to the sensory retina during morphogenesis. The establishment and continual development of the ellipsoid and myoid appear to be primarily responsible for the elongation of photoreceptor cells.

Be ready for the out-of-control ED patient

Increased use of emergency departments has opened up physicians and hospitals to a variety of unusual liability charges, especially with regard to the violent or destructive patient. In addition, the expansion of the legal concept of "foreseeability" has made this litigation more difficult to defend in court. Therefore, it is vital for an emergency department to have a sound, working screening system and accurate method of documenting patient conduct.

Apical bearing and success with the Bausch and Lomb Soflens (polymacon) contact lens

Thirty-three patients (63 eyes) were fitted with Bausch and Lomb soflens (polymacon) contact lenses. The initial lenses were selected with the mean posterior apical radius 0.45 mm flatter than the flat keratometer reading of the cornea (S.D. = +/-0.31 MM). Forty-eight eyes (76%) were successfully fitted and 15 eyes (25%) were unsuccessfully fitted. Among the successfully fitted eyes, 31 were fitted with the initial lens, 12 required steeper lenses, and 5 required flatter lenses. The final successfully fitted lenses were on the average 0.40 mm flatter (S.D. = +/-0.32 mm) than the flat keratometer reading of the cornea. The unsuccessfully fitted lenses were not significantly different than the successfully fitted lenses, being 0.47 mm flatter (S.D. = +/-O.32 mm) than the flat keratometer reading of the cornea. Although the central lens-cornea relationship is helpful in fitting the Soflens, the number of successful results are increased significantly by changing to a lens with different parameters when lens performance and patient response are not optimal.