Microfluidic Device for Simple Diagnosis of Plant Growth Condition by Detecting miRNAs from Filtered Plant Extracts

Plants are exposed to a variety of environmental stress, and starvation of inorganic phosphorus can be a major constraint in crop production. In plants, in response to phosphate deficiency in soil, miR399, a type of microRNA (miRNA), is up-regulated. By detecting miR399, the early diagnosis of phosphorus deficiency stress in plants can be accomplished. However, general miRNA detection methods require complicated experimental manipulations. Therefore, simple and rapid miRNA detection methods are required for early plant nutritional diagnosis. For the simple detection of miR399, microfluidic technology is suitable for point-of-care applications because of its ability to detect target molecules in small amounts in a short time and with simple manipulation. In this study, we developed a microfluidic device to detect miRNAs from filtered plant extracts for the easy diagnosis of plant growth conditions. To fabricate the microfluidic device, verification of the amine-terminated glass as the basis of the device and the DNA probe immobilization method on the glass was conducted. In this device, the target miRNAs were detected by fluorescence of sandwich hybridization in a microfluidic channel. For plant stress diagnostics using a microfluidic device, we developed a protocol for miRNA detection by validating the sample preparation buffer, filtering, and signal amplification. Using this system, endogenous sly-miR399 in tomatoes, which is expressed in response to phosphorus deficiency, was detected before the appearance of stress symptoms. This early diagnosis system of plant growth conditions has a potential to improve food production and sustainability through cultivation management.

Ionic heat dissipation in solid-state pores

Energy dissipation in solid-state nanopores is an important issue for their use as a sensor for detecting and analyzing individual objects in electrolyte solution by ionic current measurements. Here, we report on evaluations of heating via diffusive ion transport in the nanoscale conduits using thermocouple-embedded SiN_x pores. We found a linear rise in the nanopore temperature with the input electrical power suggestive of steady-state ionic heat dissipation in the confined nanospace. Meanwhile, the heating efficiency was elucidated to become higher in a smaller pore due to a rapid decrease in the through-water thermal conduction for cooling the fluidic channel. The scaling law suggested nonnegligible influence of the heating to raise the temperature of single-nanometer two-dimensional nanopores by a few kelvins under the standard cross-membrane voltage and ionic strength conditions. The present findings may be useful in advancing our understanding of ion and mass transport phenomena in nanopores.

Detecting Single Molecule Deoxyribonucleic Acid in a Cell Using a Three-Dimensionally Integrated Nanopore

Amplification-free genome analysis can revolutionize biology and medicine by uncovering genetic variations among individuals. Here, the authors report on a 3D-integrated nanopore for electrolysis to in situ detection of single-molecule DNA in a cell by ionic current measurements. It consists of a SiO₂ multipore sheet and a SiN_x nanopore membrane stacked vertically on a Si wafer. Single cell lysis is demonstrated by 10⁶  V m^-1 -level electrostatic field focused at the multinanopore. The intracellular molecules are then directly detected as they move through a sensing zone, wherein the authors find telegraphic current signatures reflecting folding degrees of freedom of the millimeter-long polynucleotides threaded through the SiN_x nanopore. The present device concept may enable on-chip single-molecule sequencing to multi-omics analyses at a single-cell level.

ZnO/SiO2 core/shell nanowires for capturing CpG rich single-stranded DNAs

Atomic layer deposition (ALD) is capable of providing an ultrathin layer on high-aspect ratio structures with good conformality and tunable film properties. In this research, we modified the surface of ZnO nanowires through ALD for the fabrication of a ZnO/SiO2 (core/shell) nanowire microfluidic device which we utilized for the capture of CpG-rich single-stranded DNAs (ssDNA). Structural changes of the nanowires while varying the number of ALD cycles were evaluated by statistical analysis and their relationship with the capture efficiency was investigated. We hypothesized that finding the optimum number of ALD cycles would be crucial to ensure adequate coating for successful tuning to the desired surface properties, besides promoting a sufficient trapping region with optimal spacing size for capturing the ssDNAs as the biomolecules traverse through the dispersed nanowires. Using the optimal condition, we achieved high capture efficiency of ssDNAs (86.7%) which showed good potential to be further extended for the analysis of CpG sites in cancer-related genes. This finding is beneficial to the future design of core/shell nanowires for capturing ssDNAs in biomedical applications.

