Abstract 243: Differential effects of combination treatment of biochanin A and statins on glioblastoma multiforme cell proliferation and cell metabolism

Glioblastoma Multiforme (GBM) is a deadly brain cancer and represents the most common central nervous system (CNS) tumors in adults. Although GBM does not metastasize, its aggressive growth and invasive nature are responsible for poor patient prognosis. The current standard therapy for newly diagnosed GBM patients involves surgical resection, followed by radiation and chemotherapy with Temozolomide. However, its rapid rate of infiltration into normal brain tissue ultimately renders the therapy ineffective. Epidemiological studies on dietary isoflavones (e.g., genistein, biochanin A) have shown their anti-cancer potential in different cancers. Though primarily used in management of hyperlipidemia and cardiovascular diseases, statins are known to exert anti-proliferative effects. We therefore hypothesized that a combination treatment of biochanin A & statins (e.g., Atorvastatin, Lovastatin, Simvastatin, Fluvastatin and Pravastatin) exerts enhanced anticancer effects on GBM U-87 MG and T98 G cells. Our studies showed statins induced differential effects on viability of GBM cells in combination with biochanin A, with U-87 MG being more susceptible than T98 G cells. The combination treatment of biochanin A and atorvastatin also decreased invasion in U-87 MG cells. Additionally, cell metabolism studies using seahorse XFp analyzer showed a switch in their metabolic phenotype with an increase in mitochondrial respiration and a decrease in glycolytic activity with the combination treatment. We also performed metabolite extraction on GBM cells for a global unbiased profiling of metabolites using a single extraction procedure and dual separation analysis by LCMS. A differential analysis of alternative GBM treatment indicated statistically significant changes in carbohydrate and amino acid metabolism as well as alterations to various degradation pathway intermediates. Together, the combination treatment-induced effects on GBM cell lines are differential and our results may have potential implications in developing combination therapies with biochanin A in vivo and support the design of new and better therapies for the treatment of a lethal cancer like GBM.

Citation Format: Vilas S. Desai, Eric Buchhalter, Max Cabanzo, Arushi Tiwari, Gagan Kaushal, James C. Lai, Alok Bhushan. Differential effects of combination treatment of biochanin A and statins on glioblastoma multiforme cell proliferation and cell metabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 243.

Prospective clinical trial of Intravitreal aflibercept treatment for PolypoIdal choroidal vasculopathy with hemorrhage or exudation (EPIC study): 6 month results

Background

Polypoidal choroidal vasculopathy is a variant of choroidal neovascularization and neovascular age related macular degeneration presenting with hemorrhagic and exudative changes within the macula and/or peripapillary region leading to vision loss. In contrast to neovascular age related macular degeneration, polypoidal choroidal vasculopathy has differing clinical manifestations and treatment strategies. Historically, polypoidal choroidal vasculopathy complexes are less responsive to anti-vascular endothelial growth factor therapy with no prospective clinical trials evaluating aflibercept in management of polypoidal choroidal vasculopathy. Herein we prospectively evaluate the efficacy and safety of intravitreal aflibercept in polypoidal choroidal vasculopathy.

Methods

A prospective, open-label, investigator-sponsored trial of intravitreal aflibercept for polypoidal choroidal vasculopathy in 21 eyes was conducted. Injections were administered monthly for 3 initial treatments, then every other month with monthly evaluations. The primary outcome measures were the mean change in best corrected visual acuity and adverse events. Secondary outcome measures included stabilization of vision, presence of subretinal hemorrhage, serous detachment, retinal pigment epithelial detachment, and regression of polypoidal complexes on indocyanine green angiography.

Results

At 6 months, the median visual acuity was 20/40 (range 20/25–20/200) with a mean Early Treatment Diabetic Retinopathy Study vision of 68.4 letters. There was a gain of 2.76 Early Treatment Diabetic Retinopathy Study letters at 6 months (p = 0.15). No patient developed severe vision loss (≤15 letters) and vision was stable or improved in 19/21 eyes (91 %). Subretinal fluid resolved in 13/18 eyes (72 %), and subretinal hemorrhage resolved in 6/8 eyes (75 %) respectively. The polyps regressed in 14/21 eyes (67 %) and the branching vascular network decreased in 1 eye and was stable in all other eyes. The retinal pigment epithelial detachment improved in 13/15 eyes (87 %). Bimonthly treatment occurred in 15/21 patients (71 %). There were no adverse events.

Conclusions

Intravitreal aflibercept results in stabilization of vision, resolution of exudative and hemorrhagic complications with regression of polyps in polypoidal choroidal vasculopathy. Eyes with polypoidal choroidal vasculopathy previously treated with ranibizumab and bevacizumab can show marked improvement in the retinal pigment epithelial detachments and persistent polyps with aflibercept therapy.

Trial registration

Clinical trials.gov NCT01871376, June 4^th 2013

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-016-0305-2) contains supplementary material, which is available to authorized users.

Polypoidal choroidal vasculopathy exudation and hemorrhage: results of monthly ranibizumab therapy at one year

PURPOSE

To evaluate the efficacy and safety of monthly intravitreal injections of ranibizumab in patients with polypoidal choroidal vasculopathy (PCV) and active exudation or hemorrhage.

METHODS

A prospective, single practice, open label trial of monthly intravitreal ranibizumab (0.5 mg) injections for PCV in 13 eyes of 13 patients who completed the 1-year study. The primary outcome measure was stabilization of vision (loss of <15 ETDRS letters). Secondary outcome measures included incidence of ocular and systemic adverse events, changes in subretinal hemorrhage, central foveal thickness, and polypoidal complexes on indocyanine green angiography at 1 year.

RESULTS

No patient lost ≥ 15 letters in visual acuity at 1 year. Three patients (23%) gained ≥ 15 letters at 12 months. Subretinal hemorrhage resolved in 9/9 eyes (100%). Macular edema improved in 5/5 eyes (100%). Subretinal fluid completely resolved in 4/9 eyes (44%), decreased in 2/9 eyes (22%), and increased in 3/9 eyes (33%). Polypoidal complexes decreased in 5/13 eyes (38%).

CONCLUSION

Continuous monthly intravitreal ranibizumab decreases leakage and hemorrhage in eyes with exudative and hemorrhagic complications of PCV. Branching vascular networks persisted, and polypoidal complexes decreased in only 5/13 (38%) eyes with continuous antiangiogenic therapy at 1 year.

Schwannoma of the auricle

OBJECTIVES

We report an extremely rare case of schwannoma of the auricle.

METHODOLOGY

A case report and review of the world literature concerning schwannoma of the auricle are presented.

RESULTS

Schwannoma is a benign, encapsulated, slow-growing neoplasm. Approximately 25-45% of all schwannomas occur in the head and neck, whereas schwannomas of the external ear are extremely uncommon, with only nine cases reported in the English literature since the first report in 1977. In this report, we describe the case of a 47-year-old male patient who presented with a 2-year history of a slow-growing mass in the left auricle, which was managed by wide surgical excision. We believe this case to be the second case of schwannoma of the auricle reported.

CONCLUSIONS

To our knowledge, this is the second report in the world literature of auricle schwannoma. Schwannoma should be considered in the evaluation of any tumour of the auricle.

A pre-paid newborn hearing screening programme: a community-based study

OBJECTIVES

To help obstetric hospitals and clinics to implement newborn hearing screening and to test the feasibility of a pre-paid model for screening.

PATIENTS AND METHODS

From July 2005 to August 2008, we organised a coordinated newborn hearing screening team with portable automated auditory brainstem response (AABR) to provide in-patient screening after delivery and out-patient re-screening at one month of age in birthing facilities throughout Changhua County, Taiwan. This was a community-based study organised by otolaryngologists at a tertiary referral centre.

