Biomedical subjects

J Hom

Publications and source records attributed to J Hom.

13 recordsLinked to original sources

PubMed1992

Left cerebral dominance for bilateral simultaneous sensory stimulation?

Hom and Reitan (1982) reported findings with respect to sensorimotor deficits in groups with lateralized cerebral lesions, but evaluated the results only within a framework that related cerebral dominance to deficits that resulted from lateralized lesions. Some of the variables they studied, however, depend upon evidence of retention of functions by one hemisphere under conditions of distracting input. While the right cerebral hemisphere appears to be dominant for tactile-perceptual abilities in terms of resulting deficits, the present study suggests that the left cerebral hemisphere is dominant for certain non-language functions that reflect maintenance of sensory-perceptual abilities under conditions of distracting stimuli.

Agnosia↗

PubMed1991

A comparison between bromodeoxyuridine and 3H thymidine labeling in human breast tumors.

The fraction of tumor cells in the DNA synthesis (S) phase of the cell cycle is a strong prognostic indicator in human breast cancer. Most studies measuring S-phase in primary tumors have used either in vitro labeling with 3H thymidine or DNA flow cytometry. The former involves a cumbersome and time-consuming radioactive assay, while the latter is heavily dependent on the quality of the preparation and the effectiveness of the algorithms used. In this study, in vivo or in vitro labeling with bromodeoxyuridine (BrdUrd) was compared with in vitro labeling using 3H thymidine in a series of 33 human breast tumors. Thymidine labeling showed strong correlation with both in vitro (r = 0.96) and in vivo (r = 0.83) BrdUrd incorporation. The reliability between observers was higher for BrdUrd counting (r = 0.94) than for thymidine counting (r = 0.87). The mean labeling index of 15 tumors labeled in vivo with BrdUrd was 5.9% compared to 4.7% for 18 tumors labeled in vitro (p = 0.34). There was poor correlation between flow cytometric and microscopic analysis of BrdUrd incorporation (r = 0.37). We conclude that microscopic analysis of in vivo or in vitro BrdUrd incorporation is a rapid and reliable method to estimate breast tumor proliferation.

Analysis of Variance↗

PubMed1991

Experiences with depression in a dementia clinic.

Of 317 consecutive cases seen in a dementia clinic, 19 (6%) had little or no objective evidence of cognitive impairment on clinical examination and extensive neuropsychological testing. Of the remaining 298 cases, 192 (64%) were diagnosed as probable or possible Alzheimer's disease (AD). Of the 19 nondemented cases, 8 (42%) were thought to have cognitive difficulty due to depression. In the AD group, only 4 cases (2%) were thought to be depressed and only 2 of the 4 met DSM-III-R criteria for major depression. There was no relationship between Hamilton Rating Scale for Depression scores and either cognitive or behavioral measurements of dementia severity, suggesting that the difference between the two groups was not due to underreporting by AD patients. The authors concluded that a tertiary care setting, depression is a common cause of cognitive complaints in persons without organic disease and a rare cause of excess morbidity in AD.

Adult↗

PubMed1990

Single photon tomography in Alzheimer's disease and the dementias.

Measurements of brain blood flow has evolved over the past 50 years, and during the latter half of that time radionuclide techniques have been used to study this important function. Using Xenon 133 and scintillation multiprobe systems, several teams of investigators measured regional cerebral blood flow (rCBF), and noted that under many circumstances it could be equated with local brain physiological activity. The dementias were investigated using the scintillation multiprobe method, and posterior flow deficits were described in patients who were thought to have Alzheimer's disease. The multiprobe technique gave way first to planar, and then tomographic imaging, with initial favorable results achieved by positron emission tomography (PET). Soon investigators learned to measure rCBF with single-photon emission computed tomography (SPECT) using high-sensitivity systems and 133Xe as a tracer, or high-resolution systems with 123I-iodoamphetamine (IMP), and later, 99mTc-HMPAO. Three-dimensional tomographic imaging shows to advantage the flow patterns that characterize Alzheimer's disease, with rCBF reductions in temporal, parietal, and sometimes frontal areas, as opposed to randomly distributed deficits in multiinfarct dementia, reduced frontal flow in entities such as Pick's disease, and others. Herein we will review our own experience with high-sensitivity rCBF SPECT in 119 patients with dementia, and with high-resolution SPECT, using a new, three-camera scanner and 99mTc-HMPAO in an additional 39 patients. SPECT rCBF study of patients with dementia and Alzheimer's disease, will aid in separating patients with untreatable Alzheimer's from those patients who may have treatable causes of dementia, and will be useful in evaluating experimental drugs for the treatment of Alzheimer's disease.

