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Over the last several years, the U.S. capital markets have witnessed a palpable rise in the number and influence of so-called “activist investors”, meaning large, institutional investment funds employing an investment strategy of acquiring relatively large blocs of stock in publicly traded companies and wielding their legal rights as stockholders to effect some sort of policy change within the company but without attempting to acquire control. This fact concomitantly has engendered a heated debate as to whether activists’ rising influence is normatively “good” or “bad”. One thing in particular that makes this debate so contentious is activism’s resistance to easy characterization: on the one hand, stockholder activists primarily wield only the legal rights that the corporation law (and specifically the Delaware General Corporation Law (the “DGCL”), as Delaware is the State of incorporation for the majority of the U.S.’s publicly traded corporations) confers on investors to protect their investments, but, on the other hand, activist campaigns may cause collateral damage to the companies involved, implicating boards of directors’ fiduciary duties to protect the enterprise against threats to the corporate bastion. Simply put, does stockholder activism merely represent “dissent within the forum” that Delaware law is designed to safeguard, or are activists the proverbial “barbarians at the gate” that Delaware law entrusts corporate directors to repel? Whatever the answer to these and related questions, the extent to which stockholder activism primarily implicates the legal rights and duties of investors and directors vis-a-vis each other means that the DGCL and the Delaware courts necessarily serve an important intermediary role. And yet, the public policy of the State of Delaware as to matters of corporate internal affairs is to enable private ordering and eschew “one size fits all” approaches to the innumerable ways in which market participants may choose to deploy their capital as efficiently as possible in their respective circumstances. In other words, the intent of Delaware corporation law — and the function of Delaware courts in interpreting and enforcing that law — is not to take a position on the outcome of the debate surrounding stockholder activism, but to safeguard the debate itself. In this chapter, we highlight through practical examples the Delaware courts’ core competency in deciding these sometimes vexing questions in context with the tools available.

To improve the computer connectivity and network strategies to connect U.S. county health departments (CHDs), state health departments (SHDs), and the Centers for Disease Control (CDC) for reporting notifiable conditions.HSPNET-L mailing list discussions and individual Internet communications were used to compare selected features of notifiable conditions networking in the United States, France, and the United Kingdom.In the US, the CHD is the agency that first responds to an infectious disease outbreak on receiving notifications from physicians. Prompt recognition by the SHD that a widespread outbreak has occurred depends on the way in which county data are received, the "age" of the data, and the time taken to analyze them. Similarly, the recognition of the national scale of the outbreak depends on the promptness with which SHDs report to the CDC and the age of the data. An analysis of the French Communicable Disease Network suggests that an expansion of electronic links between US CHDs and SHDs will improve timeliness. Electronic data exchange allows CHDs to set up a local database and reduces transcription errors, mailing costs, and telephone costs.A fuller use of e-mail or other electronic communication by US CHDs will allow them to use a local database as a tool for managing local disease outbreaks more effectively and independently. Federal and state agency access to the CHD databases will enable early reporting of epidemic outbreaks. Periodic posting of public health information on Internet servers is recommended for immediate access to the public health data by Internet users worldwide.

Existing clinical networks in the USA and elsewhere are rewiewed to show the current impact of telemedicine on the access, quality, and cost of health care. There is substantial evidence that telemedicine can improve health care in each of these areas. The quality of health care can be enhanced in both rural and urban small hospitals by restoring or increasing the availability of consultants. Video-conferencing is proving successful in providing health care access to inmates of prisons and mental institutions. In the Veterans Administration hospitals, and at other sites, patient records can be transferred by E-mail between medical centers. Telemedicine has been shown to decrease the “time-to-treatment” in an Australian rural practice. Telemetry applications for nursing home and home-bound patients are expected to increase and to provide an improved quality of health care. Significant savings can be achieved in administration and consulting costs. The main obstacle to the present development of telemedicine is the unavailability of insurance reimbursement.

