Variations in the corneal surface temperature with contact lens wear

This paper presents the two-dimensional simulation of heat propagation in the human eye model during contact lens wear with finite element analysis. Three types of contact lens are studied: Lotrafilcon A, Balafilcon A, and Etafilcon A. The models are solved for both steady and transient solutions. The corneal surface temperature during contact lens wear is found to decrease (average, 0.52 ± 0.05°C compared with a bare cornea for all lens types). A contact lens with a higher water content has a lower steady state temperature than a contact lens with a lower water content does. Various initial temperatures for the contact lens are found to affect the first 400 s of the temperature variation. When the initial temperature is lower than the corneal temperature, a reduction in temperature is observed during contact lens insertion while the opposite is observed when the initial temperature is higher than the corneal temperature. The increase in evaporation rate when a contact lens is worn increases the cooling effect on the ocular surface. This is suggested to be the cause of lower corneal surface temperature when wearing a contact lens.

Fractal analysis of replication site images of the human cell nucleus

Epi-fluorescent microscopic images of the mammalian cell nucleus taken during the early, mid and late S (synthetic) phase of the cell cycle suggest that the mass of replicating DNA that belong to the cell nucleus can be characterized as a space filling fractal curve. We reason from a biological standpoint and our understanding of naturally occurring fractals that our microscopic images reveal portions of the spatially complex DNA molecule and present methods for computing the fractal dimensions of the images. Results presented here suggest that our methodology based on fractal properties can distinguish replication of DNA occurring in early versus mid or late S-phase.

Development and applications of the k0-based internal mono standard INAA method

The k0-based internal monostandard instrumental neutron activation analysis (IM-INAA) method, developed and standardized in our laboratory, is capable of analyzing both small and large samples of different sizes and shapes. Use of in-situ relative efficiency makes the method geometry independent. In this paper, we present the development of this methodology and applications to two types of alloys namely, stainless steel and brass. A stainless steel certified reference material, BCS 466 was also analyzed to evaluate the accuracy of the method. Absolute concentrations in these alloys were arrived by a standard-less method. The method has also been applied for the analysis of large-size wheat samples (0.45-1 kg) and the results were compared with the data obtained for selected elements in sub-samples (50-1000 mg).

A New Report of Cymbidium spp. Pseudobulb Rot Orchestrated by Erwinia carotovora, Fusarium oxysporum, and Mucor hiemalis f. sp. hiemalis

Cymbidium spp. is an orchid of great horticultural value cultivated extensively in Eastern Himalaya, India. Since 1995, growers have experienced huge crop losses in every monsoon month because of pseudobulb rot. Pseudobulbs initially turned soft and pulpy followed by oozing of a dark brown liquid with a foul odor (early phase). With increasing severity, the bulbs and roots lose weight as the internal tissues gradually disintegrate (middle phase). Finally, the bulb becomes hollow, fibrous, and dry causing death of the plant (later phase). Surveys from 2002 to 2005 showed that disease incidence ranged from 60 to 100%. Rotted tissue was plated on nutrient agar and potato dextrose agar media. Three organisms were consistently isolated from 50 samples collected from 30 different localities. They were identified as Erwinia carotovora (2), Fusarium oxysporum (3), and Mucor hiemalis f. sp. hiemalis (1) and were predominant at the earlier, middle, and later stages of disease, respectively. Identifications were further confirmed by the Agricultural Research Institute (ARI), Pune, India. Pseudobulbs were surface sterilized with 0.5% sodium hypochlorite for 1 min, washed by sterile distilled water, and dipped separately into three different spore/cell suspensions (10⁵ CFU/ml) for 1 min. Another set of sterilized bulbs was dipped first into E. carotovora, then into F. oxysporum 12 days later, and then into M. hiemalis f. sp. hiemalis 15 days after the second dip. For the control set, bulbs were dipped into sterile distilled water. Samples were incubated aseptically at 20°C with a relative humidity of 80%, and all inoculated bulbs were evaluated for disease 47 days after the first inoculation. When samples were inoculated separately, E. carotovora exhibited maximum (70%) tissue disintegration followed by F. oxysporum (30%) and M. hiemalis f. sp. hiemalis (10%), but none of the individual pathogens caused 100% tissue disintegration. Complete destruction was observed after 47 days of first inoculation when these three pathogens were inoculated consecutively according to their serial occurrence. It is an interesting report on host-pathogen combination as three pathogens act in sequence toward ultimate demolition of the host. We report this rot as a synergistic activity of three pathogens to cause an uncontrolled epidemic disease of Cymbidium spp. References: (1) J. C. Gilman. Page 37 in: A Manual of Soil Fungi. Iowa State College Press. Ames, IA, 1945. (2) J. G. Holt. Page 469 in: Bergey's Manual of Systematic Bacteriology. Vol. I. Williams and Wilkins. Baltimore/London, 1984, (3) C. V. Subramaniam. Page 657 in: Hyphomycetes. Indian Council of Agricultural Research (ICAR). New Delhi, 1971.