Alzheimer Disease↗

PubMed1990

Generalized cognitive function after stroke.

The present investigation was designed to determine the effect of cerebrovascular lesions upon general neuropsychological function. The performances of 60 patients with lateralized or diffuse cerebrovascular lesions were compared to 20 controls on cognitive and intellectual measures. Multivariate analyses indicated markedly poorer performances by the cerebrovascular groups on measures of generalized cerebral function, and no differences on such measures were found between the left- and right-damaged groups. The lateralized CVD groups demonstrated a differential tendency towards lower performances on VIQ for the left group and on PIQ for the right group. The results indicate significant neuropsychological impairment which extends beyond the expected lateralized dysfunctions, or selected deficits, associated with the damaged hemisphere. These findings indicate the importance of evaluating generalized as well as specific cognitive functions in clinical assessment of cerebrovascular lesions.

Attention↗

PubMed1990

Inhibition of Trichomonas vaginalis motility by monoclonal antibodies is associated with reduced adherence to HeLa cell monolayers.

Adherence of trichomonads to host epithelial cells appears to be a critical step in the pathogenesis of trichomoniasis. We evaluated the effect of a panel of 10 monoclonal antibodies on attachment of [35S]methionine-radiolabeled Trichomonas vaginalis strains to HeLa cell monolayers. Of 10 monoclonal antibodies, 3 totally eliminated motility of PHS2J strain trichomonads and reduced their adherence to 48 to 60% of control values (P less than 0.001). However, none of the monoclonal antibodies affected motility or adherence of STD13 strain trichomonads. Although the antibodies all reacted with PHS2J trichomonads by immunofluorescence, there was no correlation between inhibition of adherence and findings on either immunofluorescence or radioimmunoprecipitation. Direct microscopic observations showed that incubation with the monoclonal antibodies did not cause cytolysis of T. vaginalis. In quantitative cultures there was no difference in the number of colonies produced by parasites that had been incubated with antibodies that inhibited or had no effect on adherence. We conclude that our monoclonal antibodies reduced adherence not by cytotoxic effects or by competing for specific sites mediating adherence of the protozoa, but by inhibiting motility of T. vaginalis.

Animals↗

PubMed1989

Purification of a glycosyl-phosphatidylinositol-specific phospholipase D from human plasma.

Mammalian plasma contains a phospholipase D, which is specific for the glycosyl-phosphatidylinositol anchor found on many eukaryotic cell surface proteins (Davitz, M. A., Hereld, D., Shak, S., Krakow, J., Englund, P. T., and Nussenzweig, V. (1987) Science 238, 81-84; Low, M. G., and Prasad, A. R. S. (1988) Proc. Natl. Acad. Sci. U. S. A. 85, 980-984; Cardoso de Almeida, M. L., Turner, M. J., Stambuk, B. V., and Schenkman, S. (1988) Biochem. Biophys. Res. Commun. 150, 476-482). We have purified this phospholipase D to homogeneity by a four-step procedure involving a Mono Q and phenyl-5PW columns, followed by wheat germ lectin affinity chromatography and finally another Mono Q column. A 4,500-fold purification was achieved with a 5% yield. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the homogeneous enzyme has a Mr of 110,000 and appears to consist of a single polypeptide chain. It exhibits identical substrate specificity as compared with the crude preparation, is active over a broad pH range (4.0-8.5), inhibited by the thiol-blocking agent p-chloromercuriphenylsulfonic acid and by 1,10-phenanthroline, and is partially heat-labile.

