Consensus Guidelines for Ocular Surveillance of von Hippel-Lindau Disease

PURPOSE

To develop guidelines for ocular surveillance and early intervention for individuals with von Hippel-Lindau (VHL) disease.

DESIGN

Systematic review of the literature.

PARTICIPANTS

Expert panel of retina specialists and ocular oncologists.

METHODS

A consortium of experts on clinical management of all-organ aspects of VHL disease was convened. Working groups with expertise in organ-specific features of VHL disease were tasked with development of evidence-based guidelines for each organ system. The ophthalmology subcommittee formulated questions for consideration and performed a systematic literature review. Evidence was graded for topic quality and relevance and the strength of each recommendation, and guideline recommendations were developed.

RESULTS

The quality of evidence was limited, and no controlled clinical trial data were available. Consensus guidelines included: (1) individuals with known or suspected VHL disease should undergo periodic ocular screening (evidence type, III; evidence strength, C; degree of consensus, 2A); (2) patients at risk of VHL disease, including first-degree relatives of patients with known VHL disease, or any patient with single or multifocal retinal hemangioblastomas (RHs), should undergo genetic testing for pathologic VHL disease gene variants as part of an appropriate medical evaluation (III/C/2A); (3) ocular screening should begin within 12 months after birth and continue throughout life (III/C/2A); (4) ocular screening should occur approximately every 6 to 12 months until 30 years of age and then at least yearly thereafter (III/C-D/2A); (5) ocular screening should be performed before a planned pregnancy and every 6 to 12 months during pregnancy (IV/D/2A); (6) ultra-widefield color fundus photography may be helpful in certain circumstances to monitor RHs, and ultra-widefield fluorescein angiography may be helpful in certain circumstances to detect small RHs (IV/D/2A); (7) patients should be managed, whenever possible, by those with subspecialty training, with experience with VHL disease or RHs, or with both and ideally within the context of a multidisciplinary center capable of providing multiorgan surveillance and access to genetic testing (IV/D/2A); (8) extramacular or extrapapillary RHs should be treated promptly (III/C/2A).

CONCLUSIONS

Based on available evidence from observational studies, broad agreement was reached for a strategy of lifelong surveillance and early treatment for ocular VHL disease. These guidelines were endorsed by the VHL Alliance and the International Society of Ocular Oncology and were approved by the American Academy of Ophthalmology Board of Trustees.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

The real-world efficacy and safety of faricimab in neovascular age-related macular degeneration: the TRUCKEE study - 6 month results

BACKGROUND/OBJECTIVE

Investigate real-world patients receiving faricimab for the treatment of neovascular age-related macular degeneration (nAMD).

SUBJECTS/METHODS

Multicenter, retrospective chart review was conducted on patients treated with faricimab for nAMD from February 2022 to September 2022. Collected data includes background demographics, treatment history, best-corrected visual acuity (BCVA), anatomic changes, and adverse events as safety markers. The main outcome measures are changes in BCVA, changes in central subfield thickness (CST) and adverse events. Secondary outcome measures included treatment intervals and presence of retinal fluid.

RESULTS

After one injection of faricimab, all eyes (n = 376), previously-treated (n = 337) and treatment-naïve (n = 39) eyes demonstrated a + 1.1 letter (p = 0.035), a + 0.7 letter (p = 0.196) and a + 4.9 letter (p = 0.076) improvement in BCVA, respectively, and a - 31.3 μM (p < 0.001), a - 25.3 μM (p < 0.001) and a - 84.5 μM (p < 0.001) reduction in CST, respectively. After three injections of faricimab, all eyes (n = 94), previously-treated (n = 81) and treatment-naïve (n = 13) eyes demonstrated a + 3.4 letter (p = 0.03), a + 2.7 letter (p = 0.045) and a + 8.1 letter (p = 0.437) improvement in BCVA, and a - 43.4 μM (p < 0.001), a - 38.1 μM (p < 0.001) and a - 80.1 μM (p < 0.204) reduction in CST, respectively. One case of intraocular inflammation was observed after four injections of faricimab and resolved with topical steroids. One case of infectious endophthalmitis was treated with intravitreal antibiotics and resolved.

CONCLUSIONS

Faricimab has demonstrated improvement or maintenance of visual acuity for patients with nAMD, along with rapid improvement of anatomical parameters. It has been well-tolerated with low incidence of treatable intraocular inflammation. Future data will continue to investigate faricimab for real-world patients with nAMD.

Advances in retinopathy of prematurity imaging

Retinopathy of prematurity (ROP) remains the leading cause of childhood blindness worldwide. Recent advances in ROP imaging have significantly improved our understanding of the pathogenesis and pathophysiological course of ROP including the acute phase, regression, reactivation, and late complications, known as adult ROP. Recent progress includes various contact and noncontact wide-field imaging devices for fundus imaging, smartphone-based fundus photography, wide-field fluorescein angiography, handheld optical coherence tomography (OCT) devices for wide-field en face OCT images, and OCT angiography. Images taken by those devices were incorporated in the recently updated guidelines of ROP, the International Classification of Retinopathy of Prematurity, Third Edition (ICROP3). ROP imaging has also allowed the real-world adoption of telemedicine- and artificial intelligence (AI)-based screening. Recent study demonstrated proof of concept that AI has a high diagnostic performance for the detection of ROP in a real-world screening. Here, we summarize the recent advances in ROP imaging and their application for screening, diagnosis, and management of ROP.

Referable Macular Hemorrhage-A Clinically Meaningful Screening Target in Newborn Infants. Position Statement of the Association of Pediatric Retina Surgeons

Universal newborn eye screening facilitates early diagnosis of ocular abnormalities and mitigates vision loss. "Referral warranted" eye disease is present at birth in about 5.5% of term infants, with "macular hemorrhage impinging on the fovea" representing about 50% of referral warranted disease. The Association of Pediatric Retina Surgeons held a symposium on February 9, 2021 that culminated in a position statement on "referable macular hemorrhage" (RMH) in newborn infants. RMH is meaningful in that in can cause amblyopia through deprivation, can be readily captured with wide-angle photography in a safe and efficient manner, and may lead to early intervention with mitigation of vision loss. [Ophthalmic Surg Lasers Imaging Retina. 2022;53:3-6.].

80 Years of vision: preventing blindness from retinopathy of prematurity

Retinopathy of prematurity (ROP) is one of the leading yet preventable causes of childhood blindness worldwide. The purpose of this review is to provide a practical template for observational and treatment methods in order to reduce the overall incidence of any ROP and to improve both short-term and long-term outcomes once Type 1 ROP (treatable ROP) develops.

OUTER RETINAL INJURY SECONDARY TO MEMBRANE PEELING WITH INTERNAL LIMITING MEMBRANE FORCEPS

PURPOSE

To present a case of visually significant retinal injury due to internal limiting membrane (ILM) peeling using ILM forceps alone.

METHODS

Case report.

RESULTS

A 60-year-old woman who underwent ILM peeling for an epiretinal membrane presented with linear central scotomata. Peeling had been initiated and performed with ILM forceps alone, without the use of other surgical instruments. Fundus examination and spectral domain optical coherence tomography imaging confirmed the presence of several discrete areas of inner and outer retinal injury in the macula, which corresponded to her scotomata.