RESULTS

Ten medical facilities participated in our screening programme. 7,139 out of 12,901 neonates delivered in these facilities during the period were screened for hearing loss. 105 (1.47%) babies who did not pass the in-patient screening were re-screened at one month old. Forty (0.56%) babies referred from the re-screening were sent for diagnostic work-up and six of them failed to show up. The overall follow-up rate was 94.3% (99/105). Eleven babies with bilateral hearing loss and eight babies with unilateral hearing loss were diagnosed. The incidence of bilateral hearing loss in our programme was 1.5/1000. The screening rate descended from medical centre to clinic (p < 0.0001). There was no significant difference between the referral rates for different levels of birthing facilities (p = 0.5611).

CONCLUSIONS

Our study demonstrates that a pre-paid model using AABR is feasible at all three levels of medical facilities. Pre-paid community-based screening might be an option for developing countries in the implementation of universal newborn hearing screening.

Resource utilization of living donor versus deceased donor liver transplantation is similar at an experienced transplant center

Although living donor liver transplantation (LDLT) has been shown to decrease waiting-list mortality, little is known of its financial impact relative to deceased donor liver transplantation (DDLT). We performed a retrospective cohort study of the comprehensive resource utilization, using financial charges as a surrogate measure-from the pretransplant through the posttransplant periods-of 489 adult liver transplants (LDLT n = 86; DDLT n = 403) between January 1, 2000, through December 31, 2006, at a single center with substantial experience in LDLT. Baseline characteristics differed between LDLT versus DDLT with regards to age at transplantation (p = 0.02), male gender (p < 0.01), percentage Caucasians (p < 0.01) and transplant model for end-stage liver disease (MELD) score (p < 0.01). In univariate analysis, there was a trend toward decreased total transplant charges with LDLT (p = 0.06), despite increased surgical charges associated with LDLT (p < 0.01). After adjustment for the covariates that were associated with financial charges, there was no significant difference in total transplant charges (p = 0.82). MELD score at transplant was the strongest driver of resource utilization. We conclude that at an experienced transplant center, LDLT imposes a similar overall financial burden than DDLT, despite the increased complexity of living donor surgery and the addition of the costs of the living donor. We speculate that LDLT optimizes transplantation by transplanting healthier and younger recipients.

Increased incidence of sterile endophthalmitis following intravitreal preserved triamcinolone acetonide

AIM

To report an increased incidence of sterile endophthalmitis following intravitreal injection of preserved triamcinolone acetonide (IVTA) from 1 May to 31 July 2006.

METHODS

Charts were reviewed for all patients who underwent IVTA injections between 1 January 2005 and 31 July 2006 at the offices of a referral vitreo-retinal practice. Patients were included if they presented post-IVTA with a clinical picture consistent with endophthalmitis.

RESULTS

Between 1 January 2005 and 31 July 2006, 554 eyes underwent IVTA. Eleven eyes (1.9%) developed an endophthalmitis. All eleven eyes underwent vitreous tap and intravitreal injection of antibiotics. All cultures and gram stains were negative for bacterial or fungal organisms. From 1 May to 31 July 2006, 97 eyes underwent IVTA. Nine eyes (9.3%) developed sterile endophthalmitis. This represented a statistically significant (p<0.0001) clustering of cases. Triamcinolone acetonide phials from affected lot numbers were analysed and were all found to be negative for bacterial endotoxin (<0.05 EU/ml).

CONCLUSION

Over the 19-month period analysed, 11 cases of sterile endophthalmitis occurred following IVTA, and nine of these cases were clustered over a 3-month period. No endotoxin was detected in the phials tested. The aetiology of this increased incidence of sterile endophthalmitis is still unclear.

Visual outcome and bacterial sensitivity after methicillin-resistant Staphylococcus aureus-associated acute endophthalmitis

PURPOSE

To determine the frequency, visual outcome, and bacterial sensitivity in cases of methicillin-resistant Staphylococcus aureus (MRSA)-associated acute postoperative endophthalmitis occurring after cataract surgery.

DESIGN

Retrospective, consecutive, observational case series.

METHODS

Sixty-four cases of acute endophthalmitis occurring within six weeks after cataract surgery were identified over a three-year interval at a single vitreoretinal practice. Cases related to MRSA were studied and visual outcomes and bacterial sensitivities were recorded.

RESULTS

Thirty-three of the 64 eyes were culture positive, and six of the 33 cases (18.2%) demonstrated MRSA infection. All six eyes were started on fluoroquinolone antibiotics two or three days before surgery. Corneal abnormalities were noted in five of the six cases (83.3%), ranging from wound infection to diffuse corneal opacification. Visual acuity at last follow-up was no light perception (NLP) in two eyes, hand movements in two eyes, and 20/30 or better in two eyes. One eye with NLP vision underwent enucleation within three days of presentation because of panophthalmitis and impending sepsis. All six organisms were sensitive in vitro to both gentamicin and vancomycin. No organism was sensitive to any fluoroquinolone antibiotic, although not all organisms were tested against all fluoroquinolones.

CONCLUSIONS

MRSA infection accounts for 18% of culture-positive cases of endophthalmitis in this study and was associated with a poor visual outcome in two-thirds of our patients. MRSA organisms may be resistant in vitro to all generations of fluoroquinolone antibiotics, but do seem to be sensitive to gentamicin and vancomycin. The incidence of MRSA endophthalmitis seems to have increased significantly since the Endophthalmitis Vitrectomy Study was published in 1996.

Characterisation of plasmids encoding CTX-M-3 extended-spectrum β-lactamase from Enterobacteriaceae isolated at a university hospital in Taiwan

CTX-M-3 is the most common extended-spectrum beta-lactamase produced by Enterobacteriaceae in Taiwan. The present study was conducted to characterise the genetic environment surrounding bla(CTX-M-3). A total of 11 ceftriaxone-resistant isolates were studied: Escherichia coli (n=4), Klebsiella pneumoniae (n=5) and Salmonella enterica serotypes Anatum (SA831R) and Potsdam (SC72). Molecular methods used included polymerase chain reaction, sequencing, DNA-DNA hybridisation, conjugation, physical mapping and restriction fragment length polymorphism (RFLP) analysis. All isolates examined carried bla(CTX-M-3) on large plasmids (>70kb). The resistance plasmids of the two Salmonella and two K. pneumoniae strains (KP104 and KP116) were confirmed to be conjugative in vitro. RFLP analysis indicated that the plasmids were different. Physical mapping also revealed the difference between the two Salmonella plasmids, pSA831R (82kb) and pSC72 (74kb). An insertion sequence, ISEcp1, was found upstream of each bla(CTX-M-3) gene. However, sequencing of downstream regions of the bla genes showed two different patterns: the presence of orf477 in pSA831R and of orf1-mucA in pSC72, pKP104 and pKP116. IncI1-type oriT and nikA sequences were present in the plasmids of all the clinical isolates tested, except S. Anatum. Different bla(CTX-M-3)-carrying plasmids were identified among the enterobacteria studied. The presence of ISEcp1 in all isolates may be associated with the widespread resistance among Enterobacteriaceae. Although the plasmids were not identical, they appeared to belong to the same incompatibility group (IncI1-like plasmids), suggesting that they are genetically related but may have evolved divergently over time.

Acute endophthalmitis in eyes treated prophylactically with gatifloxacin and moxifloxacin

PURPOSE

To study the use of prophylactic fourth-generation fluoroquinolone antibiotics, gatifloxacin and moxifloxacin, and bacterial sensitivity in cases of acute postoperative endophthalmitis following cataract surgery.

