Correction to: Feasibility Study of a Novel Protease-Activated Fluorescent Imaging System for Real-Time, Intraoperative Detection of Residual Breast Cancer in Breast Conserving Surgery

The article Feasibility Study of a Novel Protease-Activated Fluorescent Imaging System for Real-Time, Intraoperative Detection of Residual Breast Cancer in Breast Conserving Surgery, written by Barbara L. Smith et al., was originally published electronically on the publisher's internet portal on January 2, 2020, without open access.

Feasibility Study of a Novel Protease-Activated Fluorescent Imaging System for Real-Time, Intraoperative Detection of Residual Breast Cancer in Breast Conserving Surgery

BACKGROUND

Obtaining tumor-free margins is critical to prevent recurrence after lumpectomy for breast cancer. Unfortunately, current approaches leave positive margins that require second surgeries in 20-40% of patients. We assessed the LUM Imaging System for real-time, intraoperative detection of residual tumor.

METHODS

Breast lumpectomy cavity walls and excised specimens were assessed with the LUM Imaging System after 1 mg/kg intravenous LUM015, a protease-activatable fluorescent agent. Fluorescence at potential sites of residual tumor in lumpectomy cavity walls was evaluated intraoperatively with a sterile hand-held probe, with real-time predictive results displayed on a monitor intraoperatively, and later correlated with histopathology.

RESULTS

In vivo lumpectomy cavities and excised specimens were imaged after LUM015 injection in 45 women undergoing breast cancer surgery. Invasive ductal and lobular cancers and intraductal cancer (DCIS) were included. A total of 570 cavity margin surfaces in 40 patients were used for algorithm development. Image analysis and display took approximately 1 s per 2.6-cm-diameter circular margin surface. All breast cancer subtypes could be distinguished from adjacent normal tissue. For all imaged cavity surfaces, sensitivity for tumor detection was 84%. Among 8 patients with positive margins after standard surgery, sensitivity for residual tumor detection was 100%; 2 of 8 were spared second surgeries because additional tissue was excised at sites of LUM015 signal. Specificity was 73%, with some benign tissues showing elevated fluorescent signal.

CONCLUSIONS

The LUM015 agent and LUM Imaging System allow rapid identification of residual tumor in the lumpectomy cavity of breast cancer patients and may reduce rates of positive margins.

Optical imaging with a novel cathepsin-activatable probe for enhanced detection of colorectal cancer

We evaluated a cysteine cathepsin-activatable optical imaging probe (LUM015) with improved kinetics relative to larger macromolecules for detection and characterization of colorectal cancer (CRC), and thereby assessed its potential use in fluorescence-guided colonoscopy. We showed that LUM015 is stable in plasma. In-vitro studies demonstrated selectivity of LUM015 for targeting cathepsins; there was robust increase in emitted fluorescence signal from the cathepsin overexpressing HT-29 CRC cells within 1-5 minutes after incubation with LUM015 compared to the cells incubated with combination of LUM015 and a pan-protease inhibitor (as negative control). Biodistribution, differential accumulation of the probe in the tumor and tumor-to-background fluorescence signal ratio of LUM015 were compared to ProSense680, a commercially available protease-activatable optical imaging probe, over 24 hours after intravenous injection of the probes in nude mice with subcutaneously implanted HT-29 tumors. LUM015 showed distinct kinetics compared to ProSense680 with time to peak signal for subcutaneous tumor-to-colon ratio of 3.3±0.3 (mean ± SD) at 4-8 hours compared to 2.9±0.2 at 24 hours, respectively (n=8 for each group). Near-infrared fluorescence imaging and dual channel colonoscopy of the mice with orthotopic colon tumors showed tumor-to-colon ratio of 3.7±0.2 in HT-29 tumors (n=4), 2.8±0.1 in genetically engineered mice with APC^KOKras^LSL-G12Dp53^flox/flox mutation (n=4), and 4.1±0.1 in mice with APC^LoxP/LoxPMsh2^LoxP/LoxP mutation (n=4) at 6 hours after LUM015 administration. Immunohistochemistry and laser confocal microscopy of the extracted tumors confirmed high expression of cysteine cathepsins in all colon tumor types tested. Optical imaging with cathepsin-activatable LUM015 in multiple models of CRC highlights its potential for increasing the efficacy of CRC screening and therapeutic procedures.

Abstract CT220: Expansion into multiple institutions for training in the use of the LUM Imaging System for intraoperative detection of residual cancer in the tumor bed of female subjects with breast cancer

Background: Obtaining tumor-free margins is critical for local control in breast conserving surgery. Currently, 20-40% of lumpectomy patients have positive margins that require surgical re-excision; this is a significant burden for patients, surgeons and the healthcare system. Therefore, it is of paramount importance that all cancer be resected from the tumor bed during lumpectomy surgery. The LUM Imaging System consists of a fluorescence-based imaging agent, a hand-held wide-field detector (LUM Imaging Device) used to image the surgical cavity walls intraoperatively in real-time after the resection of the main lumpectomy specimen, and a proprietary tumor detection algorithm that highlights regions in the tumor bed suspected to contain residual cancer.

Methods: This multi-site clinical study is designed to refine the tumor detection algorithm developed in previous studies by correlating images generated by the LUM Imaging System with histopathology results. This is a prospective, interventional feasibility study and is an introductory arm to a pivotal study which will evaluate the safety and efficacy of the LUM Imaging System in reducing the positive margin rate during standard of care lumpectomies. Up to 250 adult female breast cancer patients undergoing lumpectomies are being enrolled at sixteen medical centers across the US. The novel imaging agent, LUM015, is injected into all enrolled subjects prior to their lumpectomy procedure. Subjects undergo the standard of care lumpectomy followed by intraoperative use of the LUM Imaging System which helps guide surgeons in identifying potential residual tumor tissue. The primary objective is to assess performance characteristics of the LUM Imaging System and to fine-tune the tumor detection algorithm. A secondary objective is to develop and refine the process of implementing the LUM Imaging System into institution-specific workflows during lumpectomies. A comprehensive process to evaluate the LUM Imaging System has been implemented and will be reported. This study is being conducted under an Investigational Device Exemption (IDE) approved by the FDA.

To date, 72 subjects have been imaged using the LUM Imaging System.

Successful implementation of standardized tissue collection, naming conventions, and LUM Imaging System training is intended to improve the quality and integrity of the data collected in the upcoming pivotal clinical trial to evaluate the safety and efficacy of the LUM Imaging System.