CONCLUSION

This is a case of visually significant retinal injury due to ILM peeling that was performed with ILM forceps alone. Improper peeling technique can transmit injurious forces to the retina. Surgeons must be mindful of the biomechanical forces involved in ILM peeling to minimize traction on the retina.

Inversion Recovery Ultrashort TE MR Imaging of Myelin is Significantly Correlated with Disability in Patients with Multiple Sclerosis

BACKGROUND AND PURPOSE

MR imaging has been widely used for the noninvasive evaluation of MS. Although clinical MR imaging sequences are highly effective in showing focal macroscopic tissue abnormalities in the brains of patients with MS, they are not specific to myelin and correlate poorly with disability. We investigated direct imaging of myelin using a 2D adiabatic inversion recovery ultrashort TE sequence to determine its value in assessing disability in MS.

MATERIALS AND METHODS

The 2D inversion recovery ultrashort TE sequence was evaluated in 14 healthy volunteers and 31 patients with MS. MPRAGE and T2-FLAIR images were acquired for comparison. Advanced Normalization Tools were used to correlate inversion recovery ultrashort TE, MPRAGE, and T2-FLAIR images with disability assessed by the Expanded Disability Status Scale.

RESULTS

Weak correlations were observed between normal-appearing white matter volume (R = -0.03, P = .88), lesion load (R = 0.22, P = .24), and age (R = 0.14, P = .44), and disability. The MPRAGE signal in normal-appearing white matter showed a weak correlation with age (R = -0.10, P = .49) and disability (R = -0.19, P = .31). The T2-FLAIR signal in normal-appearing white matter showed a weak correlation with age (R = 0.01, P = .93) and disability (R = 0.13, P = .49). The inversion recovery ultrashort TE signal was significantly negatively correlated with age (R = -0.38, P = .009) and disability (R = -0.44; P = .01).

CONCLUSIONS

Direct imaging of myelin correlates with disability in patients with MS better than indirect imaging of long-T2 water in WM using conventional clinical sequences.

Segmental Scleral Buckle Surgical Technique for Repair of a Rhegmatogenous Retinal Detachment in Retinoblastoma: A Case and Review of the Literature

Purpose

The aim of this study was to describe the surgical repair of a rhegmatogenous retinal detachment (RRD) with a posterior break in a child with retinoblastoma (RB).

Methods

Retrospective case report and review of the English language literature. Retrospective review of an 11-month-old male with bilateral retinoblastoma who developed a RRD with a posterior retinal break in his better-seeing eye after treatment with cryotherapy. A review of all published cases to date of RRD in patients with RB is presented.

Results

The patient underwent a posterior segmental scleral buckle without subretinal fluid drainage with successful reattachment of the retina and no extraocular extension of RB.

Conclusions

RRDs in RB patients may be successfully repaired with anatomic success and no extraocular tumor extension. Even for patients with a posterior break, a segmental scleral buckle without drainage of subretinal fluid is a viable option and long-term excellent vision is a possible outcome.

Late-Onset Retinal Findings and Complications in Untreated Retinopathy of Prematurity

PURPOSE

To investigate late retinal findings and complications of eyes with a history of retinopathy of prematurity (ROP) that did not meet treatment criteria and did not receive treatment during infancy.

DESIGN

Retrospective, nonconsecutive, noncomparative, multicenter case series.

PARTICIPANTS

Three hundred sixty-three eyes of 186 patients.

METHODS

Data were requested from multiple providers on premature patients with a history of ROP and no treatment during infancy who demonstrated late retinal findings or complications and included age, gender, gestational age and weight, zone and stage at infancy, visual acuity, current retina vascularization status, vitreous character, presence of peripheral retinal findings such as lattice retinal tears and detachments (RDs), retinoschisis, and fluorescein findings.

MAIN OUTCOME MEASURES

Rate of RDs and factors conferring a higher risk of RDs.

RESULTS

The average age was 34.5 years (range, 7-76 years), average gestational age was 26.6 weeks (range, 23-34 weeks), and average birth weight was 875 g (range, 425-1590 g). Findings included lattice in 196 eyes (54.0%), atrophic holes in 126 eyes (34.7%), retinal tears in 111 eyes (30.6%), RDs in 140 eyes (38.6 %), tractional retinoschisis in 44 eyes (11.9%), and visible vitreous condensation ridge-like interface in 112 eyes (30.5%). Fluorescein angiography (FA) was performed in 113 eyes, of which 59 eyes (52.2%) showed leakage and 16 eyes (14.2%) showed neovascularization. Incomplete vascularization posterior to zone 3 was common (71.6% of eyes). Retinal detachments were more likely in patients with a gestational age of 29 weeks or less (P < 0.05) and in eyes with furthest vascularization to posterior zone 2 eyes compared with zone 3 eyes (P = 0.009).

CONCLUSIONS

Eyes with ROP not meeting the treatment threshold during infancy showed various late retinal findings and complications, of which RDs were the most concerning. Complications were seen in all age groups, including patients born after the Early Treatment for Retinopathy of Prematurity Study. Contributing factors to RDs included atrophic holes within peripheral avascular retina, visible vitreous condensation ridge-like interface with residual traction, and premature vitreous syneresis. We recommend regular examinations and consideration of ultra-widefield FA examinations. Prospective studies are needed to explore the frequency of complications and benefit of prophylactic treatment and if eyes treated with anti-vascular endothelial growth factor therapy are at risk of similar findings and complications.

Coats-like Exudative Vitreoretinopathy in Retinitis Pigmentosa: Ocular Manifestations and Treatment Outcomes

PURPOSE

To provide a comprehensive review of the ocular manifestations, outcomes, and genetic findings in patients with Coats-like retinitis pigmentosa (RP).

DESIGN

Multicenter, retrospective, nonconsecutive case series.

PARTICIPANTS

Patients with a diagnosis of RP demonstrating Coats-like exudative vitreoretinopathy between January 1, 2008, and October 1, 2019.

METHODS

Evaluation of ocular findings at RP diagnosis and at time of presentation of Coats-like exudative vitreoretinopathy, pedigree analysis, genetic testing, retinal imaging, and anatomic outcomes after treatment.

MAIN OUTCOME MEASURES

Visual acuity, ophthalmoscopy results, OCT results, fluorescein angiography results, and identification of genetic mutations.

RESULTS

Nine patients diagnosed with RP and demonstrating Coats-like exudative vitreoretinopathy were included. Median age at time of RP diagnosis was 8 years (range, 1-22 years), and median age at presentation of Coats-like exudative vitreoretinopathy was 18 years (range, 1-41 years). Seven patients were female, and 2 were male. The genetic cause of disease was identified in 6 patients. Three patients demonstrated Coats-like fundus findings at the time of RP diagnosis. Exudative retinal detachment (ERD) localized to the infratemporal periphery was present in all patients, with bilateral disease observed in 7 patients. In all treated patients, focal laser photocoagulation was used to treat leaking telangiectasias and to limit further ERD expansion. Cystoid macular edema refractory to carbonic anhydrase inhibitor therapy and ultimately amenable to treatment with intravitreal anti-vascular endothelial growth factor injection was observed in 4 patients.

