Direct activation of retinal ganglion cells with subretinal stimulation

Recent advances in the design and implementation of vision prostheses have made these devices a promising therapeutic option for restoring sight to blind patients in the near future. The success of vision prostheses in providing clinically useful vision, however, depends critically on our understanding of the retinal neural mechanisms evoked during electrical stimulation, and how these mechanisms can be controlled precisely to elicit the desired visual percept. We demonstrate here that subretinal stimulation can reliably elicit stimulus- locked short latency (< or = 2 ms) responses. To our knowledge, this is the first report of such responses using the subretinal paradigm. These responses could be readily distinguished from within the stimulus artifacts using cell-attached extracellular recording or whole-cell patch clamp. The thresholds for these short latency responses were determined for ON, OFF and ON- OFF type retinal ganglion cell classes across cathodic biphasic pulses of 0.1-5.0ms. No significant difference was found for the mean latency and the threshold for the different cell types over the pulse range tested.

A wearable real-time image processor for a vision prosthesis

Rapid progress in recent years has made implantable retinal prostheses a promising therapeutic option in the near future for patients with macular degeneration or retinitis pigmentosa. Yet little work on devices that encode visual images into electrical stimuli have been reported to date. This paper presents a wearable image processor for use as the external module of a vision prosthesis. It is based on a dual-core microprocessor architecture and runs the Linux operating system. A set of image-processing algorithms executes on the digital signal processor of the device, which may be controlled remotely via a standard desktop computer. The results indicate that a highly flexible and configurable image processor can be built with the dual-core architecture. Depending on the image-processing requirements, general-purpose embedded microprocessors alone may be inadequate for implementing image-processing strategies required by retinal prostheses.

A six-panel PCR of both plasma and blood for EBV-DNA as tumor marker for nasopharyngeal carcinoma patients treated in the United States

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Background: Studies of plasma from nasopharyngeal carcinoma (NPC) patients from endemic regions demonstrate that circulating DNA derived from EBV may be used as a tumor marker, but data from non-endemic regions or in whole blood are limited. Methods: ViraCor Laboratories (Lee's Summit, MO) performed PCR for EBNA, EBER, and LMP on both plasma and whole blood of 11 NPC patients undergoing therapy at the Hospital of the University of Pennsylvania. Results were correlated with disease status via review of chart records and imaging reports. Results: 7 of 11 patients tested were positive for circulating EBV derived DNA. 2 patients were treated with induction chemotherapy with suppression to 0 copies of circulating DNA for all plasma measures, but not whole blood measures (LMP 0, EBER 100 and EBNA 200 copies for one patient and LMP 100, EBNA 100 and EBER 300 copies for the other). The first of these patients remains free of disease but the other retains a large mass believed to be active disease, but which has not grown over 8 months following therapy. 5 patients, including the 2 patients treated with induction therapy, were treated with chemoradiotherapy. PCR following therapy was negative on all plasma measures for the 4 patients who remain free of disease (at intervals of 7, 12, 13 and 16 months). 2 of these patients retained low-level EBV on at least 1 whole-blood measure–1 for EBNA alone (100 copies) and the other for both EBER and EBNA (300 and 100 copies). 2 patients were treated for metastatic disease. 3 episodes of progression were all accompanied by increases in plasma EBV (EBNA from 13,700 to 21,100 with EBER 1600 to 9400 and EBNA 1800 to 2200 to 3000 with EBER 100 to 100 to 500). Conclusions: This pilot data on a population treated in the United States is consistent with larger data sets obtained in endemic regions demonstrating that EBV is an effective tumor marker for prognosis and to follow therapy. It is the first to demonstrate greater specificity of plasma measures over whole blood measures, and it raises the hypothesis that whole blood measures may be more sensitive. Further prospective study is warranted in non-endemic populations both to validate the measure and to facilitate translational research into biologic factors driving the behavior of these tumors.

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Variability in the biological response to anti-CD20 B cell depletion in systemic lupus erythaematosus

OBJECTIVE

To study the effects in systemic lupus erythaematosus (SLE) of B cell directed therapy with rituximab, a chimeric monoclonal antibody directed at CD20+ B cells, without concomitant immunosuppressive therapy in mild to moderate SLE.

METHODS

Patients (n=24) with active SLE and failure of >or=1 immunosuppressive were recruited from three university centres into this phase I/II prospective open-label study. Patients were followed for 1 year to assess safety, efficacy and biological effects.

