Integrated high-quality factor optical resonators in diamond.

The realization of an integrated diamond photonic platform, based on a thin single crystal diamond film on top of a silicon dioxide/silicon substrate, is reported. Using this approach, we demonstrate high-quality factor single crystal diamond race-track resonators, operating at near-infrared wavelengths (1550 nm). The devices are integrated with low-loss diamond waveguides terminated with polymer pads (spot size converters) to facilitate in- (out-) coupling of light from (to) an optical fiber. Optical characterization of these resonators reveal quality factors as high as ~250,000 and overall insertion losses as low as 1 dB/facet. Scattering induced mode splitting as well as signatures of nonlinear effects such as optical bistability are observed at an input pump power of ~100 mW in the waveguides.

Quantitative studies on the precursors of cytotoxic lymphocytes. VI. Second signal requirements of specifically activated precursors isolated 12 h after stimulation.

It is shown that, in a mixed lymphocyte reaction, the production of cytotoxic T lymphocytes (CL) from cytotoxic T lymphocyte precursors (CLP) requires two signals which are separated time. Using a flow cytometer-cell sorter and a vital, fluorescent DNA stain, Hoechst 3342, CLP specific for the stimulator cells can be separated from other CLP and from stimulator cells 12 h after initiation of mixed lymphocyte cultures. These CLP are in a state of partial activation and can produce CL in the absence of stimulator cells if a second signal in the form of a concanavalin A-induced spleen cell supernate factor is added. Specific CL are also generated when the partially activated CLP are cultured with both nude spleen cells and stimulator cells. In this case it appears that an interaction between the stimulator cells and the nude spleen cells leads to production of the second signal.

Spontaneous clearance of hepatitis C after liver and renal transplantation.

Spontaneous clearance of hepatitis C virus (HCV) is rare in immunocompromised patients, such as those who have undergone organ transplantation. It has been recognized that patients receiving liver transplantation for HCV-related disease have decreased graft and patient survival compared with those transplanted for other etiologies. There is a growing trend toward treating HCV recurrence aggressively after liver transplantation. For other organ transplant recipients with concurrent HCV, treatment is not often an option, given the high rates of graft rejection and loss secondary to interferon and its immunomodulatory effects. Although spontaneous clearance of HCV has been reported in recipients of solitary liver and renal transplants, a common factor arising in these cases has been previous exposure to interferon. To date, no reports of spontaneous clearance of HCV RNA have been reported in a multiorgan transplant recipient. A case of spontaneous clearance of HCV RNA in an immunocompromised patient, within five months of simultaneous liver and kidney retransplantation is described. Importantly, this patient had no previous exposure to interferon.

Stimulation of CD5 enhances signal transduction by the T cell antigen receptor.

After the addition of a CD3 monoclonal antibody to peripheral T cells that have been previously stimulated with phytohemagglutinin, inositol phosphates are produced at a rapid rate for 2 min and at a much slower rate thereafter. Stimulation of CD5 allows CD3-mediated production of inositol phosphates to be sustained at a brisk rate for greater than 20 min and augments the initial CD3-mediated increase in inositol trisphosphate and release of intracellular Ca2+. Thus, perturbation of CD5 by monoclonal antibody enhances the ability of the CD3-antigen receptor complex to couple to the inositol phospholipid pathway. This effect of CD5 is independent of any direct effect of the CD5 monoclonal antibody on the levels of inositol phosphates.

Electrical impedance in assessing human body composition: the BIA method.

Fundamental aspects of the body impedance analysis (BIA) method were investigated to determine limitations. This method measures body impedance with a low-level (800 microA) 50-KHz current conducted through the tissues. A linear regression equation was proposed to relate impedance measurements to total body fat. The hydrostatic densitometric method (underwater weighing) was used to validate the proposed mathematical expression. A correlation coefficient of 0.98 between these two methods was obtained. The overall results from this study indicate the usefulness of the BIA method in determining percent body fat in humans provided body fluids are not perturbed several hours before the measurements.

