Patellofemoral replacement: the third compartment.

Isolated patellofemoral arthritis is a common condition and there are varying opinions on the most effective treatments. Non-operative and operative treatments have failed to demonstrate effective long-term treatment for those in an advanced stage of the condition. Newer designs and increased technology in patellofemoral replacement (PFR) have produced more consistent outcomes. This has led to a renewed enthusiasm for this procedure. Newer PFR prostheses have addressed the patellar maltracking issues plaguing some of the older designs. Short-term results with contemporary prostheses and new technology are described here.

Immune response to dietary proteins, gliadin and cerebellar peptides in children with autism.

The mechanisms behind autoimmune reaction to nervous system antigens in autism are not understood. We assessed the reactivity of sera from 50 autism patients and 50 healthy controls to specific peptides from gliadin and the cerebellum. A significant percentage of autism patients showed elevations in antibodies against gliadin and cerebellar peptides simultaneously. For examining cross-reaction between dietary proteins and cerebellar antigens, antibodies were prepared in rabbits, and binding of rabbit anti-gliadin, anti-cerebellar peptides, anti-MBP, anti-milk, anti-egg, anti-soy and anti-corn to either gliadin- or cerebellar-antigen-coated wells was measured. In comparison to anti-gliadin peptide binding to gliadin peptide at 100%, the reaction of anti-cerebellar peptide to gliadin peptide was 22%, whereas the binding of anti-myelin basic protein (MBP), anti-milk, anti-egg and anti-soy to gliadin was less than 10%. Further examination of rabbit anti-gliadin (EQVPLVQQ) and anti-cerebellar (EDVPLLED) 8 amino acid (AA) peptides with human serum albumin (HSA) and an unrelated peptide showed no binding, but the reaction of these antibodies with both the cerebellar and gliadin peptides was greater than 60%. This cross-reaction was further confirmed by DOT-immunoblot and inhibition studies. We conclude that a subgroup of patients with autism produce antibodies against Purkinje cells and gliadin peptides, which may be responsible for some of the neurological symptoms in autism.

Detection of cis-trans isomers of a synthetic peptide fragment of erythropoietin.

The synthesis of the protected fragment t-butoxycarbonyl-alanine-isoleucine-serine(benzyl)-proline (Pro)-Pro-OH derived from the hormone erythropoietin is described. The analysis of the peptide by high-pressure liquid chromatography (HPLC) and thin-layer chromatography (TLC) yields apparently inconsistent results. Although HPLC consistently indicates the presence of only one component, TLC reveals a number of distinct species. Because satisfactory amino acid analysis and fast atom bombardment-mass spectrometry results are obtained, we think it possible that the distinct components arise from the cis-trans isomerization of the peptide bonds to the prolyl residues. An analysis using capillary electrophoresis under basic conditions identifies four components in the final product. Also, under similar conditions proton nuclear magnetic resonance spectroscopy is able to confirm the presence of cis and trans isomers. The results from this study demonstrate the usefulness of each of the four techniques in identifying the isomerism of the standard amino acid-Pro bond with respect to the peptide's ionic state.

Localization of a time-delayed, monocular virtual object superimposed on a real environment.

Observers adjusted a pointer to match the depicted distance of a monocular virtual object viewed in a see-through, head-mounted display. Distance information was available through motion parallax produced as the observers rocked side to side. The apparent stability of the virtual object was impaired by a time delay between the observers' head motions and the corresponding change in the object position on the display. Localizations were made for four time delays (31 ms, 64 ms, 131 ms, and 197 ms) and three depicted distances (75 cm, 95 cm, and 113 cm). The errors in localizations increased systematically with time delay and depicted distance. A model of the results shows that the judgment error and lateral projected position of the virtual object are each linearly related to time delay.

Context-specific adaptation of vertical vergence to correlates of eye position.

Vertical phoria (vertical vergence in the absence of binocular feedback) can be trained to vary with non-visual cues such as vertical conjugate eye position, horizontal conjugate eye position and horizontal vergence. These prior studies demonstrated a low-level association or coupling between vertical vergence and several oculomotor cues. As a test of the potential independence of multiple eye-position cues for vertical vergence, context-specific adaptation experiments were conducted in three orthogonal adapting planes (midsagittal, frontoparallel, and transverse). Four vertical disparities in each of these planes were associated with various combinations of two specific components of eye position. Vertical disparities in the plane were associated with horizontal vergence and vertical conjugate eye position; vertical disparities in the frontoparallel plane were associated with horizontal and vertical conjugate eye position; and vertical disparities in the transverse plane were associated with horizontal vergence and horizontal conjugate eye position. The results demonstrate that vertical vergence can be adapted to respond to specific combinations of two different sources of eye-position information. The results are modeled with an association matrix whose inputs are two classes of eye position and whose weighted output is vertical vergence.

