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Biomedical subjects

L Kaufman

Publications and source records attributed to L Kaufman.

At least 109 records · Page 6Linked to original sources
PubMed1995

Kinetic images of neuronal activity of the human brain based on the spatio-temporal MNLS inverse: a theoretical study.

Prior work proved that it is possible to find a unique solution to the problem of defining the configuration of electric current underlying observed extracranial magnetic fields, if sufficient priori knowledge of the source configuration is available. This minimum-norm least-squares (MNLS) inverse solution for a magnetic source image (MSI) is extended here to include temporal as well as spatial parameters of the underlying current pattern. This capitalizes on the temporal resolution of magnetoencephalography (MEG), which is on the order of milliseconds. Other forms of functional brain imaging are far less sensitive to the rate of change of states of the brain. Influences on the quality of the resulting MSI by measurement noise and errors in determining the image surface are characterized. A new technique for reducing noise in the inverse problem is developed by taking into consideration the spatial and time-dependence of the noise detected by the sensors. This new approach to regularization reduces the contribution from noisy measurements to the inverse calculation, and therefore improves the stability of the inverse.

Brain Mapping↗
PubMed1995

Real-time interactions in MRI.

With the advent of magnetic resonance fluoroscopic imaging, it is possible to obtain images at a rate which can be considered effectively real-time. Image refresh rates can be as low as 0.5 s. Such rates are fast enough to allow MR to be used for guidance of surgical instruments during micro-surgical procedures. Examples include the localization of biopsy needles within a tumor, localization of surgical tools for application of therapeutic drugs or the proper positioning of optical fibers for application of laser heat. It may also be used for long duration monitoring of a patient in an attempt to diagnose rare and short duration clinical events.

Biopsy↗
PubMed1995

Coccidioidomycosis among visitors to a Coccidioides immitis-endemic area: an outbreak in a military reserve unit.

An outbreak of coccidioidomycosis occurred in a US Marine reserve unit based in Tennessee after a 3-week training exercise in California that involved substantial exposure to soil and dust. Interviews and serologic testing were done on three occasions (6, 11, and 15 weeks) after the men returned from California, and spherulin skin tests were done at 6 months. Of 27 men, 8 (30%) had evidence of recent coccidioidal infection. Of these, 7 (88%) had an illness consistent with coccidioidomycosis that, despite medical evaluation, was diagnosed incorrectly in 5 men (71%). Diagnosis of coccidioidal pneumonia outside an area in which Coccidioides immitis is endemic is unlikely unless the health care provider is aware that the patient traveled recently. Detection of coccidioidomycosis could be facilitated if organizations that regularly send people to C. immitis-endemic regions were to inform these persons about the risks of infection.

Adult↗
PubMed1995

Measurement of breast implant volume with magnetic resonance imaging.

In principle, tomographic imaging of breast implants provides the information needed to compute implant volume. We have investigated the reliability of this measurement as a means of diagnosing the loss of gel from the implant. We find that measurement errors, postimplantation changes of the implant, uncertainties in the patients' records, and lack of knowledge of the implant temperature in the body can lead to significant discrepancies, making this measurement unreliable as a diagnostic tool.

Breast Implants↗
PubMed1995

MRI findings in subjects with breast implants.

One-hundred and nineteen implants were imaged in an open-sided low-field magnetic resonance imaging system. Thirty-four of these implants were removed, and postoperative reports were made available. We found a variety of signs associated with the implants, including internal structures, loss of saline in double-lumen implants, intracapsular and extracapsular fluid accumulations, signal dropout regions most likely associated with calcifications, and debris and fluid in the silicone, as well as degradation of the silicone, disruptions of the capsule and bulging, and extracapsular silicone. Conclusions of intact versus ruptured were made on the basis of these findings and found to be confirmed in 32 of 34 cases, with 1 false-positive and 1 false-negative result. Based on MRI criteria for a broad sample of the population, 27 percent of the implants were considered ruptured.

Adult↗
PubMed1995

Nasal resistance--a reliable assessment of nasal patency?

This study was undertaken to determine the distribution of nasal resistance in a healthy white population. One hundred subjects without nasal complaints were selected for the investigation. The test subjects were divided into two groups on the basis of anterior rhinoscopy. Group 1 included 60 subjects with rhinoscopically normal noses. Group 2 included 40 subjects with rhinoscopically abnormal noses. The pressure-flow data were recorded via active anterior mask rhinomanometry. The analogue pressure and flow signals were sampled and digitized by a computer system according to the time averaging method. Nasal resistance was calculated according to the recommendations of the International Committee on Standardization of Rhinomanometry. The normality of unilateral nasal resistance data distributions was assessed by the Kolmogorov-Smirnov Goodness of Fit Test at inspiratory and expiratory corresponding pressures of 50 Pa, 75 Pa, 100 Pa, and 150 Pa. The distributions of the calculated total resistance data were estimated at inspiratory and expiratory reference pressures of 75 Pa and 100 Pa. The data distributions of the two groups were compared using the Mann-Whitney U-test. Distributions for unilateral resistance were frequently found to deviate from normality. The distributions of total nasal resistance data never showed significant deviation from normality. More non-normal distributions were observed in Group 2 than in Group 1. Significant differences were determined between the two sub-groups for the non-decongested data. The entire group of subjects was homogeneous for the decongested data. The subjective assessment of nasal patency appeared not to be a sufficient criterion for the selection of subjects for normative studies in rhinomanometry. The presence of anatomical abnormalities and the influence of the nasal cycle could be responsible for the skewness of nasal resistance data in the normative studies in rhinomanometry.