RESULTS

In total, 18 of the patients scheduled to receive the full lymphoma dose of rituximab were evaluable for B cell levels in peripheral blood. Of these, 17 had effective CD19+ B cell depletion (<5 cells/microl). However, six of the depleted patients showed B cell return before 24 weeks. A total of 70% of patients improved by week 55, as defined by an SLE Disease Activity Index (SLEDAI) score improvement of >or=2 units from baseline. The degree of CD19+ B cell depletion was correlated with SLEDAI improvement at week 15 (r=0.84). In general, rituximab infusions were well tolerated. Approximately a third of the patients developed human anti-chimeric antibody (HACA) titres, which correlated with poor B cell depletion. Most patients (9 of 14) did not respond to immunisations with Pneumovax and tetanus toxoid.

CONCLUSIONS

Rituximab is a promising new therapy for SLE. The variability of responses in patients with SLE may be related to HACA formation. The failure to respond to immunisations is surprising, in view of the apparently low risk of infections. Better biological markers are necessary to follow these patients during treatment.

Engineered vaginal lactobacillus strain for mucosal delivery of the human immunodeficiency virus inhibitor cyanovirin-N

Women are at significant risk of human immunodeficiency virus (HIV) infection, with the cervicovaginal mucosa serving as a major portal for virus entry. Female-initiated preventatives, including topical microbicides, are urgently needed to help curtail the HIV/AIDS pandemic. Here we report on the development of a novel, live microbicide that employs a natural vaginal strain of Lactobacillus jensenii engineered to deliver the potent HIV inhibitor cyanovirin-N (CV-N). To facilitate efficient expression of CV-N by this bacterium, the L. jensenii 1153 genome was sequenced, allowing identification of native regulatory elements and sites for the chromosomal integration of heterologous genes. A CV-N expression cassette was optimized and shown to produce high levels of structurally intact CV-N when expressed in L. jensenii. Lactobacillus-derived CV-N was capable of inhibiting CCR5-tropic HIV(BaL) infectivity in vitro with a 50% inhibitory concentration of 0.3 nM. The CV-N expression cassette was stably integrated as a single copy into the bacterial chromosome and resolved from extraneous plasmid DNA without adversely affecting the bacterial phenotype. This bacterial strain was capable of colonizing the vagina and producing full-length CV-N when administered intravaginally to mice during estrus phase. The CV-N-producing Lactobacillus was genetically stable when propagated in vitro and in vivo. This work represents a major step towards the development of an inexpensive yet durable protein-based microbicide to block the heterosexual transmission of HIV in women.

Prognostic value of FDG-PET scan imaging in lymphoma patients undergoing autologous stem cell transplantation

We conducted a retrospective analysis of 50 lymphoma patients (Hodgkin's disease and non-Hodgkin's lymphoma) who had an 18F-fluoro-deoxyglucose positron emission tomography (FDG-PET) scan after at least two cycles of salvage chemotherapy and before autologous stem cell transplantation (ASCT) at our institution. The patients were categorized into FDG-PET negative (N = 32) and positive (N = 18) groups. The median follow-up after ASCT was 19 months (range: 3-59). In the FDG-PET-negative group, the median progression-free survival (PFS) was 19 months (range: 2-59) with 15 (54%) patients without progression at 12 months after ASCT. The median overall survival (OS) for this group was not reached. In the FDG-PET-positive group, the median PFS was 5 months (range: 1-19) with only one (7%) patient without progression at 12 months after ASCT. The median OS was 19 months (range: 1-34). In the FDG-PET-negative group, chemotherapy-resistant patients by CT-based criteria had a comparable outcome to those with chemotherapy-sensitive disease. A positive FDG-PET scan after salvage chemotherapy and prior ASCT indicates an extremely poor chance of durable response after ASCT.

Nonmyeloablative allogeneic stem cell transplantation for refractory Hodgkin's lymphoma complicated by interleukin-2 responsive progressive multifocal leukoencephalopathy

Nonmyeloablative allogeneic stem cell transplantation (NMASCT) can be used to exploit the graft-versus-tumor (GVT) potential of allogeneic donor cells in the setting of reduced conditioning regimen toxicity. This approach is particularly attractive for patients who have received extensive prior therapy and are poor candidates for traditional allogeneic stem cell transplantation. However, toxicity in heavily pretreated patients remains uncertain. Additional immunosuppression in already immunocompromised patients may result in unexpected toxicity. We report a case of probable progressive multifocal leukoencephalopathy (PML) responsive to interleukin-2 (IL-2) following a NMASCT in a 29-year-old woman with relapsed Hodgkin's lymphoma. The patient developed severe neurological symptoms approximately 6 weeks following NMASCT associated with low CD4+ cell counts and magnetic resonance imaging (MRI) was consistent with PML. IL-2 therapy resulted in increasing CD4+ counts and progressive resolution of neurological symptoms. Disruption of IL-2 therapy led to neurological deterioration, which responded to reinstitution of IL-2 therapy. The patient's lymphoma initially progressed following NMASCT, but has responded to donor leukocyte infusions (DLI). This case reiterates the potent GVT potential of NMASCT in patients with Hodgkin's disease. However, it demonstrates the potential for severe complications related to immunosuppression, especially in heavily pretreated patients. The toxicity after NMASCT should not be understated and will need to be explored further.