Oxide Nanowire Microfluidic Devices for Capturing Single-stranded DNAs

Since DNA analysis is the fundamental process for most applications in biomedical fields, capturing DNAs with high efficiency is important. Here, we used several oxide nanowire microfluidic devices to capture CpG-rich single-stranded DNAs (ssDNAs) in different pH solutions. All the oxide nanowires exhibited the highest capture efficiency around pH 7 with good capture efficiency shown by each metal oxide; ZnO/ZnO core/shell NWs (71.6%), ZnO/Al₂O₃ core/shell NWs (86.3%) and ZnO/SiO₂ core/shell NWs (86.7%). ZnO/Al₂O₃ core/shell NWs showed the best performance for capturing ssDNAs under varying pH, which suggests its suitability for application in diverse biological fluids. The capturing efficiencies were attributed to the interactions from phosphate backbones and nucleobases of ssDNAs to each nanowire surface. This finding provides a useful platform for highly efficient capture of the target ssDNAs, and these results can be extended for future studies of cancer-related genes in complex biological fluids.

Digital Pathology Platform for Respiratory Tract Infection Diagnosis via Multiplex Single-Particle Detections

The variability of bioparticles remains a key barrier to realizing the competent potential of nanoscale detection into a digital diagnosis of an extraneous object that causes an infectious disease. Here, we report label-free virus identification based on machine-learning classification. Single virus particles were detected using nanopores, and resistive-pulse waveforms were analyzed multilaterally using artificial intelligence. In the discrimination, over 99% accuracy for five different virus species was demonstrated. This advance is accessed through the classification of virus-derived ionic current signal patterns reflecting their intrinsic physical properties in a high-dimensional feature space. Moreover, consideration of viral similarity based on the accuracies indicates the contributing factors in the recognitions. The present findings offer the prospect of a novel surveillance system applicable to detection of multiple viruses including new strains.

Photolithographically Constructed Single ZnO Nanowire Device and Its Ultraviolet Photoresponse

A sparse ZnO nanowire array with aspect ratio of ca. 120 and growth rate of 1 μm/h was synthesized by controlling the density of seeds at the initial stage of nanowire growth. The spatially-separated nanowires were cut off from the growth substrate without breaking, and thus were useful in the construction of a single-nanowire device by photolithography. The device exhibited a linear current-voltage characteristic associated with ohmic contact between ZnO nanowire and electrodes. The device further demonstrated a reliable photoresponse with an IUV/Idark of ∼100 to ultraviolet light irradiation.

Tailoring Dielectric Surface Charge via Atomic Layer Thickness

Channel surface property is a crucial factor that affects capture-to-translocation dynamics of single-particles in solid-state pores. Here, we show that atomically-thin dielectrics can be used to finely tune the pore wall surface potential. We isotopically coated alumina of atomically controlled thickness on a Si₃N₄ micropore. The surface zeta-potential in a buffer was found to decrease sharply by 1 nm thick deposition that served as a water-permeable ultra-thin sheet to modulate the effective charge density of the Al₂O₃/Si₃N₄ multilayer structure. Further thickening of the atomic layer enabled to control the zeta potential with a thickness at 3.4 mV/nm resolution. Accordingly, we observed concomitant enhancement in the capture rate and the translocation speed of negatively charged polymeric particles by virtue of the mitigated electroosmotic back flow in the functionalized pore channel. This simple method is widely applicable for tailoring the surface charge properties of essentially any sensors and devices working in aqueous media.

Solid-State Nanopore Time-of-Flight Mass Spectrometer

Analysis of field-controlled dynamics of ionized substances in a vacuum enables mass spectroscopy of particles and molecules. Analogously, here we report that nanoscale tracking of electrophoretically driven fast motions of single nanoparticles allows label-free and nondestructive detection of their mass in liquid. We fine-traced the time-dependent positions of space-filtered regular motions of particles passed through a thin solid-state nanopore by dissecting the associated ionic blockade phenomena under a scope of multiphysics simulations. Characterizing the viscous-drag-mediated exponential decay in the electrophoretic speed of particles ejected into an electrolyte solution from the nanochannel, we demonstrated the discrimination of nanoparticles by the femtogram mass difference. The present method is viable for mass measurement of virtually any object that can be put through the sensing zone, the sensor capability of which may find many applications such as pathogen screening and proteomics.