This study is partially funded by a grant from the National Cancer Institute (award 1R44CA211013) to support biomedical technology development and Lumicell Inc. and is registered on Clinical Trials.gov as NCT03321929.

Citation Format: Kate Smith, Jorge M. Ferrer, Barbara L. Smith, E. Shelley Hwang, Kelly K. Hunt, Daleela G. Dodge, Stephen E. Karp, Stephanie A. Valente, Irene L. Wapnir, Lynne P. Clark, David R. Carr, Peter D. Beitsch, Donna L. Dyess, Beth-Ann Lesnikoski, Peter W. Blumencranz, Nayana S. Dekhne, Linsey P. Gold, Anees Chagpar, Katherine Kacena, Livia Gjylameti, Felix Geissler. Expansion into multiple institutions for training in the use of the LUM Imaging System for intraoperative detection of residual cancer in the tumor bed of female subjects with breast cancer [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 CT220.

Abstract CT166: Expansion into multiple institutions for training in the use of the LUM Imaging System for intraoperative detection of residual cancer in the tumor bed of female subjects with breast cancer

Clinical need: Obtaining tumor-free margins is critical for local control in breast conserving surgery. Currently, 20-40% of lumpectomy patients have positive margins that require surgical re-excision which is a burden for patients, surgeons and the healthcare system. Therefore, it is of paramount importance that all cancer be resected from the tumor bed during lumpectomy surgery.

Background: The LUM Imaging System consists of a fluorescence-based imaging agent, LUM015, a hand-held wide-field detector (LUM Imaging Device) used to image a tumor bed cavity in real-time, and a proprietary tumor detection algorithm that highlights regions of a tumor bed suspected to contain residual cancer. The LUM Imaging System may be used to scan the surgical cavity walls intraoperatively after the resection of the main lumpectomy specimen.

Trial Objectives and Methodology: This multi-site study is designed to validate the process of implementing the LUM Imaging System into institution-specific workflows during lumpectomies and to correlate images generated by the LUM Imaging System with histopathology results. This study is a prospective, interventional feasibility study and is an introductory arm to a pivotal study which will evaluate the safety and efficacy of the LUM Imaging System in reducing the positive margin rate in excised tissue during standard of care lumpectomies. Up to 165 adult female breast cancer patients undergoing lumpectomies are being enrolled at up to eleven medical centers across the US. This study is being conducted under an Investigational Device Exemption granted by the FDA. This study evaluates the use of the LUM Imaging System within the scope of the study protocol, while maintaining institutional standards on maintaining specimen tissue orientation and nomenclature. Surgeons record images of in-vivo tissue and ex-vivo tissue to measure the ratio of fluorescent intensity between the in-vivo and ex-vivo images to verify that consistent tissue contact is made during lumpectomy cavity scanning. A comprehensive process to evaluate LUM System operation is implemented and will be reported. The novel imaging agent, LUM015, is injected into all enrolled subjects and safety data is being collected.

Discussion: Successful implementation of standardized tissue collection, naming conventions, and LUM Imaging System training is intended to improve the quality and integrity of the data collected in the upcoming Pivotal clinical trial to evaluate the safety and efficacy of the LUM Imaging System. This System is also currently being evaluated in other cancer indications including gastrointestinal cancers, prostate cancer and brain cancer.

This study is funded by a grant from the National Cancer Institute to support biomedical technology development.

Citation Format: Jorge M. Ferrer, Shelly Hwang, Kelly Hunt, Daleela Dodge, Anees Chagpar, Stephen Grobmyer, Stephen Karp, Stephanie Valente, Irene Wapnir, Kate Smith, Elena Ramirez, Thomas Bischof, David Strasfeld, David Lee, Barbara Smith. Expansion into multiple institutions for training in the use of the LUM Imaging System for intraoperative detection of residual cancer in the tumor bed of female subjects with breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr CT166.

Real-time, intraoperative detection of residual breast cancer in lumpectomy cavity walls using a novel cathepsin-activated fluorescent imaging system

PURPOSE

Obtaining tumor-free surgical margins is critical to prevent recurrence in breast-conserving surgery but it remains challenging. We assessed the LUM Imaging System for real-time, intraoperative detection of residual tumor.

METHODS

Lumpectomy cavity walls and excised specimens of breast cancer lumpectomy patients were assessed with the LUM Imaging System (Lumicell, Inc., Wellesley MA) with and without intravenous LUM015, a cathepsin-activatable fluorescent agent. Fluorescence at potential sites of residual tumor was evaluated with a sterile hand-held probe, displayed on a monitor and correlated with histopathology.

RESULTS

Background autofluorescence was assessed in excised specimens from 9 patients who did not receive LUM015. In vivo lumpectomy cavities and excised specimens were then imaged in 15 women undergoing breast cancer surgery who received no LUM015, 0.5, or 1 mg/kg LUM015 (5 women per dose). Among these, 11 patients had invasive carcinoma with ductal carcinoma in situ (DCIS) and 4 had only DCIS. Image acquisition took 1 s for each 2.6-cm-diameter surface. No significant background normal breast fluorescence was identified. Elevated fluorescent signal was seen from invasive cancers and DCIS. Mean tumor-to-normal signal ratios were 4.70 ± 1.23 at 0.5 mg/kg and 4.22 ± 0.9 at 1.0 mg/kg (p = 0.54). Tumor was distinguished from normal tissue in pre-and postmenopausal women and readings were not affected by breast density. Some benign tissues produced fluorescent signal with LUM015.

CONCLUSION

The LUM Imaging System allows rapid identification of residual tumor in the lumpectomy cavity of breast cancer patients and may reduce rates of positive margins.

Abstract P4-01-05: In vivo, intraoperative margin detection utilizing the Lumicell margin assessment system

This abstract was withdrawn by the authors.

A Novel Imaging System Distinguishes Neoplastic from Normal Tissue During Resection of Soft Tissue Sarcomas and Mast Cell Tumors in Dogs

OBJECTIVE

To assess the ability of a novel imaging system designed for intraoperative detection of residual cancer in tumor beds to distinguish neoplastic from normal tissue in dogs undergoing resection of soft tissue sarcoma (STS) and mast cell tumor (MCT).

STUDY DESIGN

Non-randomized prospective clinical trial.

ANIMALS

12 dogs with STS and 7 dogs with MCT.

METHODS

A fluorescent imaging agent that is activated by proteases in vivo was administered to the dogs 4-6 or 24-26 hours before tumor resection. During surgery, a handheld imaging device was used to measure fluorescence intensity within the cancerous portion of the resected specimen and determine an intensity threshold for subsequent identification of cancer. Selected areas within the resected specimen and tumor bed were then imaged, and biopsies (n=101) were obtained from areas that did or did not have a fluorescence intensity exceeding the threshold. Results of intraoperative fluorescence and histology were compared.