DESIGN

Retrospective, consecutive, observational case series.

METHODS

Forty-two eyes of 42 patients with acute endophthalmitis occurring within six weeks after cataract surgery were identified. All patients were seen in a referral vitreoretinal practice over a two-year time interval. The number of patients using prophylactic gatifloxacin or moxifloxacin and results of bacterial culture and sensitivity to all fluoroquinolone antibiotics were recorded.

RESULTS

Thirty-one of 42 eyes (74%) were treated with perioperative gatifloxacin or moxifloxacin and 24 eyes (57%) were continuously taking one of these antibiotics at the time of diagnosis. Nineteen eyes (45%) had a positive bacterial culture. The most frequent organism isolated was coagulase-negative Staphylococcus. Sensitivities were performed for 14 gram-positive organisms, and sensitivities to ciprofloxacin (50%), ofloxacin (44%), levofloxacin (46%), gatifloxacin (38%), and moxifloxacin (38%) were noted. Five organisms were resistant to gatifloxacin and moxifloxacin with a minimum inhibitory concentration of 8 microg/ml. All gram-positive organisms were sensitive to vancomycin. Median visual acuity improved from hand motions to 20/40 at last follow-up.

CONCLUSION

Acute endophthalmitis can develop after cataract surgery despite the prophylactic use of fourth-generation fluoroquinolone antibiotics. Gram-positive organisms causing acute endophthalmitis are frequently resistant to all fluoroquinolones, including a significant number of cases resistant to gatifloxacin and moxifloxacin.

VISUAL IMPROVEMENT FOLLOWING INTRAVITREAL BEVACIZUMAB (AVASTIN) IN EXUDATIVE AGE-RELATED MACULAR DEGENERATION

PURPOSE

To study the visual and anatomic outcome of intravitreal bevacizumab injection in the treatment of exudative age-related macular degeneration (AMD).

METHODS

Retrospective review of patients who received one or more intravitreal bevacizumab injections for exudative AMD. Outcome measures include standardized visual acuity, optical coherence tomography (OCT), macular thickness and volume, intraocular pressure, and blood pressure at 24 or more weeks follow-up.

RESULTS

Fifty eyes of 48 patients were identified. Patients were observed for a median length of follow-up of 34 weeks (range, 24-50 weeks). Thirty-six eyes (72%) had prior treatment with pegaptanib (Macugen) and/or photodynamic therapy (PDT) and 14 eyes (28%) were treatment-naive. Mean visual acuity increased by 6.5 letters (P < 0.01) at 4 weeks and 5.3 letters (P < 0.01) at 24 weeks after initial bevacizumab injection. At 24 weeks, naive eyes had a mean increase of 14.2 letters (P < 0.001) and previously treated eyes had a mean increase of 2.8 letters (P = 0.06). Overall, mean OCT macular thickness and volume decreased by 73 micro m (P < 0.001) and 1.0 mm3 (P < 0.001) respectively at last follow-up. At last follow-up, all eyes received an average of 3.5 injections and experienced an average of 1.08 recurrences. There was no incidence of severe vision loss or adverse effect.

CONCLUSION

Intravitreal bevacizumab has the potential for improvement in vision in both naive and previously treated eyes for at least 6 months. The benefit is more pronounced in eyes without prior pegaptanib and/or PDT.

CENTRAL RETINAL VEIN OCCLUSION IN PATIENTS TREATED WITH LONG-TERM WARFARIN SODIUM (COUMADIN) FOR ANTICOAGULATION

PURPOSE

To describe the clinical features of persons who developed central retinal vein occlusion (CVO) while being treated with Coumadin for chronic anticoagulation.

METHODS

In a retrospective, comparative, noninterventional case series of patients diagnosed with CVO while being treated with Coumadin as a systemic anticoagulant, visual and anatomical outcomes were compared with those for a cohort of patients diagnosed with CVO who were not treated with any systemic anticoagulation.

RESULTS

Fourteen eyes of 14 patients treated with Coumadin were identified. At presentation, the median international normalization ratio (INR) was 2.20 (range, 1.3-5.0). Eight patients (57%) had a therapeutic INR at the time of CVO. Their visual acuity and perfusion status were similar to those of patients with subtherapeutic INR. At the last follow-up (median, 16 months), visual acuity and perfusion status of the group of 14 eyes were similar to baseline findings (P = 0.62). Clinical features and outcomes were similar to those for a cohort of patients with CVO who were not being treated with systemic anticoagulation.

CONCLUSION

CVO can occur in patients being treated with Coumadin for systemic anticoagulation. Final visual acuity and perfusion status were similar to those in a cohort of patients with CVO who were not treated with Coumadin. Although visual acuity is unaffected, ensuring that the INR for these patients remains in the therapeutic range may be important to help prevent secondary systemic thrombotic and embolic disease.

Comparison of Retrobulbar and Sub–Tenon's Capsule Injection of Local Anesthetic in Vitreoretinal Surgery

OBJECTIVE

To compare the efficacy and efficiency of retrobulbar versus sub-Tenon's capsule injection of local anesthetic in vitreoretinal surgery.

DESIGN

Prospective, randomized, double-masked clinical trial.

PARTICIPANTS AND INTERVENTION

Sixty-four eyes from 61 patients undergoing vitreoretinal surgery were randomized to receive either retrobulbar or sub-Tenon's capsule injection of 5 ml of a 50:50 mixture of 4% lidocaine and 0.75% bupivacaine.

MAIN OUTCOME MEASURES

The primary outcome measured was intraoperative eye pain, which was rated by patients in both groups using an 11-point (0-10) numerical visual analogue scale immediately after surgery and again the next morning. The surgeons indicated whether they perceived patient discomfort during 4 different stages of the operation: opening of the conjunctiva, vitrectomy (if performed), placement of scleral buckle (if performed), and closing of the conjunctiva. The preincision time, need for supplemental local anesthesia, and use of IV sedation for additional pain control were compared between the two groups.

RESULTS

Thirty-four eyes were randomized to retrobulbar injections, and 30 eyes were randomized to sub-Tenon's capsule injections. There was no significant difference in patient-reported intraoperative pain scores between the retrobulbar and sub-Tenon's capsule groups when assessed immediately after surgery (median, 2.0 vs. 2.0; P = 0.52) or the next day (median, 2.0 vs. 1.0; P = 0.26). The surgeons reported no difference between the two groups in terms of the percentages of patients with pain during opening of the conjunctiva (20.6% vs. 3.3%; P = 0.058), vitrectomy (31% vs. 32%; P = 1.00), placement of scleral buckle (33.3% vs. 40%; P = 1.00), and closing of the conjunctiva (26.5% vs. 26.7%; P = 1.00). There was a suggestion that preincision time was longer in the sub-Tenon's capsule group. Approximately equal percentages of patients in each group required supplemental local anesthesia (38% vs. 37%; P = 0.90) or IV medication (85% vs. 70%; P = 0.14) for pain control.

CONCLUSIONS

Sub-Tenon's capsule injection of local anesthetic seems as effective as retrobulbar injection at controlling intraoperative pain in vitreoretinal surgery.

B-scan ultrasonography for the detection of macular thickening

PURPOSE

To report the sensitivity and specificity of B-scan ultrasonography to detect macular thickening.

DESIGN

Observational case series.