There is now abundant experimental evidence available to indicate that large-scale Quantum Computing (QC) is feasible. QC uses entirely different physical principles to those used by the classical computer. It depends on several characteristic quantum properties. These properties include quantum bit (“qubit”) entanglement where the states of two or more atomic particles influence one another. The information about these states can overlap and provide the very large parallel-computing power of the QC. The objective of the present report is to summarize the status of the development of QC, and to suggest medical domains that will most benefit by the substitution of QC for classical high-performance computing

Recent suggestions that tumor-cell targeting of elastin-rich tissues (e.g., lung) correlates with the presence of surface elastin receptors have been investigated. Receptors for insoluble (fibrous) elastin and for soluble elastin peptides have been implemented in these correlations. A rapid assay for binding of insoluble elastin has been devised. Two of the cell lines tested (M27 and MAT-LyLu), which metastasize to the lung, strongly bound fibrous elastin whereas a third (B16-F10) did not. None of 4 metastatic cell lines that do not target the lung (A549, 3LL, TA3, TA3-iso2) bound fibrous elastin. The ability of cell lines to interact with soluble elastin was tested by cell attachment to high-molecular-weight soluble elastin peptides adsorbed on a plastic surface. Three of 7 tested cell lines, B16-F10, M27 and TA3, attached to a soluble elastin coating. In contrast to the rapid binding of insoluble elastin particles, the cell interaction with immobilized soluble elastin peptides was delayed, suggesting that induction of receptors for soluble elastin and/or modification of the elastin coat was occurring. Thus, all 3 tested cell lines where metastases target the lung, namely, MAT-LyLu, B16-F10 and M-27, show soluble- or insoluble-elastin interactions, whereas, of 4 cell lines not targeting lungs, only one, TA3, reacts with soluble elastin.

It is difficult to find time in the medical curriculum for teaching medical informatics in the face of ever expanding course requirements. Horizontal integration with current topics appears to be the most realistic way to include it. Since medical informatics teaches health professionals to streamline the handling of voluminous medical information, it may have claim to a special priority. In several European countries, medical informatics is federally mandated as a part of the medical curriculum. Without it, the ever increasing extent to which clinics, wards, and offices are being computerized can pose problems for newly graduated health professionals. This is especially true for nurses who often have to face patient-monitoring equipment on their own. In spite of the excellent efforts of the National Library of Medicine to train medical informatics professionals, the lack of teaching staff is still a factor in the slow adoption of the discipline. An inclusion of a specialization in medical informatics in more schools of public health curricula could be helpful in this regard.

Elastin and collagen are abundant fibrous molecules in the stroma. Tumor cells invading the stroma are in contact with fibers of both types much of the time. Both may serve as footholds for the traction required for movement. Elastin has an additional role. Elastin peptides are known to stimulate receptor signaling and chemotaxis, which could explain the morphometric changes (membrane and organelle polarization and cell volume shrinkage) that we have reported for certain tumor cell lines invading elastic lamina. Elastin and its peptides emerge as possible invasion enhancers for some tumor cells. In ongoing work we are screening human tumors that contact elastin (e.g., breast carcinomas) to see if the presence of elastin receptors correlates with early dissemination of metastatic tumor cells.

Many medical centers lack access to the parallel-computing capability that is now needed for large-scale, genetic diagnostic information. Such enhanced computer resources are also needed for recent diagnostic physiological model simulations, and for enhancements in medical imaging. Increases in classical parallel processing capability are incremental and expensive. Quantum computing is the only new computing method that promises a very-large increase in parallel-processing capability. The reason is that the classical-computing unit of information, the 0-bit, or the 1-bit, is replaced by the quantum qubit unit which can be superposed as multiple strings of 0’s and 1’s. Medical-center research units may also need enhanced parallel computing ability for genome research, protein structure prediction, and the use of new simulations of physiological models. It is suggested that health-research funding and collaboration needs to be directed towards the final development of large-scale quantum computing.

In the course of development of an in vivo invasion model, sublines of a series of allogenic and isogeneic carcinoma cell lines have been selected that show enhanced invasion of the peritoneum. It was found that, during the proliferation of tumor cell lines in ascitic form in the abdominal cavity, small numbers of cells infiltrated or firmly adhered to the peritoneum in at least 8/12 of the tumor-host combinations tried. After thorough washing of the peritoneum it was disaggregated by an enzyme mixture, and the resulting mixture of normal and tumor cells was inoculated intraperitoneally. Peritoneal isolations were made serially for 3 to 12 times. In 6 of 8 cases where the isolation produced a stable ascites, the cells showed enhanced peritoneal invasion compared with the parent cell line. The invasion of some of the cell lines was tested in another invasion model consisting of cultured mouse buccal mucosa (9/10 cell lines invaded the explant). In 3/3 cell lines showing enhanced peritoneum invasion in vivo, there was no enhanced invasion of the buccal mucosa. The enhanced peritoneum invasion appears to be tissue specific rather than a general increase in invasion potential. Pairs of high- and low-invasive cell lines were obtained that should be useful for screening for invasion modulating agents using the mouse ascites/peritoneum in vivo model. It is suggested that the method might be generalized to produce various tumor cell lines that target for the normal tissues that are adjacent to proliferating solid or circulating tumors.