Allogeneic cell therapy for patients who relapse after autologous stem cell transplantation

Allogeneic donor leukocytes can be used after nonmyeloablative conditioning to exploit their graft-versus-tumor (GVT) activity in the setting of reduced conditioning-regimen toxicity. This approach may be particularly useful for patients who relapse after autologous stem cell transplantation (SCT). However, GVT activity, toxicity, and ability to establish mixed chimerism may differ in patients who were heavily pretreated prior to SCT compared with patients treated earlier in the course of their disease. We have performed a series of studies of nonmyeloablative allogeneic transplantation and present data on the subset of 14 patients treated for relapse after autologous SCT: 4 patients received no conditioning and unstimulated donor leukocyte infusions (DLI), 10 patients received conditioning with fludarabine and cyclophosphamide followed by unstimulated or granulocyte-colony-stimulating factor (G-CSF)-stimulated allogeneic peripheral blood stem cells (PBSCs), 4 patients received no graft-versus-host disease (GVHD) prophylaxis, and 10 patients received cyclosporine GVHD prophylaxis. All but 1 patient had sustained donor chimerism at least 30 days after allogeneic cell therapy (ACT), and 8 patients had more than 80% donor chimerism after ACT. Acute GVHD developed in 11 patients (grade III-IV, n = 6). Aplasia was more frequent in the patients receiving unstimulated PBSCs, despite the development of mixed chimerism. There were 6 complete responses and 4 partial responses; response was independent of conditioning and growth-factor stimulation of the donor graft. Five patients died of treatment-related causes and 4 patients died from progressive disease. Four patients remained alive 27 to 194 weeks (median, 66 weeks) after ACT. Prior autologous SCT may define a subset of patients at particularly high risk for GVHD and other toxicity after ACT. However, these data show that ACT with either DLI or G-CSF-stimulated blood cells results in direct GVT activity in some patients with Hodgkin's disease, myeloma, and non-Hodgkin's lymphoma, even after relapse from autologous SCT. Most patients developed donor chimerism with minimal conditioning. Alternative prophylactic regimens that control GVHD while maintaining GVT are needed to improve outcomes in these heavily pretreated patients.

Determination of enantiomers in a synthetic argininal peptide using capillary zone electrophoresis and high-performance liquid chromatography

SCH 201781 is a synthetic argininal peptide containing two chiral centers and an aromatic sulfonamide group. It can exist as four reversible forms, the aldehyde, the hydrate, and two diastereomeric aminals. Capillary zone electrophoresis (CZE) and reversed-phase high-performance liquid chromatographic (HPLC) methods were developed to separate and quantitate the enantiomers in SCH 201781. Comparable results were obtained using both methods. The CZE method uses direct injection, while the HPLC method requires a precolumn derivatization and is more time consuming. The CZE method provides superior sensitivity to the HPLC method. Both methods were shown to be precise and reproducible.

Rituximab (anti-CD20 monoclonal antibody) therapy for progressive intermediate-grade non-Hodgkin's lymphoma after high-dose therapy and autologous peripheral stem cell transplantation

We evaluated the response and toxicity of rituximab in the setting of progressive intermediate grade non-Hodgkin's lymphoma (NHL) after autologous peripheral stem cell transplantation (PSCT). Seven patients with a median age of 59 years (45-62), ECOG performance status 0-1, and CD20-positive diffuse large cell lymphoma with progression after PSCT were treated. All patients initially received 4-weekly infusions of rituximab (375 mg/m2). The maximum response was three CR and four PR. Median progression-free survival was 197 days (range 60-282). With a median follow-up of 204 (115-299) days, the patients' disease status is classified as two CR, one PR, and four PD. Four of five patients with ECOG performance status of 1 prior to treatment showed improvement to status 0 after treatment with rituximab. While follow-up is short, these results suggest that rituximab has significant activity in intermediate-grade non-Hodgkin's lymphoma that has relapsed after PSCT.