CONCLUSIONS

Coats-like vitreoretinopathy is present in up to 5% of all RP patients. The term Coats-like RP is used colloquially to describe this disease state, which can present at the time of RP diagnosis or, more commonly, develops late during the clinical course of patients with longstanding RP. Coats-like RP is distinct from Coats disease in that exudative pathologic features occur exclusively in the setting of a coexisting RP diagnosis, is restricted to the infratemporal retina, can affect both eyes, and does not demonstrate a male gender bias. Given the risk of added vision loss posed by exudative vitreoretinopathy in patients with RP, a heightened awareness of this condition is critical in facilitating timely intervention.

Longitudinal Examination of Fellow-Eye Vascular Anomalies in Coats' Disease With Widefield Fluorescein Angiography: A Multicenter Study

BACKGROUND AND OBJECTIVE

Retinovascular anomalies in the fellow eyes of patients with Coats' disease have been described, but the clinical significance is unknown, as well as whether these lesions progress over time.

PATIENTS AND METHODS

This is an international, multicenter, retrospective, observational cohort study of fellow-eye abnormalities on widefield fluorescein angiography in patients with Coats' disease.

RESULTS

Three hundred fifty eyes of 175 patients with Coats' disease were analyzed. A total of 33 patients (18.8%) demonstrated abnormal fellow-eye findings: 14 (42.4%) telangiectasias, 18 (54.5%) aneurysms, six (18.2%) segmental non-perfusion, six (18.2%) leakage, and two (6.0%) vascular tortuosity. All eyes were asymptomatic, and none of the lesions progressed over time. There was no association between fellow-eye findings with severity of Coats' disease (P = .16), patient age (P = .16), or presence of systemic vascular disease (P = .16).

CONCLUSIONS

The vascular abnormalities in fellow eyes of patients with Coats' disease did not progress over time. Observation is a reasonable initial management strategy. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:221-227.].

Ocular Manifestations of Cutis Marmorata Telangiectatica Congenita

PURPOSE

To describe the range of ocular manifestations in cutis marmorata telangectatica congenita (CMTC).

DESIGN

Multicenter, retrospective, nonconsecutive case series.

PARTICIPANTS

Patients with a diagnosis of CMTC referred for ophthalmologic evaluation between January 1, 2015, and December 31, 2018.

METHODS

Evaluation of ocular findings at presentation, systemic manifestations suggestive of a diagnosis of CMTC, genetic testing, and visual outcomes after treatment.

MAIN OUTCOME MEASURES

Visual acuity, findings on ophthalmoscopy, and results of fluorescein angiography.

RESULTS

Nine patients with CMTC diagnosed clinically based on stereotypical cutaneous vascular malformations were included. The median age at presentation was 8 weeks (range, 2 weeks-4 years). Six patients were female and 3 were male. Avascular retina was identified on dilated fundus examination, fluorescein angiography, or both in 11 eyes of 6 patients. Retinal neovascularization was present bilaterally in 2 patients at presentation. One patient demonstrated retinal venous tortuosity, and another patient showed mild straightening of nasal retinal vessels in both eyes. Two patients (2 eyes) demonstrated retinal detachment (RD). Both were managed surgically. One infant demonstrated RD, whereas the other child showed extensive neovascularization and later progressed to combined tractional-rhegmatogenous detachment. A unique constellation of lacy peripheral capillary anomalies with prominent terminal vascular bulbs was noted in 3 patients. Granular pigment abnormalities were noted in the macula in 5 patients. Two patients demonstrated glaucoma, 1 requiring surgical intervention. Two patients demonstrated features of Adams-Oliver syndrome, with genetic testing identifying a Notch1 mutation in 1 patient.

CONCLUSIONS

Retinal vascular abnormalities in CMTC may occur more frequently than recognized previously. Given the variability of ocular involvement and the potential for rapidly progressive retinal vascular abnormalities and development of RD, complete ophthalmologic evaluation including measurement of intraocular pressure, gonioscopy, dilated fundus examination, and fluorescein angiography is recommended in infants with suspected CMTC shortly after birth. The distinct pattern of lacy capillary anomalies with prominent terminal bulbs seen in CMTC has not been described in other syndromes of vascular dysgenesis. Therefore, ophthalmic examination may be a valuable method to distinguish CMTC from other disorders demonstrating similar dermatologic and systemic manifestations.

Musculoskeletal ultrasound for intra-articular bleed detection: a highly sensitive imaging modality compared with conventional magnetic resonance imaging

Essentials The best imaging modality for joint blood detection in hemophilia is unknown. Blood appearance and detection thresholds were studied with ultrasound and conventional MRI. Ultrasound is sensitive to low volume and concentration of blood, whereas conventional MRI is not. The findings establish the validity of ultrasound for rapid bleed detection in hemophilia care.

SUMMARY

Background There is increasing demand for musculoskeletal ultrasound (MSKUS) to detect hemophilic joint bleeding, but there is uncertainty regarding blood detection concentration thresholds or if magnetic resonance imaging (MRI) is more accurate. Aims Compare the sensitivity of blood detection by MSKUS and MRI. Methods Increasing blood concentrations in plasma were imaged with MSKUS and MRI 1-2 h, 3-4 days and 7 days after blood withdrawal in vitro, and after injection into cadaveric pig joints. Additionally, effusions in the joints of two patients with hemophilia joints were imaged, followed by aspiration. MSKUS was performed using an 8-18-MHz linear transducer; MRI was performed at 3T using T1-weighted and T2-weighted fat-suppressed sequences. Images were reviewed by a hematologist certified in MSKUS and a musculoskeletal radiologist. Results MSKUS permitted the detection of blood in vitro and in pig joint spaces at concentrations as low as 5%, demonstrated by the presence of echogenic signals that were absent with plasma alone. In contrast, no differences between fluids were discernible on the T1-weighted or T2-weighted MRI images. Results were confirmed in the two patients with hemophilia. Blood clots demonstrated varying and dynamic echogenicity patterns over time and, using MRI, were visualized best with T2 sequences. Conclusion MSKUS is extremely sensitive in detecting low concentrations of intra-articular blood and in discriminating between bloody and non-bloody fluid, whereas conventional MRI is not. These observations demonstrate the advantages of MSKUS over MRI in detecting intra-articular blood, and show that MSKUS is ideal for rapid bleed detection in the clinic.

Control of metamorphic buffer structure and device performance of In(x)Ga(1-x)As epitaxial layers fabricated by metal organic chemical vapor deposition

Using a step-graded (SG) buffer structure via metal-organic chemical vapor deposition, we demonstrate a high suitability of In0.5Ga0.5As epitaxial layers on a GaAs substrate for electronic device application. Taking advantage of the technique's precise control, we were able to increase the number of SG layers to achieve a fairly low dislocation density (∼10(6) cm(-2)), while keeping each individual SG layer slightly exceeding the critical thickness (∼80 nm) for strain relaxation. This met the demanded but contradictory requirements, and even offered excellent scalability by lowering the whole buffer structure down to 2.3 μm. This scalability overwhelmingly excels the forefront studies. The effects of the SG misfit strain on the crystal quality and surface morphology of In0.5Ga0.5As epitaxial layers were carefully investigated, and were correlated to threading dislocation (TD) blocking mechanisms. From microstructural analyses, TDs can be blocked effectively through self-annihilation reactions, or hindered randomly by misfit dislocation mechanisms. Growth conditions for avoiding phase separation were also explored and identified. The buffer-improved, high-quality In0.5Ga0.5As epitaxial layers enabled a high-performance, metal-oxide-semiconductor capacitor on a GaAs substrate. The devices displayed remarkable capacitance-voltage responses with small frequency dispersion. A promising interface trap density of 3 × 10(12) eV(-1) cm(-2) in a conductance test was also obtained. These electrical performances are competitive to those using lattice-coherent but pricey InGaAs/InP systems.