Background: BIND-014 is a novel, prostate-specific membrane antigen (PSMA)targeted, polymeric nanoparticle-containing docetaxel (DTXL). PSMA is expressed on prostate cancer cells and on vasculature of non-prostate solid tumors. The PK profile of BIND-014 is characterized by reduced CL and V(D). These characteristics together with PSMA targeting, potentially lead to greater tumor uptake and improved activity of BIND-014 compared to conventional solvent-based DTXL (sb-DTXL). In a Phase 1 clinical trial, BIND-014 was well tolerated and displayed multiple clinical response. Methods: Preclinical PK studies were performed in tumor-bearing mice and cynomolgus monkeys. Clinical PK was measured in patients with solid tumors. BIND-014 was administered intravenously and blood samples were collected up to 96 hours post-dose. Plasma was analyzed for total and encapsulated DTXL using LC/MS-MS. PK parameters were determined by non-compartmental analysis. Results: BIND-014 preclinical and clinical PK demonstrated monophasic plasma concentration-time profiles were well differentiated from sb-DTXL. BIND-014 displayed higher Cmax and AUC with reduced CL and V(D) compared to sb-DTXL. In all species, the V(D) of BIND-014 was close to the blood volume. Evaluation of encapsulated DTXL plasma concentrations in patients and cynomolgus monkeys demonstrated means of 91% and 92% of total DTXL, respectively, indicating that most circulating DTXL was encapsulated in nanoparticles. Conclusion: BIND-014 displays a PK profile well differentiated from sb-DTXL and consistent with retention of BIND-014 nanoparticles in the blood compartment and controlled release of DTXL. In contrast, sb-DTXL displays rapid CL and a high V(D). The PK characteristics of BIND-014 are associated with increased intratumoral DTXL concentrations and tumor growth suppression in preclinical models, and may lead to greater efficacy in patients. Preclinical and clinical PK differences between BIND-014 and sb-DTXLTumor bearing mouseCynomolgus monkeysPatients with solid tumorsBIND-014sb-DTXLΔBIND-014sb-DTXLΔBIND-014sb-DTXLΔDose (mg/m2)304060C(max) (μg/mL)100.80.7713065.52.72423.81.515.3AUC(0-t) (μg•h/mL)684.72.1326431.04.1105229.22.8580.4t(½) (h)4.38.80.54.719.40.26.1180.3CL (L/h/m2)0.04414.00.0030.0929.40.010.2210.01V(D) (L/m2)53.353.30.0040.63264.40.0023.61130.03 Citation Format: Jason Summa, Daniel Von Hoff, Jasgit Sachdev, Monica Mita, Patricia LoRusso, Peter Eisenberg, Howard Burris, Lowell Hart, Hagop Youssoufian, Donald Parsons, Susan Low. Pharmacokinetics of BIND-014 (docetaxel nanoparticles for injectable suspension) in preclinical species and patients with advanced solid tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5514. doi:10.1158/1538-7445.AM2015-5514

Before the Internet era, and prior to the use of teleinformatics, information was gathered via paper-based forms. In this early period, the system of notification of infectious diseases came to maturity and became firmly entrenched in the public health practice of most developed countries. When teleinformatics began to be used in public health, 10 to 15 years ago, the high potential of electronic networking became clear as a result of several national and regional experiments. The New York State Department of Health implemented ‘HEALTHCOM’, a statewide health care network, and France developed the ‘Reseau SENTINELLES’. For several years, the Centers for Disease Control (CDC) in USA has been alerting state epidemiologists through an electronic text-message system.

(1995). Some Tumor Cell Protein Kinases Activated by Receptors as Markers, Including Elastin Receptors. Cancer Investigation: Vol. 13, No. 6, pp. 629-636.