A human xenograft model for testing early events of epithelial neoplastic invasion.

We report on a model of human prostate tumor cell invasion using the SCID (severe combined immunodeficient) mouse diaphragm. Tumor cells were injected into SCID mice intraperitoneally and the diaphragms harvested three to five weeks later. Electron microscopy showed tumor cell penetration of the mesothelial cell layer and adhesion to the underlying basement membrane on the inferior surface of the mouse diaphragm, where colonies developed. Immunohistochemistry showed invasion by tumor cells through the basement membrane into the muscle of the diaphragm, presence of human tumor cells among the muscle cells and the presence of selected proteins on the invasion front of the tumor cells. Digital image analysis enabled quantitative comparison of events in the metastatic cascade by variants of the tumor cell line and evaluation of the effectiveness of a putative tumor inhibitor. Results suggest that the SCID mouse diaphragm model is a convenient, effective, easily oriented and reproducible in vivo model of the early events associated with human prostate tumor cell invasion.

Signal transduction in the archaeon Halobacterium salinarium is processed through three subfamilies of 13 soluble and membrane-bound transducer proteins.

Eubacterial transducers are transmembrane, methyl-accepting proteins central to chemotaxis systems and share common structural features. We identified a large family of transducer proteins in the Archaeon Halobacterium salinarium using a site-specific multiple antigenic peptide antibody raised against 23 amino acids, representing the highest homology region of eubacterial transducers. This immunological observation was confirmed by isolating 13 methyl-accepting taxis genes using a 27-mer oligonucleotide probe, corresponding to conserved regions between the eubacterial and first halobacterial phototaxis transducer gene htrI. On the basis of the comparison of the predicted structural domains of these transducers, we propose that at least three distinct subfamilies of transducers exist in the Archaeon H. salinarium: (i) a eubacterial chemotaxis transducer type with two hydrophobic membrane-spanning segments connecting sizable domains in the periplasm and cytoplasm; (ii) a cytoplasmic domain and two or more hydrophobic transmembrane segments without periplasmic domains; and (iii) a cytoplasmic domain without hydrophobic transmembrane segments. We fractionated the halobacterial cell lysate into soluble and membrane fractions and localized different halobacterial methyl-accepting taxis proteins in both fractions.

A cross-coupling model of vertical vergence adaptation.

Vertical disparity vergence aligns the two eyes in response to vertical misalignment (disparity) of the two ocular images. An adaptive response to vertical disparity vergence is demonstrated by the continuation of vertical vergence when one eye is occluded. The adaptive response is quantified by vertical phoria, the eye alignment error during monocular viewing. Vertical phoria can be differentially adapted to vertical disparities of opposite sign located at two positions along the horizontal or vertical head-referenced axes. Vertical phoria aftereffects vary in amplitude as the eyes move from one adapted direction of gaze to another along the adaptation axis. A cross-coupling model was developed to account for the spatial variations of vertical phoria aftereffects. The model is constrained according to both single cell recordings of eye position sensitive neurons, and eye position measurements during and following adaptation. The vertical phoria is computed by scaling the activities of eye position sensitive neurons and converting the scaled activities into a vertical vergence signal. The three components of the model are: neural activities associated with conjugate eye position, cross-coupling weights to scale the activities, and vertical vergence transducers to convert the weighted activities to vertical vergence. The model provides a biologically plausible mechanism for vertical vergence adaptation.

An adaptable association between vertical and horizontal vergence.

Vertical phoria (vergence error under monocular viewing conditions) can be trained to vary with conjugate eye position. The adaptive response controls the vertical alignment of the two eyes in the absence of binocular disparity and is used to compensate for binocular changes of the oculomotor system induced by developmental and environmental factors. Vertical phoria was associated with horizontal disparity vergence by adapting vertical vergence to two vertically disparate targets separated along the depth axis. This association was primarily dependent on the horizontal vergence as opposed to monocular eye position or binocular conjugate eye position. Following this adapted association with horizontal disparity vergence, vertical phoria aftereffects were also evoked by accommodative vergence. Previous reports have demonstrated an adapted association between vertical phoria and conjugate eye position. The current report examines the difference in the vertical phoria resulting from adaptation to vertically disparate targets separated along either the vertical axis or depth axis. The amplitude of the vertical vergence aftereffect was approximately 4 times greater for targets separated along the depth axis than in the vertical meridian. The association between vertical phoria with conjugate eye position and horizontal vergence is proposed to result from a cross-coupling of vertical vergence with supranuclear regions that control conjugate and horizontal vergence eye movements. A selective interaction would enable the oculomotor system to correct disturbances in specific supranuclear regions as they interface with vertical vergence.

Distance cues for vertical vergence adaptation.