Chromatography, Affinity↗

PubMed1989

The effect of acetazolamide on regional cerebral blood flow in patients with Alzheimer's disease or stroke as measured by single-photon emission computed tomography.

Regional cerebral blood flow (rCBF) was assessed in 35 patients with possible or probable Alzheimer's disease (AD) and in 16 patients known to have had at least one stroke. Patients were evaluated before and after the administration of 1 g acetazolamide (ACZ) by means of a rotating four-detector single-photon emission computed tomograph (SPECT) and inhaled Xe-133. RCBF values in mL/minute/100 g were derived from eight cortical regions of interest (ROI), and from the whole transverse section as a measure of whole brain flow (WBF). ROI/WBF ratios were calculated for each ROI in paired determinations done before and 15 minutes after the administration of ACZ. Results were compared with those previously obtained in a study of 15 normal, healthy volunteer subjects. ROI/WBF ratios greater than 2 standard deviations (SD) below the mean for a given ROI in the normal group were regarded as probably abnormal, whereas ratios greater than 4 SD below the mean were considered definitely abnormal. After ACZ administration, the number of ROI greater than 2 SD below the normal mean decreased significantly in the AD group and was unchanged in the stroke patients. However, the number of ROI/WBF ratios greater than 4 SD below the normal mean fell in the AD group and rose in the stroke group, with the difference in behavior highly statistically significant. Thus, the response of low-flow areas to ACZ differs in AD and in stroke, which could be of ultimate diagnostic significance.

Acetazolamide↗

PubMed1988

Verbal processing by the brain.

Reitan and Wolfson (1985) have proposed a model of brain-behavior relationships which postulates a three-part organization of higher-level aspects of central processing: Verbal and related language functions (mainly left hemisphere), visual-spatial and related abilities (mainly right hemisphere), and conceptual abilities (both hemispheres). Three groups of subjects (controls, left cerebral lesions, and right cerebral lesions) and two strictly verbal tests (the Word Finding Test and the Vocabulary subtest from the Wechsler Scale) were used as a partial test of this model. Left cerebral lesions impaired Vocabulary scores but right cerebral lesions had little if any impairing effect. However, on the Word Finding Test, which has a strong conceptual requirement in addition to the verbal requirement, the group with left cerebral lesions continued to show striking impairment but the group with right cerebral lesions also showed significant impairment as compared to the control group. Additional studies are needed to test the proposed model in more detail.

Adult↗

PubMed1988

Regulation of cellular and humoral immune responses to collagen type I or collagen type II.

We have investigated the characteristics of antigen-specific reductions in murine immune responses to rat collagen type I (R-CI), chick collagen type II (C-CII) or bovine collagen type II (B-CII). Intravenous pretreatment with the appropriate soluble collagen or collagen-coupled spleen cells led to the development of antigen-specific reduced immune responses, the former treatment being more effective than the latter. In the case of CII, pretreatment with R-CI or non-related antigens was ineffective. However, pretreatment with denatured bovine-CII, native bovine-CII or chick-CII led to immune hyporesponsiveness for either the homologous or heterologous CII molecule. A delayed development of the diminished immune responses was observed for the cell-mediated immune response (CMI), as measured by in vivo delayed-type hypersensitivity (DTH), in that no reduction was evident at Day 7 but a significantly decreased response was observed at Day 14. Collagen-specific IgG and IgM antibody responses were consistently reduced by the pretreatment and remained reduced during the study period. The antigen-specific hyporesponsive state was not sensitive to cyclophosphamide treatment and was not transferable with hyporesponsive spleen cells. Additionally, we have induced unresponsiveness to CII by treating mice with an antibody directed to T helper cells (GK1.5). This treatment led to profound reductions in CII CMI responses as well as CII antibody levels. However, this unresponsive state is not permanent and not transferable with spleen cells from treated mice. These two types of procedures, soluble B-CII i.v. or GK1.5 treatment, not only resulted in CII hyporesponsive states, but also produced delayed onset and decreased incidence of arthritis in the appropriate strains.