METHODS

Seventy-seven eyes of 40 consecutive patients (age range, 7-80 years) in a retinal specialty practice were examined. A single masked ultrasound operator performed B-scan ultrasonography on all eyes and graded macular thickening. The final assessment of macular thickening was based on biomicroscopy findings combined with fluorescein angiography (FA) and optical coherence tomography (OCT). The presence or absence of macular thickening as determined by B-scan ultrasonography was compared with the final clinical assessment, FA findings, and OCT measurements.

RESULTS

B-scan ultrasonography detected macular thickening with a high degree of sensitivity (91%) and specificity (96%). There was a high degree of agreement between findings on ultrasonography and FA (kappa = 0.80). Ultrasonographic diagnosis correlated with OCT measurements for both central macular thickness (r =.65, P <.001) and volume (r =.56, P <.001).

CONCLUSIONS

Ultrasonographic detection of macular thickening correlates with findings on slit-lamp biomicroscopy, FA, and OCT. B-scan ultrasonography is a potentially useful technique for assessing macular thickness when biomicroscopy is impossible or when patients cannot tolerate FA or OCT.

Comparison of silicone oil versus gas tamponade in the treatment of idiopathic full-thickness macular hole

PURPOSE

To compare anatomic and functional outcomes of macular hole surgery with either silicone oil or C(3)F(8) gas tamponade.

DESIGN

Retrospective comparative interventional study.

PARTICIPANTS

Fifty-four eyes of 51 patients underwent pars plana vitrectomy for macular holes. Thirty-one eyes were treated with silicone oil tamponade, and 23 eyes were treated with C(3)F(8) tamponade.

METHODS

Demographics, preoperative and postoperative characteristics, and complications were analyzed.

MAIN OUTCOME MEASURES

Preoperative and postoperative visual acuity, initial hole closure, number of persistent or recurrent holes, number of reoperations, and final hole closure.

RESULTS

The silicone oil and gas tamponade groups were demographically similar. The rate of hole closure after one operation with oil tamponade was significantly lower than that with gas tamponade (65% vs. 91%; P = 0.022). The percentage of patients undergoing a second operation was significantly higher in the oil group (35% vs. 4%; P = 0.006). However, with reoperations, the final rate of hole closure was similar between the oil and gas groups (90% vs. 96%; P = 0.628). The final median visual acuity for the gas group was significantly better than for the oil group (20/50 vs. 20/70; P = 0.047).

CONCLUSIONS

C(3)F(8) gas proved to be a more effective tamponade than silicone oil with respect to achieving initial closure of macular holes. Eyes receiving an oil tamponade required significantly more reoperations to achieve a similar rate of hole closure compared with eyes undergoing a gas tamponade. Final visual acuity was better for gas-operated eyes than for silicone-operated eyes.

Visual outcomes following macular translocation with 360-degree peripheral retinectomy

OBJECTIVE

To evaluate visual outcomes following macular translocation with 360 degrees peripheral retinectomy in patients with subfoveal choroidal neovascularization secondary to age-related macular degeneration.

METHODS

In a prospective study, 15 consecutive patients with large subfoveal choroidal neovascularization underwent macular translocation with 360 degrees peripheral retinectomy and silicone oil tamponade. Preoperative and postoperative photographs and fluorescein angiograms were obtained to evaluate lesion size and characteristics and translocation results. Standardized near and distance visual acuity and reading speed were measured preoperatively and 6 and 12 months postoperatively.

MAIN OUTCOME MEASURES

Changes in and final levels of near and distance visual acuity and reading speed.

RESULTS

Median lesion size was 9 Macular Photocoagulation Study disc areas (range, 4-16 disc areas). In all patients, the fovea was successfully translocated off the subfoveal lesion. The median near visual acuity logMAR score (logarithm of the minimum angle of resolution) improved significantly from 0.54 units to 0.40 units (Snellen equivalent, 20/70 to 20/50; P =.02) at the 6-month follow-up and stabilized at 0.54 (12 months postoperatively; Snellen equivalent, 20/70). Seven (54%) of 13 patients and 7 (58%) of 12 patients achieved reading speeds of 70 words/min or greater at the 6-month and 12-month postoperative visits, respectively. Median preoperative distance visual acuity (20/100) was maintained at both the 6-month and 12-month examinations. No postoperative retinal detachments occurred in this series.

CONCLUSION

Macular translocation with 360 degrees peripheral retinectomy and silicone oil tamponade stabilizes and can sometimes improve near and distance visual acuity and reading speed in patients with vision loss from subfoveal neovascular age-related macular degeneration.

Reactivation of retinal toxoplasmosis despite evidence of immune response to highly active antiretroviral therapy

We report a case of retinal toxoplasmosis that occurred in a patient with acquired immunodeficiency syndrome who had a previous diagnosis of cerebral toxoplasmosis, despite the patient having had a robust immune response to highly active antiretroviral therapy. Clinical decisions about whether to discontinue secondary prophylaxis for opportunistic infections continue to be challenging.

Alternations in quantities and activities of erythrocyte cytosolic carbonic anhydrase isoenzymes in glucose-6-phosphate dehydrogenase-deficient individuals

BACKGROUND

This study was designed to evaluate the quantitative and activity alterations of cytosolic carbonic anhydrase (CA) isoenzymes in the erythrocytes of glucose-6-phosphate dehydrogenase (G6PD)-deficient individuals.

METHODS

Western Blot and CA esterase activity analysis were employed to measure cytosolic erythrocyte CA isoenzymes.

RESULTS

The total CA activities were analyzed from erythrocytes of 30 healthy and 30 G6PD-deficient individuals. The mean values with standard error (SE) were 22.9+/-1.69 U/gHb and 27.2+/-2.1 U/gHb (P<0.01), respectively. The ratio of CAI/CAII of G6PD-deficient individuals (1.28+/-0.06) was significantly lower than that of the normal subjects (3.79+/-0.18) (P<0.001). Furthermore, the concentration of CAIII in G6PD-deficient individuals was significantly lower than that of the normal subjects (P<0.001) and there were significant correlations between the concentration of CAI, CAII, CAIII, and ratio of CAI/CAII, and the activity concentration of G6PD.

CONCLUSIONS

Different carbonic anhydrase isoenzymes may serve different roles in the G6PD-deficient erythrocyte. CAI could be used as an indicator for hemolytic anemia. CAII is able to compensate for the functions of CAI and increased expression of CAII will promote oxidative damage. CAIII can provide the G6PD-deficient persons with some extent of protection against oxidative damage.

Bioadhesives for intraocular use

BACKGROUND/PURPOSE

A safe, effective adhesive could be useful in the management of retinal holes or tears and selected complicated retinal detachments, as well as for attaching a small electronic device (retinal prosthesis) to the retina. In this study, we examined nine commercially available compounds for their suitability as intraocular adhesives.

METHODS

The following materials were studied: commercial fibrin sealant, autologous fibrin, Cell-Tak, three photocurable glues, and three different polyethylene glycol hydrogels. An electronic strain gauge measured the adherence forces between different glues and the retina. The stability of hydrogels at body temperature and the impermeability of the hydrogel adhesive to dextran blue were examined. Long-term biocompatibility testing of the most promising glues in terms of adhesive force, consistency, and short-term safety (hydrogels) were done in rabbits. Funduscopy, electroretinogram, and histology of the retina were performed.

RESULTS

Hydrogels had 2 to 39 times more adhesive force (measured in mN) than the other glues tested. They liquefied at body temperature after 3 days to a few months. Hydrogels were impermeable to dextran blue. One type of hydrogel proved to be nontoxic to the retina.

CONCLUSIONS

Hydrogels proved to be superior for intraocular use in terms of consistency, adhesiveness, stability, impermeability, and safety.