Evaluation of the antioxidant activity of wheatgrass (Triticum aestivum L.) as a function of growth under different conditions

The antioxidant activity of wheatgrass, which is consumed as a dietary supplement, was estimated at different levels. The methods employed include FRAP (ferric reducing antioxidant power), ABTS (2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid) and DPPH (1,1'-diphenyl-2-picrylhydrazyl) assays. Aqueous and ethanol extracts of wheatgrass grown under different conditions over a period of 6, 7, 8, 10 and 15 days were used. Lipid peroxidation and oxygen radical absorbance capacity (ORAC) were determined and utilized to check the potency of a few selected extracts. Different conditions used for growth were (1) tap water, (2) tap water with nutrients, (3) soil and tap water, and (4) soil with nutrients. For comparison, a commercially available wheatgrass tablet was analysed. To explain the reasons behind the observed differences, the total phenolic and flavonoid contents of the extracts were measured. These contents increased with growth under all the conditions. The ethanol extracts were found to have a higher phenolic and flavonoid content than the aqueous extracts. The highest FRAP values occurred on day 15 of growth under condition 4, the values being 0.463 and 0.573 mmol of ascorbic acid and Trolox equivalents/100 g fresh wheatgrass for aqueous and ethanol extracts, respectively. In the aqueous extracts no specific trend was observed with the DPPH assay for the different conditions nor for the growth period. In the case of ethanol extracts, however, it increased with the growth period and the wheatgrass grown in condition 4 was found to be the most effective. These extracts were also found to inhibit significantly ascorbate-Fe2+ induced lipid peroxidation in rat liver mitochondria. The ORAC values of aqueous and ethanol extracts of day 10 with condition 4 were found to be 39.9 and 48.2, respectively, being higher than those reported for many natural extracts or vegetables.

Intraspinal synovial cysts: A retrospective study

BACKGROUND

We report the clinical presentation, radiographic studies, intraoperative findings, histopathological analysis, and post-treatment outcome in 26 patients diagnosed with spinal synovial cysts (SSCs).

AIMS

To describe the clinical presentation, radiographic studies, operative findings, and postoperative follow-up in 26 patients with SSCs.

SETTINGS AND DESIGN

The study was retrospective in design, involving chart review. Individual patient data was tabulated and patterns were recognized.

MATERIALS AND METHODS

The charts for 26 patients who underwent surgical extirpation of SSC between April 1993 and October 2002 were retrospectively reviewed. Specifically, initial clinical presentation, pertinent radiographs (X-rays, magnetic resonance imaging, computed tomography), intraoperative findings, histopathology, and postoperative follow-up were noted.

STATISTICAL ANALYSIS USED

Patient data was tabulated and analyzed for patterns in demographics, symptoms and histopathology.