A comprehensive, multispecialty approach to an acute exacerbation of chronic central pain in a tetraplegic

STUDY DESIGN

We present a case report describing the multidisciplinary treatment of a tetraplegic spinal cord injury (SCI) patient who developed an acute exacerbation of chronic central pain.

OBJECTIVE

To bring further awareness to the importance of using a comprehensive, multidisciplinary approach in treating acute exacerbation of chronic central pain in SCI patients.

SETTING

University of California Irvine Medical Center, Orange, CA, USA.

CASE REPORT

We present a 34-year-old man with a past medical history of C5 American Spinal Injury Association B tetraplegia secondary to a surfing accident 8 years prior, central pain syndrome, spasticity, autonomic dysreflexia and anxiety who arrived at the emergency room with a 1-month history of worsening acute on chronic pain refractory to opioid escalation. The multispecialty treatment plan included treatment of the patient's urinary tract infection by the primary medicine service, management of the patient's depression by the psychiatric service, treatment of bowel obstruction by general surgery and adjustment of pain medications by pain management. The patient was found to have stable neurological findings, neuroimaging unchanged from prior imaging and a urinary tract infection. Hospitalization was complicated by severe colonic dilation that required disimpaction by general surgery.

CONCLUSION

The treatment of this patient's acutely worsened central pain highlights the importance of applying a multidisciplinary approach to SCI patients with an acute exacerbation of chronic central pain. In this case, the multispecialty treatment plan included treatment of the patient's urinary tract infection by the primary medicine service, management of the patient's depression by the psychiatric service, treatment of bowel obstruction by general surgery, and adjustment of pain medications by pain management.

Spinal 5-HT3 receptors facilitate behavioural hypersensitivity induced by elevated calcium channel alpha-2-delta-1 protein

BACKGROUND

Peripheral nerve injury induces up-regulation of the calcium channel alpha-2-delta-1 proteins in the dorsal root ganglia and dorsal spinal cord that correlates with neuropathic pain development. Similar behavioural hypersensitivity was also observed in injury-free transgenic (TG) mice over-expressing the alpha-2-delta-1 proteins in neuronal tissues. To investigate pathways regulating alpha-2-delta-1 protein-mediated behavioural hypersensitivity, we examined whether spinal serotonergic 5-HT3 receptors are involved similarly in the modulation of behavioural hypersensitivity induced by either peripheral nerve injury in a nerve injury model or neuronal alpha-2-delta-1 over-expression in the TG model.

METHODS

The effects of blocking behavioural hypersensitivity in these two models by intrathecal or systemic injections of 5-HT3 receptor antagonist, ondansetron, were compared.

RESULTS

Our data indicated that the TG mice displayed similar behavioural hypersensitivities to non-painful mechanical stimulation (tactile allodynia) and painful thermal stimulation (thermal hyperalgesia) as that observed in the nerve injury model. Interestingly, tactile allodynia and thermal hyperalgesia in both models can be blocked similarly by intrathecal, but not systemic, injection of ondansetron.

CONCLUSIONS

Our data suggest that spinal 5-HT3 receptors are likely to play a role in alpha-2-delta-1-mediated behavioural hypersensitivities through a descending serotonergic facilitation.

Dual inversion recovery ultrashort echo time (DIR-UTE) imaging and quantification of the zone of calcified cartilage (ZCC)

OBJECTIVE

To develop ultrashort echo time (UTE) magnetic resonance imaging (MRI) techniques to image the zone of calcified cartilage (ZCC), and quantify its T2*, T1 and T1ρ.

DESIGN

In this feasibility study a dual inversion recovery UTE (DIR-UTE) sequence was developed for high contrast imaging of the ZCC. T2* of the ZCC was measured with DIR-UTE acquisitions at progressively increasing TEs. T1 of the ZCC was measured with saturation recovery UTE acquisitions at progressively increasing saturation recovery times. T1ρ of the ZCC was measured with spin-locking prepared DIR-UTE acquisitions at progressively increasing spin-locking times.

RESULTS

The feasibility of the qualitative and quantitative DIR-UTE techniques was demonstrated on phantoms and in six cadaveric patellae using a clinical 3 T scanner. On average the ZCC has a short T2* ranging from 1.0 to 3.3 ms (mean ± standard deviation = 2.0 ± 1.2 ms), a short T1 ranging from 256 to 389 ms (mean ± standard deviation = 305 ± 45 ms), and a short T1ρ ranging from 2.2 to 4.6 ms (mean ± standard deviation = 3.6 ± 1.2 ms).

CONCLUSION

UTE MR based techniques have been developed for high resolution imaging of the ZCC and quantitative evaluation of its T2*, T1 and T1ρ relaxation times, providing non-invasive assessment of collagen orientation and proteoglycan content at the ZCC and the bone cartilage interface. These measurements may be useful for non-invasive assessment of the ZCC, including understanding the involvement of this tissue component in osteoarthritis.

Abstract P4-03-01: Distance of breast cancer from the skin influence axillary nodal metastasis

Background: In breast cancer, axillary lymph node status is one of the most important prognostic variables and a crucial component to the staging system. Moreover, cancers underlying skin are willing to access to the lymphatics and cause lymphatic dissemination. Therefore, there seems an association between proximity of breast cancer to the skin and the incidence of axillary node positivity or local recurrence.

The aim of this study was to determine whether distance of breast cancers from the skin affects the the clinical and pathologic features including the likelihood of axillary nodal metastases, ipsilateral breast cancer recurrence, and recurrence free survival.

Methods: Between January 2003 and December 2009, data were collected prospectively regarding 1005 consecutive breast cancer patients who underwent surgical treatment. The exclusion criteria were non-invasive carcinoma (e.g. Ductal Carcinoma In Situ), prior breast surgery, previous radiotherapy or neo-adjuvant chemotherapy and previous endocrine therapy. The distance of the tumor from the skin surface was measured from the skin to the most anterior hypoechoic leading edge of the lesion.

Results: A total of 891 patients were included in the statistical analysis, 603(68%) had no axillary nodal metastasis, 288(32%) had axillary nodal metastasis. Distance of breast cancer from the skin less than 3mm induced more axillary nodal metastasis (P = 0.039). However, there was no statistical significant correlation between distance of breast cancer from the skin less than 3mm and ipsilateral breast tumor recurrence (P = 0.788) or recurrence-free survival (P = 0.353).

Conclusion: Breast cancers located closer to the skin have a higher incidence of axillary nodal metastasis. When evaluating a breast cancer patient and considering the risk of nodal metastasis the distance of the tumor from the skin should be considered.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-03-01.