Murine breast cancer cell lines were developed to selectively invade the peritoneum while they proliferated in ascites form in the abdominal cavity. In a dominant form of invasion, tumor cells showed special affinity for elastin fibers and squeezed through narrow gaps in the elastic fiber meshwork of the stroma. Even in fixed tissue, such cells could be recognized as being in the process of invasive migration because of their dumbbell shape. This appearance was similar to that of diapedetic blood cells traversing bone marrow sinus endothelium. Three-dimensional STERECON graphics reconstruction from serial thick sections of 44 such cells was carried out. The reconstructions showed that, in mid-penetration, the cells spread extensively over the exterior surface of the elastic fiber meshwork. The cell surface contact of these forward projections was mainly with the elastic fiber outer coat of microfibrils, but small areas of the cell surface also fused directly to inner-core elastin. The morphological rearrangement of the cytoskeleton was minimal in both types of attachment areas. The location of these forward facing attachments is consistent with mechanisms for pulling the invasive cell through the gap. Lamellopodia formation and clustering of cytoplasmic organdies occurred more commonly at the forward-facing part of the cell. Morphometry of the reconstructions showed that a contraction of the whole cell occurred during the squeezing/migration process suggestive of an additional pushing process. However, our invasive cell lines showed marked differences in the degree of cell shrinkage. The process of adhesion and squeezing of tumor cells through elastin meshworks in vivo is clearly a complex phenomenon. Changes in cell surface activity appear to play a significant role in establishing the necessary ‘foothold’ component of invasion and, possibly, in the generation of tractive force as well.

Stereology, or the derivation of quantitative, three-dimensional (3-D) data about cells by statistical analysis of the structures of random sections, is widely used in cytology and pathology. However, there are situations where this approach is inadequate, and only an analysis of a homogeneous population of whole cells will give the required results. This involved 3-D reconstruction from physical or optical sections, or tomography or photogrammetry of whole-cell mounts. Use of stereo views of individual sections or projections adds considerably to the information available for both contouring and reconstruction. Recent image-processing advances in clinical radiography have shown, for the first time, that rapid, high-resolution digitization and contrast enhancement enable nearly all structural details to be routinely extracted from the micrographs and adequately portrayed. Three-D whole-cell reconstructions provide the digital data for many kinds of morphometric measurements on both whole cells and their individual organelles and membranes. Rapid fixation or freezing allows improved quantitative structure/function correlations of organelles with disturbances in cell metabolism or gene expression.

Digitized micrographs provide advantages in making 3-D reconstructions from serial sections. The use of image enhancement, magnification zoom, synthetic stereo, and rapid interactive review of the entire set of serial sections improves the accuracy and ease of reconstruction. We use the STERECON system for tracing contours from serial sections, storing the contour data, editing, and displaying the 3-D reconstructions. STERECON has options for stereoscopic input and display. Either digitized or conventional photographic images can be used with the system.Structures can be traced more easily in digitally-enhanced images. Digital image enhancement techniques have been extensively developed in the medical imaging field, and many of the same techniques are also useful for microscopy. Among the most difficult images to deal with photographically are those which have uneven exposure or a large variation in density. Since photographic film has a wider dynamic range than paper, it is difficult to bring out details in both light and dark areas of the image on the same print. Dodging results in loss of contrast which cannot always be recovered by using higher contrast grades of paper. Routine digital techniques can easily deal with this situation. In addition, nearly invisible, very-low-contrast structures in the image can be made distinct. Most importantly, edges of structures can be enhanced for more accurate tracing of contours. The extension of this is automatic contouring, which is used with varying degrees of success, depending on the complexity of the image.

Individual head and neck carcinomas show extreme regional cellular differentiation. Some cells are rich in keratin filaments (T cells) and some have little keratin and a high density of free ribosomes (R or RT cells). We attempted to isolate these two cell types in order to test their relative invasiveness in an in vitro model. The high frequency of mitosis of hyperkeratinized cells showed that there was no constraint on the motility of cell division. High-voltage electron microscopy of serial thick sections and three-dimensional graphic reconstruction demonstrated that keratin cytoskeleton filaments were cross-linked into short, thick bundles. However, the keratin cytoskeleton was absent from some portions of the cytoplasm. In normal differentiated keratinized cells, a more uniform spanning of the whole cell by thin keratin intermediate-filament bundles was evident. The cytoplasm may be more mobile in the keratinized tumor cells. Even heavily keratinized T cells, like the less keratinized cell types, may have invasive motility.