Vertical vergence can be trained to respond to vertical and/or horizontal conjugate eye position, horizontal vergence, and vertical head tilt. This cross-coupling is manifest as a vertical phoria aftereffect (monocular vertical vergence response) that varies with direction and distance of gaze. The function of the spatially dependent adaptation is to maintain the calibration between vertical eye alignment and intended placement of the two retinal images. Oculomotor adaptation stabilizes our sense of spatial localization and calibrates a body-referenced coordinate representation of visual space that is necessary for visually guided motor responses. We have tested the possible association of vertical phoria adaptation with perceptual cues to distance in the absence of any other associated motor activity. During adaptive training, vertical disparity vergence was associated with variations of perceptual distance cues (including loom, overlap, relative size, and relative motion), oculomotor distance cues (horizontal vergence), or a combination of both classes of cues. We observed that in a 2-h period the open-loop (monocular) vertical vergence response could not be trained to occur as an aftereffect in association with the perceptual cues to distance, whereas it could be trained in association with oculomotor cues. We conclude that the spatial specificity of vertical vergence aftereffects caused by short-term adaptation results from an associated cross-coupling with supranuclear sources of oculomotor activity.

Facility capability assessment.

An inspection and evaluation procedure has been developed to assess the capabilities of contract toxicology laboratories. This procedure has been used for the inspection of 18 different contract toxicology laboratories. There are 10 areas inspected: 1. Facility 2. Personnel 3. Operations 4. Animals/Animal Care 5. Standard Operating Procedures 6. Quality Assurance 7. Equipment 8. Test Article 9. Data 10. Archives. Each of these areas is divided into categories with each category divided further into specific topics. Points are assigned to each topic. The points earned by the laboratory reflect the inspector's assessment of the laboratory's quality in each area. Area scores are added and a percentage score for the facility is calculated. This approach provides a clear distinction among the laboratories evaluated. The facility inspection and rating system played an important role in screening laboratories when the author worked for the Atlantic Richfield Company (ARCO) corporate toxicology department. It highlighted strengths and weaknesses of individual laboratories.

Correlation of light-scattering measurement and visual ranking of optical surfaces.

Visual ranking of optical surfaces with a Nomarski differential interference contrast microscope correlates well with a modified fractallike dimension and the average intensity of their scattered light ield.

Product review: the Coreco Oculus-500 imaging system.

Recent developments in computer imaging technology have brought about significant improvements in the display resolution and capabilities of desk-top imaging systems. The Coreco, Inc. Oculus-500 is a group of high resolution imaging boards for use with IBM-AT and compatible computers. The tested $8000 system consists of a 2 Mb interface board, display/controller board, driver, toolkit, and software interface package. With a display resolution of 1280 x 1024 @ 60 Hz non-interlaced, the OC-500 offers excellent resolution. The accompanying software is being further developed by a responsive company, but can in places be tedious to use. However, the result of understanding the software is a system with superb capabilities.

A subchronic inhalation toxicity study in rats exposed to silicon carbide whiskers.

To determine whether inhaled silicon carbide whiskers (SiC) cause lung damage in rats, four groups (50 males/50 females each) of rats were exposed to air only or to one of three concentrations of SiC 6 hr/day, 5 days/week for 13 weeks. Half (25 males/25 females/group) were euthanized at the end of exposure, the remainder 26 weeks later. Mean concentrations were 0, 630, 1746, and 7276 SiC whiskers/ml (0.09, 3.93, 10.7, and 60.5 mg/m3). Although there were no concentration-related changes in body weight, clinical chemistry, or hematological data attributable to SiC, lung weights were increased in the high concentration exposure group at both euthanization times. In all whisker-exposed groups, after 13 weeks of exposure, the incidence of the following lung and lymph node lesions was higher than in controls: inflammatory lesions; bronchiolar, alveolar, and pleural wall thickening; focal pleural fibrosis in lung; and reactive lymphoid hyperplasia in bronchial and mediastinal lymph nodes. After 26 weeks of recovery, lung inflammatory lesions had decreased and fewer rats had enlarged lymph nodes, but the incidence of alveolar wall thickening, focal pleural wall thickening, and adenomatous hyperplasia of lung had increased further. Incidence and severity appeared to be dose-related. Therefore, until longer term studies are undertaken and it is established whether the above observed lesions will progress to more severe pathological entities, it is prudent to adopt stringent handling procedures for silicon carbide whiskers.

Christian commitment and a "Docetic" view of human emotions.

This paper encourages people in the church to discuss the danger of equating Christian commitment with a denial of one's humanity, thus developing a "docetic" view of human emotions. The paper focuses on biblical passages which are susceptible to three forms of "docetic interpretation":denial of unpleasant feelings often in the name of Christian joy, with possible damaging emotional or physical consequences;denial of human development and the possible influence of the past on present emotional and religious experience; anddenial of human value through passive acceptance of what seems to be inevitable by saying, "Thy will be done."