Adolescent↗
PubMed1995

[An outbreak of acute pulmonary histoplasmosis among travelers to a bat-inhabited cave in Brazil].

Histoplasmosis is known to be endemic in various parts of the world, especially in North and Latin America. In Japan, Histoplasma capsulatum has rarely been isolated from the natural environment. To date, only seven cases of histoplasmosis have been reported in Japan including some that were contracted in foreign countries. Herein, we report the occurrence of acute histoplasmosis among Japanese travelers who were exposed to bat guano in a cave near Manaus, Brazil. A group of 8 Japanese travelers entered a cave for a total of 2 hours in March, 1993. All the visitors had been healthy and had no history of abnormal chest roentgenograms. From 10 to 20 days after the exposure, 7 (87.5%) of the 8 individuals developed abnormal symptoms including fever, malaise, loss of appetite, myalgia, arthralgia, chest pain and dry cough. Five (62.5%) had nodular infiltrative shadows with or without hilar lymphadenopathy in the chest roentgenograms. Eight (100%) of the individuals showed serologic evidence of histoplasmosis. Despite the small number of subjects, this high rate of infection may be related to the fact that the subjects stayed in an enclosed area where air exchange was minimal, at the end of a deep cave infested with numerous bats. The cave involved has never been documented as being endemic for histoplasmosis. The threat of H. capsulatum infection in bat-inhabited caves should be emphasized to travelers and also to physicians.

Adult↗
PubMed1995

Comparative evaluation of commercial Premier EIA and microimmunodiffusion and complement fixation tests for Coccidioides immitis antibodies.

A total of 409 serum and cerebrospinal fluid specimens from human subjects with proven coccidioidomycosis, with other infections, or with no apparent illness were tested for antibodies to Coccidioides immitis by the Premier EIA (Meridian Diagnostics, Inc., Cincinnati, Ohio), which tests for immunoglobulin G (IgG) and IgM responses to coccidioidal antigens, and by the conventional complement fixation (CF) or immunodiffusion (ID) assays for antibodies corresponding to those detected by the tube precipitin (TP) or CF tests. Of the 409 specimens, 47 were from persons with confirmed coccidioidomycosis and all were positive for C. immitis antibodies in IDCF tests and enzyme immunoassays (EIAs) for both IgG and IgM. The EIA for detecting both IgG and IgM antibodies proved to be sensitive for detecting coccidioidomycosis case sera positive by the IDCF, IDTP, and CF tests. Maximal sensitivity for diagnosing coccidioidomycosis is dependent upon detection of both IgG and IgM antibodies in the EIA. The EIA, however, was not absolutely specific, since some sera from patients with confirmed blastomycosis and some from patients with noncoccidioidal disease produced false-positive reactions.

Antibodies, Fungal↗
PubMed1995

Development of specific fluorescent-antibody test for tissue form of Penicillium marneffei.

The diagnosis of penicilliosis marneffei can be difficult because the clinical manifestations mimic those of tuberculosis, histoplasmosis, and other mycotic infections. Furthermore, the tissue form of Penicillium marneffei can be confused with those of Histoplasma capsulatum and Cryptococcus neoformans. To facilitate the rapid detection and identification of P. marneffei in clinical materials, we sought to develop a specific indirect fluorescent-antibody (IFA) reagent for this dimorphic pathogen. Preliminary IFA studies with yeast-like cells (fission arthroconidia) of P. marneffei indicated that these cellular elements stained with antiglobulins against culture filtrate antigens and whole yeast-like cellular antigens. Both types of antiglobulins reacted with the yeast-like cells of P. marneffei and with H. capsulatum, but not with their respective mycelial forms. The antiglobulins also failed to react with the yeast and hyphal forms of a variety of other heterologous fungi. Specific antiglobulins useful in an IFA test for identifying P. marneffei yeast-like cells in culture or in clinical materials were produced by adsorptions with yeast-form cells of H. capsulatum. The yeast-like culture filtrate antigens of P. marneffei are preferred for use in the production of the specific antiglobulins because they stained P. marneffei yeast-like elements more intensely than antiglobulins produced against intact yeast-like cells.

Animals↗
PubMed1995

Prognostic factors in advanced prostatic carcinoma treated with total androgen blockade. Flutamide with orchiectomy or with LHRH analogues. A Belgian multicentric study of 546 patients.