RESULTS

SSCs were more common in females than males (17:9 ratio). Presenting symptoms were back pain with radiculopathy in 13 (50%), radicular pain in the absence of back pain in 10 (38%), and back pain without radicular pain in three (11%). In addition, 17 patients (65%) had sensory deficit, and 9 (35%) had motor deficit. Most SSCs occurred at the lumbar (19/26) or lumbosacral (5/26) regions, with only 2 (2/26) in the thoracic region. One patient had bilateral SSC at the L4-5 level. Intraoperatively, each cyst was located adjacent to a degenerated facet joint. These lesions could grossly be identified intraoperatively and histopathological confirmation was achieved in all the cases.

CONCLUSIONS

SSCs are important lesions to consider in the differential diagnosis of lumbar epidural masses and surgical resection leads to significant improvement in the majority of cases.

Chronic subdural haematoma complicating spinal anaesthesia

Cranial subdural haematoma formation following spinal anaesthesia is exceptionally rare. A 38-year-old male developed headache two days after testicular surgery under spinal anaesthesia. The headache progressed in spite of analgesics, and three weeks later cranial CT showed a large chronic subdural haematoma in the left fronto-parietal region. The patient improved after surgical decompression. The pathogenesis of subdural haematoma formation after dural puncture is discussed and the literature briefly reviewed. Prolonged and severe post-dural puncture headache should be viewed with suspicion and investigated promptly to rule out any intracranial complication.

Classification of cardiac abnormalities using heart rate signals

The heart rate is a non-stationary signal, and its variation can contain indicators of current disease or warnings about impending cardiac diseases. The indicators can be present at all times or can occur at random, during certain intervals of the day. However, to study and pinpoint abnormalities in large quantities of data collected over several hours is strenuous and time consuming. Hence, heart rate variation measurement (instantaneous heart rate against time) has become a popular, non-invasive tool for assessing the autonomic nervous system. Computer-based analytical tools for the in-depth study and classification of data over day-long intervals can be very useful in diagnostics. The paper deals with the classification of cardiac rhythms using an artificial neural network and fuzzy relationships. The results indicate a high level of efficacy of the tools used, with an accuracy level of 80-85%.

Development of an Internal Monostandard Instrumental Neutron Activation Analysis Method Based on In Situ Detection Efficiency for Analysis of Large and Nonstandard Geometry Samples

A k0-based internal monostandard instrumental neutron activation analysis method for determination of relative elemental concentration in samples of large size and irregular geometry has been developed. In this method, one of the elements present in the sample is used as comparator. A priori knowledge of the concentration of one of the constituents is required to convert the relative concentration into absolute values. The problems of gamma-ray self-attenuation and geometrical effects that arise in the assay of large and nonstandard geometry samples were overcome by an in situ relative detection efficiency calibration procedure, which requires one or more activation products emitting gamma-rays over a wide range of the spectrum. To minimize the problem of neutron flux perturbations that may arise in large samples, irradiations were carried out using a thermal column with thermal neutron component of more than 99.9%. The method has been standardized with samples of silica (approximately 0.5 kg) and water (0.5 L) spiked with known amounts of different elements and has been advantageously applied to some alloy and metal samples of irregular geometry, where complete compositional characterization was carried out using mass balance. This approach is highly valuable for analysis of large, irregularly shaped samples if not too high demands are set to the degree of accuracy.

Sixth nerve schwannoma: a case report with literature review

A 40-year-old woman presented with diplopia and left VI nerve palsy. After investigations, diagnosis of a meningioma in the parasellar-prepontine region was considered. Following angiography and embolization, near-total excision of the tumour attached to abducens nerve was performed. Histological examination was consistent with the diagnosis of schwannoma. This is the thirteenth case report of a schwannoma of cranial nerve VI and the first such case where embolization of feeding tumour vessels was performed.