High-throughput single nanoparticle detection using a feed-through channel-integrated nanopore

The outstanding sensitivity of solid-state nanopore sensors comes at a price of low detection efficiency due to the lack of active means to transfer objects into the nanoscale sensing zone. Here we report on a key technology for high-throughput single-nanoparticle detection which exploits mutual effects of microfluidics control and multipore electrophoresis in nanopore-in-channel units integrated on a thin Si₃N₄ membrane. Using this novel nanostructure, we demonstrated a proof-of-concept for influenza viruses via hydropressure regulation of mass transport in the fluidic channel for continuous feeding of biosamples into the effective electric field extending out from the nanopores, wherein the feed-through mechanism allowed us to selectively detect charged objects in physiological media such as human saliva. With the versatility of nanopore sensing technologies applicable to analytes of virtually any size from cells to polynucleotides, the present integration strategy may open new avenues for practical ultrasensitive bioanalytical tools.

Electric field interference and bimodal particle translocation in nano-integrated multipores

Parallel integration of multiple channels is a fundamental strategy for high-throughput particle detection in solid-state nanopores wherein understanding and control of crosstalk is an important issue for the post resistive pulse analysis. Here we report on a prominent effect of cross-channel electric field interference on the ionic current blockade by nanoparticles in nano-spaced pore arrays in a thin Si3N4 membrane. We systematically investigated the variations in resistive pulse profiles in multipore systems of various inter-channel distances. Although each pore acted independently when they were formed at excessively far distances, we observed significant cross-pore electrostatic interactions under close-integration that led the multipores to virtually act as a single-pore of equivalent area. As a result of the interference, the resistive pulse height demonstrated bimodal distributions due to the pronounced particle trajectory-dependence of the ionic blockade effects. Most importantly, the overcrowded multi-channel structure was found to deliver significant crosstalk with serious degradation of the sensor sensitivity to particle sizes. The present results provide a guide to design multipore structures regarding the trade-off between the detection throughput and sensor sensitivity.

High-throughput single-particle detections using a dual-height-channel-integrated pore

We report a proof-of-principle demonstration of particle concentration to achieve high-throughput resistive pulse detections of bacteria using a microfluidic-channel-integrated micropore. We fabricated polymeric nanochannels to trap micrometer-sized bioparticles via a simple water pumping mechanism that allowed aggregation-free size-selective particle concentration with negligible loss. Single-bioparticle detections by ionic current measurements were then implemented through releasing and transporting the thus-collected analytes to the micropore. As a result, we attained two orders of magnitude enhancement in the detection throughput by virtue of an accumulation effect via hydrodynamic control. The device concept presented may be useful in developing nanopores and nanochannels for high-throughput single-particle and -molecule analyses.

Volume discrimination of nanoparticles via electrical trapping using nanopores

Electrophoretic capture of an oversized object on a solid-state nanopore is a useful approach for single-particle analyses via post electrical and optical measurements. Here we report on nanoparticle discriminations by the volume through combining this nanopore trap method with the cross-membrane ionic current measurements. We investigated ion transport through a pore channel being partially occluded by an electrophoretically-drawn nanoparticle at the orifice. We found distinct difference in the amount of current blockage by particles of different sizes. Multiphysics simulations revealed dominant contribution of particle volume over the other properties. We also demonstrated single-particle discriminations of two different sizes in a mixture solution. The present results demonstrate that this electrical capturing is a promising technique to immobilize a target at a single particle level that concomitantly offer wealth of information concerning their volume.

Silicon substrate effects on ionic current blockade in solid-state nanopores

We investigated the roles of silicon substrate material compositions in ionic current blockade in solid-state nanopores. When detecting single nanoparticles using an ionic current in a Si3N4 nanopore supported on a doped silicon wafer, resistive pulses were found to be blunted significantly via signal retardation due to predominant contributions of large capacitance at the ultrathin membrane. Unexpectedly, in contrast, changing the substrate material to non-doped silicon led to the sharpening of the spike-like signal feature, suggesting a better temporal resolution of the cross-channel ionic current measurements by virtue of the thick intrinsic semiconductor layer that served to diminish the net chip capacitance. The present results suggest the importance of the choice of Si compositions regarding the capacitance effects to attain better spatiotemporal resolution in solid-state nanopore sensors.

