Human T-cell leukemia-associated cell surface glycoprotein GP37: studies with three monoclonal antibodies and a rabbit antiserum

Three monoclonal antibodies (mAbs), termed SN2, SN2a and SN2b, were used in the present work to study a human T-cell leukemia-associated cell surface glycoprotein, GP37. Strong specificity of mAbs SN2, SN2a and SN2b for T leukemia cells was demonstrated by radioimmunoassay and fluorescence-activated cell sorter (FACS) analysis. GP37 was not detected on normal human peripheral blood lymphocytes, purified normal T-cells, normal thymocytes nor normal bone marrow cells. Furthermore, GP37 was barely detectable on phytohemagglutinin (PHA)- and Concanavalin A (Con A)-activated T-cells. The results indicate clinical utility of these mAbs. Competitive binding experiments show that the epitopes recognized by SN2 and SN2a are sufficiently close to each other to allow complete reciprocal inhibition of binding whereas the epitopes recognized by SN2 and SN2b are less close to allow only partial reciprocal binding inhibition. The biochemical nature of antigenic determinants defined by these mAbs was studied by treating T leukemia cells with trypsin, chymotrypsin, thermolysin, neuraminidase and mixed glycosidases. The results suggest that the antigenic determinants defined by these mAbs all consist of the protein moiety of the glycoprotein GP37. No significant antigenic modulation was observed when T leukemia cells were reacted with SN2. In a sequential immunoprecipitation experiment, a 125I-labeled leukemia antigen preparation was first treated with a rabbit anti-T leukemia antiserum. The latter had been prepared by immunizing a rabbit with a partially purified human T leukemia antigen preparation and showed a good specificity for T leukemia cells. Subsequent treatment of the labeled antigen preparation with SN2 showed that SN2 antigen had been precleared. Thus, both mouse mAb SN2 and the rabbit anti-T leukemia antiserum react with the same GP37 molecule.     

Effect of age on behavioral and enzymatic changes during thiamin deficiency

Open field behavior and whole brain enzymatic activities were determined during thiamin deficiency in two strains of young, as well as in aged mice. In young CD-1 mice, thiamin deficiency reduced total distance traveled and vertical movements after 7 days and the decline was more than 50% by day 9. The behavioral deficit was highly correlated to decreases in 2-oxoglutarate dehydrogenase activity (KGDH). The open field behavior of Balb/c mice was about 40% less than in CD-1 mice and responded in a qualitatively different manner to thiamin deficiency. The activity of the Balb/c mice increased and then decreased with thiamin deficiency. The activity of 3 month old mice peaked on day 6 (126% of initial score), whereas 10 and 30 month mice showed a much greater increase (about 175% of initial scores), but on day 7. Although the activity of the thiamin dependent enzyme transketolase (TK) was affected similarly at all ages, the activity of KGDH in the aged brain was more sensitive to thiamin deficiency than in the young; KGDH activity declined 41%, 57% or 74% at 3, 10, or 30 months, respectively. Thus, the current mouse model is an attractive one to study the interaction of thiamin deficiency with aging.     

Changes in peritoneal myeloid populations and their proinflammatory cytokine expression during infection with Listeria monocytogenes are altered in the absence of gamma/delta T cells

Evidence that gamma/delta T cells play a broad, immunoregulatory role has been accumulating steadily. We show here that myeloid cells are disregulated after peritoneal infection with Listeria monocytogenes in mice lacking gamma/delta T cells. Inflammatory populations of neutrophils and monocytes recruited to the site of infection remained longer. Intracellular cytokine analysis showed that frequencies of myeloid cells producing interleukin-12 and tumor necrosis factor alpha were higher and remained elevated longer after infection in mice genetically deficient in gamma/delta T cells. In vivo dye-tracking studies indicated that the majority of inflammatory monocytes differentiated into resident tissue macrophages in situ. In vitro experiments confirmed that monocytes harvested from mice lacking gamma/delta T cells were defective in their maturation process. This evidence suggests that gamma/delta T cells promote differentiation in the monocyte/macrophage lineage. These cells are important for bactericidal activity, inflammatory cytokine production, clearance of inflammatory neutrophils, and ultimately, antigen presentation to T cells. Regulation of monocyte/macrophage differentiation may underlie a broad segment of the phenotypic alterations that have been reported in mice lacking gamma/delta T cells.     

Oscillatory discharge in the visual system: does it have a functional role?