Prognostic factors were evaluated in advanced loco-regional (M0) or distant metastatic (M1) prostatic carcinoma treated with total androgen blockade (flutamide with either orchiectomy of LHRH-analogues), in 546 patients from a Belgian multicentric study. After a mean follow-up of 16.5 months (maximum 37 months) 113 (21%) patients had progressed (90 were patients with M1 disease (31%)). The estimated median progression-free survival exceeded 37.5 months. The results of a univariate analysis show that the following parameters are important prognostic factors with respect to progression-free survival in these patients: M stage, G grade, ECOG performance status, weight loss, concomitant disease, pain, dysuria and haemoglobin (Lee-Desu test, p < or = 0.01). From a multivariate analysis (Cox regression) the following prognostic factors were indicative of a decrease in progression-free survival: M1 stage, high initial G grade, ECOG performance status > I, high serum PSA, presence of concomitant disease, presence of pain and absence of dysuria. Age did not appear to be a statistically significant prognostic factor.

Aged↗
PubMed1995

Chronic nasal obstruction in children. A fiberscopic study.

In this prospective study, fiberscopies were gently performed in 375 paediatric patients. The purpose of the study was to evaluate the nasal and nasopharyngeal anatomy and aetiologies of chronic nasal obstruction using fiberoptic examination in children. The essential advantage of this examination is that it allows a more thorough inspection of these cavities. The authors demonstrated that there exists a significant relationship between the relative size of the adenoid tissue and nasal obstruction complaints in children (p < 0.001). When the presence of adenoid hypertrophy was confirmed endoscopically, surgery proved to be highly efficacious in relieving chronic nasal obstruction.

Adenoidectomy↗
PubMed1994

A natural focus of Histoplasma capsulatum var. duboisii is a bat cave.

The natural reservoir of Histoplasma capsulatum var. duboisii, the etiological agent of histoplasmosis duboisii (African histoplasmosis) is not yet known. We report the isolation of H. capsulatum var. duboisii from soil admixed with bat guano and from the intestinal contents of a bat in a sandstone cave in a rural area, Ogbunike in Anambra State of Nigeria. Eight of 45 samples of soil admixed with bat guano yielded H. capsulatum var. duboisii. Of the 35 bats belonging to the species Nycteris hispida and Tadirida pumila examined, only one (N. hispida) yielded this fungus from its intestinal contents. Identification of the isolates as Histoplasma was confirmed by exoantigen tests and by mating with tester strains of H. capsulatum. In vitro conversion to large yeast from suggestive of H. capsulatum var. duboisii was obtained on brain heart infusion agar supplemented with sheep blood and glutamine or cysteine. Pathogenicity tests with mice for all the isolates confirmed their identity by the demonstration of large yeast forms (8-15 microns in diameter) within giant cells in the infected tissues. Investigations on the possible occurrence of human infections in the area are in progress.

Animals↗
PubMed1994

Oral histoplasmosis in a patient infected with HIV. A case report.

Histoplasmosis is a frequent complication of HIV infection and is usually the result of reactivation. In the immunocompromised host, histoplasmosis may cause a chronic pulmonary infection or disseminated disease. In the setting of disseminated disease, oral lesions are present in 30% to 50% of patients and may occur in almost every part of the oral mucosa. The most common sites are the tongue, palate, and buccal mucosa. In some cases, oral lesions appear to be the primary or only manifestation of disease. We have been able to find only five case reports in the literature of histoplasmosis in HIV infection with oral lesions. In two of the cases, histoplasmosis was apparently localized to the oral cavity, whereas two cases also had evidence of disseminated disease, the fifth was undetermined. We report one such case of apparently localized oral histoplasmosis in a patient with HIV infection.

AIDS-Related Opportunistic Infections↗
PubMed1994

Oral histoplasmosis in India: a case report and an overview of cases reported during 1968-92.

Oral histoplasmosis in a 30-year-old male with no history of travel outside India is described. An ulcerating lesion was located on the hard palate. A chest X-ray was normal. Based on physical examination, regional lymph nodes, liver and spleen were not involved. The diagnosis was established by demonstrating yeast-like budding cells in a biopsy of the lesion and by isolating Histoplasma capsulatum in pure culture. The identity of the isolate was confirmed by a chemiluminescent DNA-probe assay and the exoantigen test. A review of the Indian literature from 1968 to 1992 revealed the occurrence of 25 authentic cases of histoplasmosis in India. In 19 cases, lesions were confined to the oral cavity confirming prior observation that histoplasmosis in Indian patients tends to occur primarily in extrapulmonary sites, particularly the oral cavity.

Adult↗
PubMed1994

Characteristics of magnetic resonance sequences used for imaging silicone gel, saline, and gel-saline implants at low field strengths.

RATIONALE AND OBJECTIVES: Low-field magnetic resonance imaging (MRI) evaluation of breast implants is described, with emphasis on the capabilities provided by different imaging sequences. METHODS: Open architecture MR images using a .064-T permanent magnet and three-dimensional Fourier transform and inversion recovery sequences were obtained. A breast coil was designed and built for this project. Symptomatic and asymptomatic patients with silicone, saline-silicone and saline implants, and phantoms were part of this study. Phase images were used to differentiate protons in silicone, water, and fat. RESULTS AND CONCLUSIONS: Low-field MRI permitted differentiation of silicone, water, and fat. Implant anatomy and surrounding pathology could be imaged and identified.

Adult↗