Biomedical subjects

R Ballinger

Publications and source records attributed to R Ballinger.

13 recordsLinked to original sources

PubMed2000

Veterans Affairs Multicenter Low Vision Enhancement System (LVES) study: clinical results. Report 1: effects of manual-focus LVES on visual acuity and contrast sensitivity.

PURPOSE: The Department of Veterans Affairs LVES Study is a multicenter study to determine the effectiveness of the Low Vision Enhancement System (LVES) as a visual rehabilitation device. The purpose of this study was to explore the efficacy of the Beta 1 manual-focus LVES for improving visual acuity and contrast sensitivity. METHODS: Patients whose visual acuity was 20/80 or worse in the better eye from any disease, who did not have significant visual field loss, who had previous low vision experience and were capable of working with the LVES were enrolled in a comprehensive prospective multicenter clinical evaluation. Initially, corrected spectacle visual acuities were measured using a standardized ETDRS chart. Contrast sensitivities were also measured with spectacle correction using a standardized Peli-Robson chart. These results were then compared to the acuities and contrast sensitivity obtained with the LVES at optimal magnification. Also, visual acuities were measured using an Eschenbach 3x spectacle-mounted binocular telescope, then compared to the acuities obtained using the LVES set at the lowest magnification (3x). RESULTS: All patients who completed the study demonstrated an improvement in visual acuity, with a median improvement of six lines of Snellen equivalent acuity using the LVES. Improvement in visual acuity was the same in both ARMD and non-ARMD causes of vision loss. Mean contrast sensitivity improved in 52 of 58 patients tested, with a mean improvement of 0.49 log units. CONCLUSION: The LVES significantly improves both visual acuity and contrast sensitivity in visually impaired patients who fall within the study criteria. Up to 10-fold improvement in visual acuity and up to 1.80 log units improvement in contrast sensitivity were noted in the study group when the LVES was used.

Adult↗

PubMed1995

CMV retinitis.

BACKGROUND: Cytomegalovirus (CMV) retinitis is the most common ocular opportunistic infection in patients with AIDS. CMV retinitis is often asymptomatic and usually appears when the patient's CD4 lymphocyte levels fall below 50/mm3. The infection may present a variety of clinical appearances and must be carefully differentiated from cotton-wool spots in early infection. PURPOSE: This paper reviews the natural history of CMV infection in both the normal population and in patients with AIDS. CMV retinitis presenting in AIDS patients is then described in detail with clinical presentations of fundus features. Finally, the management of patients who may be at risk or have developed CMV retinitis is reviewed. Recent data on suggested management protocols are also provided. CONCLUSIONS: Cases of CMV retinitis will continue to increase as the AIDS epidemic progresses. The primary care practitioner will play an increasingly important role in the diagnosis and management of patients with this infection.

AIDS-Related Opportunistic Infections↗

PubMed1991

Sucrose polyester: a new oral contrast agent for MRI.

Sucrose polyester (a dietary fat substitute) opacifies the entire gastrointestinal tract of the rat with oral administration in magnetic resonance imaging (MRI). These results suggest the potential use of this material as an oral contrast agent for human abdominal MRI studies.

Animals↗

PubMed1990

XPERT NCT--a clinical evaluation.

A clinical evaluation of the XPERT NCT (Reichert Ophthalmic Instruments) applanation non-contact tonometer was conducted at the Baltimore VA Medical Center. Each of 620 eyes were measured by the XPERT and then by one of seven operators of varied experience, each using one of four calibrated Goldmann applanation tonometers (GATs). Measured pressures ranged from 1 to more than 60 mmHg. The interval between XPERT and GAT measurements varied from a few minutes to almost 1 hour. Despite the increased potential variability of our protocol, the XPERT agreed very closely with GAT. Population IOP means agreed within 0.3 mmHg; regression coefficients defining XPERT's calibration, relative to GAT, were slope (m) = 1.025, and Y intercept (b) = 0.7 mmHg. The standard deviation of matched pair differences, was Sd = 2.7 mmHg. We conclude that the XPERT NCT is a highly accurate and reliable instrument. Our experience showed it to be convenient and well accepted by staff and patients. It proved faster, easier to use, and its "air-puff" is quieter and less intense than NCT I and II. In the companion paper, we examined the reliability of GAT used as a clinical comparison reference in evaluating the XPERT.