Endoscopic ultrasound for the evaluation of Nissen fundoplication integrity: a blinded comparison with conventional testing

BACKGROUND

For patients whose symptoms develop after Nissen fundoplication, the precise mechanism of anatomic failure can be difficult to determine. The authors have previously reported the endosonographic hallmarks defining an intact Nissen fundoplication in swine and the known causes of failure. The current clinical trial tested the hypothesis that a defined set of endosonographic criteria can be applied to determine fundoplication integrity in humans.

METHODS

The study enrolled seven symptomatic and nine asymptomatic subjects at a mean of 6 years (range, 1-30 years) after Nissen fundoplication. A validated gastroesophageal reflux disease (GERD)-specific questionnaire and medication history were completed. Before endoscopic ultrasound (EUS), all the patients underwent complete conventional testing (upper endoscopy, esophagram, manometry, 24-h pH). A diagnosis was rendered on the basis of combined test results. Then EUS was performed by an observer blinded to symptoms, medication use, and conventional testing diagnoses. Because EUS and esophagogastroduodenoscopy (EGD) are uniformly performed in combination, the EUS diagnosis was rendered on the basis of previously established criteria combined with the EGD interpretation. The diagnoses then were compared to examine the contribution of EUS in this setting.

RESULTS

The technique and defined criteria were easily applied to all subjects. All symptomatic patients had heartburn and were taking proton pump inhibitors (PPI). No asymptomatic patients were taking PPI. All diagnoses established with combined conventional testing were detected on EUS with upper endoscopy. Additionally, EUS resolved the etiology of a low lower esophageal sphincter pressure in two symptomatic patients and detected the additional diagnoses of slippage in two subjects. Among asymptomatic subjects, EUS identified additional diagnoses in two subjects considered to be normal by conventional testing methods.

CONCLUSION

According to the findings, EUS is a feasible method for evaluating post-Nissen fundoplication hiatal anatomic relationships. The combination of EUS and EGD allows the mechanism of failure to be detected in patients presenting with postoperative symptoms after Nissen fundoplication.

Repeated sequences of interspike intervals in baroresponsive respiratory related neuronal assemblies of the cat brain stem

Many neurons exhibit spontaneous activity in the absence of any specific experimental perturbation. Patterns of distributed synchrony embedded in such activity have been detected in the brain stem, suggesting that it represents more than "baseline" firing rates subject only to being regulated up or down. This work tested the hypothesis that nonrandom sequences of impulses recur in baroresponsive respiratory-related brain stem neurons that are elements of correlational neuronal assemblies. In 15 Dial-urethan anesthetized vagotomized adult cats, neuronal impulses were monitored with microelectrode arrays in the ventral respiratory group, nucleus tractus solitarius, and medullary raphe nuclei. Efferent phrenic nerve activity was recorded. Spike trains were analyzed with cycle-triggered histograms and tested for respiratory-modulated firing rates. Baroreceptors were stimulated by unilateral pressure changes in the carotid sinus or occlusion of the descending aorta; changes in firing rates were assessed with peristimulus time and cumulative sum histograms. Cross-correlation analysis was used to test for nonrandom temporal relationships between spike trains. Favored patterns of interspike interval sequences were detected in 31 of 58 single spike trains; 18 of the neurons with significant sequences also had short-time scale correlations with other simultaneously recorded cells. The number of distributed patterns exceeded that expected under the null hypothesis in 12 of 14 data sets composed of 4-11 simultaneously recorded spike trains. The data support the hypothesis that baroresponsive brain stem neurons operate in transiently configured coordinated assemblies and suggest that single neuron patterns may be fragments of distributed impulse sequences. The results further encourage the search for coding functions of spike patterns in the respiratory network.

Antigen-specific cancer immunotherapy using a GM-CSF secreting allogeneic tumor cell-based vaccine

Granulocyte-macrophage colony-stimulating factor (GM-CSF)-transduced autologous tumor cell-based vaccines are currently one of the major forms of cancer vaccines. However, the preparation of GM-CSF-transduced autologous tumor vaccines is time-consuming and technically challenging. In addition, the host antigen presenting cells, rather than the tumor vaccine cells themselves, present tumor-specific antigens and prime the host T cells. Therefore, we tested the efficacy of antigen-specific allogeneic tumor vaccines. We used human papillomavirus 16 (HPV-16) E7 protein as a model tumor antigen, which is associated with the development of most cervical carcinoma. B16, a C57BL/6 (H-2(b)) derived melanoma cell line, was genetically engineered to produce GM-CSF alone (B16GM), HPV-16 E7 alone (B16E7), or both (B16GME7). These vaccine cells were injected into BALB/c (H-2(d)) mice (10(6) cells/mouse). Two weeks later, mice were challenged with 10(5) live HPV-16 E7(+) BL-1 (H-2(d)) tumor cells and monitored for tumor progression twice weekly. To determine the effective cell population in the antitumor immunity elicited by B16GME7, we carried out in vivo antibody depletion experiments using CD4 and CD8 specific antibodies. In addition, as a measure of the immune responses produced by B16GME7, we performed an in vitro cytotoxic T lymphocyte assay using a standard chromium release method. We found that all of the mice vaccinated with B16GME7 remained tumor free 49 days post-BL-1 challenge. In contrast, mice vaccinated with B16GM and B16E7 did not show any tumor protection against a similar dose of BL-1 cells. Furthermore, the antitumor immunity produced by B16GME7 was dependent on both CD4 and CD8 T cells. In addition, E7-specific cytotoxic T lymphocyte activity could be readily demonstrated in mice immunized with B16GME7. These results suggest that allogeneic tumor cells transduced with GM-CSF and the tumor antigen, HPV-16 E7, cannot only generate an E7-specific cytotoxic T lymphocytes response in vitro, but can also elicit a potent antitumor immune response against an E7 expressing tumor in vivo.

A noninvasive method for quantifying and distinguishing inflammatory skin reactions

BACKGROUND

The ribonuclease protection assay (RPA) represents a technology that allows detection of small amounts of intact RNA. Recent progress in understanding cytokine networks in the skin suggests that measurements of cytokine mRNA levels could provide a method to distinguish various reactions such as irritant contact dermatitis and allergic contact dermatitis that can occur in the skin.

OBJECTIVE

We attempted to differentiate and quantitate irritant and immunologic skin reactions by measuring mRNA levels.

METHODS

We have used the technique of tape stripping human skin to remove superficial cell layers and have extracted RNA from these skin samples. This RNA was used for RPA analysis.

RESULTS

By means of RPA analysis, we have demonstrated distinct cytokine profiles that appear to discriminate, for example, irritant from immunologic skin reactions.

CONCLUSION

We have shown that multiple cytokine mRNA levels can be defined in these RNA samples obtained from the skin. This approach assesses not only the cytokine gene profiles, but at the same time may quantify the severity of common irritant versus allergic skin reactions.