The ultrastructural and three-dimensional arrangement of elastic reticulum and collagen in mouse parietal peritoneum is described for the first time. As seen by high-voltage electron microscope stereoscopy of thick sections, the EL forms a three-dimensional network without free ends. The central part of the EL fibre is not amorphous but contains irregular 500-100 nm fibrils along its length. Large bundles of banded collagen (also without free ends) course in and out of the elastic reticulum. The production of these two interlacing networks implies the presence of a histo-architectural sensing and orientation system for the projected cytoplasmic processes of stromal fibroblasts and also bidirectional chain assembly for both collagen and elastin. Bilaterial assembly patterns have been described for collagen but not for elastin. The periodicity of the banded collagen varies in different regions of the fibre. A similar banding periodicity variation has been reported for Type I tendon collagen in association with local tension variations and curvature of the fibres. An unbanded type of collagen (so far not characterized as to type) lies between the elastic reticulum and the mesothelial cell basal lamina. It is speculated that the banded collagen may play a role in control of transudate across peritoneum and its disorganization in inflammation may relate to affect ascites production.

Structural changes of carcinoma cells and fibroblasts migrating through small spaces in the elastic-collagen reticulum of mouse peritoneum have been studied by high-voltage electron microscopy of serial thick sections and by computer graphics reconstruction of cell profiles. The change of shape profile of an individual cell, between serial sections is large and the distribution of organelles is very non-uniform and changes markedly between sections. Conclusions about adhesion, intercell contact, cell shape and polarization of cytoplasmic organelles could only be reached by assessing a complete set of serial sections. Our preliminary results suggest that interesting structural changes occur in both carcinoma cells and fibroblasts when migrating through this tissue.

SUMMARY Levels of impairment of electron-microscopic images of biological specimens stemming from radiation damage are assessed in a rapid visual procedure that involves taking a pair of low-fluence micrographs of a specimen area before and after a fraction of the picture area has been more seriously damaged by applying a measured electron fluence. The pair of micrographs is treated as a mock-stereo pair and is given contrasting colours. Lateral displacements of specimen details appear as false relief and changes in electron lucency as false colour.

A carcinoma invasion system (Krebs-2 and Ehrlich tetraploid ascites tumors invading mouse peritoneum) was studied by high-voltage electron microscope (HVEM) stereoscopy, conventional (medium voltage) electron microscopy (MVEM), and cytochemistry. Tumor cells entered areas of peritoneum (mainly parietal) only where mesothelial cells were damaged and where there was inflammation of the underlying stroma. The initial invasion was different from that of most other invading carcinomas in that there was minimal breakdown of basal lamina and collagen. Neither tumor cells, inflammatory leukocytes nor peritoneal fibroblasts showed significant secondary lysosome production or release of intracellular or extracellular acid phosphatase. Morphological and cytochemical criteria suggest that in some invading carcinomas, as with non-tumor migrating cells such as leukocytes, widespread proteolysis due to diffusion of proteases is not a prerequisite for invasion of stromal connective tissue.

SUMMARY A user evaluation has been made by electron microscopists of an X-ray film for routine electron microscopy. The recent improvements in mammographic X-ray films, with the attempt to reduce the patient dose required to produce a high-resolution mammogram, have resulted in some useful films for medium- and high-voltage electron microscopy. They can yield essential cytological information with a reduction of the electron fluence (exposure) applied to the specimen of more than an order of magnitude compared with conventional electron-microscope films. Their use is indicated in situations where beam damage is severe.

This review attempts a physical definition of the technical problems and achievements in applying the high-voltage electron microscope (HVEM) to biological and medical research. It is hoped that the review will summarize for biologists, funding agencies, and institutions the achievements of the HVEM, its future prospects, and the main problem areas that still need to be explored.

The construction of a microminiature axial magnetic field probe, and its associated instrumentation, is described. With an active area measuring approximately 100×100 μ, and an over‐all cross‐sectional dimension of 1.2 mm diam, the probe is sufficiently small to be maneuvered about within the polepiece of a conventional electron microscope objective lens. The axial component of the magnetic field can be measured on, as well as off, the axis of the polepiece to a higher spatial resolution than can be achieved with a commercial axial probe.