A distributed control model for the air-righting reflex of a cat

A multisegment, multijoint model of a falling animal is presented to examine the effectiveness of a two-stage control scheme in a zero-momentum self-righting maneuver. The model contains a much larger number of degrees of freedom than is required to execute a self-righting maneuver and is thus capable of providing multiple solutions for the same task. The decentralized control scheme is designed to achieve gross turning in minimum time and to maintain a steady orientation relative to gravity after the turn has been achieved. The scheme is able to determine the sequence of steps necessary to execute the motor task and also incorporates learning features. Results from various simulations are presented and their implications discussed.

Stereotactic radiosurgery for brain metastases: comparison of lung carcinoma vs. non-lung tumors

In the medical literature, stereotactic radiosurgery (SRS) for brain metastases results in rates of local control of 65 to 85 %. To define patient selection criteria, we measured the survival in a population with a high proportion of non-small cell lung carcinoma (NCS lung) metastases that occurred soon after primary diagnosis. Between 9/89 and 10/93 30 adults (21 M, 9 F) had SRS for metastatic NSC lung carcinoma (14 patients) vs. non-lung carcinomas (16 patients having breast (3), renal (3), melanoma (3), GI (2, thyroid (1) or carcinoma of unknown origin (4)). The metastases were solitary for 22 patients and multiple for 8 patients. Average ages (y) (+/-SD) were 58.6+/-10.4 for NSC lung patients and 53.4+/-12.5 (p = 0.32) for non-lung patients. The average interval (months) from diagnosis of the primary to metastasis was 23.8+/-41.4 for all patients. This interval was shorter for NSC lung patients: 3.1+/-6.0 vs. 48.0+/-51.7 (p < 0.001) for non-lung patients. Twenty seven patients had conventional radiotherapy (XRT) before (24 patients) or after (3 patients) SRS. Doses (cGy) were 3303+/-841 for 13 NSC lung patients and 4256+/-992 for 14 non-lung patients (p = 0.034). The median time from primary diagnosis to SRS was shorter for the NSC lung patients (11 mo) compared to the non-lung patients (35 mo). SRS was given for recurrence of metastases after XRT for 11/14 NSC lung patients and 13/16 non-lung patients. The doses (cGy) of SRS were 1579+/-484 vs. 1682+/-476 (p=0.45) for the NSC lung and non-lung groups, respectively. After SRS a decrease in metastasis diameter was observed in 10 of 14 NSC lung patients vs. 12 of 16 non-lung patients (p=0.85 Chi-square). Twenty-seven of the 30 patients have died. For all patients, the median survival after diagnosis of the primary and after radiosurgery was 31.3 and 8.4 months, respectively. The median survival (95% CI) from primary diagnosis was 24.3 months (13.2-27.3) for NSC lung patients and 46.5 months (39.2-65.5) for non-lung patients (p=0.005 logrank test). The median survival (95% CI) after SRS was 7.9 months (3.0-14.3) for the NSC lung patients and 8.4 (2.9-11.9) months for the non-lung patients (p=0.98 logrank test). Within the two groups, no difference in survival was observed for patients who had SRS sooner (< 1 yr for NSC lung; < 3 yr for non-lung) after primary diagnosis: 9.3 vs. 6.5 mo for NSC lung (p=0.21) and 10.5 vs. 7.2 mo for non-lung (p=0.87). In this series, the shortened intervals from primary diagnosis to SRS for NSC lung metastases was associated with post-SRS survivorship that was equivalent to the more favorable non-lung group.

Functional outcome and patient satisfaction in total knee patients over the age of 75

Seventy-four patients, age 75 or older, who had undergone 98 primary total knee arthroplasties were evaluated in a retrospective cohort study, with validated questionnaires that assessed self-reported pain, physical function, mental health, and satisfaction. Average follow-up period was 34 months (range, 12-67 months). Overall, 90.8% reported improvement, 88.8% were satisfied with the results of surgery, and 91.8% felt they had made the right decision. Dissatisfaction with the results correlated with poorer mental health scores, decreased physical function, and increased bodily pain scores (P < .05). Satisfaction was correlated with better pain scores on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and SF-36 (P < .05) but not with Hospital for Special Surgery scores (P = .328). Poor surgical results leading to revision surgery (5%) were associated with preoperative deformity greater than 20 degrees. Based on this patient-assessed outcome analysis, total knee arthroplasty is a worthwhile and beneficial procedure in the elderly.