RESULTS

The imaging system correctly distinguished cancer from normal tissue in 93/101 biopsies (92%). Using histology as the reference, the sensitivity and specificity of the imaging system for identification of cancer in biopsies were 92% and 92%, respectively. There were 10/19 (53%) dogs which exhibited transient facial erythema soon after injection of the imaging agent which responded to but was not consistently prevented by intravenous diphenhydramine.

CONCLUSION

A fluorescence-based imaging system designed for intraoperative use can distinguish canine soft tissue sarcoma (STS) and mast cell tumor (MCT) tissue from normal tissue with a high degree of accuracy. The system has potential to assist surgeons in assessing the adequacy of tumor resections during surgery, potentially reducing the risk of local tumor recurrence. Although responsive to antihistamines, the risk of hypersensitivity needs to be considered in light of the potential benefits of this imaging system in dogs.

A mouse-human phase 1 co-clinical trial of a protease-activated fluorescent probe for imaging cancer

Local recurrence is a common cause of treatment failure for patients with solid tumors. Intraoperative detection of microscopic residual cancer in the tumor bed could be used to decrease the risk of a positive surgical margin, reduce rates of reexcision, and tailor adjuvant therapy. We used a protease-activated fluorescent imaging probe, LUM015, to detect cancer in vivo in a mouse model of soft tissue sarcoma (STS) and ex vivo in a first-in-human phase 1 clinical trial. In mice, intravenous injection of LUM015 labeled tumor cells, and residual fluorescence within the tumor bed predicted local recurrence. In 15 patients with STS or breast cancer, intravenous injection of LUM015 before surgery was well tolerated. Imaging of resected human tissues showed that fluorescence from tumor was significantly higher than fluorescence from normal tissues. LUM015 biodistribution, pharmacokinetic profiles, and metabolism were similar in mouse and human subjects. Tissue concentrations of LUM015 and its metabolites, including fluorescently labeled lysine, demonstrated that LUM015 is selectively distributed to tumors where it is activated by proteases. Experiments in mice with a constitutively active PEGylated fluorescent imaging probe support a model where tumor-selective probe distribution is a determinant of increased fluorescence in cancer. These co-clinical studies suggest that the tumor specificity of protease-activated imaging probes, such as LUM015, is dependent on both biodistribution and enzyme activity. Our first-in-human data support future clinical trials of LUM015 and other protease-sensitive probes.

A Fluorescence-Guided Laser Ablation System for Removal of Residual Cancer in a Mouse Model of Soft Tissue Sarcoma

The treatment of soft tissue sarcoma (STS) generally involves tumor excision with a wide margin. Although advances in fluorescence imaging make real-time detection of cancer possible, removal is limited by the precision of the human eye and hand. Here, we describe a novel pulsed Nd:YAG laser ablation system that, when used in conjunction with a previously described molecular imaging system, can identify and ablate cancer in vivo. Mice with primary STS were injected with the protease-activatable probe LUM015 to label tumors. Resected tissues from the mice were then imaged and treated with the laser using the paired fluorescence-imaging/ laser ablation device, generating ablation clefts with sub-millimeter precision and minimal underlying tissue damage. Laser ablation was guided by fluorescence to target tumor tissues, avoiding normal structures. The selective ablation of tumor implants in vivo improved recurrence-free survival after tumor resection in a cohort of 14 mice compared to 12 mice that received no ablative therapy. This prototype system has the potential to be modified so that it can be used during surgery to improve recurrence-free survival in patients with cancer.

Abstract 2056: Identification of microscopic ovarian tumor foci utilizing a novel imaging device in a murine ovarian cancer model, an opportunity to improve optimal cytoreduction

Survival of ovarian cancer patients is directly related to the amount of residual disease present after debulking surgery. In 80% of the cases, extensive microscopic cancer remains even after the patient is deemed optimally debulked. Hence, detection of sub-mm cancer clusters during tumor excision is a critical unmet need. Recent studies have shown that reducing the dimensions of residual cancer to less than 1 mm significantly improves clinical outcomes. In the present study we evaluate the performance of a fluorescent, molecular imaging agent, LUM015 (Lumicell, Wellesley, MA), which is activated by cathepsin enzymes in the tumor, and a wide-field-of-view imaging device (Lumicell) to detect sub-mm residual cancer clusters in an mouse model for ovarian cancer.

In this study, we generated orthotopic ovarian cancer mouse models(n=10) with well characterized serous ovarian cancer cell lines, CP70 and SKOV3. Once the tumor disseminated, the imaging agent LUM015 (3.52 mg/kg) was injected via the tail vein, and after 6 hours, the mice were euthanized. Tumor debulking was performed throughout the abdominal cavity. After debulking, the whole abdominal wall was dissected in 4 quadrants, organs were harvested and all were imaged with the LUM device. Features exhibiting high fluorescence were marked and dissected, prepared into slides, and stained with hematoxylin and eosin for pathologic correlation with LUM015 fluorescence imaging.

In 36 tissues from orthotopic ovarian cancer mouse models, LUM015 imaging system could detect the tumor presence with 100% of sensitivity and 60% of specificity. We demonstrated that the imaging system can detect sub-mm cancer clusters that could not be identified with visual inspection.

With a cathepsin activated fluorescence imaging molecule (LUM015) and a wide-field-of-view imaging device, we detected microscopic residual ovarian cancer tumors in orthotopic xenograft models after debulking grossly with high sensitivity. Translation of this imaging technology into the clinical setting may help to detect microscopic residual tumor features during the debulking operation in ovarian cancer.