Complete migration of ventriculoperitoneal shunt into the ventricle

Proximal migration of ventriculoperitoneal (VP) shunt is extremely rare. A medium pressure VP shunt was inserted in a 10-month-old infant suffering from severe hydrocephalus. One month later, complete migration of the shunt into the lateral ventricle was encountered. Possible causative mechanisms and the literature on this subject are briefly discussed.

Compact storage of medical images with patient information

Digital watermarking is a technique of hiding specific identification data for copyright authentication. This technique is adapted here for interleaving patient information with medical images to reduce storage and transmission overheads. The text data are encrypted before interleaving with images to ensure greater security. The graphical signals are compressed and subsequently interleaved with the image. Differential pulse-code-modulation and adaptive-delta-modulation techniques are employed for data compression, and encryption and results are tabulated for a specific example.

Laparoscopic management of abdominal complications in ventriculoperitoneal shunt surgery

Ventriculoperitoneal (VP) shunts are among the most frequently performed operations in the management of hydrocephalus. Abdominal complications, though rare, are reported to occur in 5-47%. VP shunt obstruction or malfunction leads to raised intracranial pressure, which requires immediate intervention. Recently we have used the laparoscope to manage abdominal complications of VP shunt in two patients. The first patient had hydrocephalus secondary to tubercular meningitis. She developed recurrent intraabdominal cerebrospinal fluid (CSF) pseudocysts, possibly due to subtle peritoneal infection. In the second patient, who developed hydrocephalus following subarachnoid haemorrhage, the lower end of the shunt was malfunctioning due to retraction into the extraperitoneal tissues. The distal end of the VP shunt was revised in both patients with the help of a laparoscopically assisted technique. Thus, a conventional laparotomy, along with its various associated postoperative problems, was avoided without compromising the quality of surgery.

Cranial subdural haematoma after spinal anaesthesia

Intracranial subdural haematoma is an exceptionally rare complication of spinal anaesthesia. A 20-yr-old male underwent appendicectomy under partial spinal and subsequent general anaesthesia. A week later, he presented with severe headache and vomiting not responding to bed rest and analgesia. Magnetic resonance imaging showed a small acute subdural haematoma in the right temporo-occipital region. The patient improved without surgical decompression. The pathogenesis of headache and subdural haematoma formation after dural puncture is discussed and the literature briefly reviewed. Severe and prolonged post-dural puncture headache should be regarded as a warning sign of an intracranial complication.

Malignant peripheral nerve sheath tumor of the cauda equina

Only one case of malignant peripheral nerve sheath tumor (MPNST) affecting the cauda equina region has been reported earlier. A 32-year-old male with congenital multiple subcutaneous swellings presented with low back pain, progressive paraparesis and bladder-bowel dysfunction. Magnetic resonance imaging (MRI) demonstrated a heterogeneously enhancing intradural lesion at L2-L4. At operation, on opening the dura, multiple nodular, firm matted masses attached to the lumbosacral nerve roots were encountered. Peripheral lesions were partially excised. Histopathological exam revealed varied cellularity with necrosis and pleomorphic nuclei suggestive of MPNST. MRI features, pathophysiological characteristics and the literature are reviewed.

Seasonal variation of births in rural West Bengal: magnitude, direction and correlates

This paper examines seasonal variation of births in a rural community of West Bengal, India, by exploring data from the 1992-93 National Family Health Survey. Suitable time series analyses were used to determine the seasonal pattern of births and to estimate peaks. The trigonometric regression technique was used to carry out this objective. The study attempted to link the results of the regression analysis to the atmospheric temperature of the region during 1987-91, the distribution of respondents' husbands' occupations and the marriage pattern of the community. It was found that, in the study population, conceptions were numerous in the first quarter of a calendar year and the distribution of conceptions over calendar months was negatively associated with the average monthly temperature. In addition, the marriage pattern of the community and the occupational distribution of the fathers also had a significant effect on the distribution of births over calendar months. It is hoped that the findings will boost the development of needs-based maternal and child health (MCH) and family planning programmes in the community.