1. The discharge of individual neurons in the visual cortex and lateral geniculate nucleus (LGN) of anesthetized and paralyzed cats and kittens was examined for the presence of oscillatory activity. Neural firing was evoked through the monoptic or dichoptic presentation of drifting gratings and random sequences of flashed bars. The degree to which different oscillatory frequencies were present in neural discharge was quantified by computation of the power spectra of impulse train responses. 2. Action potentials from single cells were recorded extracellularly and isolated on the basis of amplitude. Receptive-field properties of the neurons under study were characterized initially by their discharge in response to gratings of sinusoidal luminance. By varying orientation and spatial frequency, optimal stimulus characteristics were determined. Oscillation analysis was performed on spike trains acquired during repeated presentations of the optimal stimulus by identification of power spectra peaks in the frequency range of rhythmic potentials observed in electroencephalograph studies (30-80 Hz). The amplitude and frequency of the largest peak in this range was used to characterize oscillatory strength and frequency. All discharge in which the peak amplitude exceeded the high-frequency noise by a factor > 1.5 was classified as oscillatory. 3. Of the 342 cortical cells examined, 147 cells displayed oscillatory activity in the 30 to 80-Hz range during portions of their visual response. Sixty out of 169 simple cells, 82 out of 166 complex cells, and 5 out of 7 special complex cells exhibited oscillations. There was no laminar bias in the distribution of oscillatory cells; the proportions of oscillatory cells were similar in all layers. All oscillatory discharge was variable with respect to frequency and strength between successive presentations of the same optimal stimulus. In as little as 10 s, for example, peak frequencies shifted by a factor of two. For many cells, these trial-to-trial variations obscured detectable oscillations when all trials were averaged together. 4. The potential role of neuronal maturation in the generation of oscillatory activity was investigated by studying neuronal responses from kittens at 4 wk postnatal. Of the 80 kitten cells studied, 27 exhibited oscillatory discharge. Although oscillations in the kitten visual cortex spanned the same frequency range as that seen in the adult, oscillations in the midfrequency range (36-44 Hz) are more common in the adult cortex. 5. To explore the possibility that oscillations might play a functional role in vision, we investigated the dependence of oscillations on different stimulus parameters.(ABSTRACT TRUNCATED AT 400 WORDS)     

Restriction of visual experience to a single orientation affects the organization of orientation columns in cat visual cortex

Summary and Conclusions In six dark reared, 4-weak-old kittens visual experience was restricted to contours of a single orientation, horizontal or vertical, using cylindrical lenses. Subsequently, the deoxyglucose method was used to determine whether these artificial raising conditions had affected the development of orientation columns in the visual cortex. After application of the deoxyglucose pulse one hemifield was stimulated with vertical, the other with horizontal contours. Thus, from interhemispheric comparison, changes in columnar systems corresponding to experienced and inexperienced orientations could be determined. The following results were obtained: (1) Irrespective of the restrictions in visual experience, orientation columns develop in areas 17, 18, 19 and in the visual areas of the posterior suprasylvian sulcus. (2) Within area 17, spacing between columns encoding the same orientations is remarkably regular (1 mm), is not influenced by selective experience and shows only slight interindividual variation. (3) In non-striate areas the spacing of columns is less regular and the spatial frequency of the periodicity is lower. (4) The modifiability of this columnar pattern by selective experience is small within the granular layer of striate cortex but substantial in non-granular layers: Within layer IV columns whose preference corresponds to the experienced orientation are wider and more active than those encoding the orthogonal orientation but the columnar grid remains basically unaltered. Outside layer IV the columnar system is maintained only for columns encoding the experienced orientations. The deprived columns by contrast frequently fail to extend into non-granular layers and remain confined to the vicinity of layer IV. (5) These modifications in the columnar arrangement are more pronounced in striate cortex than in non-striate visual areas and, within the former, more conspicuous in the central than in the peripheral representation of the visual field. It is concluded that within layer IV the blue print for the system of orientation columns is determined by genetic instructions: first order cells in layer IV develop orientation selectivity irrespective of experience whereby the preference for a particular orientation is predetermined by the position in the columnar grid. Dependent on experience is, however, the expansion of the columnar system from layer IV into non-granular layers. It is argued that all distortions following selective rearing can be accounted for by competitive interactions between intracortical pathways, the mechanisms being identical to those established for competitive processes in the domain of ocular dominance columns. It is proposed that such experience dependent modifiability of connections between first and second order cells is a necessary prerequisite for the development of orientation selectivity in cells with large and complex receptive fields.This work has partially been supported by a grant from the Deutsche Forschungsgemeinschaft, SFB 50, A14Dedicated to Prof. D. Ploog on the occasion of his 60th anniversaryResearch Fellow of the Alexander-von Humboldt-Stiftung     

Innovations in curriculum design: A multi-disciplinary approach to teaching statistics to undergraduate medical students

Background  

Statistics is relevant to students and practitioners in medicine and health sciences and is increasingly taught as part of the medical curriculum. However, it is common for students to dislike and under-perform in statistics. We sought to address these issues by redesigning the way that statistics is taught.     