Citation Format: Youngjeong Na, Tim Kwok, Christopher Awtrey, David B. Strasfeld, Jorge M. Ferrer, David Lee, Michael J. Birrer. Identification of microscopic ovarian tumor foci utilizing a novel imaging device in a murine ovarian cancer model, an opportunity to improve optimal cytoreduction. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2056. doi:10.1158/1538-7445.AM2014-2056

CD27+ B cells from a subgroup of common variable immunodeficiency patients are less sensitive to apoptosis rescue regardless of interleukin-21 signalling

Common variable immunodeficiency (CVID) is a primary immunodeficiency characterized by hypogammaglobulinaemia and recurrent infections. Although the underlying cause is unknown, B cells from most CVID patients fail to differentiate to memory or plasma cells. We investigated if increased apoptosis could influence the fate of B cells. For this purpose we activated purified B lymphocytes of CVID patients with a surrogate T-dependent (anti-CD40) or T-independent [cytosine-phosphate-guanosine oligodeoxynucleotides (CpG-ODN) or anti-immunoglobulin (Ig)M)] stimulus with or without interleukin (IL)-21. We found that CD27(+) B cells were more sensitive than CD27(-) B cells to spontaneous apoptosis and less sensitive to rescue from apoptosis. The addition of IL-21 down-modulated the protective effect of all the stimuli on CD27(-) B cells and the protective effect of CpG-ODN and anti-IgM on CD27(+) B cells. In contrast, IL-21 rescued unstimulated CD27(-) B cells and improved the rescue of anti-CD40-stimulated CD27(+) B cells. When we compared patients and controls, mainly CD27(+) B cells from MB0 patients were less sensitive to rescue from apoptosis than those from MB1 patients and controls after activation, irrespective of the IL-21 effect. Increased apoptosis during an immune response could result in lower levels of immunoglobulin production in these patients.

A novel imaging system permits real-time in vivo tumor bed assessment after resection of naturally occurring sarcomas in dogs

BACKGROUND

Treatment of soft tissue sarcoma (STS) includes complete tumor excision. However, in some patients, residual sarcoma cells remain in the tumor bed. We previously described a novel hand-held imaging device prototype that uses molecular imaging to detect microscopic residual cancer in mice during surgery.

QUESTIONS/PURPOSES

To test this device in a clinical trial of dogs with naturally occurring sarcomas, we asked: (1) Are any adverse clinical or laboratory effects observed after intravenous administration of the fluorescent probes? (2) Do canine sarcomas exhibit fluorescence after administration of the cathepsin-activated probe? (3) Is the tumor-to-background ratio sufficient to distinguish tumor from tumor bed? And (4) can residual fluorescence be detected in the tumor bed during surgery and does this correlate with a positive margin?

METHODS

We studied nine dogs undergoing treatment for 10 STS or mast cell tumors. Dogs received an intravenous injection of VM249, a fluorescent probe that becomes optically active in the presence of cathepsin proteases. After injection, tumors were removed by wide resection. The tumor bed was imaged using the novel imaging device to search for residual fluorescence. We determined correlations between tissue fluorescence and histopathology, cathepsin protease expression, and development of recurrent disease. Minimum followup was 9 months (mean, 12 months; range, 9-15 months).

RESULTS

Fluorescence was apparent from all 10 tumors and ranged from 3 × 10(7) to 1 × 10(9) counts/millisecond/cm(2). During intraoperative imaging, normal skeletal muscle showed no residual fluorescence. Histopathologic assessment of surgical margins correlated with intraoperative imaging in nine of 10 cases; in the other case, there was no residual fluorescence, but tumor was found at the margin on histologic examination. No animals had recurrent disease at 9 to 15 months.

CONCLUSIONS

These initial findings suggest this imaging system might be useful to intraoperatively detect residual tumor after wide resections.

CLINICAL RELEVANCE

The ability to assess the tumor bed intraoperatively for residual disease has the potential to improve local control.

Intraoperative detection and removal of microscopic residual sarcoma using wide-field imaging

BACKGROUND: The goal of limb-sparing surgery for a soft tissue sarcoma of the extremity is to remove all malignant cells while preserving limb function. After initial surgery, microscopic residual disease in the tumor bed will cause a local recurrence in approximately 33% of patients with sarcoma. To help identify these patients, the authors developed an in vivo imaging system to investigate the suitability of molecular imaging for intraoperative visualization. METHODS: A primary mouse model of soft tissue sarcoma and a wide field-of-view imaging device were used to investigate a series of exogenously administered, near-infrared (NIR) fluorescent probes activated by cathepsin proteases for real-time intraoperative imaging. RESULTS: The authors demonstrated that exogenously administered cathepsin-activated probes can be used for image-guided surgery to identify microscopic residual NIR fluorescence in the tumor beds of mice. The presence of residual NIR fluorescence was correlated with microscopic residual sarcoma and local recurrence. The removal of residual NIR fluorescence improved local control. CONCLUSIONS: The authors concluded that their technique has the potential to be used for intraoperative image-guided surgery to identify microscopic residual disease in patients with cancer. Cancer 2012. © 2012 American Cancer Society.

Molecular origin of strain softening in cross-linked F-actin networks

Two types of measurement are presented that relate molecular events to macroscopic behavior of F-actin networks. First, shear modulus is measured by oscillating an embedded microbead. Second, a microbead is translated at constant rate and transitions in the resisting force are observed. The loading rate dependence of the force at the transitions is similar to that of the molecular unbinding force, suggesting that they share a common origin. Reversibility tests of shear modulus provide further evidence that strain softening of F-actin networks is caused by force-induced rupture of cross-links.

Abstract 4316: A novel wide field-of-view imaging device for real-time, intra-operative tumor bed assessment

Limb-sparing surgery for extremity soft tissue sarcoma removes all cancer cells at the primary tumor site in the majority of patients. However, without radiation therapy, microscopic residual sarcoma cells left behind in the tumor bed will cause a tumor recurrence in approximately one-third of patients. Therefore, adjuvant radiation therapy is delivered to most patients, even when the tumor bed lacks residual cancer. Here, we present an imaging system for residual cancer assessment, consisting of a novel wide field-of-view imaging device and a protease-activated fluorescent probe. We demonstrate that this system directly images microscopic residual sarcoma cells in the tumor bed of mice when primary soft tissue sarcomas are resected. Moreover, this system can detect single tumor cells that have activated the fluorescent probe in vivo. This technology has the potential to be used as an intra-operative tool to identify microscopic residual disease for soft tissue sarcoma and other cancers with the goal of reducing rates of local recurrence, re-operation for positive margins, and adjuvant radiation therapy to tumor beds that lack residual cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4316.

Passive and active microrheology for cross-linked F-actin networks in vitro

Actin filament (F-actin) is one of the dominant structural constituents in the cytoskeleton. Orchestrated by various actin-binding proteins (ABPs), F-actin is assembled into higher-order structures such as bundles and networks that provide mechanical support for the cell and play important roles in numerous cellular processes. Although mechanical properties of F-actin networks have been extensively studied, the underlying mechanisms for network elasticity are not fully understood, in part because different measurements probe different length and force scales. Here, we developed both passive and active microrheology techniques using optical tweezers to estimate the mechanical properties of F-actin networks at a length scale comparable to cells. For the passive approach we tracked the motion of a thermally fluctuating colloidal sphere to estimate the frequency-dependent complex shear modulus of the network. In the active approach, we used an optical trap to oscillate an embedded microsphere and monitored the response in order to obtain network viscoelasticity over a physiologically relevant force range. While both active and passive measurements exhibit similar results at low strain, the F-actin network subject to high strain exhibits non-linear behavior which is analogous to the strain-hardening observed in macroscale measurements. Using confocal and total internal reflection fluorescent microscopy, we also characterize the microstructure of reconstituted F-actin networks in terms of filament length, mesh size and degree of bundling. Finally, we propose a model of network connectivity by investigating the effect of filament length on the mechanical properties and structure.