Nitric oxide: the "second messenger" of insulin

Incubation of various tissues, including heart, liver, kidney, muscle, and intestine from mice and erythrocytes or their membrane fractions from humans, with physiologic concentration of insulin resulted in the activation of a membrane-bound nitric oxide synthase (NOS). Activation of NOS and synthesis of NO were stimulated by the binding of insulin to specific receptors on the cell surface. A Lineweaver-Burk plot of the enzymatic activity demonstrated that the stimulation of NOS by insulin was related to the decrease in the Km for L-arginine, the substrate for NOS, with a simultaneous increase of Vmax. Addition of NG-nitro-L-arginine methyl ester (LNAME), a competitive inhibitor of NOS, to the reaction mixture completely inhibited the hormone-stimulated NO synthesis in all tissues. Furthermore, NO had an insulin-like effect in stimulating glucose transport and glucose oxidation in muscle, a major site for insulin action. Addition of NAME to the reaction mixture completely blocked the stimulatory effect of insulin by inhibiting both NO production and glucose metabolism, without affecting the hormone-stimulated tyrosine or phosphatidyl-inositol 3-kinases of the membrane preparation. Injection of NO in alloxan-induced diabetic mice mimicked the effect of insulin in the control of hyperglycemia (i.e., lowered the glucose content in plasma). However, injection of NAME before the administration of insulin to diabetic-induced and nondiabetic mice inhibited not only the insulin-stimulated increase of NO in plasma but also the glucose-lowering effect of insulin.

Spatial and temporal dynamics of DNA replication sites in mammalian cells

Fluorescence microscopic analysis of newly replicated DNA has revealed discrete granular sites of replication (RS). The average size and number of replication sites from early to mid S-phase suggest that each RS contains numerous replicons clustered together. We are using fluorescence laser scanning confocal microscopy in conjunction with multidimensional image analysis to gain more precise information about RS and their spatial-temporal dynamics. Using a newly improved imaging segmentation program, we report an average of approximately 1,100 RS after a 5-min pulse labeling of 3T3 mouse fibroblast cells in early S-phase. Pulse-chase-pulse double labeling experiments reveal that RS take approximately 45 min to complete replication. Appropriate calculations suggest that each RS contains an average of 1 mbp of DNA or approximately 6 average-sized replicons. Double pulse-double chase experiments demonstrate that the DNA sequences replicated at individual RS are precisely maintained temporally and spatially as the cell progresses through the cell cycle and into subsequent generations. By labeling replicated DNA at the G1/S borders for two consecutive cell generations, we show that the DNA synthesized at early S-phase is replicated at the same time and sites in the next round of replication.

Segregation of transcription and replication sites into higher order domains

Microscopy shows that individual sites of DNA replication and transcription of mammalian nuclei segregate into sets of roughly 22 and 16 higher order domains, respectively. Each domain set displayed a distinct network-like appearance, including regions of individual domains and interdigitation of domains between the two networks. These data support a dynamic mosaic model for the higher order arrangement of genomic function inside the cell nuclei.

Surface matching of multimodality image volumes by a fuzzy elastic registration technique

Multimodality image registration is useful in diagnostic imaging and treatment planning for radiation therapy. In this paper, we present a technique which registers the surfaces of two volumes acquired by different medical imaging modalities. We represent the image volumes in terms of their surface elements known as tiles. We identify the fuzzy variables, assign fuzzy membership functions to them and generate a fuzzy rule database. The fuzzy algorithm reduces the discrepancy between the two set of tiles until the surfaces are matched. In order to study the efficacy of our approach, we severely warp a simulated image and register it with its original. We register CT and MR volumes of humanoid phantom images. Finally, we present the results at the end of the article.