Traumatic hyphema in children: risk factors for complications

OBJECTIVE

To identify risk factors associated with higher rates of ocular complications in children with traumatic hyphema.

METHODS

Consecutive inpatient records from July 1990 through December 1997 were retrospectively reviewed for all children (aged < or = 18 years) who were admitted to the Wilmer Ophthalmological Institute, Baltimore, Md, within 48 hours of a closed-globe injury leading to hyphema. Data obtained included age, sex, race, sickle cell status, initial and final visual acuities, hyphema size and intraocular pressure at presentation, the occurrence of a secondary hemorrhage, subsequent intraocular pressure elevations, and therapeutic interventions.

RESULTS

Forty children fulfilled the inclusion criteria: 20 African American, 1 Asian American, and 19 white. Five of the 20 African American children had sickle cell trait, and 1 had sickle cell anemia. The rate of secondary hemorrhage was statistically higher in the African American population (P =.05), but no statistical difference existed between the rate of secondary hemorrhage in patients with and without sickle cell hemoglobinopathy. Sickle cell hemoglobinopathy was associated with a higher intraocular pressure at presentation (P =.03) and during inpatient follow-up (P =.02).

CONCLUSIONS

In the setting of traumatic hyphema, African American children appear to be at greater risk for developing a secondary hemorrhage. In our patients, sickle cell hemoglobinopathy increased the risk of intraocular pressure elevation, but did not seem to increase the risk of rebleeding beyond that associated with race. Larger studies are needed to validate these observations.

Brain regional development of the activity of alpha-ketoglutarate dehydrogenase complex in the rat

This study was initiated to test the hypothesis that the development of alpha-ketoglutarate dehydrogenase complex (KGDHC) activity, like that of pyruvate dehydrogenase complex, is one of the late developers of tricarboxylic acid (TCA) cycle enzymes. The postnatal development of KGDHC in rat brain exhibits four distinct region-specific patterns. The age-dependent increases in olfactory bulb (OB) and hypothalamus (HYP) form one pattern: low in postnatal days (P) 2 and 4, KGDHC activity rose linearly to attain adult level at P30. The increases in mid-brain (MB) and striatum (ST) constitute a second pattern: being <40% of adult level at P2 and P4, KGDHC activity rose steeply between P10 and P17 and attained adult level by P30. The increases in cerebellum (CB), cerebral cortex (CC), and hippocampus (HIP) form a third pattern: being 25-30% of adult level at P2 and P4, KGDHC activity doubled between P10 and P17 and rose to adult level by P30. KGDHC activity development is unique in pons and medulla (PM): being >60% of the adult level at P2, it rose rapidly to adult level by P10. Thus, KGDHC activity develops earlier in phylogenetically older regions (PM) than in phylogenetically younger regions (CB, CC, HIP). Being lowest in activity among all TCA cycle enzymes, KGDHC activity in any region at any age will exert a limit on the maximum TCA cycle flux therein. The results may have functional and pathophysiological implications in control of brain glucose oxidative metabolism, energy metabolism, and neurotransmitter syntheses.

Oscillating reed valves--an experimental study

The results of experiments on the threshold behavior and large-amplitude oscillation of "outward-swinging door" vibrating flap valves in an air environment are reported and compared with the predictions of a simple nonlinear theory that parametrizes aerodynamic effects by means of a simple damping coefficient together with a contraction coefficient for the flow. The agreement is acceptably good for the threshold blowing pressure for valve oscillation, the large-signal vibration amplitude, the pressure jump in the transition from threshold to large-signal behavior, and the variation in vibration frequency, all as functions of reservoir volume. The calculated pressure waveform in the reservoir has the observed phase and magnitude but fails to reproduce finer details. It is concluded that the simple theory provides an adequate account of the behavior of such valves. There are just two parameters in the theory, describing jet contraction and aerodynamic damping, respectively. Since these may depend significantly upon the detailed geometry, valves with different shapes may behave in quantitatively different ways.

Nonlinear determination of Michaelis-Menten kinetics with model evaluation through estimation of uncertainties

A structured analytic approach was developed to evaluate enzyme kinetic parameters using non-linear least-squares fitting. The approach was implemented in a software package called KinSim and designed to run on Windows 95, 98, and NT platforms. The software and the theoretical approach were tested using kinetic data obtained using citrate synthase with acetyl CoA as a substrate and octanoyl CoA as an inhibitor. Using the software, the data were evaluated for statistical certainty of the presence of competitive and non-competitive inhibition of the enzyme. Given the determination of the presence of both components of inhibition in the experimental setup, the software was used to determine the inhibitory kinetics from the experimental data, including non-normal distributions of uncertainty. Finally, the software was used to evaluate the sensitivities of the experiment design at each concentration of substrate used. The theoretical approach as implemented in the user-friendly software allows investigators to use a structured procedure for evaluating and planning enzyme kinetic and related metabolic studies.

Health beliefs and optimism as predictors of preventive health decisions in Hong Kong Chinese

The effects of components of the Health Belief Model and optimism on preventive intention were examined in 144 Hong Kong Chinese. Two variables related to the Health Belief Model, susceptibility and severity, were experimentally manipulated for an imaginary flu outbreak and a hypothetical vaccine. Participants indicated their intention to take the hypothetical vaccine after reading each of the 4 combinations of high versus low susceptibility and severity. Analysis suggested that both higher susceptibility and higher severity were associated with stronger behavioral intention to take the vaccine. Higher optimism scores were significantly associated with lower intention to take preventive action. In addition, a significant interaction was observed for optimism and severity. The effect of optimism was higher when severity was low than when it was high. Implications of these findings for research among Chinese were discussed.

Consistency in choice of social referent

Similarity has been an important but ill-defined concept in social comparison theory. For social comparisons of competence, similarity should be defined within the same evaluative social context, for example, the same school for students or the same workplace for workers. 104 postsecondary school students, 96 full-time university students, and 81 part-time mature university students were recruited to participate in this study. They filled out a questionnaire to indicate whether they compared themselves with each of 11 categories of social referent in each of 10 domains of competence. Comparers preferred to choose those in the same evaluative social context as referents for social comparisons in domains of competence, and their comparisons with dissimilar others were rare. This preference was consistent across the three different samples.

Breakdown of tolerance to a neo-self antigen in double transgenic mice in which B cells present the antigen

Transgenic (Tg) mice expressing a foreign Ag, hen egg lysozyme (HEL), under control of the alphaA-crystallin promoter ("HEL-Tg" mice) develop immunotolerance to HEL attributed to the expression of HEL in their thymus. In this paper we analyzed the immune response in double (Dbl)-Tg mice generated by mating the HEL-Tg mice with Tg mice that express HEL Abs on their B cells ("Ig-Tg" mice). The B cell compartment of the Dbl-Tg mice was unaffected by the HEL presence and was essentially identical to that of the Ig-Tg mice. A partial breakdown of tolerance was seen in the T cell response to HEL of the Dbl-Tg mice, i.e., their lymphocyte proliferative response against HEL was remarkably higher than that of the HEL-Tg mice. T-lymphocytes of both Dbl-Tg and Ig-Tg mice responded to HEL at concentrations drastically lower than those found stimulatory to lymphocytes of the wild-type controls. Cell mixing experiments demonstrated that 1) the lymphocyte response against low concentrations of HEL is due to the exceedingly efficient Ag presenting capacity of the Ab expressing B cells and 2) breakdown of tolerance in Dbl-Tg mice can also be attributed to the APC capacity of B cells, that sensitize in vivo and stimulate in vitro populations of T cells with low affinity toward HEL, assumed to be escapees of thymic deletion. These results thus indicate that T cell tolerance can be partially overcome by the highly potent Ag presenting capacity of Ab expressing B cells.