Phenotypic characterisation of T-lymphocytes in COPD: abnormal CD4+CD25+ regulatory T-lymphocyte response to tobacco smoking

Tobacco smoking induces an inflammatory response in the lungs of all smokers but, for reasons that are still poorly understood, only a proportion of them develop chronic obstructive pulmonary disease (COPD). Recent evidence indicates that this inflammatory response persists after smoking cessation, suggesting some type of auto-perpetuation mechanism similar to that described in autoimmune disorders. T-lymphocytes (CD4+ and CD8+) have been implicated in the pathogenesis of both COPD and several autoimmune processes. A subtype of regulatory CD4+ T-cells expressing CD25 (Tregs) plays a critical role in the maintenance of peripheral tolerance and the prevention of autoimmunity, but their potential role in COPD has not been explored. The present study sought to evaluate maturation (CD45RA/CD45R0) and activation markers (CD28) of T-lymphocytes and to explore potential Treg abnormalities in COPD. Flow cytometry was used to characterise T-lymphocytes obtained from blood and bronchoalveolar lavage fluid (BALF) in 23 patients with moderate COPD, 29 smokers with normal lung function and seven never-smokers. The main findings were that in BALF: patients with COPD showed higher CD8+CD45RA+ and lower CD8+CD45R0+ than smokers with normal lung function; and compared with never-smokers, smokers with preserved lung function showed a prominent upregulation of Tregs that was absent in patients with COPD. These observations indicate a final maturation-activation state of CD8+ T-lymphocytes in chronic obstructive pulmonary disease and, for the first time, identify a blunted regulatory T-cell response to tobacco smoking in these patients, further supporting a potential involvement of the acquired immune response in the pathogenesis of the disease.

Single M13 bacteriophage tethering and stretching

The ability to present biomolecules on the highly organized structure of M13 filamentous bacteriophage is a unique advantage. Where previously this viral template was shown to direct the orientation and nucleation of nanocrystals and materials, here we apply it in the context of single-molecule (SM) biophysics. Genetically engineered constructs were used to display different reactive species at each of the filament ends and along the major capsid, and the resulting hetero-functional particles were shown to consistently tether microscopic beads in solution. With this system, we report the development of a SM assay based on M13 bacteriophage. We also report the quantitative characterization of the biopolymer's elasticity by using an optical trap with nanometer-scale position resolution. Expanding the fluctuating rod limit of the wormlike chain to incorporate enthalpic polymer stretching yielded a model capable of accurately capturing the full range of extensions. Fits of the force-extension measurements gave a mean persistence length of approximately 1,265 nm, lending SM support for a shorter filamentous bacteriophage persistence length than previously thought. Furthermore, a predicted stretching modulus roughly two times that of dsDNA, coupled with the system's linkage versatility and load-bearing capability, makes the M13 template an attractive candidate for use in tethered bead architectures.

Intracellular cytokine profile of T lymphocytes in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by an excessive inflammatory response to inhaled particles, mainly tobacco smoking. T lymphocytes are important regulatory cells that secrete several cytokines and participate actively in this inflammatory response. According to the pattern of cytokines secreted, the immune response is classified as cytotoxic or type 1 [interferon (IFN)-gamma-, interleukin (IL)-2-dependent] and humoral or type 2 (IL-4-, IL-5-, IL-10- and IL-13-dependent). This paper sought to compare the intracellular profile of cytokine expression determined by flow cytometry in T lymphocytes harvested from bronchoalveolar lavage (BAL) and peripheral blood in patients with COPD, smokers with normal lung function and never smokers. We found that BAL T lymphocytes from COPD patients had a higher percentage of positive stained cells for most of the cytokines analysed when compared to never smokers or smokers with normal lung function. Differences reached statistical significance for IL-4, IL-10 and IL-13, particularly in CD8(+) T cells. Furthermore, the expression of most of these cytokines was related inversely to the degree of airflow obstruction present suggesting local activation and/or selective homing of T lymphocytes to the lungs in COPD patients. These observations were not reproduced in circulating T lymphocytes. These results suggest that BAL T lymphocytes in patients with COPD produce more cytokines than in controls and tend to show a type 2 pattern of intracellular cytokine expression, particularly a Tc-2 profile. This is related inversely to the degree of airflow obstruction present.

Costimulatory molecules and cytokine production by T lymphocytes in common variable immunodeficiency disease

Common variable immunodeficiency (CVID) is a heterogeneous syndrome characterized by hypogammaglobulinaemia and recurrent infections. Although early works pointed to a primary B-lymphocyte defect as a cause of the disease, a failure in T-lymphocyte cooperation has also been suggested. T cells exert their costimulatory function through either membrane costimulatory molecules or secreted cytokines, both having an influence in the development of the humoral response. The aim of our study was to evaluate whether an abnormal expression and induction of costimulatory molecules or alterations in the production of cytokines by T cells cause deficient T/B cooperation in CVID patients. We studied the expression and upregulation of costimulatory molecules (CD28, CD40L/CD154 and CTLA-4/CD152) and production of cytokines (IL-2, IL-4, IL-6, IL-10, IFN-gamma and TNF-alpha) in purified T lymphocytes from CVID patients stimulated with optimal doses of anti-CD3 or suboptimal doses of anti-CD3 and anti-CD28. Stimulated T cells from CVID patients expressed normal levels of CD28, CD40L/CD154 and CTLA-4/CD152 when compared with controls. Except for higher production of IL-4 after stimulation with anti-CD3, T cells of CVID patients produced similar amounts of cytokines compared with controls. An imbalance between costimulatory molecules expression (CD28, CD40L/CD154 and CTLA-4/CD152) and cytokine production by T cells does not explain a deficient cooperation between T and B cells in this group of CVID patients.