Corpectomy for multi-level cervical spondylosis and ossification of the posterior longitudinal ligament

The choice of a surgical approach for multi-level cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL) is still a controversial issue. While most of the surgeons are still performing decompression by laminectomy, some are doing multi-level anterior decompression. Few neurosurgeons are performing decompression by corpectomy. We have treated 26 patients by median cervical corpectomy during the last 4 years. These patients were followed up for a mean period of 25 months. Twenty one (80%) patients had a good outcome, 2 patients remained unchanged and 3 expired. Review of the literature and our experience indicates that patients with CSM and OPLL should be operated by median cervical corpectomy (anterior approach).

Pilot study of controlled-release pilocarpine in normal subjects

OBJECTIVES

Current systemic treatments with sialogogues for patients with xerostomia are limited because of minimal efficacy, short duration of activity, or problems with side effects. The purpose of this pilot study was an initial assessment of safety, efficacy, duration of action, multiple dose tolerance, and side effects of a controlled-release formulation of pilocarpine hydrochloride.

STUDY DESIGN

Eight healthy hospitalized subjects were given 15 mg of a controlled-release pilocarpine formulation every 12 hours for three doses. Saliva and blood samples were collected at assigned intervals. Repeated measures analysis and paired t tests were used for statistical analyses.

RESULTS

A significant (p < 0.05) increase in both parotid and whole saliva output followed all three doses beginning within 1 hour of dosing and lasting over 10 hours. Mean plasma pilocarpine concentration reached a maximum of 8.2 ng/ml at approximately 1 hour after the first dose, 11.5 ng/ml after the third dose, and declined to near baseline (0.06 ng/ml) 24 hours after the final dose. None of the participants showed evidence of adverse effects including complaints of sweating or gastrointestinal discomfort.

CONCLUSIONS

A controlled-release formulation of pilocarpine may overcome the therapeutic weaknesses of current pilocarpine preparations by prolonging salivary secretion and reducing undesirable side effects.

Giant cell tumor of sphenoid-diverse presentation: report of two cases

Two rare cases of giant cell tumors of the sphenoid bone are presented. We discuss their imaging, unpredictable biological behavior and management together with a review of the pertinent literature.

A patient-specific in vivo tumor model

A significant body of research, spanning approximately the last 25 years, has focused upon the task of developing a better understanding of tumor growth through the use of in vitro mathematical models. Although such models are useful for simulation, in vivo growth differs in significant ways due to the variety of competing biological, biochemical, and mechanical factors present in a living biological system. An in vivo, macroscopic, primary brain tumor growth model is developed, incorporating previous in vitro growth pattern research as well as scientific investigations into the biological and biochemical factors that affect in vivo neoplastic growth. The tumor growth potential model presents an integrated, universal framework that can be employed to predict the direction and extent of spread of a primary brain tumor with respect to time for a specific patient. This framework may be extended as necessary to include the results of current and future research into parameters affecting neoplastic proliferation. The patient-specific primary brain tumor growth model is expected to have multiple clinical uses, including: predictive modeling, tumor boundary delineation, growth pattern research, improved radiation surgery planning, and expert diagnostic assistance.

Posterior occipitoaxial fusion for atlantoaxial dislocation associated with occipitalized atlas

Between 1989 and 1994, 50 patients suffering from congenital atlantoaxial dislocation with either an assimilated atlas or a thin or deficient posterior arch of the atlas were treated with occipitocervical fusion using the technique described by Jain and colleagues in 1993 with a few modifications. An artificial bridge created from the occipital bone along the margin of the foramen magnum was fused to the axis using sublaminar wiring and interposed strut and lateral onlay bone grafts. Ten patients (20%) also underwent atlantoaxial lateral joint fusion by intraarticular instillation of bone chips. In 22 patients (44%) with irreducible dislocation, posterior fusion was preceded by transoral odontoidectomy. In seven patients (14%) with ventral compression, who showed marked clinical improvement on traction despite radiological evidence of persisting atlantoaxial dislocation, occipitocervical fusion was performed without ventral decompression. Seven patients (14%) underwent a single-stage transoral odontoidectomy and posterior fusion. There was no perioperative mortality and the osseous fusion rate was 88%. Of the 43 patients available at follow-up examination (range 3-12 months), 31 patients (72.09%) improved, seven (16.28%) remained the same, and five (11.6%) deteriorated in comparison with their preoperative status. Hence, this technique achieves a stable occipitocervical arthrodesis without supplemental external orthoses and facilitates early postoperative mobilization.