Evaluation Studies as Topic↗

PubMed1989

Correlations between abnormal auditory P300 topography and positive symptoms in schizophrenia: a preliminary report.

P300 component amplitude in the left temporal scalp region, shown in three previous studies to differentiate normals from schizophrenics, was found to be significantly correlated with the Thought Disorder Index (TDI) and the Scale for the Assessment of Positive Symptoms (SAPS). These correlations occurred primarily in the P300 waveform derived from the Goodin paradigm. These findings suggest a brain processing disturbance in positive symptom schizophrenia that may be reflected by electrophysiological abnormalities detectable in the temporal scalp region.

Adult↗

PubMed1989

CT abnormalities in schizophrenia. A preliminary study of their correlations with P300/P200 electrophysiological features and positive/negative symptoms.

Computed tomographic scans were scored blindly for the size of cerebrospinal fluid spaces in a group of nine medicated schizophrenics and a group of nine age-matched normal volunteers without psychiatric or medical problems. Overall, ten of the 18 computed tomography (CT) features measured were significantly enlarged in the schizophrenic group. These abnormal CT features were then correlated with electrophysiological and clinical measurements performed on the schizophrenic patients. Left sylvian fissure enlargement, thought to reflect temporal lobe tissue loss, was highly correlated with a left temporal scalp region feature of the auditory P300 measure (T3 electrode) that differentiated schizophrenics and normals, and both the left sylvian fissure enlargement and the P300 measure were highly correlated with positive symptoms (total score on the Scale for the Assessment of Positive Symptoms). Frontal superficial (cortical) sulcal enlargement was prominent in the schizophrenic group and was highly correlated with another electrophysiological measure, auditory P200, at left central scalp locations. There was no significant correlation between left sylvian fissure and frontal sulcal enlargement within the schizophrenic group, and intercorrelations between CT variables in the schizophrenic group were, in general, less significant than in the control group. Although we should be cautious about generalizability because of the small number of patients, these data are compatible with the hypothesis that different subgroups of schizophrenic pathological features are characterized by different CT, electrophysiological, and clinical presentations.

Adult↗

PubMed1989

Quantitative analytical electron microscopy of multiphase alloys.

In this paper, we present a technique for analysis of composition gradients, using an analytical electron microscope, within the primary phase of a two-phase alloy for the case where the second-phase particle size is similar to the size of the irradiated volume. If the composition difference between the two phases is large, the detected compositional fluctuations associated with varying phase fractions may mask any underlying composition gradient of the primary phase. The analysis technique was used to determine grain boundary chromium concentration gradients in a nickel-base superalloy, alloy X-750. The technique may also be of use in other alloy systems.

Chromium Alloys↗

PubMed1989

Clinical correlations of auditory P200 topography and left temporo-central deficits in schizophrenia: a preliminary study.

A number of studies using nontopographic analyses have reported an amplitude decrement of the auditory P200 component in schizophrenics compared to normal controls. Here we report a topographic analysis of the auditory P200 (204-272 ms; peak to baseline) in chronic medicated schizophrenics (N = 11) and normal controls (N = 18) and the correlation between this measure and clinical symptoms in schizophrenia. Exploratory T-statistic mapping (SPM) and "protected" Hotelling's T-squared contrasts of integrated voltages over the entire scalp showed that schizophrenics' P200 component had diminished amplitude in the left temporo-central region. Furthermore, P200 amplitude in the same scalp region during the experimental condition of counting infrequent tones was highly correlated with negative symptoms in the schizophrenic group.

Adult↗

PubMed1989

Metastatic carcinoma of unknown primary: complete response to second-line treatment with plicamycin.