Particle Capture in Solid-State Multipores

Utilization of multiple-channel structure is a promising way of accomplishing high-throughput detections of analytes in solid-state pore sensors. Here we report on systematic investigation of particle capture efficiency in Si₃N₄ multipore systems of various array configurations. We demonstrated enhanced detection throughput with increasing numbers of pore channels in a membrane. Meanwhile, we also observed significant contributions of the interchannel crosstalk in closely integrated multipores that tended to deteriorate throughput performance by causing shrinkage of the absorption zone via the interference-derived weakening of the electric field around the pore orifice. At the same time, the interference-derived electric field distributions were also found to diminish the electroosmotic contributions to the particle capture efficiency. The present findings can be useful in designing pore arrays with optimal throughput performance.

Selective detections of single-viruses using solid-state nanopores

Rapid diagnosis of flu before symptom onsets can revolutionize our health through diminishing a risk for serious complication as well as preventing infectious disease outbreak. Sensor sensitivity and selectivity are key to accomplish this goal as the number of virus is quite small at the early stage of infection. Here we report on label-free electrical diagnostics of influenza based on nanopore analytics that distinguishes individual virions by their distinct physical features. We accomplish selective resistive-pulse sensing of single flu virus having negative surface charges in a physiological media by exploiting electroosmotic flow to filter contaminants at the Si₃N₄ pore orifice. We demonstrate identifications of allotypes with 68% accuracy at the single-virus level via pattern classifications of the ionic current signatures. We also show that this discriminability becomes >95% under a binomial distribution theorem by ensembling the pulse data of >20 virions. This simple mechanism is versatile for point-of-care tests of a wide range of flu types.

Temporal Response of Ionic Current Blockade in Solid-State Nanopores

Signal delay is a crucial factor in resistive pulse analyses using low-thickness-to-diameter aspect-ratio pores that aim to detect fine features in the ionic current blockade during the fast translocation of individual analytes to attain single-molecule tomography. Here we report on evaluations of the ionic current response to dynamic motions of nanoparticles in ultrathin solid-state nanopores. We systematically investigated the effects of pore resistance and membrane capacitance on resistive pulse waveforms under different salt concentration conditions and device configurations. The results revealed substantial modifications in the resistive pulse waveforms due to a slow charging/discharging processes at the water-touching thin dielectrics in the solid-state nanopore chips. We also provide a device design to improve the temporal resolution without compromising the spatial sensitivity. The present findings offer a breakthrough toward nanoporescopy to measure the nanoscopic shape of single-bioparticles and -molecules in electrolyte solution.

Identification of Individual Bacterial Cells through the Intermolecular Interactions with Peptide-Functionalized Solid-State Pores

Bioinspired pore sensing for selective detection of flagellated bacteria was investigated. The Au micropore wall surface was modified with a synthetic peptide designed from toll-like receptor 5 (TLR5) to mimic the pathogen-recognition capability. We found that intermolecular interactions between the TLR5-derived recognition peptides and flagella induce ligand-specific perturbations in the translocation dynamics of Escherichia coli, which facilitated the discrimination between the wild-type and flagellin-deletion mutant (ΔfliC) by the resistive pulse patterns thereby demonstrating the sensing of bacteria at a single-cell level. These results provide a novel concept of utilizing weak intermolecular interactions as a recognition probes for single-cell microbial identification.

Rapid structural analysis of nanomaterials in aqueous solutions

Rapid structural analysis of nanoscale matter in a liquid environment represents innovative technologies that reveal the identities and functions of biologically important molecules. However, there is currently no method with high spatio-temporal resolution that can scan individual particles in solutions to gain structural information. Here we report the development of a nanopore platform realizing quantitative structural analysis for suspended nanomaterials in solutions with a high z-axis and xy-plane spatial resolution of 35.8 ± 1.1 and 12 nm, respectively. We used a low thickness-to-diameter aspect ratio pore architecture for achieving cross sectional areas of analyte (i.e. tomograms). Combining this with multiphysics simulation methods to translate ionic current data into tomograms, we demonstrated rapid structural analysis of single polystyrene (Pst) beads and single dumbbell-like Pst beads in aqueous solutions.