Durability of sodium sulfate-treated polylysine-alginate microcapsules

Chelated hollow microcapsules are unstable under in vitro conditions because of their hygroscopic nature. Nongel inducing cations, such as Na+, stabilize the outer membrane of the alginate-polylysine-alginate microcapsules leading to more stable beads. We made different batches of empty capsules with a mean +/- SEM diameter of 607+/-11 microns, and found that within 1 week of incubating these capsules in normal saline at 37 degrees C, they increased to 718+/-10 microns (p < 0.05, n = 5). In initial experiments, we made different batches of capsules and divided them into two groups. One group was left untreated (control) whereas the other was treated with 6 mM Na2SO4 for 30 min, before incubation in saline at 37 degrees C. Control capsules increased in weight and size, before beginning to melt in less than 1 week. In contrast, treated capsules rapidly lost weight and remained intact during 1 month of follow-up. In perifusion experiments, we found no deleterious effect of sodium sulfate treatment on the function of islets enclosed in the capsules.     

Search for a human leukemia virus

Summary In summary, we examined the bone marrow and blood of 107 leukemic children for the presence of virus or virus-like structures. Material for study included both fresh specimens and cells cultivated over varying periods of time. In four instances in which patients' plasma was inoculated onto human amnion cells and in one instance of cultivated bone marrow, we observed particles morphologically similar to myxoviruses. Indirect immunofluorescence testing for antigens of murine leukemia viruses failed to demonstrate fluorescence in leukemic cells. Studies are in progress on a continuous leukemic bone marrow culture to recover in recognizable form either replicating virus or viral genome.Dedicated to ProfessorJohn F. Enders on the occasion of his 70th birthday.These studies were supported by U.S.P.H.S. Grants CA 05176, CA 08480 and CA 07054, from the National Cancer Institute and by American Lebanese Syrian Associated Charities (ALSAC).     

Is personal continuity of care compatible with free choice of doctor? Patients' views on seeing the same doctor.

While much has been written about the benefits of personal continuity of care there has been little research about the views of patients. In this cross sectional study 111 patients from three group practices (one of which ran a personal list system) were interviewed at home within a week of consulting a general practitioner. Patients were selected randomly from a systematic series of consulting sessions and a semi-structured interview was administered. Patients receiving more personal continuity of care were likely to be older, to have booked their most recent appointment further in advance, to desire personal continuity of care, to have an external health locus of control and to have a lower extroversion score. In the practice with a personal list, patients had a high level of continuity of care, were satisfied and showed little interest in having a choice of doctor. In the combined list practices patients valued their choice of doctor but often could not exercise it enough and they were more critical. They made more suggestions for change than those in the practice with a personal list system, mostly about receptionists and appointments. It is concluded that most patients like to see the same doctor, but they may not be willing to wait two days for this if there is a quicker option. It may be difficult to deliver both personal continuity of care and choice in group practice.     

Immunohistochemical Localization of p53 in Human Thyroid Neoplasms: Correlation with Biological Behavior

Molecular analyses of thyroid tumors have documented mutations in the tumor suppressor p53 gene almost exclusively in anaplastic carcinomas. In contrast, immunohistochemistry has localized p53 in differentiated papillary and follicular thyroid cancers. To establish the significance of p53 immunolocalization in these lesions, 78 thyroid tumors of follicular derivation were examined. All tumors were classified by strict criteria and the extent of tumor was determined morphologically. Immunohistochemical staining for p53 was performed on paraffin sections of formalin-fixed tumor tissue. The results of staining were correlated with diagnosis, tumor extent and clinical outcome. Immunopositivity for p53 was diffuse and strong in all five anaplastic carcinomas examined. There was no staining in five of six follicular adenomas. Four of nine follicular carcinomas had some degree of nuclear staining, but this was focal; all nine tumors were confined to the thyroid at the time of examination. Of 49 papillary carcinomas, 26 were intrathyroidal, and 7 of these were occult; there was no p53 positivity in any occult lesion and only 5 of the 19 palpable lesions stained. In contrast, among 23 papillary carcinomas with extrathyroidal extension or metastases, only 9 were negative for p53 immunoreactivity. Five of seven tall cell papillary carcinomas and one of two insular carcinomas had p53 immunopositivity and this correlated with aggressive behavior. These results support the tumorigenic role of p53 mutations postulated for anaplastic thyroid carcinomas and indicate that localization of p53 by immunohistochemistry is a useful prognostic index of clinical behavior in differentiated thyroid carcinomas of follicular cell derivation.