Antigen-specific immunotherapy for murine lung metastatic tumors expressing human papillomavirus type 16 E7 oncoprotein

An important goal of cancer immunotherapy is to prevent and treat tumor metastasis. We have previously reported a recombinant vaccinia-based vaccine (Sig/E7/LAMP-1) that demonstrated significant anti-tumor effect in a subcutaneous tumor challenge model. In this study, we investigated the potency of the Sig/E7/ LAMP-1 vaccine in preventing and treating metastatic tumors. A tumor metastasis model was generated by injecting human papillomavirus type 16 (HPV-16) E6/E7 expressing tumor cells, designated TC-1, into the tail vein of syngeneic C57BL/6 mice. All the naive mice injected with 1 x 10(6) TC-1 cells developed tumors confined exclusively to the lungs within 1 month. For in vivo tumor prevention experiments, mice were vaccinated with Sig/E7/ LAMP-1 followed by tumor challenge. While tumor growth was observed in all of the mice (10/10) in the control groups, 8 of 10 vaccinated mice (80%) remained tumor-free 2 months post-tumor challenge. For in vivo treatment experiments, mice were first inoculated with TC-1 cells and then vaccinated with Sig/E7/ LAMP-1. Treatment with Sig/E7/LAMP-1 was effective in eliminating preexisting tumor cells in 4 of 5 vaccinated mice. Most importantly, treatment with Sig/E7/LAMP-1 resulted in regression of fully established lung tumors in 10% (5/10) of vaccinated mice. Our data suggest that the Sig/E7/LAMP-1 vaccine is effective in controlling the hematogenous spread of TC-1 tumor cells. In addition, the TC-1 lung metastasis model can be used to test the efficacy of various E6/E7-specific vaccines and immunotherapeutic strategies.

Functional effects of overexpression of protein kinase C-alpha, -beta, -delta, -epsilon, and -eta in the mast cell line RBL-2H3

The rat basophilic leukemic (RBL-2H3) cell line was stably transfected with the endogenously expressed Ca2+-dependent protein kinase C-alpha (PKC-alpha) and -betaI and the Ca2+-independent delta and epsilon isoforms to study their functional roles. In addition, the Ca2+-independent PKC-eta was expressed. All transfected PKC isoforms translocated to the membrane-containing fraction in response to aggregation of the IgE-sensitized high affinity receptor for IgE (Fc epsilonRI) with the Ag dinitrophenyl(25)-BSA. All PKC transfectants, except PKC-eta, showed increased proliferative responses, and aggregation of Fc epsilonRI further enhanced the rate of proliferation. The PKC transfectants also showed increased phosphoinositide hydrolysis in response to Ag aggregation of receptors. No marked differences in the Ca2+ responses of the transfectants to Ag or thapsigargin were observed. Overexpression of PKC-alpha or -epsilon specifically inhibited receptor-dependent cytosolic phospholipase A2 (cPLA2) activity, whereas this activity was enhanced in the PKC-betaI transfectant. Analysis of the secretory response revealed that overexpression of PKC-betaI and -eta significantly enhanced secretion. A broad spectrum of cytokine mRNAs was detected in all transfectants, and overexpression of PKC-betaI significantly enhanced the receptor-dependent production of IL-2 and IL-6 mRNA. These studies identify PKC-alpha and -epsilon as negative regulators of cPLA2 activity and demonstrate the importance of PKC-beta as a positive modulator of secretion, cPLA2 activity, and cytokine production in this mast cell line.

Functional effects of overexpression of protein kinase C-alpha, -beta, -delta, -epsilon, and -eta in the mast cell line RBL-2H3

The rat basophilic leukemic (RBL-2H3) cell line was stably transfected with the endogenously expressed Ca2+-dependent protein kinase C-alpha (PKC-alpha) and -betaI and the Ca2+-independent delta and epsilon isoforms to study their functional roles. In addition, the Ca2+-independent PKC-eta was expressed. All transfected PKC isoforms translocated to the membrane-containing fraction in response to aggregation of the IgE-sensitized high affinity receptor for IgE (Fc epsilonRI) with the Ag dinitrophenyl(25)-BSA. All PKC transfectants, except PKC-eta, showed increased proliferative responses, and aggregation of Fc epsilonRI further enhanced the rate of proliferation. The PKC transfectants also showed increased phosphoinositide hydrolysis in response to Ag aggregation of receptors. No marked differences in the Ca2+ responses of the transfectants to Ag or thapsigargin were observed. Overexpression of PKC-alpha or -epsilon specifically inhibited receptor-dependent cytosolic phospholipase A2 (cPLA2) activity, whereas this activity was enhanced in the PKC-betaI transfectant. Analysis of the secretory response revealed that overexpression of PKC-betaI and -eta significantly enhanced secretion. A broad spectrum of cytokine mRNAs was detected in all transfectants, and overexpression of PKC-betaI significantly enhanced the receptor-dependent production of IL-2 and IL-6 mRNA. These studies identify PKC-alpha and -epsilon as negative regulators of cPLA2 activity and demonstrate the importance of PKC-beta as a positive modulator of secretion, cPLA2 activity, and cytokine production in this mast cell line.

Delayed radiosensitization of human colon carcinoma cells after a brief exposure to 2',2'-difluoro-2'-deoxycytidine (Gemcitabine)

We have shown that 2',2'-difluoro-2'-deoxycytidine (dFdCyd; Gemcitabine), a deoxycytidine analogue, is a potent radiation sensitizer when cells are exposed to it continuously for >16 h in low concentrations (in the range of 10 nM). However, the most common method of clinical administration is by short-term infusion (30-90 min). Therefore, we wished to determine under what conditions dFdCyd could produce radiosensitization after a relatively brief exposure to drug. We hypothesized that the long half-life of the phosphorylated metabolites of dFdCyd would produce long-lasting dNTP pool perturbation, particularly dATP pools, leading to radiosensitization hours or even days after the drug was removed from the medium. We tested this hypothesis by exposing HT29 human colon cancer cells for 2 h to clinically relevant concentrations of dFdCyd, removing the drug from the medium, and assessing radiation sensitivity up to 72 h later. We found that 100 nM dFdCyd, which was noncytotoxic, radiosensitized HT29 cells up to 48 h after drug removal. During this period, there was an increase in the S phase population, whereas by 72 h after drug removal, the cell cycle distribution resembled that seen under control conditions. dATP pools remained depleted throughout the 72-h period after drug treatment. This study supports the hypothesis that radiosensitization occurs in cells that are replicating DNA in the presence of perturbed dNTP pools. Furthermore, they may be useful in the design of rational clinical trials using dFdCyd as a radiation sensitizer.

Processing and routing of a membrane-anchored form of proneuropeptide Y

To investigate factors governing proteolytic processing and routing of biologically active peptides in the secretory pathway, cDNAs for preproneuropeptide Y (preproNPY) and preproneuropeptide Y fused to a membrane anchor were transfected into pituitary cells. The anchor was the transmembrane and COOH-terminal cytoplasmic domain of peptidylglycine alpha-amidating monooxygenase (PAM); these domains are essential for correct routing of integral membrane forms of PAM. Like proneuropeptide Y (proNPY), the integral membrane form of proNPY was a good substrate for the endogenous prohormone convertases, yielding soluble NPY stored in regulated secretory granules. Tethering of proNPY to the membrane resulted in only a small delay in the rate of cleavage to produce mature NPY and in the arrival of NPY in regulated secretory granules. In contrast, the COOH-terminal region of proNPY remained attached to the transmembrane/COOH-terminal domain of PAM and was rerouted to the vicinity of the trans-Golgi network, where integral membrane forms of PAM are concentrated. Thus, the COOH-terminal of proNPY cannot override the signals in the PAM membrane anchor.