Calculations of beam spread for 1-MeV electrons within photographic emulsions based on a simplified model of multiple scattering are used to predict the performance of emulsions as a function of the silver-halide content and thickness of the emulsion layer. Experimental results are given for the sensitivity, resolution, figure of merit, and sensitivity per unit emulsion thickness for a range of photographic films exposed to 1-MeV electrons. Multiple scattering of 1-MeV electrons proves not to be the limiting factor that governs the resolution in the tested commercial films having conventional emulsion thicknesses and silver-halide contents. A new film design is proposed in order to mitigate the serious problem of the low sensitivity of the existing photographic films to 1-MeV electrons, which entails inordinate radiation damage to biological specimens during high-voltage micrography. This film would have an enhanced silver-halide content (as much as 65% AgBr by volume) and an increased emulsion thickness (up to 55 μm). As compared with a parent film having an emulsion 20% AgBr by volume and 25 μm thick, the proposed film should provide sensitivity enhanced sevenfold, with only about 17% loss in resolution. The new film should also show improved performance at conventional accelerating voltages (40–100 kV). Especial advantages are expected both in studying intrinsically radiation-sensitive objects and in studying those that require multiple exposures to the same specimen area, as in tilt series or time-lapse series.

Differential staining of basophilic “dark cells” of epithelia in thick epoxy sections with toluidine blue is critically affected by fixation and embedding conditions. Optimal conditions are described.

The relation between the degree of use and the available assistance has been surveyed for 18 high-voltage (⩾1 MV terminal voltage) electron microscope operations. The survey elicited information about the available time, the budget, the technical staff, and the numbers of users, projects, and micrographs produced. Large differences in activity were found among the installations. High output seems to depend on the extent of local and regional interest and also on the expertise and numbers of the technical staff. Only five of the installations regularly operate more than one shift a day. Restriction to one shift is usually due either to lack of user demand or to lack of funding for additional technicians. Except at three dedicated biological HVEMs in the United States, biologists have made much less use of the HVEM than have materials scientists. The reasons have not been established. Some additional suggestions (based upon information not derived from the survey) are offered for improved management of HVEM operations.

Intragastric feeding of dimethylbenz-[a]anthracene in corn oil together with urethane in the drinking water and forced breeding were successful in rapidly inducing (2-4 months) mammary tumors (adenoacanthomas) in inbred NYLR/Nya mice, which have a low incidence of spontaneous breast tumors and of other tumors. The tumors could be quickly and permanently transformed to an ascites form by intraperitoneal inoculation of enzyme-dissociated cells and subsequent serial passage of free cells. Only 10 (3 in some cases) serial passages were required, thus conveniently providing multiple isogeneic carcinoma cell lines in this strain of mice. Some tumor cell lines proliferated strongly in the abdominal cavity even on the first passage.

In the past, biological sections ranging in thickness from 0.10- to 0.50-micron have usually been examined with high-voltage (greater than 500 kV) electron microscopes (HVEM). Now investigators are increasingly using intermediate voltage (200-500 kV) electron microscopes (IVEM), which are more readily available and demand less maintenance. In a study of "typical" plastic-embedded, stained sections of mouse liver ranging from 0.10 to 1.0 micron thick, we determined the resolution obtainable at 100, 200, and 1000 kV. At all three accelerating voltages the resolution (2.7 nm) for 0.10-micron sections was limited only by the sections stain granularity. For 0.25-micron thickness the resolutions were 5.8, 3.1, and 3.1 nm at 100, 200, and 1000 kV, respectively. The maximum usable thickness at 200 kV with resolution sufficient to resolve membranes clearly was between 0.75 and 1.0 micron, depending on the magnification. Resolution at 100 kV was adequate for screening sections up to 1.0-micron thick for preparation defects prior to examination with an IVEM or HVEM.

A comprehensive computer-graphics-based system (STERECON) is described for tracing and digitizing contours from individual or stereopair electron micrographs. The contours are drawn in parallel planes within the micrographs. Provision is also made for tracing and digitizing in full three-dimensional (3-D) coordinates in any direction along linear structures such as cytoskeletal elements. The stereopair micrographs are viewed in combination with the contours being traced on a graphics terminal monitor. This is done either by projecting original electron micrograph (EM) negatives onto a screen and optically combining these images with contour lines being drawn on the monitor, or by first digitizing the images and displaying them directly on the monitor along with the contour lines. Prior image digitization allows computer enhancement of the structures to be contoured. Correction and alignment routines are included to deal with variable section thickness, section distortion and mass loss, variations in photography in the electron microscope, and terminal screen curvature when combining projected images with contour lines on the monitor. The STERECON system organizes and displays the digitized data from successive sections as a 3-D reconstruction. Reconstructions can be viewed in any orientation as contour stacks with hidden lines removed; as wire-frame models; or as shaded, solid models with variable lighting, transparency, and reflectivity. Volumes and surface areas of the reconstructed objects can be determined. Particular attention was paid to making the system convenient for the biological user. Users are given a choice of three different stereo-viewing methods.