Interlaced optical force-fluorescence measurements for single molecule biophysics

Combining optical tweezers with single molecule fluorescence offers a powerful technique to study the biophysical properties of single proteins and molecules. However, such integration into a combined, coincident arrangement has been severely limited by the dramatic reduction in fluorescence longevity of common dyes under simultaneous exposure to trapping and fluorescence excitation beams. We present a novel approach to overcome this problem by alternately modulating the optical trap and excitation beams to prevent simultaneous exposure of the fluorescent dye. We demonstrate the dramatic reduction of trap-induced photobleaching effects on the common single molecule fluorescence dye Cy3, which is highly susceptible to this destructive pathway. The extension in characteristic fluorophore longevity, a 20-fold improvement when compared to simultaneous exposure to both beams, prolongs the fluorescence emission to several tens of seconds in a combined, coincident arrangement. Furthermore, we show that this scheme, interlaced optical force-fluorescence, does not compromise the trap stiffness or single molecule fluorescence sensitivity at sufficiently high modulation frequencies. Such improvement permits the simultaneous measurement of the mechanical state of a system with optical tweezers and the localization of molecular changes with single molecule fluorescence, as demonstrated by mechanically unzipping a 15-basepair DNA segment labeled with Cy3.

Blunted gamma delta T-lymphocyte response in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterised by an excessive inflammatory response to inhaled particles, mostly tobacco smoking. Although inflammation is present in all smokers, only a percentage of them develop COPD. T-lymphocytes are important effector and regulatory cells that participate actively in the inflammatory response of COPD. They comprise the T-cell receptor (TCR)-alpha beta (CD4+ and CD8+) and TCR-gamma delta T-lymphocytes. The latter represent a small percentage of the total T-cell population, but play a key role in tissue repair and mucosal homeostasis. To investigate TCR-alpha beta (CD4+ and CD8+) and TCR-gamma delta T-lymphocytes in COPD, the present authors determined, by flow cytometry, the distribution of both subpopulations in peripheral blood and bronchoalveolar lavage (BAL) samples obtained from patients with COPD, smokers with normal lung function and never-smokers. The present study found that: 1) the distribution of CD4+ and CD8+ lymphocytes in blood and BAL was similar in all three groups; 2) compared with nonsmokers, gamma delta T-lymphocytes were significantly increased in smokers with preserved lung function; and 3) this response was blunted in patients with COPD. These results highlight a novel, potentially relevant, pathogenic mechanism in chronic obstructive pulmonary disease.

Chronobiology of labour pain perception: an observational study

BACKGROUND

Circadian variation may affect many biological and pharmacological phenomena.

METHODS

To assess circadian variations in labour pain perception, 222 consecutive nulliparous women with uncomplicated pregnancy, spontaneous labour, cervical dilatation (3-5 cm), ruptured membranes and normal fetal heart rate tracings were studied. Visual analogue pain scores (VAPS) were analysed and divided into four periods: night (1:01 a.m. to 7:00 a.m.), morning (7:01 a.m. to 1:00 p.m.), afternoon (1:01 p.m. to 7:00 p.m.) and evening (7:01 p.m. to 1:00 a.m.). VAPS were also compared between daytime (morning+afternoon) and nocturnal (evening+night) periods.

RESULTS

Daytime mean VAPS were lower than nocturnal scores [75.6 (15.1) vs 85.7 (14.1), P<0.0001]. VAPS were lower in the morning than in the afternoon, evening and night periods (anova, P<0.0001).

CONCLUSION

Labour pain perception appears to be chronobiological, and this might be taken into account when enrolling parturients in studies designed to assess or treat labour pain.

Adult-onset subacute sclerosing panencephalitis: clinico-pathological findings in 2 new cases

Subacute sclerosing panencephalitis (SSPE), an uncommon disease usually affecting children and adolescents, is caused by persistent measles infection that progresses to chronic infection with fatal outcome. The debut of this disease in adults is rare, with a small number of cases in the medical literature. This article presents the clinical, radiologic and post-mortem neuropathologic findings in 2 new cases of women with SSPE (1 of them during pregnancy), which showed very atypical clinical characteristics, presentation and evolution. The influence of pregnancy on the course of the disease was unfavorable, in keeping with earlier reports. Our patients showed a very prolonged biphasal clinical course, with a period of disease-free remission that lasted several years. Histological study disclosed features of inflammatory disease associated with others of a neurodegenerative nature, such as the formation of neurofibrillary tangles, which would relate SSPE with other tauopathies.

The pharmacokinetics and pharmacodynamics of fludarabine phosphate in patients with renal impairment: a prospective dose adjustment study

A significant number of chronic lymphocytic leukemia, follicular non-Hodgkin's lymphoma and Waldenström's macroglobulinemia patients, treated with fludarabine phosphate (fludarabine), are elderly with diminished renal function. Since the kidney eliminates approximately 60% of fludarabine's primary metabolite (F-ara-A), dose modification is necessary for all patients with impaired renal function including elderly patients. In this study, 22 patients with varying levels of renal function received a single intravenous dose of fludarabine (25 mg/m3), followed one week later by five (one per day) doses that were adjusted according to three predefined creatinine clearance (CLcr) levels. Relationships between renal function and F-ara-A clearance, F-ara-A exposure and F-ara-A--related toxicities were examined. The results demonstrate that total F-ara-A clearance correlated with CLcr and that F-ara-A exposure levels and patient toxicity profiles were similar across treatment groups.

IN CONCLUSION

The CLcr-based fludarabine dose adjustments used in this study provided reasonably equivalent F-ara-A exposure with acceptable safety in patients with varying degrees of renal function.

[Dural puncture in obstetric analgesia. Epidemiologic features and therapeutic management]

OBJECTIVE

To assess the time of occurrence, circumstances and presenting symptoms of unintentional dural puncture (UDP), the location and intensity of postdural puncture headaches (PDPH), and the efficacy of their treatment by epidural blood-patch (EBP).

STUDY DESIGN

Cohort study.

PATIENTS

Cases of UDP recorded over a 4-year period in an obstetric anaesthesia unit.

METHODS

The following variables were studied: maternal age, weight and height, hour of occurrence and number of puncture attempts, existence of reflux of cerebrospinal fluid (CSF) through the needle, experience of the practitioners, subsequent modalities of obstetrical analgesia, frequency of occurrence, clinical characteristics and therapeutic management of PDPH. In case of EBP, the amount of blood and the efficacy of the procedure were also recorded.