Tailoring particle translocation via dielectrophoresis in pore channels

Understanding and controlling electrophoretic motions of nanoscopic objects in fluidic channels are a central challenge in developing nanopore technology for molecular analyses. Although progress has been made in slowing the translocation velocity to meet the requirement for electrical detections of analytes via picoampere current measurements, there exists no method useful for regulating particle flows in the transverse directions. Here, we report the use of dielectrophoresis to manipulate the single-particle passage through a solid-state pore. We created a trap field by applying AC voltage between electrodes embedded in a low-aspect-ratio micropore. We demonstrated a traffic control of particles to go through center or near side surface via the voltage frequency. We also found enhanced capture efficiency along with faster escaping speed of particles by virtue of the AC-mediated electroosmosis. This method is compatible with nanopore sensing and would be widely applied for reducing off-axis effects to achieve single-molecule identification.

Particle Trajectory-Dependent Ionic Current Blockade in Low-Aspect-Ratio Pores

Resistive pulse sensing with nanopores having a low thickness-to-diameter aspect-ratio structure is expected to enable high-spatial-resolution analysis of nanoscale objects in a liquid. Here we investigated the sensing capability of low-aspect-ratio pore sensors by monitoring the ionic current blockades during translocation of polymeric nanobeads. We detected numerous small current spikes due to partial occlusion of the pore orifice by particles diffusing therein reflecting the expansive electrical sensing zone of the low-aspect-ratio pores. We also found wide variations in the ion current line-shapes in the particle capture stage suggesting random incident angle of the particles drawn into the pore. In sharp contrast, the ionic profiles were highly reproducible in the post-translocation regime by virtue of the spatial confinement in the pore that effectively constricts the stochastic capture dynamics into a well-defined ballistic motion. These results, together with multiphysics simulations, indicate that the resistive pulse height is highly dependent on the nanoscopic single-particle trajectories involved in ultrathin pore sensors. The present finding indicates the importance of regulating the translocation pathways of analytes in low-aspect-ratio pores for improving the discriminability toward single-bioparticle tomography in liquid.

High thermopower of mechanically stretched single-molecule junctions

Metal-molecule-metal junction is a promising candidate for thermoelectric applications that utilizes quantum confinement effects in the chemically defined zero-dimensional atomic structure to achieve enhanced dimensionless figure of merit ZT. A key issue in this new class of thermoelectric nanomaterials is to clarify the sensitivity of thermoelectricity on the molecular junction configurations. Here we report simultaneous measurements of the thermoelectric voltage and conductance on Au-1,4-benzenedithiol (BDT)-Au junctions mechanically-stretched in-situ at sub-nanoscale. We obtained the average single-molecule conductance and thermopower of 0.01 G0 and 15 μV/K, respectively, suggesting charge transport through the highest occupied molecular orbital. Meanwhile, we found the single-molecule thermoelectric transport properties extremely-sensitive to the BDT bridge configurations, whereby manifesting the importance to design the electrode-molecule contact motifs for optimizing the thermoelectric performance of molecular junctions.

Thermoelectric voltage measurements of atomic and molecular wires using microheater-embedded mechanically-controllable break junctions

We developed a method for simultaneous measurements of conductance and thermopower of atomic and molecular junctions by using a microheater-embedded mechanically-controllable break junction. We find linear increase in the thermoelectric voltage of Au atomic junctions with the voltage added to the heater. We also detect thermopower oscillations at several conductance quanta reflecting the quantum confinement effects in the atomic wire. Under high heater voltage conditions, on the other hand, we observed a peculiar behaviour in the conductance dependent thermopower, which was ascribed to a disordered contact structure under elevated temperatures.

PACAP Receptor (PAC1-R) Expression in Rat and Rhesus Monkey Thymus

The expression of PACAP receptor (PAC1-R) was investigated in the thymus of rats and rhesus monkeys. In the rat thymus, PAC1-R positive cells were found in the intermediate type of thymic epithelial cells of the medulla. PAC1-R-positive cells were also seen in the thymic medulla of the rhesus monkey. The thymus showed unusual structures in some rhesus monkey dams (F0) and offspring (F1) exposed to 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). Additionally, in these rhesus monkeys, PAC1-R expression was different from that in the control thymus.

Electromagnetic cross sections of double giant dipole resonances in 136Xe and 208Pb within the phonon damping model

The electromagnetic cross sections of the double giant dipole resonances (DGDR) in 136Xe and 208Pb are calculated using the strength functions obtained within the phonon damping model. The parameters of the model have been selected to describe reasonably well the single giant dipole resonance in these nuclei. The results are found in an overall agreement with the recent experimental data for the DGDR cross sections in exclusive measurements at near-relativistic energies.

