A compact high-performance low-field NMR apparatus for measurements on fluids at very high pressures and temperatures.

We discuss an innovative new high-performance apparatus for performing low-field Nuclear Magnetic Resonance (NMR) relaxation times and diffusion measurements on fluids at very high pressures and high temperatures. The apparatus sensor design and electronics specifications allow for dual deployment either in a fluid sampling well logging tool or in a laboratory. The sensor and electronics were designed to function in both environments. This paper discusses the use of the apparatus in a laboratory environment. The operating temperature and pressure limits, and the signal-to-noise ratio (SNR) of the new system exceed by a very wide margin what is currently possible. This major breakthrough was made possible by a revolutionary new sensor design that breaks many of the rules of conventional high pressure NMR sensor design. A metallic sample holder capable of operating at high pressures and temperatures is provided to contain the fluid under study. The sample holder has been successfully tested for operation up to 36 Kpsi. A solenoid coil wound on a slotted titanium frame sits inside the metallic sample holder and serves as an antenna to transmit RF pulses and receive NMR signals. The metal sample holder is sandwiched between a pair of gradient coils which provide a linear field gradient for pulsed field gradient diffusion measurements. The assembly sits in the bore of a low-gradient permanent magnet. The system can operate over a wide frequency range without the need for tuning the antenna to the Larmor frequency. The SNR measured on a water sample at room temperature is more than 15 times greater than that of the commercial low-field system in our laboratory. Thus, the new system provides for data acquisition more than 200 times faster than was previously possible. Laboratory NMR measurements of relaxations times and diffusion coefficients performed at pressures up to 25 Kpsi and at temperatures up to 175 °C with crude oils enlivened with dissolved hydrocarbon gases (referred to as "live oils") are shown. This is the first time low-field NMR measurements have been performed at such high temperatures and pressures on live crude oil samples. We discuss the details of the apparatus design, tuning, calibration, and operation. NMR data acquired at multiple temperatures and pressures on a live oil sample are discussed.

Using PCA and LVQ neural network for automatic recognition of five types of white blood cells.

Designing an effective classifier has been a challenging task in the previous methods proposed in the literature. In this paper, we apply a combination of feature selection algorithm and neural network classifier in order to recognize five types of white blood cells in the peripheral blood. For this purpose, first nucleus and cytoplasm are segmented using Gram-Schmidt method and snake algorithm, respectively; second, three kinds of features are extracted from the segmented areas. Then the best features are selected using Principal Component Analysis (PCA). Finally, five types of white blood cells are classified using Learning Vector Quantization (LVQ) neural network. The performance analysis of the proposed algorithm is validated by an expert's classification results. The efficiency of the proposed algorithm is highlighted by comparing our results with those reported in a recent article which proposed a method based on the combination of Sequential Forward Selection (SFS) as the feature selection algorithm and Support Vector Machines (SVM) as the classifier.

Osteoporotic spondylolisthesis: a case report.

STUDY DESIGN: A case of spondylolisthesis caused by osteoporosis is described. OBJECTIVES: To describe the different etiologies of spondylolisthesis, and to report a new cause of pathologic spondylolisthesis previously unreported in the literature. SUMMARY OF BACKGROUND DATA: The literature on the etiology of spondylolisthesis is reviewed. Pathologic spondylolisthesis has been described with structural abnormalities, such as Paget's disease and tumors, but not with osteoporosis. METHODS: A clinical and radiographic interpretation of the reported case is presented. RESULTS: De Novo development of a spondylolisthesis at L5-S1 occurred by gradual elongation of the pars interarticularis over a period of 3 years. CONCLUSION: The reported case adds to the literature on spondylolisthesis by describing another etiology for this conclusion. Osteoporotic spondylolisthesis may well be identified more frequently in the future given the high prevalence of osteoporosis in the elderly.

Preferential susceptibility of brain tumors to the antiangiogenic effects of an alpha(v) integrin antagonist.