Animals↗

PubMed1985

Detection of Treponema pallidum in lesion exudate with a pathogen-specific monoclonal antibody.

The diagnosis of early syphilis currently requires dark-field microscopic or serologic demonstration of Treponema pallidum infection. Dark-field microscopy is not widely available and is complicated by the numerous saprophytic spirochetes which are present at oral and rectal mucosal surfaces. Serologic tests are positive in only 70 to 90% of patients with primary syphilis, and several days may be required for results to become available. We used a pathogen-specific, fluorescein-conjugated monoclonal antibody to examine lesion exudates from 61 patients for the presence of T. pallidum and compared the data with results of dark-field microscopy and serologic testing. The direct fluorescent-antibody technique revealed the presence of T. pallidum in 30 of 30 patients with early syphilis, and dark-field microscopy was positive for 29. Serologic tests were reactive for 27 of 30 patients with syphilis; in the 3 patients with nonreactive serologic tests, chancres had been present for 4, 6, and 21 days. Although 7 of 31 patients without syphilis had spiral organisms seen on dark-field microscopy, the direct fluorescent-antibody test was negative for all 31. The presence of nonpathogenic spirochetes was subsequently verified in 5 of 7 patients by using a second monoclonal antibody which reacts with nonpathogenic, as well as pathogenic, treponemes and related spirochetes. The demonstration of T. pallidum by using fluorescein-conjugated monoclonal antibodies is intrinsically specific and is as sensitive as dark-field microscopy for the diagnosis of early syphilis. This method provides a convenient, accurate means for the diagnosis of syphilis by health care providers, many of whom lack access to dark-field microscopy.

Antibodies, Bacterial↗

PubMed1985

Characterization of monoclonal antibodies to Treponema pallidum.

Thirteen hybrid cell lines which produce mouse monoclonal antibodies to Treponema pallidum, the causative agent of syphilis, have been established. All of the monoclonal antibodies react with T. pallidum, Nichols strain, in ELISA and in immunofluorescence assays, but do not react with normal rabbit testicular tissue in the ELISA. Two of these antibodies were demonstrated to react with the nonpathogenic treponemes T. phagedenis, biotype Reiter, T. refringens (Noguchi strain), T. vincentii, and T. denticola (strains 11 and W), as well as with Borrelia recurrentis, Leptospira interrogans, serogroup Canicola, and the swine pathogen T. hyodysenteriae. The remaining 11 antibodies react with four recently isolated strains of T. pallidum, but with none of the related nonpathogens nor with Borrelia or Leptospira. Thus, our results to date indicate that these monoclonal antibodies may identify antigenic determinants that are specific either for T. pallidum alone or for those treponemes which are pathogenic for humans. The molecular specificities of six of the 13 antibodies were determined by Western blotting. We anticipate potential usefulness of these antibodies in the investigation of the antigenic structure of T. pallidum, the taxonomic study of the pathogenic and nonpathogenic treponemes, and in the diagnosis of syphilis.

Animals↗

PubMed1975

Functional deficiency of splenic adherent cells in New Zealand black mice.

New Zealand Black (NZB) mice hyporespond after in vitro immunization to sheep erythrocytes but not after in vivo immunization. The difference between in vitro and in vivo immunization was found to involve a non-antigen-specific change in the spleen which occurs in vivo soon after priming. Adherent spleen cells from young NZB or control strain mice were compared in their ability to cooperate with nonadherent cells in the induction of a primary immune response to sheep erythrocytes in vitro. The results support the hypothesis that there is a functional deficiency of adherent cells in the spleens of unprimed NZB mice.

Animals↗