In selected groups of patients, metastatic carcinoma of unknown primary (MCUP) is highly responsive to cisplatin-based combination chemotherapy. These therapeutic responses usually are partial and shortlived. The authors report the case of a 41-year-old man whose MCUP relapsed after responding to cisplatin, bleomycin, and etoposide. Alternate-day treatment with plicamycin induced a second complete remission (CR) in this patient with minimal hematologic and metabolic toxicity. Plicamycin may prove effective in enhancing CR rate, prolonging CR duration, and salvaging cisplatin failures in MCUP.

Adult↗

PubMed1989

Two syndromes of schizophrenic psychopathology associated with left vs. right temporal deficits in P300 amplitude. Four case reports.

In four schizophrenic patients, we examined the relationship between clinical course, including neuroleptic response, and the following biological and psychological measures: topography of the auditory P300 event-related potential, computerized tomography (CT), Andreasen's positive and negative symptom scales, the Thought Disorder Index, and a neuropsychological test battery. Two previous studies in our laboratory had shown that schizophrenic patients were differentiated from a matched normal control group by a left temporal scalp region deficit in P300 topography. This present report compares two schizophrenic patients with the typical left temporal P300 topography deficit with two schizophrenic patients with a right temporal P300 topography deficit. The two right temporal deficit patients had more positive symptoms, more thought disorder, more severely impaired functioning, earlier age of onset, poorer response to neuroleptic medications, more diffuse cognitive deficits on a neuropsychological testing battery, and poorer premorbid history than the two left temporal deficit patients. There was some evidence for the presence of more CT abnormalities suggestive of frontal lobe pathology in the right temporal deficit patients.

Adolescent↗

PubMed1986

Occurrence and seasonal incidence of mosquitoes on Indian reservations in Iowa, Nebraska and South Dakota during 1983.

A mosquito surveillance program designed to prevent future human cases of Western equine encephalitis or Saint Louis encephalitis was established in 1983 on Indian reservations under the jurisdiction of the Aberdeen Area Indian Health Service in Iowa, Nebraska and South Dakota. Standard New Jersey light traps were operated on all reservations throughout the summer season while CDC miniature and encephalitis virus surveillance traps were employed for shorter periods of time on 4 reservations. Aedes vexans was the most abundant species except on the Pine Ridge, Rosebud, Winnebago and Yankton Sioux reservations in which Culex tarsalis predominated and for the Sac-n-Fox where Aedes trivittatus occurred with the greatest frequency.

Animals↗

PubMed1985

A "dipstick" enzyme immunoassay for detection of antibody to Brucella abortus in cattle sera.

An enzyme immunoassay that utilizes antigen bound to a matrix which can be removed from the substrate to stop development is described. The assay which is performed in glass or plastic disposable tubes uses Gel-Bond film strips for attachment of antigen. The only equipment requirements are a rotary shaker and a spectrophotometer (optional). The antigen coated strips are passed through a series of tubes containing test serum, wash solution, antibody-enzyme conjugate, wash solution and substrate-chromogen taking about 45 minutes to perform. In testing sera with or without antibody to Brucella abortus a very high correlation existed between same day tests and tests performed over several days as well as with data on the same sera obtained by an enzyme immunoassay in a microtiter format.

Animals↗

PubMed1984

Effects of various treatments of bovine complement on its lytic efficacy measured by two different tests.

Bovine complement was treated with various agents known to activate or inactivate one or more of the cascade components. The treated complement was then assessed for remaining hemolytic activity by a tube titration test and a radial hemolysis method. Divalent cation chelators (EDTA and EGTA); immune complexes prepared with serum and IgM, IgG1, IgG2, and IgA isotypes; smooth and rough lipopolysaccharides and lipid A; hydrazine; zymosan; cobra venom factor and brown recluse spider venom caused depletion of complement as determined in the tube titration test. Immune complexes (prepared with serum); hydrazine; cobra venom factor; EDTA and smooth lipopolysaccharide caused loss of hemolytic activity in the radial hemolysis test. This evidence suggests that the radial hemolysis test assessed complement consumed by the alternate pathway, while the tube titration method measured classical pathway consumption.

Animals↗