Hepatocellular carcinoma metastatic to bones (Case report with review of literature)

A seventy year old man presented with bone pains. Investigation revealed a metastatic bone lesion in the humerus. The primary was found in the liver. The patient achieved good palliation with chemotherapy and radiotherapy and survived for one year.

Biomedical imaging modalities: a tutorial

The introduction of advanced imaging technologies has improved significantly the quality of medical care available to patients. Non-invasive imaging modalities allow a physician to make increasingly accurate diagnoses and render precise and measured modes of treatment. Current uses of imaging technologies include laboratory medicine, surgery, radiation therapy, nuclear medicine, and diagnostic radiology. This paper provides an overview of most of the popular imaging modalities currently in clinical use. It is hoped that a general understanding of the modality from which an image is derived will help researchers in the subsequent analysis of the image data.

Segmentation of multidimensional cardiac images

One of the initial steps in the analysis of three-dimensional (3D)/four-dimensional (4D) images is Segmentation, which entails partitioning the images into relevant subsets such as object and background. In this paper, we present a multidimensional segmentation algorithm to extract object surfaces from Multidimensional Cardiac Computed Tomography (CT) scans. We propose the Generalized Morphological operators for segmentation in multidimensions. A priori knowledge of the approximate location of the object surface is communicated to the algorithm via the definition of the Search Space. The algorithm uses this definition of the Search Space to obtain the Surface Candidate elements. The search space specification reduces the computational cost and increases the reliability of the detected features.

Morphological pyramids with alternating sequential filters

The aim of this paper is to find a relationship between alternating sequential filters (ASF) and the morphological sampling theorem (MST) developed by Haralick et al. (1987). The motivation behind this approach is to take advantage of the computational efficiency offered by the MST to implement morphological operations. First, we show alternative proofs for opening and closing in the sampled and unsampled domain using the basis functions. These proofs are important because they show that it possible to obtain any level of a morphological pyramid in one step rather than the traditional two-step procedure. This decomposition is then used to show the relationship of the open-closing in the sampled and unsampled domain. An upper and a lower bound, for the above relationships, are presented. Under certain circumstances, an equivalence is shown for open-closing between the sampled and the unsampled domain. An extension to more complicated algorithms using a union of openings and an intersection of closings is also proposed. Using the Hausdorff metric, it is shown that a morphologically reconstructed image cannot have a better accuracy than twice the radius of the reconstruction structuring element. Binary and gray scale examples are presented.

Algorithm for the automated alignment of radiographs for image subtraction

The results of this study indicate that automated alignment of pairs of radiographs produces subtractions that are indistinguishable in quality from subtractions aligned manually by an experienced aligner. In developing the algorithm for automated alignment, care was taken that the criteria used for establishing a window appropriate for testing the quality of alignment were the same for both alignment techniques.

Visualization and interactive exploration of multidimensional confocal images

A confocal image analysis system is developed for automatic extraction of surface representation of biological structures. A visualization system is also developed to manipulate these surface representations and to obtain morphometrical parameters and provides a powerful tool for biomedical research such as microstructural characterization, morphogenesis, cell differentiation, tissue organization, and embryo development.