Application of the ILISPOT-IDIP system for the enumeration of different sizes of IgA spot forming cells in the murine small and large intestine.

The immunofluorescence-linked immunospot (ILISPOT) assay associated with the immunofluorescence digital image processing (IDIP) system was originally developed in our laboratory to allow enumeration of immunoglobulin (Ig) producing, spot forming cells (SFC) in a more objective and quantitative manner. In this study, the ILISPOT-IDIP system was further advanced in order to analyze different sizes of SFC (e.g., IgA producing cells) including large (L), medium (M), and small (S) cells which correspond to high (> 2.4 pg), medium (1.2-2.4 pg) and low (< 1.2 pg) IgA secreting cells by the adaptation of real time image processor and intensified video camera system. When the ILISPOT-IDIP system was used to characterize the frequency of IgA secreting cells among mononuclear cells isolated from different parts of the murine gastrointestinal (GI) tract including the small (upper, middle and lower sections) and large (colon and rectum) intestine, the small intestine contained higher numbers of IgA SFC (approximately 8.4 x 10(5) SFC/10(6) cells) when compared with large intestine (approximately 1.3 x 10(5) SFC/10(6) cells). Among the 3 areas of small intestine, the upper (approximately 3.7 x 10(5) SFC/10(6) cells) and middle (approximately 2.4 x 10(5) SFC/10(6) cells) parts had higher numbers of IgA SFC when compared to the lower small (approximately 2.3 x 10(5) SFC/10(6) cells) intestine. When these IgA producing cells in different parts of the intestine were classified into three groups according to the size of individual spots, the upper and middle intestine contained higher frequencies of large (approximately 20%) and medium (approximately 20%) SFC which corresponded to high and medium IgA secretors in comparison to the lower small (approximately 9%) and large (approximately 6%) intestine. In contrast, the lower small and large intestine were dominated by small SFC since approximately 85% of IgA producing cells were categorized as low secretors. Using the advanced ILISPOT-IDIP system, a unique distribution of different sizes (or secretion rates) of IgA producing SFC was elucidated in the different regions of the mouse small and large intestine.

Immunofluorescence-digital image processing system for the quantitation of secreted immunoglobulin by single cells.

To quantitate the amount of secreted immunoglobulin (Ig) by a single cell, the immunofluorescence digital image processing (IDIP) system was adapted to the modified enzyme-linked immunospot (ELI-SPOT) assay. In this assay, an immunofluorescence (tetramethylrhodamine isothiocyanate) conjugated antibody was used for the detection of spots instead of the usual method of enzyme coupling. We have named this the immunofluorescence-linked immunospot (ILISPOT) assay. In addition to the quantitation of secreted Ig by single cells, this method allowed us to objectively determine the exact number of Ig producing spot forming cells (SFC). 96 well culture plates were pre-coated with goat anti-mouse Ig. The mouse IgM producing hybridoma (E-3-4) was incubated in the plates for 4 h at 37 degrees C. Cells were removed prior to the addition of biotinylated goat anti-mouse mu antibody. After overnight incubation, immunofluorescence conjugated avidin was added for the visualization of spots by the IDIP system. The IDIP system consists of a fluorescent microscope equipped with a video camera and computer. The gray scale of secreted IgM was initially established as a standard by the known amount of purified IgM. By using digital image processing, the number of spots and the gray scale of individual spots were computed. The shape and pattern of gray scale data were used to distinguish between the real spots and pseudo spots. This IDIP system could detect as little as 0.19 pg of secreted IgM (1.2 x 10(5) molecules) and an average of approximately 1.33 pg (8.3 x 10(5) molecules) produced by a single cell. Adaptation of the digital image processing system to the ILISPOT assay allowed the measurement of both the amount of Ig produced at the single cell level and also the exact numbers of SFC present in a totally objective fashion.

A sensitive ELISPOT assay to detect low-frequency human T lymphocytes.