OBJECTIVE: Brain tumors are highly angiogenic, and their growth and spread depend on the generation of new blood vessels. We examined the effect of the cyclic peptide antagonist pentapeptide EMD 121974, an antiangiogenic agent, on orthotopic and heterotopic brain tumor growth. METHODS: The human brain tumor cell lines DAOY (medulloblastoma) and U87 MG (glioblastoma) were injected into either the forebrain (orthotopic) or the subcutis (heterotopic) of nude mice, and daily systemic treatment with the active peptide was initiated after tumors were established. RESULTS: All control animals with orthotopic brain tumors and that received the inactive peptide EMD 135981 daily died as a result of tumor progression within 4 to 6 weeks; tumors measured 3 to 5 mm in diameter. In contrast, mice with orthotopic tumors that were treated daily with the active peptide survived for more than 16 weeks, and histological examination of the brains after 4, 8, and 12 weeks showed either no tumors or microscopic residual tumors. The growth of these brain tumor cells injected simultaneously or separately into the subcutis of nude mice (heterotopic model) was not affected by the active peptide, suggesting that the brain environment is a critical determinant of brain tumor susceptibility to growth inhibition by this pentapeptide. CONCLUSION: The cyclic pentapeptide EMD 121974 may become a treatment option specific to brain tumors. Because of its antiangiogenic effect, its use may be especially indicated after tumors are removed surgically.

Ophthalmological outcome following orbital resection in anterior and anterolateral skull base surgery.

OBJECT: Partial resection of the orbital bones is not uncommon during the excision of anterior and anterolateral skull base tumors. Controversy exists regarding the need for and extent of the reconstruction necessary following this resection. The authors studied this factor in a series of patients. METHODS: The authors conducted a retrospective review of 56 patients in whom resection of 57 anterior or anterolateral skull base tumors and partial excision of the orbital bone were performed. Adverse ophthalmological outcomes were noted in 16 patients, in nine of whom adverse outcomes were believed to be directly related to resection of the orbital walls. Some degree of orbital reconstruction was performed during 23 of the 57 procedures. An adverse orbit-related outcome was strongly associated with resection of the orbital floor and with resection of two thirds or more of two or more orbital walls but not with the presence of absence or orbital reconstruction. The latter finding, however, is likely a function of selection bias. CONCLUSIONS: In most patients after partial excision of the orbital bones, elaborate reconstruction is not necessary. Isolated medial and lateral orbital wall defects or combined superior and lateral orbital wall defects, especially in cases in which the periorbita is intact, probably do not require primary reconstruction. In cases of orbital floor defects, whether isolated or part of a multiple wall resection, primary reconstruction is recommended.

Limited dorsiflexion predisposes to injuries of the ankle in children.

Injuries to the ankle are common in children. We investigated whether decreased dorsiflexion predisposes to such fractures and sprains. Passive dorsiflexion in children with ankle injuries was compared with that in a control group of patients with a normal ankle. The uninjured side was examined to determine flexibility in those patients with ankle injuries. In 82, the mean dorsiflexion was 5.7 degrees with the knee extended and 11.2 degrees with the knee flexed. In 85 controls, the mean dorsiflexion was 12.8 degrees with the knee extended and 21.5 degrees with the knee flexed (p < 0.001, Student's t-test). There was a strong association between decreased ankle dorsiflexion and injury in children. A flexible triceps surae appeared to absorb energy and protect the bone and ligaments, while stiffness predisposed to injury. We suggest that children with tight calf muscles should undergo a regimen of stretching exercises to improve their flexibility.

Tissue plasminogen activator (tPA) deficiency exacerbates cerebrovascular fibrin deposition and brain injury in a murine stroke model: studies in tPA-deficient mice and wild-type mice on a matched genetic background.

Although the serine protease, tissue plasminogen activator (tPA), is approved by the US Food and Drug Administration for therapy to combat focal cerebral infarction, the basic concept of thrombolytic tPA therapy for stroke was challenged by recent studies that used genetically manipulated tPA-deficient (tPA-/-) mice, which suggested that tPA mediates ischemic neuronal damage. However, those studies were potentially flawed because the genotypes of tPA-/- and wild-type control mice were not entirely clear, and ischemic neuronal injury was evaluated in isolation of tPA effects on brain thrombosis. Using mice with appropriate genetic backgrounds and a middle cerebral artery occlusion stroke model with nonsiliconized thread, which does lead to microvascular thrombus formation, in the present study we determined the risk for cerebrovascular thrombosis and neuronal injury in tPA-/- and genetically matched tPA+/+ mice subjected to transient focal ischemia. Cerebrovascular fibrin deposition and the infarction volume were increased by 8.2- and 6. 7-fold in tPA-/- versus tPA+/+ mice, respectively, and these variables were correlated with reduced cerebral blood flow up to 58% (P<0.05) and impaired motor neurological score by 70% (P<0.05). Our findings indicate that tPA deficiency exacerbates ischemia-induced cerebrovascular thrombosis and that endogenous tPA protects the brain from an ischemic insult, presumably through its thrombolytic action. In addition, our study emphasizes the importance of appropriate genetic controls in murine stroke research.

