Optimal mean-square prediction of the mobile-radio fading envelope

Long-range prediction of the mobile-radio fading envelope is an enabling technology for many fading compensation approaches. Because the fading envelope is well modeled as a bandlimited process, it has special predictability properties. In this paper, we find a linear predictor that is optimal in the mean-square sense when the predictor impulse response is energy constrained. This solution may be used to determine the minimum mean squared error of a prediction based on past values that are corrupted with estimation errors.     

A method for functional magnetic resonance imaging of olfaction

A method for generating olfactory stimuli for humans within a functional magnetic resonance imaging (fMRI) experimental design is described. The system incorporates a nasal-mask in which the change from odorant to no-odorant conditions occurs in less than 500 ms and is not accompanied by visual, auditory, tactile, or thermal cues. The mask provides an ordorant-free environment following prolonged ordorant presence. Specific imaging parameters that are conducive to the study of the human olfactory system are described. In a pilot study performed using these methods, the specific patterns of activation observed converged with published experimental and clinical findings.     

GD3/proteosome vaccines induce consistent IgM antibodies against the ganglioside GD3

The gangliosides of melanoma and other tumours of neuroectodermal origin are suitable targets for immune intervention with tumour vaccines. The optimal vaccines in current use contain ganglioside plus bacillus Calmette-Guérin and induce considerable morbidity. We have screened a variety of new adjuvants in the mouse, and describe one antigen-delivery system, proteosomes, which is especially effective. Highly hydrophobic Neisserial outer membrane proteins (OMP) form multimolecular liposome-like vesicular structures termed proteosomes which can readily incorporate amphiphilic molecules such as GD3 ganglioside. The optimal GD3/proteosome vaccine formulation for induction of GD3 antibodies in the mouse is determined. Interestingly, the use of potent immunological adjuvants in addition to proteosomes augments the IgM and IgG antibody titres against OMP in these vaccines but GD3 antibody titres are unaffected. The application of proteosomes to enhance the immune response to GD3 extends the concept of the proteosome immunopotentiating system from lipopeptides to amphipathic carbohydrate epitopes such as cell-surface gangliosides. The demonstrated safety of meningococcal OMP in humans and the data in mice presented here suggest that proteosome vaccines have potential for augmenting the immunogenicity of amphipathic tumour antigens in humans.     

c-KIT expression enhances the leukemogenic potential of 32D cells

The growth of human leukemic cells in culture and in vivo is dependent upon the presence of hematopoietic growth factors. Most populations of human leukemic acute myeloblastic leukemia (AML) cells express c-Kit on their surface and respond to Kit ligand (KL) in culture. To determine if this interaction was of potential significance in vivo we used a mouse model system. 32D cells, a murine IL-3-dependent myeloid cell line, were rendered KL responsive by transfection of the murine c-Kit. After injection of 32D or 32D-Kit cells into syngeneic hosts, animals bearing 32D-Kit cells, but not 32D cells, became moribund and were killed. These animals had circulating leukemic blast cells, infiltration of bone marrow, spleen, brain, liver, lung, and kidney. Cells recovered from some of the animals continued to be dependent upon IL-3 or KL for growth while in other cases the cells were factor independent. This model illustrates that the constitutive expression of c-Kit enhances the leukemic potential of 32D cells. The model will be useful for studying the progression of leukemia in vivo and testing whether interruption of the interaction of Kit and KL can affect the growth of leukemic cells.     

Transcellular retrograde labeling of radial glial cells with WGA-HRP and DiI in neonatal rat and hamster

Topographically distinct populations of radial glial cells in the diencephalon and mesencephalon of neonatal rats and hamsters were transcellularly labeled with wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) and with the lipophilic tracer DiI. A comparison of the histological distribution of the two tracers is suggestive of two different mechanisms of transcellular labeling. Intraocular injections of WGA-HRP resulted in the uptake of exogenously applied WGA-HRP by retinal ganglion cells, followed by anterograde axonal transport and exocytosis within the optic target nuclei. In addition to the transneuronal labeling, which is typical of such injections, we observed the transcellular labeling of the processes and somata of radial glial cells that were topographically associated with the terminal fields of the labeled axons. Similar transcellular labeling of radial glial cells associated with the axon terminal fields of the colliculogeniculate projection to the medial geniculate nucleus was observed following injections of WGA-HRP in the inferior colliculus. The transcellular labeling within the radial glial cells was discontinuous and somatopetally concentrated, indicating the existence of a retrograde active transport mechanism within the radial glial processes subsequent to its uptake following release of tracer from axons. This type of labeling can be referred to as transcellular retrograde glioplasmic transport. In contrast, DiI was used as a tracer through its capacity to diffuse within the plasmalemma. Topographically distinct populations of radial glial cells were transcellularly labeled following placements of DiI in the retina, inferior colliculus, or dorsal thalamus of fixed brains. The radial processes of labeled radial glial cells consistently extended into regions that also contained labeled axons. It is likely that the transcellular radial glial labeling with DiI occurred via transmembranous diffusion. These data indicate that a close structural and functional relation exists between axons and glial cells in the developing brain.     

Randomized study of chemoembolization as an adjuvant therapy for primary liver carcinoma after hepatectomy

From April 1990 to December 1993, 140 patients were recruited to a randomized study to evaluate transcatheter hepatic arterial chemoembolization (TACE) as an adjuvant therapy for primary liver carcinoma after hepatectomy. This study investigated the principle, techniques and results of TACE. The results showed that the intrahepatic recurrence rate was 48.9% in the patients who underwent radical resection only, but only 21.3% in the patients who also underwent TACE 3-4 weeks after hepatectomy (P < 0.01). The 1-, 2-, 3-, and 4-year survival rates were 72.3%, 52.7%, 35.1%, and 35.1% respectively for the patients who underwent radical resection only, and were 97.9%, 85.5%, 69.5%, and 56.9% for the patients who also underwent TACE 3-4 weeks after radical resection (P < 0.001). The 1-, 2-, 3-, and 4-year survival rates were 38.9%, 0%, 0%, and 0% for the patients who underwent palliative resection only, and were 68.3%, 32.3%, 21.5%, and 21.5% respectively for the patients undergoing TACE 3-4 weeks after palliative hepatectomy (P < 0.001).     

Stabilization of Cubic Zirconia with Manganese Oxide

A directionally solidified eutectic (DSE) of MnO-ZrO₂ has been investigated using a variety of electron optical techniques. It is found that considerable MnO goes into ZrO₂ to form a substitutional solid solution. About 14 wt% of MnO is soluble in ZrO₂ close to the eutectic temperature. The solubility of ZrO₂ in MnO, however, is quite low, less than 0.50 wt%. Electron diffraction experiments indicate that ZrO₂ (MnO) has the cubic fluorite structure. Diffuse scattering, similar to other cubic zirconias (e.g., CaO, MgO stabilized zirconia), is also observed in manganese-stabilized zirconia. Diffuse scattering indicates the presence of oxygen vacancies and thus confirms the defect nature of the fluorite structure. Electron energy loss spectrometry (EELS) fine structure analysis of the Mn L₂₃ edge provided clear evidence that Mn is present as Mn²⁺ in Mn-stabilized cubic ZrO₂.