Uveitis induced by lymphocytes sensitized against a transgenically expressed lens protein

PURPOSE

Previously established experimental models for lens-associated uveitis (LAU) are all mediated by antibodies. The present study analyzed the features of a novel experimental intraocular inflammatory eye disease that is mediated by lymphocytes targeted at a lens antigen.

METHODS

Conventional technologies were used to generate three lines of transgenic (Tg) mice, expressing hen egg lysozyme (HEL) under the control of the alphaA-crystallin promoter. To induce intraocular inflammation, these Tg mice were injected with lymphocytes from syngeneic wild-type donors sensitized against HEL. Before their injection, the cells were stimulated in culture with HEL. To release lenticular material, some eyes were capsulotomized. Ocular histopathologic changes were examined by routine methods. Levels of HEL antibody were measured by enzyme-linked immunosorbent assay, whereas cellular immunity was determined by the lymphocyte proliferation assay.

RESULTS

Intraocular inflammation developed in HEL-Tg mice injected with syngeneic lymphocytes sensitized against HEL. The severity of inflammation was directly related to the number of injected cells, as well as to the accessibility of HEL. The most intense inflammation was seen in Tg mice in which the lens was disintegrated due to high production of HEL. In mice with no apparent lenticular changes the inflammation was enhanced by capsulotomy. The inflammation affected all segments of the eye and persisted for at least 39 days after adoptive transfer of cells. Four days after cell injection, the inflammation consisted of subacute infiltration, with both mononuclear and polymorphonuclear leukocytes, whereas more chronic infiltration was seen at later times. Vigorous cellular immunity but no antibody to HEL was found in recipient mice, thus demonstrating the exclusive participation of cellular immunity in the pathogenesis of this experimental disease.

CONCLUSIONS

Transgenic mice expressing HEL in their lenses develop intraocular inflammation after injection of syngeneic lymphocytes sensitized against HEL. This experimental disease is a novel cell-mediated model for LAU.

Hexokinase in astrocytes: kinetic and regulatory properties

Hexokinase (HK, EC 2.7.1.1) is a key enzyme in the control of brain glucose metabolism. The regulatory role of HK in different neural cell types has not been elucidated. In this study we determined some kinetic and regulatory properties of HK in mouse cerebrocortical astrocytes in primary culture. Astroglial HK showed an absolute requirement for Mg-ATP and D-glucose. The pH optimum of HK was between 7.4 and 8.0. For astroglial HK, the Km for Mg-ATP was approximately 208 microM and Vmax approximately 35.4 mU/mg protein. At levels higher than 0.2 mM, D-glucose-1,6-bisphosphate, a known regulator of glycolysis, inhibited astroglial HK in a concentration-dependent manner, with an IC50 of approximately 0.4 mM; at 1.2 mM, it almost completely inhibited HK activity. The results obtained for astroglial HK are compatible with those reported for the highly purified preparations of brain HK. These data are of direct relevance to the assessment of glycolytic flux and its regulation in astrocytes.

Manganese mineral interactions in brain

Manganese (Mn) is an essential mineral but is toxic when taken in excess. However, whether its interactions with other minerals in organs and cells are involved in mechanisms underlying Mn toxicity is poorly understood. We designed a developmental rat model of chronic Mn treatment (Group A: 1 mg MnCl2.4H2O per ml of drinking water; Group B: 10 mg MnCl2.4H2O per ml of drinking water; Group C: 20 mg MnCl2.4H2O per ml of drinking water; Control Group given water without manganese addition). Employing the model and instrumental neutron activation analysis, we investigated two hypotheses: (i) chronic manganese treatment alters the brain regional distribution of manganese and this altered manganese distribution also leads to region-specific changes of other metals; (ii) chronic manganese treatment induces differential changes in subcellular distributions of metals and electrolytes. In the treated rats, brain Mn level showed dose-related increases, the most pronounced being noted in striatum, hypothalamus, and hippocampus: these increases also led to alterations in regional distribution pattern of Mn. In the treated rats, Fe level was increased in hypothalamus, cerebellum, hippocampus, pons and medulla, and striatum. Cu level was increased in pons and medulla, hippocampus, midbrain, and striatum. Se level was increased in cerebellum, striatum, midbrain, hypothalamus, and pons and medulla. Zn level was increased in hypothalamus and striatum. Ca level was increased in midbrain but decreased in cerebellum; however, Mg and Al levels were not markedly affected. In brains of Mn-treated rats, Mn levels in subcellular fractions were all increased, being especially marked in nuclei, mitochondria, and synaptosomes; the subcellular distributions of Fe, Cu, Zn, and Mg were differentially altered although those of Al and Ca were minimally affected. These results are consistent with our hypotheses and may have implications in manganese neurotoxicity. The cellular and molecular mechanisms underlying manganese-mineral interactions in brain are still poorly defined and merit further investigation.

Bilateral ocular ischemic syndrome secondary to giant cell arteritis progressing despite corticosteroid treatment

PURPOSE

To report the development of a bilateral ocular ischemic syndrome despite corticosteroid treatment in a patient with giant cell arteritis.

METHOD

Case report.

RESULTS

Despite receiving high-dose intravenous methylprednisolone and oral prednisone for biopsy-proven giant cell arteritis that presented as a severe anterior ischemic optic neuropathy in the right eye, a patient developed progressive ocular ischemia in that eye as well as an ocular ischemic syndrome in the fellow eye.

CONCLUSIONS

Some patients with giant cell arteritis, possibly patients with other underlying systemic vasculopathies, are refractory to what should be adequate treatment with systemic corticosteroids and may develop a bilateral ocular ischemic syndrome.

Functional studies in cultured astrocytes

Studies using primary cultures of astrocytes have made essential contributions to the understanding of astrocytic functions and neuronal-astrocytic interactions. The purposes of this article are to (i) outline principles and methodologies used in the preparation of such cultures and caveats for the interpretation of the observations made; (ii) summarize astrocytic functions in turnover of the amino acid transmitters glutamate and gamma-aminobutyric acid (GABA), in energy metabolism and in Na+,K+-ATPase-catalyzed processes and emphasize the degree to which the observations have been confirmed in intact tissue; (iii) describe regulations of astrocytic functions by transmitters and by calcium channel activity; and (iv) indicate suggestions for future functional studies using astrocytes in primary cultures and emphasize that some of the conclusions about neuronal-astrocytic interactions reached on the basis of studies in cultured cells and confirmed in intact tissue may not yet have been completely integrated into general neuroscience knowledge.

Immunotolerance against a foreign antigen transgenically expressed in the lens

PURPOSE

To extend our knowledge concerning immunotolerance against autologous lens crystallins, transgenic (Tg) mice that express a foreign antigen in their lens were generated, and the immune response against the antigen in these mice was analyzed.

METHODS

Conventional techniques were used to generate lines of Tg mice that express soluble (S-) or membrane-bound (M-) hen egg lysozyme (HEL) under the control of the alphaA-crystallin promoter. The presence of HEL in various organs was determined by the particle concentration fluorescence immunoassay (PCFIA), and reverse transcription-polymerase chain reaction technique was used to detect mRNA transcripts of the molecule. To examine the development of immunity (or tolerance), Tg mice and their wild-type controls were immunized with HEL (25 microg) in Freund's complete adjuvant and 14 days later were tested for immune response against the antigen. Cellular immunity was measured by the lymphocyte proliferation assay and cytokine production, and humoral immunity was determined by enzyme-linked immunosorbent assay.