Childhood rhabdomyosarcoma of the trunk and extremities.

Since 1979, 15 children with rhabdomyosarcoma have been treated at our institution. Included in this group are six children who presented with rhabdomyosarcoma of an extremity or trunk, requiring the use of combined multimodality therapy. The patients were clinically grouped and treated in accordance with the Intergroup Rhabdomyosarcoma Study protocol. All patients received combination chemotherapy based on their respective stage of disease at diagnosis. When feasible, the primary tumor was resected en bloc before chemotherapy was begun. After surgery, patients with unclear postoperative surgical margins and an initial good response to chemotherapy received radiotherapy to the primary site and at the regional lymphatics. Three of six patients developed or maintained a complete tumor response to induction chemotherapy. Radiotherapy maintained control of local disease in both groups. Overall, four patients, including one with disseminated disease at diagnosis, are alive, with a median survival time from diagnosis of 39 months. In children, treatment must be individualized, but complete local excision of the tumor with a tumor-free margin should be the goal. Major ablative amputation surgery was not performed.

Detection of brain tumor invasion and micrometastasis in vivo by expression of enhanced green fluorescent protein.

OBJECTIVE: To determine whether fluorescence from human brain tumor cells transfected with the enhanced green fluorescent protein (EGFP) gene in vitro and xenotransplanted into the brain of nude mice would permit the detection of brain tumor invasion and metastasis in vivo. METHODS: Daoy medulloblastoma cells were transfected with a long terminal repeat-based retroviral vector containing the EGFP gene. Stable EGFP-expressing clones were isolated and stereotactically injected into the frontal cortex of nude mice. Four weeks later, whole brain sections were examined using fluorescence microscopy, immunohistochemistry, and routine hematoxylin and eosin staining for the visualization and detection of tumor cell invasion and metastasis. RESULTS: We demonstrate that EGFP-transduced Daoy cells maintain stable high-level EGFP expression in the central nervous system during their growth in vivo. EGFP fluorescence clearly demarcated the primary tumor margins and readily allowed for the visualization of distant micrometastases and local invasion on the single-cell level. Small metastatic and locally invasive foci, including those immediately adjacent to the tumor's leading invasive edge, were virtually undetectable by routine hematoxylin and eosin staining and immunohistochemistry. EGFP expression also persisted in vitro after cell reculture from brain tissue extracts. CONCLUSION: We show, for the first time, that EGFP-transduced human brain tumor cells can be visualized by fluorescence microscopy after intracerebral implantation. This method is superior to routine hematoxylin and eosin staining and immunohistochemistry for the detection and study of physiologically relevant patterns of brain tumor invasion and metastasis in vivo.

Intravenous RMP-7 increases delivery of ganciclovir into rat brain tumors and enhances the effects of herpes simplex virus thymidine kinase gene therapy.

Herpes simplex virus thymidine kinase (HSV-tk) gene therapy for brain tumors depends on ganciclovir (GCV) and its transport across the blood-brain tumor barrier (BBTB). We examined whether RMP-7, the bradykinin analog and potent BBTB permeabilizer, could enhance the efficacy of GCV treatment of brain tumors by increasing the BBTB delivery of GCV. In vitro, a significant bystander cytocidal effect of GCV was shown in mixed HSV-tk-transduced (HSV-tk+) and control vector-transduced (HSV-tk-) C6 glioma cultures. A dose-dependent cytotoxic effect of GCV on untransformed C6 cells was also shown. In vivo, rats with 100% HSV-tk+ or 100% HSV-tk- intracerebral C6 gliomas were treated for 7 days with intravenous infusions of GCV alone or with GCV and RMP-7 (2.5 microg/kg/day). The growth of HSV-tk+ and HSV-tk- gliomas decreased with increasing doses of GCV. A high dosage (100 mg of GCV/kg/day) eradicated all HSV-tk- and HSV-tk+ tumors. An intermediate dosage (5 mg of GCV/kg/day) reduced the growth of HSV-tk- gliomas by 42% if given alone, and by 88% in combination with RMP-7. A low dosage (0.5 mg of GCV/kg/day) in combination with RMP-7 enhanced the regression of HSV-tk+ gliomas by 87% compared with GCV alone. Low-dose GCV was ineffective in HSV-tk- tumors. RMP-7 increased [3H] GCV tumoral uptake by 2.6- and 1.7-fold in the tumor center and periphery, respectively. We conclude that RMP-7 could be an important adjunctive treatment for suicide gene therapy of brain tumors, while an RMP-7/GCV combination may also have a significant antitumor effect in untransfected gliomas.