Peptide biosynthetic processing: distinguishing prohormone convertases PC1 and PC2

To determine whether manipulation of time, temperature and intragranular pH could be used to distinguish the actions of two subtilisin-related endoproteases, PC1 and PC2, in peptide biosynthesis, the biosynthetic processing of proneuropeptide Y (proNPY) and proopiomelanocortin (POMC) was examined in pituitary cell lines. AtT-20 cells express PC1 and POMC endogenously; stably transfected AtT-20 lines expressing NPY or PC2 were studied. GH3 cells express PC2 endogenously; NPY-expressing GH3 transfectants were investigated. PC1 mediated rapid processing of NPY and POMC; PC1-dependent cleavages were relatively insensitive to 20 degrees C blockade (which arrests secretory pathway transport at the trans-Golgi network) and do not require an acidic intracellular compartment (as in secretory granules). PC2 mediated much slower processing of proNPY and POMC which was totally blocked at 20 degrees C and required an acidic intracellular compartment. Thus, kinetics, abolition of intracellular pH gradients, and incubation at reduced temperatures can be used to distinguish PC1 and PC2 actions in neuroendocrine cells.

Differential effects of the protein kinase C activator phorbol 12-myristate 13-acetate on calcium responses and secretion in adherent and suspended RBL-2H3 mucosal mast cells

Adhesion of RBL-2H3 mucosal mast cells to fibronectin-coated surfaces has been linked to changes in secretion and tyrosine kinase activity. We now show that adhesion affects the sensitivity of RBL cells to the protein kinase C activator phorbol 12-myristate 13-acetate (PMA). In suspended cells, PMA inhibited antigen-induced calcium influx (as measured by manganese influx) and changes in intracellular free calcium and had complex effects on antigen-stimulated secretion. However, in adherent cells PMA had little effect on these responses. Suspended cells only secreted in response to thapsigargin if they were co-treated with PMA, while adherent cells secreted in response to thapsigargin alone. The thapsigargin-induced secretion in adherent cells was inhibited by protein kinase C down-regulation and by the protein kinase C inhibitor GF 109203X, but not by calphostin C. We suggest that protein kinase C is constitutively activated in adherent cells, possibly due to modification of the regulatory domain of the enzyme.

Radiosensitization of pancreatic cancer cells by 2',2'-difluoro-2'-deoxycytidine

PURPOSE

We have reported that the deoxycytidine analog 2',2'difluoro-2'-deoxycytidine (dFdCyd) is a potent radiosensitizer of HT29 human colon cancer cells probably through its effects on intracellular deoxyribonucleotide (dNTP) pools. Because dFdCyd has activity against pancreatic cancer in clinical trials, we wished to determine if dFdCyd would radiosensitize human pancreatic cancer cells.

METHODS AND MATERIALS

We assessed the effect of dFdCyd on radiation sensitivity of two human pancreatic cancer cell lines, Panc-1 and BxPC-3. To begin to investigate the mechanism of sensitization, we determined the effect of dFdCyd on dNTP pools and cell cycle distribution.

RESULTS

We found that dFdCyd produced radiation enhancement ratios of 1.7-1.8 under noncytotoxic conditions in both cell lines. Sensitization was not associated with intracellular levels of 2',2'-difluoro-2'-deoxycytidine triphosphate, the cytotoxic metabolite of dFdCyd, but occurred when dATP pools were depleted below the level of approximately 1 micromolar. Although both cell lines showed substantial cell cycle redistribution after drug treatment, the flow cytogram of the BxPC-3 cells would not, by itself, be anticipated to result in increased radiation sensitivity.

CONCLUSIONS

These findings demonstrate that dFdCyd is a potent radiation sensitizer of human pancreatic cancer cells and support the development of a clinical protocol using combined dFdCyd and radiation therapy in the treatment of pancreatic cancer.

Effect of irradiation on bromodeoxyuridine incorporation in human colon cancer xenografts

PURPOSE

Although we have characterized the incorporation of the thymidine analog bromodeoxyuridine (BrdUrd) into human colon cancer xenografts under a wide variety of conditions, little is known about the effect of radiation on subsequent incorporation. Because clinical protocols include, as one component, BrdUrd administration after radiation, it was important to confirm that irradiation did not prevent subsequent BrdUrd incorporation. Therefore, we studied the effect of irradiation on BrdUrd incorporation into HT29 human colon cancer xenografts.

METHODS AND MATERIALS

Two types of experiments were performed. In the first, the effect of radiation on subsequent incorporation was measured. Tumors received doses of 0, 2, 8, and 12 Gy, animals were infused with BrdUrd for 4 days, and incorporation was assessed at the end of the infusion. In the second, the effect of radiation on the elimination of BrdUrd from tumors was determined. Animals were infused with BrdUrd, tumors were irradiated with either 0 or 12 Gy, and tumor incorporation of BrdUrd was measured 1 and 3 days later.

RESULTS

Radiation affected neither the incorporation into nor the elimination of BrdUrd from human tumor xenografts.

CONCLUSIONS

These findings support the feasibility of clinical trials interdigitating BrdUrd infusion and radiation.

Tyrosine phosphorylation of protein kinase C-delta in response to the activation of the high-affinity receptor for immunoglobulin E modifies its substrate recognition

The delta isoform of protein kinase C is phosphorylated on tyrosine in response to antigen activation of the high-affinity receptor for immunoglobulin E. While protein kinase C-delta associates with and phosphorylates this receptor, immunoprecipitation of the receptor revealed that little, if any, tyrosine-phosphorylated protein kinase C-delta is receptor associated. In vitro kinase assays with immunoprecipitated tyrosine-phosphorylated protein kinase C-delta showed that the modified enzyme had diminished activity toward the receptor gamma-chain peptide as a substrate but not toward histones or myelin basic protein peptide. We propose a model in which the tyrosine phosphorylation of protein kinase C-delta regulates the kinase specificity toward a given substrate. This may represent a general mechanism by which in vivo protein kinase activities are regulated in response to external stimuli.

Development of a rapid approach to identification of tyrosine phosphorylation sites: application to PKC delta phosphorylated upon activation of the high affinity receptor for IgE in rat basophilic leukemia cells

In rat basophilic leukemia cells (RBL-2H3) activation of the high affinity receptor for IgE induces tyrosine phosphorylation of PKC delta. We carried out solid phase synthesis of 15 amino acid long oligopeptides corresponding to the sequences around each of the 19 tyrosine residues in PKC delta. Only three oligopeptides, corresponding to tyrosine 52, 155, and 565, were phosphorylated when exposed to lyn kinase. Single mutants in each of these three tyrosine residues of PKC delta were prepared. Upon expression in the RBL-2H3 cells, only the mutant in tryosine 52 showed abolition of the IgE-antigen induced tyrosine phosphorylation.