We extended the sensitivity of the ELISPOT assay by including an antigen-driven proliferation step prior to a final restimulation with antigen and irradiated antigen presenting cells (APCs). This improved sensitivity made the modified ELISPOT assay better suited to the detection of rare or low frequency T lymphocytes than the standard ELISPOT assay or alternatives such as limiting dilution analysis or in situ hybridization. Use of ELISA-grade plastic or polyvinylidene difluoride (PVDF) plates for the detection of different cytokines improved the signal-to-noise ratio for counting cytokine spots, and use of video computer imaging software improved objective quantitation. Analysis of antigen-reactive peripheral blood mononuclear cells (PBMC) from multiple sclerosis (MS) patients using both the traditional and our modified ELISPOT assay demonstrate a > 10-fold increase in numbers of myelin basic protein (MBP)-responsive T cells detected (an average of less than 1 spot forming cell (SFC) per 2 x 10(5) PBMC with the standard assay compared to 19 SFC per 2 x 10(5) PBMC with the modified assay). In addition, the modified ELISPOT assay could be performed with frozen PBMC, which permitted greater flexibility in sample processing, multiple use of a single sample as an internal standard, and simultaneous analysis of samples collected at different time points. This modified ELISPOT assay has many applications, including analysis of cytokine profiles in rare T cell populations, identification of antigen-responsive individuals as PBMC donors for T lymphocyte cloning or for therapeutic intervention, and assessment of vaccine or therapeutic efficacy as a surrogate clinical marker.

Fluorescence intensity resolution in flow systems.

The factor which can limit fluorescence intensity resolution in a flow cytometer of the type in which cells pass perpendicularly through a focussed laser beam depends on signal intensity. For the brightest sources (e.g. fluorescent DNA stains), the coefficient of variation (CV) is limited in our system to around 3% by stream hydrodynamics, unstable illumination intensity, nonstoichiometric staining, etc. The weakest detectable sources (e.g. fluorescent cell-surface labels) are limited in coefficient of variation by shot noise in the photomultiplier due to constant background light levels. Finally, over a fairly wide brightness range between these extremes, resolution is determined primarily by photoelectron statistical variation on the signal itself (i.e. "photon statistics"). Thus photon collection and detection efficiency (solid angle, barrier filter passband, detector quantum efficiency) become of primary importance.

Measurement of cytoplasmic fluorescence depolarization of single cells in a flow system.

We have built a flow system in which we can analyze and sort individual viable cells on the basis of their cytoplasmic microviscosity. The average cytoplasmic microviscosity (or cytoplasmic structuredness) of a cell can be quantitated by exciting fluorescein molecules in the cytoplasm of the cell with a polarized light source and measuring the extent of depolarization of the fluorescent signal. Changes in the state of a cell (e.g., the reception of a signal inducing the cell to differentiate) often appear to be associated with changes in cytoplasmic microviscosity, these changes being detectable within hours of the inducing signal. An example of one such change is presented.

CT scanning of lumbar discography. A useful diagnostic adjunct.

Twenty-two patients with continued, undiagnosed symptoms of low back and sciatic pain for an average of 14 months were assessed. Patients studied had prior negative evaluations, including EMG, CT scanning, and/or metrizamide myelography. Three-level, posterolateral, extradural discography was performed on the side opposite the sciatica. One to 6-hours after discography, CT scanning was performed on all injected discs: 91% demonstrated abnormal discograms at one/more levels. CT imaging demonstrated contrast tracking to the periphery of the disc in 82%. Discography reproduced the patient's symptoms in 77%. The direction of contrast tracking seen on scanning correlated with clinical symptoms in 73% and with symptoms at discography in 82%. CT scanning was thought to be a useful adjunct to lumbar discography in patients with prior negative evaluations.

Speech perception in children with cochlear implants: effects of lexical difficulty, talker variability, and word length.