RESULTS

Twenty-one patients presented with UDP (0.66%). No reflux of CSF was identified in nine cases. Most UDP occurred at the first or second attempt, usually when performed by a practitioner poorly trained in epidural analgesia in obstetrics. The risk of UDP was higher during night-time work (risk ratio: 3.0; 95% confidence interval: 1.1-8.0; p = 0.04). Subsequent analgesia was provided via the epidural route in 19 cases, subarachnoidal route in one, and intravenous route in one case. PDPH did not develop in two patients. Three patients were given prophylactic EPB, and 16 received curative EBP. A second EBP was required 24 h later in seven patients. One patient developed meralgia paresthetica following EBP.

CONCLUSION

In parturients, UDP usually results in PDPH. A rapid and effective treatment is required, mainly EBP. Another EBP is eventually necessary in some patients.

Adverse drug reactions in children reported by means of the yellow card in Spain

OBJECTIVE

To analyze the case reports concerning children (14 years or younger) in the Spanish Pharmacovigilance System over a 10-year period (1982-1991).

FINDINGS

The study of 1419 reports of adverse drug reaction (9.8% of all those received) showed the most commonly involved organs and systems to be the skin, digestive tract, and nervous system (62.8%). The most commonly involved pharmacological groups were antibiotics, respiratory medications, and vaccines (69%). The absolute number of reports is higher in children between 1 and 4 years of age (37.9%). There were more reports among males than in females. Less than 5% of the reports notified directly life-threatening or fatal reactions.

CONCLUSIONS

Adverse drug reaction are not common in pediatric patients, and most are mild. However, due to limitations of clinical trials in children, pharmacoepidemiological studies may be the only source of information on the benefit-risk profile of drugs received by these patients, and as such require special attention.

Use of ultrasound contrast in the diagnosis of carotid artery occlusion

OBJECTIVE

The purpose of this study was to evaluate the use of an echo-enhancing agent in patients with carotid artery occlusion to improve the sensitivity and specificity of carotid color flow ultrasonography.

METHOD

Between January 1997 and December 1998, a prospective study involving 85 cases of carotid artery occlusion in 84 patients was carried out. After a baseline duplex ultrasonography (DU) diagnosis, a second (DU) along with an echo-enhancement agent (SHU-508-A [Levovist]) study was carried out (echo enhancement ultrasonography diagnosis [DUEE]). In 82 cases, a contrast angiography was performed to confirm the diagnosis, whereas in the other three cases the diagnoses were confirmed with surgery.

RESULTS

From the 85 internal carotid artery occlusions diagnosed at the initial DU examination, seven came out to be false occlusions in the DUEE examination (8,2%). There was a 100% correlation of the cases between the DUEE examination and the contrast angiography in the 82 cases in which this had been done. In three of the cases, the diagnosis was confirmed surgically because these displayed severe stenoses according to the DUEE studies in symptomatic patients, and so they required urgent treatment.

CONCLUSIONS

The DUEE study is a potent diagnosis tool that allows the differentiation between true carotid artery occlusions and pseudo-occlusions.

Electron microscopic contrast of the cytoskeleton and junctional complexes of intestinal epithelial cells by ethanolic phosphotungstic acid

After glutaraldehyde fixation and treatment with ethanolic phosphotungstic acid (E-PTA) before plastic embedding, sections of rat large intestine showed a characteristic electron contrasting pattern in epithelial cells. The axis of microvilli, terminal web, a thin band below the luminal plasma membrane, centrioles and junctional complexes (tight junctions, adherens junctions, and desmosomes) appeared highly contrasted. In addition to protein components of microfilaments and intermediate filaments, proteins from the junctional complexes could also be implicated in the contrasting reaction with E-PTA. Mitochondrial membranes, chromatin masses, and nucleoli of enterocytes showed considerable electron density, whereas no reaction was found in the glycocalyx and mucin content of goblet cells. The clear visualization of cytoskeleton elements and junctional complexes by E-PTA contrasting represents a simple and valuable method for studies on the normal and pathological organization of these structures in epithelial cells.

Neurologic complications associated with hepatitis C virus infection

A series of nine patients with neurologic complications of hepatitis C virus infection is reported. Seven patients presented a combination of chronic sensory polyneuropathy, multineuropathy, and encephalopathy related to cryoglobulinemia. The noncryoglobulinemic symptoms consisted of an anterior optic neuropathy and a restless legs syndrome with small-fiber neuropathy. Corticosteroids and cyclophosphamide were useful in controlling vasculitic episodes. Interferon-alpha caused remission in half of the treated patients.

Increased risk of unintentional dural puncture in night-time obstetric epidural anesthesia

PURPOSE

To evaluate the experience of the operator and the time of epidural anesthesia as factors contributing to unintentional dural puncture (UDP).

METHODS

In a prospective analysis of recorded cases of UDP the following variables were recorded: maternal height, weight, and weight gain, type of personnel providing epidural analgesia, number of attempts, and hour of the epidural procedure. Work time was divided into day-time (8 AM to 7 PM) and night-time (7 PM to 8 AM), according to the change of coverage of the delivery suite. Night-time was divided into first (7 PM to midnight) and second parts (midnight to 8 AM). Relative risk was used to compare the incidence of UDP among different work-times.

RESULTS

A total of 1489 consecutive epidural procedures were considered. The incidence of dural puncture was 0.8% (12 cases). The relative risk was higher for night-time than day-time (risk ratio 6.33; 95% confidence interval, 1.39 to 28.80; P = 0.006). Seven cases were caused by three operators with poor expertise, and five by two skilled obstetric anesthesiologists.

CONCLUSION

Operator experience and hour of procedure appear to be two important risk factors of UDP The increased risk of UDP in night-work could result from human factors such as fatigue, sleep deprivation or interruption.

CD95 expression and function on lymphocyte subpopulations in common variable immunodeficiency (CVID); related to increased apoptosis

Apoptosis is now recognized as a central process of development and disease, and it has been proposed as one of the mechanisms that may account for the lymphopenia seen in some diseases. In this study we measured spontaneous apoptosis and CD95 expression on different cell subpopulations from CVID patients, using flow cytometric techniques. We divided our patients into two groups according to their CD4+ and CD4+CD45RA+ cell counts. Our results clearly show increased spontaneous apoptosis and CD95 expression on the CD4+ and CD4+CD45RA+ subsets from lymphopenic CVID patients compared with normal subjects and disease controls. Interestingly, our lymphopenic CVID patients presented a profound reduction in absolute counts, mainly affecting the CD4+CD45RA+ subpopulation. We also found a statistically significant direct correlation between absolute numbers of CD4+CD45RA+ T cells and spontaneous apoptosis on the same subset in CVID patients, but attempts to induce CD95-mediated apoptosis were unsuccessful despite increased CD95 expression on CD4+ T cells. These findings suggest that apoptosis could be one of the mechanisms implicated in the significant lymphopenia present in these patients.