Lack of dependence of 5-fluorodeoxyuridine-mediated radiosensitization on cytotoxicity

It has been proposed that fluoropyrimidine-mediated cytotoxicity and radiosensitization are closely correlated. We have shown that HT29 human colon cancer cells transfected with the E. coli dUTPase gene are resistant to 5-fluorodeoxyuridine (FdUrd)-mediated cytotoxicity, presumably through more effective elimination of dUTP. We used these cells to assess the association between radiosensitization and cytotoxicity produced by FdUrd. The radiation sensitivities of the clones expressing elevated dUTPase activity (dutE clones) were similar to those of untransfected HT29 cells or HT29 cells which had been transfected with only the expression vector for the E. coli gene (con clones). We found that FdUrd produced similar increases in radiation sensitivity regardless of dUTPase activity. Levels of dUTPase in the dutE clones remained elevated during the entire period of FdUrd exposure, demonstrating that the lack of difference between dutE and Con clones was not a reflection of down-regulation of dUTPase activity by FdUrd. Flow cytometry showed that all clones progressed past the G1/S-phase boundary and into early S phase during FdUrd treatment. These data suggest that the mechanisms of FdUrd-mediated cytotoxicity and radiosensitization are not closely linked. These findings, combined with our previous investigations, are consistent with the hypothesis that radiosensitization occurs in cells which progress past the G1/S-phase boundary in the presence of FdUrd.

Effects of subunit mutation on the rotational dynamics of Fc epsilon RI, the high affinity receptor for IgE, in transfected cells

Erythrosin-labeled immunoglobulin E (IgE) and time-resolved phosphorescence anisotropy were used to monitor the rotational dynamics of transfected wild-type (alpha beta gamma 2) and four mutant Fc epsilon RI receptors in the monomeric and dimeric state on P815 cells. Erythrosin-IgE bound to Fc epsilon RI on cells transfected with either beta or gamma subunits with truncated COOH-terminal cytoplasmic segments exhibit faster rotational motion than when bound to Fc epsilon RI on cells transfected with wild-type subunits. Deletion of the NH2-terminal cytoplasmic segment of the beta subunit or the COOH-terminal cytoplasmic segment of the alpha subunit does not cause any significant change in the anisotropy decay. Dimers of IgE-receptor complexes formed with anti-IgE monoclonal antibody B1E3 exhibit substantially slower anisotropy decays for all the receptor constructs used, including a receptor construct that only contains the ectodomain of the alpha subunit anchored to Chinese hamster ovary (CHO) cell membranes through a lipid tail. This loss of rotational motion of dimeric IgE-Fc epsilon RI complexes may be due to nonspecific entanglement or to specific interactions involving IgE or the extracellular portion of alpha. The results suggest that the beta and gamma subunits of the tetrameric alpha beta gamma 2 receptor participate in interactions with other membrane components even in the absence of receptor aggregation. The loss of such interactions may be related to the functional impairments previously determined for these mutants.

Alteration of lipid composition modulates Fc epsilon RI signaling in RBL-2H3 cells

We have used sonicated liposomes of phosphatidylcholine (PC), sphingomyelin (SM), or a mixture of cholesterol (chol) and PC to investigate the role of cellular lipid composition in Fc epsilon RI-mediated stimulation of RBL-2H3 cells. Overnight treatment with either PC or SM liposomes causes a substantial enhancement of antigen-stimulated degranulation and phospholipase A2 activity, whereas treatment with a PC/chol mixture results in partial inhibition of the antigen-stimulated response. The most consistent change in the cellular lipid composition that results from the PC and SM liposome treatments is an approximate 40% decrease in the chol/phospholipid (PL) ratio. The lipid treatments do not alter degranulation stimulated by AlF4- or by Ca2+ ionophore in the presence or absence of PMA, suggesting that lipid alteration affects a receptor-specific signaling process. The lipid treatments do not appear to alter antigen-stimulated tyrosine phosphorylation or Ca2+ mobilization. Possible involvement of protein kinase C (PKC) activation in the signal-enhancing effect of the PL treatments was investigated by using calphostin C and phorbol-12-myristol-13-acetate (PMA) to inhibit PKC activity and degranulation in RBL-2H3 cells. Both SM and PC treatment restore the antigen-mediated degranulation response that is inhibited by long-term treatment (> or = 16 h) with 100 nM PMA or short-term treatment (10 min) with 5 microM calphostin C. The results indicate that a decreased chol/PL ratio facilitates or enhances the receptor-mediated activation of a PKC-like pathway that plays an important role in Fc epsilon RI-stimulated degranulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Disparate modulation of plasma membrane protein lateral mobility by various cell permeabilizing agents

The mobility of a cell surface protein on cells osmotically swollen by treatment with several different cell permeabilizing agents retains specific restraints despite detachment of the plasma membrane from the cortical cytoskeleton. Fluorescence photobleaching recovery experiments indicate that the lateral diffusion constants of immunoglobulin E (IgE)-receptor complexes on the surface of rat basophilic leukemia cells increase 2-5x following permeabilization with streptolysin O or digitonin, with little change in their mobile fractions. Swelling by hypo-osmotic treatment in water enhances lateral diffusion of IgE-receptor complexes and raises the mobile fractions to near 100%. In contrast, swelling by treatment with filipin arrests lateral diffusion, although rotational mobility remains unhindered. Lateral mobility of a fluorescent lipid analogue remains unchanged under these conditions. Crosslinking by anti-IgE antibodies redistributes the IgE-receptor complexes into large patches on untreated cells and on cells swollen by permeabilization with streptolysin O or digitonin, but not on cells swollen by treatment with filipin. The results indicate a diversity of effects of the various permeabilizing agents on the mobility of membrane proteins. In particular, treatment with filipin appears to reorganize the plasma membrane into a network of fluid domains on a scale smaller than the bleaching spot size used (approximately 1.5 microns).

T-cell activation is potentiated by cytokines released by lesional psoriatic, but not normal, epidermis

BACKGROUND AND DESIGN

T-cell activation appears to be critical for the maintenance of psoriatic lesions. In this study, we determined whether cytokines released by epidermal cells from psoriatic lesions are providing signals that result in propagation of intralesional T-cell activation. Supernatants were obtained from epidermal cell cultures derived from skin biopsy specimens of psoriatic patients and normal subjects. These supernatants were added to purified normal CD4+ T cells activated via T-cell receptor (immobilized anti-CD3 and fibronectin) or via other activating pathways (anti-CDw60 or UM4D4).

RESULTS

Psoriatic supernatants (n = 9), but not normal supernatants (n = 7, P < .0006), potentiated T-cell stimulation with anti-CD3 and fibronectin to 172% +/- 41% over control stimulation levels. The degree of lesional psoriatic epidermal cell potentiation correlated with the clinical severity of the lesion (r = .82, P = .007). Psoriatic epidermal cytokine potentiation of T-cell activation was not limited to T-cell receptor mediated stimulation; potentiation of anti-CDw60-stimulated CD4+ T cells was also observed. Neutralizing antisera to interleukin 1 and interleukin 8, but not interleukin 6, were found to reduce only partly the observed potentiation of T-cell activation. To determine whether cyclosporine is down modulating T-cell-potentiating cytokine activity in psoriasis, we compared samples obtained during a double-blind clinical trial of intralesional cyclosporine. T-cell-potentiating activity from psoriatic lesional sites treated with cyclosporine was not significantly modulated relative to the activity derived from vehicle-treated or untreated sites.

CONCLUSION

These data demonstrate that lesional psoriatic epidermal cells release a balance of cytokines that potentiate T-cell activation. Because normal epidermal cells do not potentiate T-cell activation in this system, these findings demonstrate a mechanism by which the epidermis may non-specifically potentiate and perpetuate T-cell activation in psoriatic lesions.