Biomedical subjects
J Kagan
Publications and source records attributed to J Kagan.
Iris pigmentation and behavioral inhibition.
Two independent investigations of the association between the temperamental dimensions of inhibition and lack of inhibition to the unfamiliar, on the one hand, and the degree of pigmentation of the iris, on the other, revealed a statistically significant relation in Caucasian children between behavioral inhibition to the unfamiliar and blue irises and uninhibited behavior and brown irises. Several biochemical interpretations of this association were discussed and it was suggested that these behavioral styles might be influenced by biological factors that are partially marked by eye color in Caucasian populations.
Phototoxic effects of fluoranthene, a polycyclic aromatic hydrocarbon, on bacterial species.
Fluoranthene, a non-carcinogenic polycyclic aromatic hydrocarbon, inactivates Escherichia coli cells in the presence of near-ultraviolet light (NUV; 300-400 nm). E coli cells carrying defects in the uvrA6 or katF genes are sensitized to inactivation by the simultaneous treatment with fluoranthene and NUV, suggesting that DNA is a target and that hydrogen peroxide is generated. Haemophilus influenzae transforming DNA can be inactivated by the simultaneous treatment with fluoranthene and NUV confirming DNA as a target. Using the photooxidation of imidazole and histidine as probes, fluoranthene was found to generate singlet oxygen in organic and aqueous media. In water, it participated in electron transfer reactions, reducing nitro blue tetrazolium as well as ferricytochrome C. This reduction took place both in the presence of air, where superoxide anion was formed, and under argon. Simultaneous treatment with fluoranthene and NUV was incapable of inducing histidine-independent mutations. Simultaneous treatment with fluoranthene and NUV was incapable of inducing the uvrA gene product as evidenced by the absence of the induction of beta-galactosidase in an E coli operon fusion strain [uvrA215::Mud(Ap,lac)].
Administration of monthly-pulse cyclophosphamide in multiple sclerosis patients. Effects of long-term treatment on immunologic parameters.
Eleven patients with chronic progressive multiple sclerosis received monthly pulses of cyclophosphamide (CY) for approximately one year. During the final 9 months the monthly dose ranged between 1000 mg/m2 and 2000 mg/m2. This resulted in a marked (47% or greater) reduction in CD4 (T helper/inducer) cells a less striking (22%) decrease in CD8 (T suppressor/cytotoxic) cells and a decline in the CD4/CD8 ratio. The magnitude of the decrease in CD4 cells correlated with the total dose received (r = 0.88, P less than 0.05). B cells were reduced 50% and FcR+ lymphocytes were reduced 48% without comparable reduction in natural killer cells or antibody-dependent cellular cytotoxicity. Proliferative responses to PHA were suppressed. Two patients improved, seven stabilized and two continued to worsen. Monthly pulses of CY can achieve substantial and differential reduction in immune parameters and appear to slow the disease progression in some MS patients.
Alpha-chain locus of the T-cell antigen receptor is involved in the t(10;14) chromosome translocation of T-cell acute lymphocytic leukemia.
Human leukemic T cells carrying a t(10;14)(q24;q11) chromosome translocation were fused with mouse leukemic T cells, and the hybrids were examined for genetic markers of human chromosomes 10 and 14. Hybrids containing the human 10q+ chromosome had the human genes for terminal deoxynucleotidyltransferase that has been mapped at 10q23-q25 and for C alpha [the constant region of TCRA (the alpha-chain locus of the T-cell antigen receptor gene)], but not for V alpha (the variable region of TCRA). Hybrids containing the human 14q- chromosome retained the V alpha genes. Thus the 14q11 breakpoint in the t(10;14) chromosome translocation directly involves TCRA, splitting the locus in a region between the V alpha and the C alpha genes. These results suggest that the translocation of the C alpha locus to a putative cellular protooncogene located proximal to the breakpoint at 10q24, for which we propose the name TCL3, results in its deregulation, leading to T-cell leukemia. Since hybrids with the 10q+ chromosome also retained the human terminal deoxynucleotidyltransferase gene, it is further concluded that the terminal deoxynucleotidyltransferase locus is proximal to the TCL3 gene, at band 10q23-q24.
Polycyclic aromatic compounds as phototoxic mosquito larvicides.
The phototoxicity of 2-acetylnaphthalene, 1-acetylnaphthalene, 1-naphthalenecarboxaldehyde, 9-xanthenone, 9-thioxanthenone, 9-methylanthracene, anthracene, alpha-terthienyl, pyrene and fluoranthene was tested with larvae of Aedes aegypti, Ae. taeniorhynchus and Culex quinquefasciatus. The larvae were exposed to the chemicals in the presence of sunlight for intervals from 1 to 6 hr and the corresponding LC50 values calculated. The LC50 values determined when the 6-hr exposure was followed by 18 hr in the dark range from over 10 ppm to below 0.001 ppm. Naphthalene derivatives were the least active while alpha-terthienyl, anthracene, 9-methylanthracene, pyrene and fluoranthene were the most phototoxic.
The physiology and psychology of behavioral inhibition in children.
Longitudinal study of 2 cohorts of children selected in the second or third year of life to be extremely cautious and shy (inhibited) or fearless and outgoing (uninhibited) to unfamiliar events revealed preservation of these 2 behavioral qualities through the sixth year of life. Additionally, more of the inhibited children showed signs of activation in 1 or more of the physiological circuits that usually respond to novelty and challenge, namely, the hypothalamic-pituitary-adrenal axis, the reticular activating system, and the sympathetic arm of the autonomic nervous system. It is suggested that the threshold of responsivity in limbic and hypothalamic structures to unfamiliarity and challenge is tonically lower for inhibited than for uninhibited children.