RESULTS

Eyes of the high copy number M-HEL Tg mice were dystrophic, with disrupted lens, whereas no morphologic changes were detected in the eyes of the other Tg mouse lines. All Tg mice exhibited tolerance to HEL by their cellular and humoral immune compartments. The state of immunotolerance to HEL was retained in the Tg mice for as long as 10 months after removal of the main depot of this protein, by enucleation. Measurable amounts of HEL were found in the eyes of all Tg mice, but the protein could not be detected in the serum or in other organs by the sensitive PCFIA (with a threshold of 1 ng/ml). Yet, HEL mRNA was found in the thymus of the Tg mice, suggesting that minute amounts of the protein are expressed in this organ.

CONCLUSIONS

The unresponsiveness to HEL in the Tg mice seems to be due to a "central" mechanism of tolerance, mediated by a minuscule amount of HEL in the thymus. Conversely, the much larger amounts of HEL in the peripheral depot, the eyes, play a minor role if any in the tolerogenic process. It is further proposed that a similar mechanism of central tolerance is responsible for the immunotolerance against autologous lens crystallins.

Topical liposome-encapsulated FK506 for the treatment of endotoxin-induced uveitis

PURPOSE

Liposome preparations of FK506 improve the penetration of topically administered drug into the aqueous humor. The purpose of the experiment was to compare topically administered highdose oil-dissolved FK506 (OD-FK506) and low-dose liposome-bound FK506 (LB-506) for the treatment of endotoxin-induced uveitis (EIU).

METHODS

Endotoxin-induced uveitis was produced in female Lewis rats with Salmonella typhimurium endotoxin. Four hours prior to endotoxin injection, one eye received 20 mul eyedrops every four hours containing either high-dose OD-FK506 at 3 mg/ml (N = 20), low-dose LB-FK506 at 0.16 mg/ml (N = 19), prednisolone acetate 1% (N = 20), or empty liposomes (N = 20). Eyes were enucleated 24 hours after endotoxin injection and inflammatory cells were counted on histologic sections by two masked observers.

RESULTS

The mean number of infiltrating inflammatory cells per section +/- S.E.M. was 127.8 +/- 20.1, 76.8 +/- 16.7, 75.0 +/- 19.1, and 3.6 +/- 0.4 for animals treated with empty liposomes, LB-FK506, OD-FK506, and prednisolone acetate, respectively. The difference in inflammation between the empty liposome controls and the LB-FK506- and OD-FK506-treated animals was statistically significant (p = 0.03 and p = 0.02, respectively). The difference in inflammation between the high-dose OD-FK506- and low-dose LB-FK506-treated animals was not statistically significant (0 = 0.94).

CONCLUSION

In this study, low-dose LB-FK506 and high-dose (OD-FK506) were both effective in inhibiting EIU. Higher concentrations of LB-FK506 are being developed and should augment the therapeutic effect of topical FK506.

Aging is associated with a decrease in synaptosomal glutamate uptake and an increase in the susceptibility of synaptosomal vitamin E to oxidative stress

We examined the influence of aging upon the uptake of glutamate by synaptosomes, and the oxidation of synaptosomal vitamin E. Synaptosomes isolated from the cerebral hemispheres of Fischer 344 rats, 4 and 24 months old, were suspended at 37 degrees C in buffer (pH 7.4) simulating extracellular fluid containing 10 mM glucose. The Km for the high affinity uptake of tritium labeled glutamate was approximately 10 microM. The uptake of glutamate was lower in synaptosomes from older animals than those from younger animals for periods of up to 20 minutes. Upon incubation with a mixture of ferrous iron and ascorbate, more of the alpha tocopherol in synaptosomes derived from older rats was oxidized than in those derived from younger ones. Older animals may be more susceptible to excitotoxicity because: a) synaptosomal reuptake of glutamate is less efficient and b) oxidative stress induced by various agents including glutamate may be higher in synaptosomes from the older animal.

Inverse error-diffusion using classified vector quantization

This correspondence extends and modifies classified vector quantization (CVQ) to solve the problem of inverse halftoning. The proposed process consists of two phases: the encoding phase and decoding phase. The encoding procedure needs a codebook for the encoder which transforms a halftoned image to a set of codeword-indices. The decoding process also requires a different codebook for the decoder which reconstructs a gray-scale image from a set of codeword-indices. Using CVQ, the reconstructed gray-scale image is stored in compressed form and no further compression may be required. This is different from the existing algorithms, which reconstructed a halftoned image in an uncompressed form. The bit rate of encoding a reconstructed image is about 0.51 b/pixel.

Unemployment and psychological health among Hong Kong Chinese women

The impact of unemployment on psychological health, indexed by the General Health Questionnaire, was studied in 86 unemployed and 79 employed Chinese women in Hong Kong. As with findings reported in the West, the present results showed that the unemployed participants were more disturbed than their steadily employed peers. In addition, the prevalence rate of disturbance (54%) observed in the present sample of unemployed women is comparatively higher than those of Western samples reported previously. Implications of these preliminary findings for research on psychological aspects of unemployment among Hong Kong Chinese were discussed.

Permissive recognition of immunodominant determinants of the retinal S-antigen in different rat strains, primates and humans

The majority of antigenic peptides exhibit restriction in their interaction with the MHC molecules on antigen-presenting cells of different haplotypes. Certain peptides, however, are "permissive': they bind strongly to different MHC molecules and are selected as the immunodominant epitopes by animals using these MHC gene products. Here we show for the first time that several peptides from four regions of the sequence of human S-antigen (H-SAg), a retinal-specific protein, demonstrate high levels of permissiveness. Each of these peptides was found to be immunodominant in at least some of four inbred rat strains and five cynomolgus monkeys, immunized with whole H-SAg. Moreover, some of these peptides were recognized by lymphocytes from four normal controls and four patients with uveitis who responded against the H-SAg molecule. On the other hand, the permissive peptides stimulated marginal or no response in cultures of Lewis rats injected with adjuvant alone, or rat and human cell lines specific to other antigens, thus demonstrating that these peptides do not carry any non-specific mitogenic activity. One peptide, 29, which was found immunodominant in the monkeys, the uveitis patients and Lewis rats, is highly immunopathogenic in this rat strain. No good correlation between immunodominance and immunopathogenicity was found with other H-SAg peptides. The finding of cross-species permissiveness among peptides of H-SAg and similar observations with myelin proteins suggest that permissiveness could be quite prevalent among peptides of immunopathogenic antigens.

Complement-induced retinal arteriolar occlusions in the cat

PURPOSE

To develop an animal model of complement-induced retinal vasculopathy and determine whether it resembles Purtscher's retinopathy.

METHODS

Intravenous cobra venom factor was used to achieve intravascular activation of the complement system in cats. After a single bolus of cobra venom factor (75 units/kg), retinal blood flow was monitored at regular intervals by fluorescein angioscopy and angiography.

RESULTS

Multiple small retinal arteriolar occlusions were present during the initial fluorescein transit of the immediate postinjection fluorescein study in 12 of 12 animals. Small, rapidly moving gaps in the fluorescein column were seen in two thirds of the animals observed continuously by fluorescein angioscopy. Angiographically, the obstructions were transient, and filling of the associated patches of capillary nonperfusion occurred within 3 minutes. Purtscher's-like ischemic retinal infarcts did not develop in any eye. Histopathologic analysis failed to demonstrate the nature of the transient vascular obstructive lesions, but indirect evidence suggested the possibility of granulocyte aggregates.

CONCLUSION

Intravascular activation of the complement system produces transient microembolic retinal arteriolar occlusions in the cat. Although this model may represent a mild form of Purtscher's retinopathy, factors in addition to complement activation appear necessary to induce ischemic retinal infarcts.