Methods used in the structure determination of foot-and-mouth disease virus

The structure of foot-and-mouth disease virus (FMDV) strain O1 BFS 1860 has been determined to 2.9 A resolution using the molecular-replacement method [Acharya, Fry, Stuart, Fox, Rowlands & Brown (1989). Nature (London), 337, 709-716]. Crystals of the virus with average dimensions 0.12 x 0.06 x 0.12 mm belong to space group I23, a = 345 A with 1/12 of the icosahedral particle per asymmetric unit giving fivefold noncrystallographic redundancy. Oscillation diffraction photographs were collected at the SERC Synchrotron Radiation Source at Daresbury in accordance with strict disease security regulations. The ambiguity in particle orientation was resolved using a self-rotation function and starting estimates of the phases to 8 A were derived from the known structures of two picornaviruses similarly oriented in the I23 unit cell. The phases were refined and extended using iterative averaging and solvent flattening with the implementation of a simple automatic envelope-determination procedure to increase the phasing power available.

Analysis of bone X-rays using morphological fractals

The authors have applied mathematical morphology for fractal analysis on bone X-ray images. The digitized gray level image is treated as a three-dimensional surface whose fractal dimension is calculated by performing a series of dilations on this surface and plotting the area of the resulting set of surfaces against the size of the structuring element. This approach has the added advantage of encoding structural information via the use of a structuring element. The algorithm has been applied to several bone radiographs, and the results demonstrate that the fractal dimension using mathematical morphology gives a robust texture measure of trabecular bone structures.

Structural and serological evidence for a novel mechanism of antigenic variation in foot-and-mouth disease virus

Changes resulting in altered antigenic properties of viruses nearly always occur on their surface and have been attributed to the substitution of residues directly involved in binding antibody. To investigate the mechanism of antigenic variation in foot-and-mouth disease virus (FMDV), variants that escape neutralization by a monoclonal antibody have been compared crystallographically and serologically with parental virus. FMDVs form one of the four genera of the Picornaviridae. The unenveloped icosahedral shell comprises 60 copies each of four structural proteins VP1-4. Representatives from each of the genera have similar overall structure, but differences in the external features. For example, human rhinovirus has a pronounced 'canyon' that is proposed to contain the cell attachment site, whereas elements of the attachment site for FMDV, which involves the G-H loop (residues 134-160) and C-terminus (200-213) of VP1, are exposed on the surface. Moreover, this G-H loop, which is a major antigenic site of FMDV, forms a prominent, highly accessible protrusion, a feature not seen in other picornaviruses. It is this loop that is perturbed in the variant viruses that we have studied. The amino acid mutations characterizing the variants are not at positions directly involved in antibody binding, but result in far-reaching perturbations of the surface structure of the virus. Thus, this virus seems to use a novel escape mechanism whereby an induced conformational change in a major antigenic loop destroys the integrity of the epitope.

The structure of foot-and-mouth disease virus: implications for its physical and biological properties

The structure of foot-and-mouth disease virus has been solved at a resolution of 2.9 A by X-ray diffraction techniques. The overall structural organisation of the particle is similar to that seen in other picornaviruses but there are several unique features. Many of these help to explain its characteristic physical and biological properties. In particular the canyon or pit found at the surface of other picornaviruses is lacking, which has important implications for cell attachment and the process of infection. Also there are 60 large disordered protrusions at the surface corresponding to the major antigenic site. This disorder is of particular interest in relation to the striking ability of linear synthetic peptides to induce protective immunity against foot-and-mouth disease.

The three-dimensional structure of foot-and-mouth disease virus at 2.9 A resolution

The structure of foot-and-mouth disease virus has been determined at close to atomic resolution by X-ray diffraction without experimental phase information. The virus shows similarities with other picornaviruses but also several unique features. The canyon or pit found in other picornaviruses is absent; this has important implications for cell attachment. The most immunogenic portion of the capsid, which acts as a potent peptide vaccine, forms a disordered protrusion on the virus surface.