The present results demonstrated that all 3 factors --lexical difficulty, stimulus variability, and word length--significantly influenced spoken word recognition by children with multichannel cochlear implants. Lexically easy words were recognized significantly better than lexically hard words, regardless of talker condition or word length of the stimuli. These results support the earlier findings of Kirk et al(12) obtained with live-voice stimulus presentation and suggest that lexical effects are very robust. Despite the fact that listeners with cochlear implants receive a degraded speech signal, it appears that they organize and access words from memory relationally in the context of other words. The present results concerning talker variability contradict those previously reported in the literature for listeners with normal hearing(7,11) and for listeners with mild-to-moderate hearing loss who use hearing aids.(14) The previous investigators used talkers and word lists different from those used in the current study and found that word recognition declined as talker variability increased. In the current study, word recognition was better in the multiple-talker condition than in the single-talker condition. Kirk(15) reported similar results for postlingually deafened adults with cochlear implants who were tested on the recorded word lists used in the present study. Although the talkers were equally intelligible to listeners with normal hearing in the pilot study, they were not equally intelligible to children or adults with cochlear implants. It appears that either the man in the single-talker condition was particularly difficult to understand or that some of the talkers in the multiple-talker condition were particularly easy to understand. Despite the unexpected direction of the talker effects, the present results demonstrate that children with cochlear implants are sensitive to differences among talkers and that talker characteristics influence their spoken word recognition. We are conducting a study to assess the intelligibility of each of the 6 talkers to listeners with cochlear implants. Such studies should aid the development of equivalent testing conditions for listeners with cochlear implants. There are 2 possible reasons the children in the present study identified multisyllabic words better than monosyllabic words. First, they may use the linguistic redundancy cues in multisyllabic words to aid in spoken word recognition. Second, multisyllabic words come from relatively sparse lexical neighborhoods compared with monosyllabic tokens. That is, multisyllabic words have fewer phonetically similar words, or neighbors, competing for selection than do monosyllabic stimuli. These lexical characteristics most likely contribute to the differences in identification noted as a function of word length. The significant lexical and word length effects noted here may yield important diagnostic information about spoken word recognition by children with sensory aids. For example, children who can make relatively fine phonetic distinctions should demonstrate only small differences in the recognition of lexically easy versus hard words or of monosyllabic versus multisyllabic stimuli. In contrast, children who process speech using broad phonetic categories should show much larger differences. That is, they may not be able to accurately encode words in general or lexically hard words specifically. Further study is warranted to determine the interaction between spoken word recognition and individual word encoding strategies.

Esophageal speaker articulation of /s,z/: a dynamic palatometric assessment.

Esophageal talker linguapalatal contact patterns and durations during /s/ and /z/ productions were examined using dynamic palatometry instrumentation. It was found that sibilant groove narrowing is a physiologic compensation for a reduced air supply in esophageal speech. The place of esophageal /s, z/ articulation was on the anterior portion of the alveolar ridge as seen in normal speakers. Average medial groove width for esophageal /s/ was narrower than the 5-7-mm groove characteristic of normal speakers. Groove widths averaged 3 mm for /s/ and 4 mm for /z/. Systematic changes in groove widths across speech sounds, syllable position, and vowel context were also observed. Use of a narrower lingual groove was interpreted as a significant articulatory maneuver to meter out a limited intraoral air supply and effect more normal fricative durations.

The febrile infant.

While 46 percent of febrile children, aged 3 months to 24 months, will be well without treatment within 24 to 48 hours, and another 12 percent well within 72 to 96 hours, approximately 6 percent will have serious bacterial infections. The incidence of such infections tends to increase with decreasing age and increasing degree of fever. Physicians, who make specific observations of the child's color, hydration, social response, consolability, and degree of alertness after the child has been made comfortable, can identify about two thirds of those with benign illness and the one tenth who require inpatient evaluation. Of the remaining patients, those with serious illness can be further identified if their white blood count is greater than 15,000/microL, neutrophils are greater than 10,000/microL, band cells are greater than 500/microL, or sedimentation rate is more than 30 mm/h. Children with these laboratory findings should then have a chest film and blood culture and, if the former is negative, should be considered for a lumbar puncture and urine culture. Whether further observation or treatment at this point can be done as an outpatient depends on physician judgment.

The athlete's diet: a current view.