A prospective study of adverse drug reactions in hospitalized children

AIMS

There are few publications of adverse drug reactions (ADRs) among paediatric patients, though ADR incidence is usually stated to be higher during the first year of life and in male patients. We have carried out a prospective study to assess the extent, pattern and profile risk for ADRs in hospitalized patients between 1 and 24 months of age.

METHODS

An intensive events monitoring scheme was used. A total of 512 successive admissions to two medical paediatric wards (47 beds) were analysed. The hospital records were screened daily during two periods (summer, 105 days and winter, 99 days), and adverse clinical events observed were recorded.

RESULTS

A total of 282 events were detected; of these, 112 were considered to be manifestations of ADRs. The cumulative incidence was 16.6%, no differences being observed between periods. Although there were no differences between patients under and over 12 months of age, risk was found to be significantly higher among girls compared with boys (RR=1.66, 95% CI 1.03-2.52). The gastro-intestinal system was most frequently affected. The therapeutic group most commonly implicated was anti-infective drugs and vaccines (41.5%). The ADRs were mild or moderate in over 90% of cases. A consistent relationship was noted between the number of drugs administered and the incidence of ADRs.

CONCLUSIONS

Hospitalized patients exhibited an ADR risk profile that included female sex and the number of drugs administered. No particular age predisposition was observed. The most commonly prescribed drugs are those most often implicated in ADRs in paediatric patients.

A novel nonsense mutation at Glu-631 in a Spanish family with complement component 7 deficiency

Deficiency of the seventh component of complement (C7D) is frequently associated with recurrent neisserial infections. We report in the present study the genetic basis for C7D in a Spanish family. We used exon-specific polymerase chain reaction (PCR)/single-strand conformation polymorphism (SSCP) analysis as a screening step for mutations, followed by direct sequencing of the target exon. The mutation in the proband was a homozygous G-to-T transversion at nucleotide 1957, the first nucleotide of the codon GAG for Glu-631, leading to a stop codon TAG (E631X). Our result provides further evidence that the molecular pathogenesis of C7D is heterogeneous.

Electrophysiological and neurochemical study of the rat geniculo-cortical pathway. Evidence for glutamatergic neurotransmission

The projection from the dorsal lateral geniculate nucleus to the primary visual cortex of the rat was studied electrophysiologically. Electrical stimulation of the dorsal lateral geniculate nucleus and the optic tract produced three types of responses on neurons of area 17: excitation followed by inhibition, excitation and inhibition. These results extend and confirm, in adult rats, previous studies done in rat geniculate-visual cortex cocultures preparations in vitro. The role of glutamate in the neurotransmission of the rat geniculo-cortical pathway was also investigated. In a first set of experiments, the effects of kynurenate, an antagonist of glutamate receptors, on visual cortex neurons with a monosynaptic excitatory response to dorsal lateral geniculate nucleus stimulation were studied. Microiontophoresis of kynurenate in area 17 neurons selectively suppressed the excitatory response to dorsal lateral geniculate nucleus and optic tract stimulation. In a second set of experiments, the effects of electrical stimulation of the dorsal lateral geniculate nucleus and the optic tract on the release of amino acids in the rat visual cortex in vivo were studied. Using the push-pull method, we perfused a discrete region of the visual cortex with artificial cerebrospinal fluid (CSF), and the amino acid content of the perfusates was analysed by high performance liquid chromatography (HPLC). Stimulation of either the dorsal lateral geniculate nucleus or the optic tract significantly increased glutamate release in area 17. The rest of the amino acids studied did not show significant changes. The results provide evidence for the participation of glutamate in the neurotransmission of the geniculo-cortical pathway in the rat.

[Image processing in the primary visual cortex]

INTRODUCTION

Area 17 or the primary visual area forms the first link in the chain of cerebral analysis of a visual image. The neurones forming the primary visual cortex are characterized by the extreme precision of their connections, functional specialization and hierarchic organization. The spatial precision of the connections within the system for vision permit retinotopic representation in the visual cortex, so that each point of the retina is projected into a specific area of the cortex. The cortical neurones which analyze the characteristics of the image situated in a precise zone of the visual field are themselves organized into a basic functional unit known as a hypercolumn. Within each hypercolumn there are various columnar cell systems with receptive fields having similar characteristics. Thus, each hypercolumn is made up of multiple orientation columns, two ocular dominance columns and 'blob' regions. All these systems permit the analysis of different aspects of the image. The neurones belonging to the orientation columns are sensitive to the orientation, spatial frequency and movement of a visual stimulus; those of the 'blob' regions to colour, and the binocular neurones of the ocular dominance columns to depth. Within each column, the hierarchical pattern of neurone interconnections determines the successive appearance of cells with receptive fields having new properties.

The binding of benzopyranes to human serum albumin. A structure-affinity study

The binding of several benzopyranes to serum albumin was studied by equilibrium dialysis at pH 7.4 in a 67 mM sodium phosphate buffer at 37 degrees C. The equilibrium data were analyzed using a computer program for curve fitting. The binding isotherm for warfarin, 4-hydroxycoumarin, 4-chromanol, coumarin, 3-acetylcoumarin, and benzoic acid can be described by two stoichiometric dissociation constants. Elimination of the 4-hydroxyl group in the coumarin chemical structures decreases the binding affinity of the compounds on the primary binding site of serum albumin, with 4-chromanol the smallest ligand which binds to seroalbumin with high affinity. Thus, the affinity of 4-benzopyranol and the 4-hydroxybenzopyranones greater than that of benzopyranones. On the other hand, elimination of the 2-oxo group in the benzopyranone chemical structures decreases affinity for the secondary binding site.

[Transitory episode of laughter as the initial symptom of an ischemic stroke]

INTRODUCTION

Pathological laughter occurs in pseudobulbar paralysis, in psychiatric disorders and as a sign of convulsions (gelastic crisis). An extremely rare form is the "fou rire prodromique' a pathological episode of laughter preceding a stroke. The pathogenesis is unknown and classically differentiated from gelastic crises. "Fou rire prodromique' has been described in subcortical ischaemic or haemorrhagic strokes, not in cortical strokes.

CLINICAL CASE

We describe a patient with an ischaemic cerebrovascular accident due to embolism of the left Sylvian artery. The clinical picture started with a short episode of pathological laughter which preceded sensitive aphasia and weakness of the right limbs.

CONCLUSIONS

We suggest that in the case described it is impossible to differentiate between the "fou rire prodromique' and a gelastic crisis as a first sign of an embolic cerebrovascular accident.