The 13C isotope and nuclear magnetic resonance: unique tools for the study of brain metabolism

As studies of brain metabolism grow in complexity, investigators turn increasingly to nuclear magnetic resonance spectroscopy combined with 13C isotopic labeling. The unique ability to detect labeling non-destructively in specific carbon positions of individual compounds has opened the way to investigate brain metabolism in systems ranging from cellular preparations to the human brain in vivo. This review is written for investigators whose backgrounds do not include detailed knowledge of principles of nuclear magnetic resonance. Its purpose is to show the wide array of NMR techniques for 13C detection that are available for application in different systems to study aspects of brain metabolism, such as metabolic compartmentation and measurements of the tricarboxylic acid cycle rate in vivo. Basic NMR concepts are explained, and, because each detection method possesses specific advantages to address the requirements of different experimental goals, basic explanations and examples are given for each technique. The review should provide readers with a basic understanding of the methods of 13C detection by NMR and assess which of the methods are most applicable to the particular issues they may face in their own research.

Dispositional optimism and coping with academic examinations

Correlations between scores on dispositional optimism and four categories of coping strategies for academic examinations for a group of 248 Hong Kong undergraduates were .25 for Self-encouragement and -.20 for Cognitive Avoidance. These results lend partial support to the association of adaptive coping and optimism, measured by the Life Orientation Test.

IL-12 inhibits endotoxin-induced inflammation in the eye

Interleukin-12 (IL-12) is a heterodimeric cytokine that induces interferon (IFN)-gamma production and an increased generation of Th1 cells. Both IL-12 and IL-12 antagonists are being studied for the treatment of allergic reactions, autoimmune disease and malignancy. The goal of the present experiments was to examine the importance of IL-12 in endotoxin-induced ocular inflammation. The number of inflammatory cells infiltrating eyes with endotoxin-induced uveitis (EIU) was significantly increased in animals treated with intraperitoneal anti-IL-12 antibody when compared to control animals, but there was no difference in infiltrating inflammatory cells in the eyes of animals treated with IL-12 when compared to controls. In contrast, intraocular injection of IL-12 significantly inhibited the development of endotoxin-induced intraocular inflammation. The infiltrating inflammatory cells were reduced in the eyes of animals receiving intraocular IL-12 when compared to controls. Cytokine analysis of the aqueous humor obtained from eyes with EIU showed increased levels of IFN-gamma and decreased levels of IL-6 in eyes receiving intraocular IL-12. These data show that IL-12 has an inhibitory effect on endotoxin-induced inflammation in the eye and suggest that IL-12 can have an immunoregulatory function in some forms of inflammatory disease.

Liposomal formulations containing sodium mercaptoundecahydrododecaborate (BSH) for boron neutron capture therapy

Sodium mercaptoundecahydrododecaborate or BSH is a compound most widely used for boron neutron capture therapy (BNCT). Liposome formulations containing BSH, with or without steric stabilization, were prepared as potential agents for delivery of boron compounds for BNCT. Liposomes composed of DPPC/CHOL in a molar ratio 1:1 (PEG concentration: 5 mol%) were prepared having an average diameter in the range of 100-110 nm 200 mu L of liposomes (l.88 mg phospholipid/mouse and 3.5-5.8 mg BSH/kg body weight) were injected in mice via the tail vein. Both types of liposomes resulted in a significant improvement in the circulation time of BSH compared to that obtained previously after injecting free BSH. The mean percent injected BSH remaining in circulation at the end of 24 h was 19% for the PEG-liposomes compared to the corresponding value of 7% for the conventional liposomes. The mean percent uptake by the liver and spleen was not significantly different for the two types of liposomes; the blood/RES ratios were higher for the PEG-liposomes at all time points indicating that a higher fraction of injected BSH was available in circulation. The PEG-liposomes could be further explored as a means of enhance boron drug delivery to tumor cells for BNCT.

Reduced susceptibility to IL-1 and endotoxin in transgenic mice expressing IL-1 in their lens

To learn about the effects of chronic exposure to IL-1 we generated a transgenic (Tg) mouse line that expresses human IL-1 beta under the control of the lens alpha-A crystallin promoter. Expression of human IL-1 beta was restricted to the eye; neither the protein nor its mRNA were detected in various other organs of the Tg mice. The Tg mice develop severe ocular inflammation shortly after birth, which affects the lens and other eye tissues and apparently allows the release of IL-1 into the circulation. Here we report that the Tg mice exhibit decreased responsiveness to IL-1 and lipopolysaccharide (LPS), as compared to their wild-type littermate controls: (1) when injected with IL-1 the Tg mice produced lower levels of serum amyloid A than their controls; (2) thymocytes of the Tg mice responded less vigorously in culture to stimulation with IL-1; and (3) Tg mice showed lower morbidity and mortality than their controls when injected with toxic amounts of LPS. These data suggest that chronic exposure to IL-1 in the Tg mice induces partial resistance to this cytokine, analogous to the reduced responsiveness to IL-1 in animals pretreated with this proinflammatory cytokine.

The moderating effect of optimism on the relation between hassles and somatic complaints

The relations between hassles, dispositional optimism, and prospective reports of physical symptoms were examined in a group of 90 Hong Kong undergraduates. Given that most hassle scales are confounded by physical and psychological symptomatology, a decontaminated scale specifically tailored to the experiences of college students was used. Multiple regression analyses indicated that hassle scores and the interaction of hassles and optimism uniquely and reliably predicted symptom reporting. Optimism, however, did not reliably predict symptom reports when effects of hassles and the interaction of hassles and optimism were controlled. Inspection of the interaction showed that optimism predicted symptom scores only at high levels of hassles. The underlying mechanisms were discussed in the light of previous data linking optimism and adaptational outcomes via coping. It was suggested that further pursuit of the connection between optimism and coping in relation to measures of life stress would be worthwhile.

In vitro oxidation of vitamin E, vitamin C, thiols and cholesterol in rat brain mitochondria incubated with free radicals

The kinetics of oxidation of endogenous antioxidants such as vitamins C and E and thiols as well as membrane cholesterol in isolated rat brain mitochondria were studied. Oxidation was induced by incubating the mitochondria at 37 degrees C with the free radical generators 2,2' azobis (2'-amidinopropane) dihydrochloride (ABAPH) and 2,2' azobis (2,4-dimethyl) valeronitrile (ABDVN) which undergo thermal decomposition to yield free radicals. An approximate order for the in vitro ease of oxidation was: ascorbate >> alpha-tocopherol > sulfhydryls >> cholesterol. However, small amounts of ascorbate were present in the mitochondria when alpha-tocopherol and sulfhydryl compounds were getting oxidized. This observation is different from those with more homogeneous biological substrates like blood plasma or serum. The order of oxidation of the various compounds is a function of not only the redox potentials but also the (a) concentrations of the oxidized and reduced species, (b) compartmentation of the compounds and (c) enzymatic and nonenzymatic systems for the repair or regeneration of the individual antioxidants. Even though ascorbate levels are quite low within mitochondria this nutrient may play a major role as a first line of defense against oxidative stress. The lipid-soluble ABDVN was much more potent in oxidizing membrane alpha-tocopherol and thiols than the water-soluble ABAPH. With both free radical generators the rate of oxidation of the antioxidants consisted of two phases. The initial phase, that is more rapid, may represent a pool of antioxidant that is involved in immediate antioxidant protection of the organelle with the slower compartment being responsible for replenishing the faster pool whenever needed.(ABSTRACT TRUNCATED AT 250 WORDS)