As a result of new interest in prescribing individual athletic programs and healthy life styles, the average participant and the health care provider are faced with confusing information on what constitutes optimal nutrition. Not only has the efficacy of dietary supplements (high-protein, "megadose" vitamins and minerals) for improved athletic performance not been demonstrated, but these supplements can also have undesirable effects. A diet of adequate calories and composition remains the optimal source of good nutrition and must be balanced with energy output. While most mineral supplements are unnecessary, iron supplements for female athletes and for male long-distance runners may be advisable. Carbohydrate loading is the only dietary manipulation shown to affect athletic performance and then only in the endurance athlete. Conscious water replacement is needed during and after competition.

How I Manage Sports Injuries to the Larynx.

In brief: Laryngeal trauma resulting in structural damage and/or laryngospasm with compromised airway is one of the true emergencies faced by team physicians and trainers. These care givers should be familiar with the anatomy and signs and symptoms of laryngeal injury and be prepared to deal with them. Most laryngeal injuries respond well to straightening the airway and firmly moving the chin forward with pressure behind angles of the jaw to relieve laryngospasm. Reassuring the patient is important. When airway obstruction is persistent, artificial airways may most easily be established by cricothyreotomy or needle jet cricothyreotomy. All laryngeal injuries should have immediate laryngoscopy to fully evaluate the degree of injury.

The design of a microcomputer-controlled voice onset time analyzer.

In spoken syllables such as "ta," the interval between the release of the tongue constriction for the stop consonant /t/ and the onset of the vowel is called voice onset time, or VOT. Voice onset time is an important determinant of whether the initial consonant will be heard as a /t/(values of 60-90 ms) or as a /d/ (values of 0-30 ms). VOT information, immediately following a spoken syllable, can provide a speaker with feedback for modifying speech production. Such information can help the hearing-impaired learn to speak. It may also help people who learn English as a second language, since they often produce /b,d,g/ and /p,t,k/ with inappropriate VOT values. A prototype portable device measures VOT for initial voiced and voiceless stop consonants (e.g., "da" and "ta"). A dual-microphone method is used for acoustic measurement. A microphone in front of the mouth picks up the radiated acoustic signal; another over the larynx transduces vocal vibrations that mark the beginning of a vowel. Analog circuits process the transducer signals and provide gain and filtering. Filters were designed on the basis of the acoustic properties of stop consonants. The output from each analog circuit is fed to a comparator that compares the signal level with a fixed threshold voltage reference. A digital timer starts when the amplitude of the oral signal voltage exceeds a threshold and stops when the laryngeal signal voltage exceeds a threshold. VOT values obtained by the device were compared with those made from digital waveforms of words spoken by five talkers.(ABSTRACT TRUNCATED AT 250 WORDS)

Investigation of video techniques for dynamic measurements of relative vertebral-body motion in vitro.

The precision and accuracy of techniques for analysis of lumbar spinal-segment motions were evaluated using a specially designed orthogonal axis fixture and video image processing. Triplicate validation tests were performed by monitoring precisely controlled motions of the triaxial measurement device. The errors of the overall measurements were found to be less than 0.5 mm for axial and 1 degree for rotational displacements. The system accuracy was within 0.230 mm based on the calculation of the points on a calibration frame. The geometry of the calibration frame was designed with the capability to analyze the 3-D motion properties of a swine lumbar spine. Statistical analyses of the validation test data showed that the precision and accuracy of this motion-analysis system offer new opportunities for the measurement of total-length spinal-motion profiles. The system was then applied utilizing fresh thawed swine spines to test the limits of relative-motion measurements for the centers of adjacent vertebrae in a coupled unit. Lateral-medial and anterior-posterior video images of spines and the triaxial measurement devices were made simultaneously while applying cyclic axial and torsional loads. The distribution of data from six spines illustrated biological variability of relative displacements for adjacent coupled vertebrae.

The development and functioning of the sense of shame.

An extensive literature on shame has not yet sufficiently addressed the nature and functioning of this affect from the psychoanalytic, developmental point of view. This paper tries to lay the ground for such a task.