Morphine-augmented cholescintigraphy: its efficacy in detecting acute cholecystitis

Cholescintigrams were performed in 158 patients suspected of having acute cholecystitis after administration of 185 Mbq (5 mCi) of 99mTc-mebrofenin or disofenin. Morphine sulfate, 0.04 mg/kg was given intravenously if there was nonvisualization of the gallbladder at 40-60 min provided that radiotracer was seen within the small bowel. Acute cholecystitis was deemed present if there was nonvisualization of the gallbladder 30 min post-morphine administration; no cystic duct obstruction was present if the gallbladder was demonstrated pre- or post-morphine administration. A final diagnosis was estimated in 51 postoperative patients histologically, the remainder having their final diagnosis gleaned from their medical records. The sensitivity, specificity, positive and negative predictive value of morphine-augmented cholescintigraphy in detecting acute cholecystitis was 94.6, 99.1, 97.2, and 98.3%, respectively. These findings indicate that morphine-augmented cholescintigraphy detects acute cholecystitis with as high a degree of accuracy as conventional hepatobiliary scintigraphy, yet requires only 1.5 hr to establish the diagnosis.

Indium-111-leukocyte imaging in acute cholecystitis

Eleven patients with suspected acute cholecystitis underwent sequential 99mTc-iminodiacetic derivative (IDA) and 111In-white blood cell (WBC) imaging to determine if 111In-WBCs accumulate within an acutely inflamed hemorrhagic gallbladder wall and, thus, could be employed as a reasonable alternative to 99mTc-IDA scintigraphy in detecting acute cholecystitis. Seven patients had surgically confirmed acute cholecystitis. Of these cases, five had a true-positive 99mTc-IDA and 111In-WBC, one an indeterminate 111In-WBC and true-positive 99mTc-IDA, and one a true-positive 111In-WBC and false-negative 99mTc-IDA scan. The remaining four patients did not have acute cholecystitis. All visualized their gallbladder within 1 hr after 99mTc-IDA administration and none had 111In-WBC gallbladder wall uptake. Both 111In-WBC and 99mTc-IDA scintigraphy accurately detected acute cholecystitis: hepatobiliary scintigraphy demonstrated a cystic duct obstruction and 111In-WBC imaging detected the inflammatory infiltrate within the gallbladder wall. The sensitivity and specificity of each was 86% and 100%, respectively.

Clinical studies of cancer radioimmunodetection with carcinoembryonic antigen monoclonal antibody fragments labeled with 123I or 99mTc

Seventy-three patients with diverse cancers containing carcinoembryonic antigen received 123I-labeled anti-carcinoembryonic antigen monoclonal antibody F(ab')2 fragment [38 patients], 99mTc-labeled anti-carcinoembryonic antigen monoclonal antibody Fab' fragment [23 patients], or both reagents at different times [6 patients] for evaluation of antibody targeting and imaging [radioimmunodetection (RAID)], using planar and single-photon emission computed tomography. The results indicated that antibody fragments are preferred for early tumor imaging (within 24 h). Rapid targeting and clearance from blood and normal organs of the antibody fragments (blood median t1/2 elimination of 26.5 and 13.2 h for the F(ab')2 and Fab' fragments respectively) permitted the use of short-lived radionuclides, such as 123I (13.3 h) and 99mTc (6 h), and confirmed that selective antibody accretion in tumors occurred very soon after administration, such as between 2 and 5 h. Scan interpretations at 24 h for the 123I-labeled F(ab')2 and at 2-5 h for the 99mTc-labeled Fab' revealed overall sensitivities, on a tumor site basis, of 95.9 and 94.9%, respectively. On a site basis, the overall accuracies were 94.2 and 93.8% for the 123I and 99mTc immunoconjugates, respectively. In the 6 patients studied with both radioimmunoconjugates, a high concordance in detection was found. Both imaging agents also revealed a high number of putatively new tumor sites not disclosed by other radiological methods at the time of the RAID studies, of which 40.0 and 20.5% were subsequently confirmed as tumor for the 123I and 99mTc agents, respectively, within an 11-month follow-up period. This represented 24 proven occult tumor sites in 19 patients given the 123I-immunoconjugate and 16 proven occult tumor sites in 9 patients receiving the 99mTc agent. The new lesions were found up to 17 and 7 months earlier for 123I-RAID and 99mTc-RAID, respectively, than with other detection methods. The smallest tumors identified were below 0.5 cm, especially with the 99mTc immunoconjugate and single-photon emission computed tomography imaging. The findings of this study confirm previous evidence that RAID is a safe and a potentially useful new method of cancer detection. Despite the excellent results with the 123I-F(ab')2 antibody fragment, its poor availability and high cost limit its clinical use. Therefore, the 99mTc agent, which is made by an instant, 1-step, 1-vial, direct labeling method, appears to be the method of choice for rapid and accurate detection of cancer by RAID.