Rat mammary tumor TMT-081 was employed as a model for blood vessel invasion because its mode of metastasis resembles that of human tumors. The invasive mechanism was studied with two methods of serial transplantation: transfer of enzymatically dispersed solid tumors, and transfer of buffy coat containing circulating tumor cells. The latter method produced greater invasion of blood vessels, including larger veins and occasionally arteries, perhaps by obviating damage to tumor cells during enzyme treatment. The course of migration was traced by three-dimensional examination in the high voltage electron microscope, as well as the light microscope. Two broad patterns were found for the course of invasion of small and large vessels respectively.

Dark cells (DC) could be reproducibly demonstrated by differential toluidine-blue staining and electron microscopy (EM) of NYLR/Nya 16- to 19-day embryo and new born skin and phorbol ester-treated or untreated young adult skin, High-voltage electron microscopy on the same or adjacent sections showed that toluidine-blue staining picks out some but not all the DC seen by EM. The ultrastructure of DC was similar in all the above situations, except that phorbol ester-induced DC showed a less contracted nucleus. No support was obtained for DC as stem cells either for basal-cell hyperplasia or for development of hair follicle or gland outgrowths. Most of the severely contracted DC (Types 3 and 4) were assumed to have undergone an apoptotic type of cell death. Two phenomena that may have caused the contraction and apoptosis were observed. Formation of a "contraction vacuole" adjacent to the DC probably led to a loss of intercellular communication. An apparent necrosis of dermal capillaries in areas of abundant follicle downgrowth probably produced local anoxia. Further characterization of DC requires a search for cytochemical or immunologic markers, analysis of intracellular calcium and other elements, and the cloning of sub populations of basal cells that can be selectively induced to form DC.

The kinematical shape transform is applied successfully to derive crystal thicknesses, using the electron diffraction patterns from tilted crystals of both wet and negatively stained beef−liver catalase.

Projecting subunits were seen on the cristae of all 11 types of mitochondria examined by electron microscopy. These consisted of a stem, 30 to 35 A wide and 45 to 50 A long, and a round head 75 to 80 A in diameter. The outer membranes of rat liver mitochondria showed regular arrays of hollow cylindrical subunits 60 A by 60 A.

We now have the tools to quantitate and correctly interpret the size, shape, and distribution of organelles in cells. It appears likely that the results will require some changes in some basic assumptions of ultrastructural cytology. This should also result in some new biochemical hypotheses about control of cell metabolism.

In an experiment to evaluate the merit of isopycnic centrifugation as a method of separating cell types in human head and neck squamous cell carcinomas, cells have been isolated from four specimens of these tumors and subjected to isopycnic centrifugation in continuous Percoll gradients. Cell types were identified by electron microscopy. The R- (ribosome-rich), T- (tonofilament-rich), and RT- (intermediate) cell types yielded broad bands overlapping extensively with one another, and partially with the bands of leukocytes. The pattern differed for each tumor studied, so that universal density levels separating given cell types could not be found. Isopycnic centrifugation proves less suitable in analyzing cells dispersed from solid tumors than for cells in suspended culture, blood, effusions, etc., probably because of heterogeneous growth conditions of cells in solid tumors.

A differentially pumped environmental chamber, or DIFPEC, has been developed for the AEI EM7 1.2 MV HVEM. The chamber is suitable for imaging and diffraction studies and is capable of operation at pressures approaching one atmosphere. Any mixture of gases can be used including water vapor supplied from an internal reservoir. Correct operation is demonstrated by measurements of temperature, pressure, and water consumption. High resolution (0.2 nm) diffraction patterns were recorded from unfixed, unstained, fully hydrated catalase crystals. This is good functional test of DIFPEC operation and specimen preparation because catalase disorders irreversibly of exposed to less than 95% relative humidity. High- and low-angle diffraction patterns were recorded from unfixed, unstained, fully hydrated rat hemoglobin crystals. All patterns were recorded using 10-4 C/cm2. Whole cell mounts prepared in different ways were imaged and show that 5.3 kPa of nitrogen gas has no detrimental effect on image contrast or resolution. The column vacuum and differentially pumped volume pressure were measured for a number of pumping configuration, as well as for several gases and pressures in the specimen volume. The pressure in the high vacuum portion of the objective lens gap is conductance-limited when the DIFPEC is in place.