Generalization of the N(p)N(n)N(p)N(n) scheme and the structure of the valence space

The N(p)N(n) scheme, which has been extensively applied to even-even nuclei, is found to be a very good benchmark for odd-even, even-odd, and doubly-odd nuclei as well. There are no apparent shifts in the correlations for these four classes of nuclei. The compact correlations highlight the deviant behavior of the Z = 78 nuclei and are used to deduce effective valence proton numbers near Z = 64 as well as to study the evolution of the Z = 64 subshell gap.

Severity of the regional wall motion and its effects on global left ventricular diastolic filling in patients with single-vessel coronary artery disease and previous myocardial infarction: assessment with radionuclide ventriculography

The severity of the regional wall motion and its effects on the global left ventricular diastolic filling were analyzed with use of radionuclide techniques in 19 patients with isolated disease of the left anterior descending coronary artery with previous myocardial infarction. Regional maximum inward movements in the noninfarcted lateral region occurred at a time close to the global end-systole, but occurred far beyond the global end-systole in the infarcted septal and apical regions, resulting in the occurrence of the regional asynchronous wall motion between the infarcted and noninfarcted regions after the global end-systole. A positive correlation between this end-systolic asynchronous wall motion and the asynchronous filling in early diastole was found (r = 0.69, p less than 0.001). A negative correlation between the asynchronous filling in early diastole and the global peak filling rate was also found (r = -0.58, p less than 0.01). Thus, the end-systolic regional asynchronous wall motion causes the subsequent regional asynchronous filling in early diastole, which may cause impairment of the global left ventricular filling in patients with single-vessel coronary artery disease with previous myocardial infarction.

Inhomogeneous contribution of late diastolic filling to filling volume in patients with isolated disease of the left anterior descending coronary artery: assessment with radionuclide ventriculography

Contributions of late diastolic filling (slow filling and atrial systolic phases) to total filling volume in both global and regional left ventricle were analyzed using radionuclide techniques in 21 patients with isolated left anterior descending coronary artery disease without previous myocardial infarction. A computer program subdivided the image of the left ventricle into four regions at a geometric center of the area. The time-activity and its first-derivative curves of the global and regional left ventricles were computed. In the global left ventricle, the percent contributions of late diastolic filling to total filling volume were significantly increased in patients with one-vessel disease than in control subjects (20 +/- 5%, 28 +/- 4%; p less than 0.001). In the regional left ventricle, in patients with one-vessel disease, the percent contributions of late diastolic filling to total filling volume were significantly increased in the septal (25 +/- 5%, 34 +/- 8%; p less than 0.001) and in the apical regions (21 +/- 4%, 28 +/- 4%; p less than 0.001) which were perfused by stenosed vessel. In contrast, there were no significant differences in this value between the two groups in the normally perfused lateral region (22 +/- 6%, 25 +/- 5%; p = NS). These results indicate that the late diastolic filing makes a larger contribution to the left ventricular filling in the affected regions than in the normally perfused regions, and that the increased late diastolic filling in the affected regions are the cause for the increased late diastolic filling in the global left ventricle in patients with one-vessel disease.

[Approach to the diagnostic colposcopy--a scoring method of colposcopic pattern]

In order to arrive at a final diagnosis of early cervical cancer by colposcopy alone, a colposcopic scoring system was applied to 172 patients with the disease. Each colposcopic pattern was scored from one point (for white epithelium) to 9 (for invasive cancer). The results obtained were as follows; 1) With these scoring criteria, stage 0 cancers were restricted to below 10 points and were characterized colposcopically by white epithelia with gland openings 2) In stage I-a lesion, atypical vessels, punctuation by irregular arrangement of the dots and concentration of abnormal gland openings were usually observed, and these findings were combined with each other to show a more complicated colposcopic pattern reflected in 11 to 18 points of the score 3) Frank invasions were indicated by 19 points or more, and punctuations or mosaics were seldom found in this stage, although the early "I-b" cancer was difficult to distinguish from I-a with this method 4) The diagnoses from this scoring system were identical with the final diagnoses confirmed by surgical methods in 66.7% of stage 0, 59.4% of I-a and 76.5% of I-b.