Excited state properties of alpha-terthienyl and related molecules.
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In vivo activity of affinity-purified helper factor from antigen-specific helper clone.
Supernatant from culture of a virally transformed OVA-specific helper T clone (C-41) was examined for the presence of soluble helper factor. Inoculation of helper clone supernatant into DNP-KLH-primed mice enhanced the IgG anti-DNP response when given with DNP-OVA. The C-41 supernatant did not trigger the DNP-primed B cells in mice when injected with hapten (DNP) coupled to an unrelated carrier (BSA). The carrier-dependent helper activity of C-41 supernatant in vivo demonstrates the presence of an antigen-specific T helper factor in the media of the cultured helper clone. Extensive immunization of F1(C57BL X BALB/c) mice with the helper clone resulted in the production of anti C-41 antibodies. Monoclonal antibodies prepared from the immunized mice were screened for specificity of binding to other transformed T lines and clones, some specific to OVA. Monoclonal antibodies that stained the C-41 cells exclusively were considered clone-specific. Supernatants of the helper clone were passed over columns of anti-clone-specific antibodies. The eluates from three antibodies were active as antigen-specific helper factor, i.e., they elevated the IgG anti-DNP response in vivo in a linked recognition fashion in the presence of DNP-OVA. The affinity-purified factor was inactive when injected with DNP-BSA or DNP-BSA + OVA. Thus, we describe the antigen-specific immune function of a clone-produced helper factor in normal mice.
The inactivation of acetylcholinesterase by alpha-terthienyl and ultraviolet light. Studies in vitro and in larvae of the mosquito Aedes aegypti.
Acetylcholinesterase (EC 3.1.1.7) was inactivated photochemically in solution, in the presence of dissolved terthiophene sensitizers. Alpha-terthienyl (2,2':5,2"-terthiophene) and its isomers 3,2':5',2"- and 3,2':5',3"-terthiophenes showed very similar sensitizing properties. With all three terthiophenes, the photosensitization was completely suppressed under anaerobic conditions, and therefore the inactivation process required the presence of oxygen. The enzyme was inactivated in vivo when fourth instar larvae of the mosquito Aedes aegypti were treated with alpha-terthienyl in the presence of long-wavelength ultraviolet light. No inactivation was observed when the organisms were treated with the ultraviolet light alone, with the chemical alone, or with a previously irradiated sample of the chemical. This paper represents the first example of acetylcholinesterase inactivation in vivo by a photoactive insecticide.
The ovicidal activity of cis-dehydromatricaria ester: time-dependance of its enhancement by UV light.
Freshly laid eggs of Drosophila melanogaster were treated with the polyacetylenic compound cis-dehydromatricaria ester. The toxicity of the chemical was enhanced by treatments with long-wavelength ultraviolet light, and the maximum effect was observed when the UV irradiation was performed 4-5 h after the initial contact of the eggs with the chemical.
Oxygen requirement for near-UV mediated cytotoxicity of phenylheptatriyne to Escherichia coli.
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The phototoxicity of 2,5-diphenyloxazole (POP) and 1,4-bis(5-phenyloxazol-2-yl)benzene (POPOP).
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Failure of the human autologous mixed lymphocyte reaction in the absence of foreign antigens.
The autologous mixed lymphocyte reaction (AMLR) is thought to represent the in vitro proliferation of T cells in response to stimulation by autologous histocompatibility antigens present on non-T cells. We have investigated the possibility that xenogeneic determinants act as the stimulating antigens in the human AMLR. Exposure of lymphocytes to fetal calf serum and/or sheep red blood cells during fractionation triggers substantial proliferation of T cells, plaque-forming cell responses, and interleukin 2 production. In contrast, lymphocytes isolated and cultured in the absence of any known foreign substances failed to respond in the AMLR, yet responded significantly when cultured in the presence of fetal calf serum. These results suggest that without exposure to foreign antigens, the human AMLR is difficult to demonstrate in vitro.
The effect of vibration on vision during microsurgery.
This study was initiated to assess the effects of vibrating optics on a microsurgeon's ability to visualize. The results have led to criteria of image displacement versus frequency which could be applied to the design of a surgical-microscope mounting system. To provide minimum added strain to the microsurgeon, the ideal microscope mounting system should not transmit vibration from the hospital environment to the microscope optics at a level that is detectable by the visual system of the surgeon. This can be avoided by isolating the microscope mounting system from the vibratory environment of the hospital and by designing the microscope support system to minimize vibrations at frequencies that are most readily detectable by the human visual system.
The idea of spatial ability.
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The emergence of self.
Longitudinal and cross-sectioned investigations of children from three different cultural settings reveal the emergence of behaviors during the last half of the second year that imply the first appreciation of standards on prohibited actions, recognition of the ability to gain goals, and awareness of the self's feeling states. It was suggested that these competences were inevitable consequences of maturational changes in the central nervous system as long as children were growing in a world of objects and people. The foundations for a moral evaluation of aggression and self-consciousness appear to be universal milestones of the second year of life.
Cognitive profiles in reading disability.
A group of 35 reading disable (RD) boys and 35 matched controls were studied over a two-year period in order to evaluate the validity of traditional hypotheses about the cause of serious reading impairment in preadolescent boys for whom the common disadvantages of economic privation, bilingualism, and emotional instability were absent. The popular hypothesis of perceptual deficit was not supported by the data, although the finding that most RD boys have a short-term memory deficit was affirmed. The most important new finding was that about one-fourth of the RD boys had serious difficulty in maintaining an efficient set to process and/or evaluate information, especially when that information was contained in oral speech.