A unique design for a polarimetric fiber -optic pressure sensor, its performance, and some preliminary experimental results are presented. Methods for reducing temperature sensitivity, which often limits the sensor's resolution, are alsodescribed.1. INTRODUCTIONDetection capabilities of pressure sensors are often limitedby their sensitivity to temperature changes. Fiber -optic (FO)sensors are very sensitive to temperature changes and makeexcellent temperature sensorsl. One challenge to developing sensitive FO pressure sensors (FOPS's) is to reduce theirtemperature sensitivity. The Mach -Zehnder FOPS in [2] minimizes interferometer noise by utilizing a nonlineargeometry for the optical fiber (OF) and phase sensitive detection. A FO sensor that utilizes a two core OF to measurepressure and temperature simultaneously is described in [3]. The FOPS described in [4] detects pressure by opticallymeasuring the resonant frequency of a small mechanically resonant structure. Operating this sensor at high frequenciesand using materials with thermally stable properties minimizes

Analysis of electron diffraction patterns from rat hemoglobin taken at 200 kV on a wet stage yields intensity data to a resolution of 2-3 A which are as reproducible as those from typical X-ray diffraction. Some crystals were so similar that the differences in measured intensities were insignificant (R = 0.056), but in other cases real differences between crystals were observed (R = 0.33). Dynamic scattering was insignificant under our diffraction conditions; however, exposures to electron doses as low as 10(-2) e/A2 produced detectable changes in measured intensities. Limits to the reproducibility of the data are set by radiation damage and errors in microdensitometry.

Cytological changes occurring in young oocytes of the mouse, following whole-body x-irradiation, have been examined by light and electron microscopy. Two minutes after a dose of 200 r, a drop occurs in the number of mitochondria per oocyte. The normal number of mitochondria is restored in the next few minutes. Five to 6 hours after a dose of 7 r, and 30 to 45 minutes following a dose of 200 r, all the oocytes are markedly contracted. In the next 2 hours (at a dose of 7 r), some cells shrink further and become pycnotic, while others expand and show signs of karyolysis. Of the expanded cells, some (about 50 per cent of total young oocytes) become morphologically normal. In both pycnotic and karyolytic nuclei, the nucleolus was contracted but without loss of its fibrillar structure. The contracted nucleolus appeared similar to those seen in some nearly mature normal oocytes (these oocytes have a high natural death rate). No other cell type in the ovary was affected by doses of x-rays up to 200 r. Observations on the nucleus of the normal oocyte are included. In the dictyate stage of meiotic prophase the chromosomes were dispersed into bundles of 100 A microfibrils. The main component of the nucleolus was found to be tightly coiled fibrils of 60 to 100 A, which appear to have a close relationship with the microfibrils of the chromosomes.

Morphological changes of rat-liver mitochondria brought about by swelling and ATP-induced contraction were studied by electron microscopy. The course of swelling is proposed to be as follows: Entering of water (and solutes) causes breakage of the outer membrane and formation of protrusion of the inner membrane. The distention of the inner membrane is accompanied by loss of density of the matrix and by disapperance and change of shape of the cristae, probably due to their unfolding and evagination. Both membranes seem to possess a limited ability to stretch. Addition of ATP to mitochondria swollen in the presence of either orthophosphate, oleate and thyroxine gave rise to structures different from mitochondria before the onset of swelling. Restoration of the mitochondrial morphology was not observed. It is thought that the processes initiated by ATP are not a simple reversal of swelling.

Identification of single cells in frozen sections of tissue in the light microscope (LM) with subsequent reprocessing for examination in the high-voltage electron microscope (HVEM) for ultrastructural characterization offers an expedient route for studying such processes as the dissemination of cancers by single-cell invasion. The HVEM combines a high resolution that enables more certain identification of a cell and assessment of its activity at the instant of fixation with the convenience of an allowed thickness range (0.25-2.0 μm) close to that employed by the pathologist using the LM.Employment of frozen sections allows adequate ultrastructural preservation, while at the same time enabling recognition of specific cell types by immuno-histochemistry or enzyme histochemistry. Only very brief aldehyde fixation is required—about four minutes. After reembedding, tissue containing marked cells is dissected out for reprocessing for the HVEM. Ultrastructural examination in turn enables more detailed identification and characterization of cell types. The LM staining process is illustrated with results from immuno-histochemical recognition of single invading squamous carcinoma cells in head-and-neck cancer.