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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Groups of C57BL/6J, male mice were exposed to 300 ppm benzene via inhalation for 115 exposures (6 h/day, 5 days/week), a regimen known to cause thymic lymphoma in these animals. The effects of these exposures on lymphoid parameters were determined by measuring the numbers of B- and T-lymphocytes and mitogen-induced proliferation of B- and T-lymphocytes in bone marrow, spleen, and thymus after 6, 30, and 115 exposures. The numbers of B-lymphocytes in bone marrow and spleen and the numbers of T-lymphocytes in thymus and spleen were found to be markedly reduced after all 3 periods. Mitogen-induced proliferation of bone marrow and splenic B-lymphocytes exhibited a progressive depression throughout the exposure period reaching a point of no observable response after 115 exposures. Splenic T-cell mitogen-induced proliferation was also markedly depressed throughout the exposures, but there was no evidence of a progressive decline in this response during the exposures. Bone marrow cellularity increased 3-fold and the numbers of thymic T-cells increased 15-fold in benzene-exposed mice between the 6th and 30th exposure. No corresponding increase in splenic cells was observed in benzene-exposed mice during this interval. The marked increases in the numbers of cells in bone marrow and thymus are interpreted as arising from compensatory proliferation of a subpopulation of cells in response to the exposures. The absence of increases in cell number in the spleen is interpreted as reflecting the lack of lymphoid restorative capacity in this organ. The marked increases of thymic and bone marrow cellularity are discussed relative to the known ability of this benzene exposure regimen to produce thymic lymphoma in these animals.
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PMID:Protracted exposure of C57BL/6 mice to 300 ppm benzene depresses B- and T-lymphocyte numbers and mitogen responses. Evidence for thymic and bone marrow proliferation in response to the exposures. 387 53

In 1982, White et al published an assessment of quantitative leukemia risk associated with lifetime occupational exposure to benzene. At about the same time, IARC (1982) published estimates of quantitative cancer risk associated with industrial chemicals. Benzene was one of the two chemicals selected by IARC for its risk estimation. This paper presents a summary of these assessments along with new study results demonstrating adverse effects on bone marrow and peripheral blood cells as a result of low-level benzene exposure. Mathematical extrapolations based on epidemiologic studies are consistent with a finding of significant risk of dying from leukemia under the current occupational permissible exposure limit of 10 ppm. Although a significant reduction of risk could be expected to be achieved by reducing exposure to 1 ppm, a significant risk may still remain. The uncertainty of the dose-response projections rests on the underlying estimates of relative risk of death from leukemia, the estimates of benzene exposure (dose), and the appropriateness of the mathematical model. Recent findings in experimental animals demonstrate chromosomal damage to bone marrow cells, significant depression of the bone marrow, and disturbances of immune system function as a result of less than 1 week of exposure to the current permissible benzene exposure limit of 10 ppm. This was the lowest dose tested. These experimental findings provide further evidence of a potentially significant risk of bone marrow proliferative cancer (leukemia) as a result of low-dose benzene exposure.
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PMID:Projections of leukemia risk associated with occupational exposure to benzene. 389 May 30

Today there seems to be sufficient data to incriminate benzene as a potent carcinogenic agent causing leukemia, malignant lymphoma, multiple myeloma and lung cancer, as well as numerous disorders of the bone marrow depression. Other factors (such as genetic and individual susceptibility) may have a role in the development of these different types of malignancies and hematologic disorders. In this paper, data concerning all these problems are presented and discussed.
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PMID:Benzene as a leukemogenic and carcinogenic agent. 402 42

In a short-term (6 h/day X 6 days) benzene inhalation dose-response study, mitogen-induced blastogenesis of both B- and T-lymphocytes in male, C57Bl mice was observed to be significantly depressed at relatively low levels of benzene. Exposure to 10 ppm benzene resulted in a significant depression in femoral lipopolysaccharide (LPS)-induced B-colony-forming ability, while total numbers of B-lymphocytes at this concentration were not significantly depressed. Similarly, splenic phytohemagglutinin (PHA)-induced blastogenesis was significantly depressed at 31 ppm, without a concomitant significant depression in numbers of T-lymphocytes. These data indicate that concentrations of benzene at or near the current standard for occupational exposure (10 ppm) can affect certain immune-associated processes.
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PMID:Depressions in B- and T-lymphocyte mitogen-induced blastogenesis in mice exposed to low concentrations of benzene. 660 67

The influence of different kinds of industrial solvents on the vestibular function of rats has been studied by recording nystagmus, induced by accelerated rotation. The effect was related to the blood levels of the solvents. One group of solvents, including halogenated saturated hydrocarbons like dichloromethane, caused depression of the vestibulo-oculomotor reflex (VOR). Another group, including benzene compounds like xylene, toluene, styrene and cumene and halogenated unsaturated hydrocarbons like trichloroethylene caused an excitation of the VOR. The most striking chemical similarity between the different solvents in the last group is the occurrence of double-bonds. If the animals were exposed simultaneously to solvents from both groups the excitatory effect prevailed and was even potentiated. It is suggested that solvents cause depression or excitation of the VOR by interaction with central pathways in the reticular formation and the cerebellum.
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PMID:Vestibulo-ocular disturbances in rats exposed to organic solvents. 660 11

Exposure of C57Bl mice to 10 ppm benzene (the current occupational exposure limit) for 6 h/day, 5 days/week causes a progressive depression in the in vitro colony forming ability of one of the erythroid progenitor cells, the colony-forming unit-erythroid (CFU-E). Colony growth of cells from exposed mice was only 5% of control colony growth after 178 days of exposure. Burst-forming-cell growth was depressed to 55% of control growth after 66 days but returned to control growth values at 178 days. In addition, benzene-exposed mice exhibited depressions in the numbers of splenic nucleated red cells and in the numbers of circulating red cells and lymphocytes. These results suggest that low-level exposure to benzene may be hematotoxic.
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PMID:Repeated exposure of C57Bl mice to inhaled benzene at 10 ppm markedly depressed erythropoietic colony formation. 670 20

Leaves of Kalanchoe daigremontiana, K tubiflora, K fedtschenkoi, K tomentosa, K tomentosa X K beharensis, and 4 cultivars of K blossfeldiana were tested for toxicity to 2-week-old Leghorn chicks. These species were analyzed for percentage of alkaloids, aliphatic nitro compounds, soluble oxalates, and nitrates and were examined qualitatively for cyanogenic glycosides. The solubility of the toxic principle in K daigremontiana was determined. Leaves of K daigremontiana, K tubiflora, and K fedtschenkoi were toxic to chicks at dosage levels of 8 to 12 mg/g of body weight. Toxic signs included depression, muscular incoordination, twitching and spiraling of the neck, tremors, convulsions, paralysis, and death. Kalanchoe tomentosa, K tomentosa X K beharensis, and 4 cultivars of K blossfeldiana were nontoxic at the highest dosage levels tested. Aliphatic nitro compounds and cyanogenic glycosides were not detected in any species. Alkaloids, nitrates, and soluble oxalates were present only in nontoxic concentrations. The toxic principle in K daigremontiana was soluble in 50%, 80%, and 100% ethanol, slightly soluble in water and acetone, and insoluble in benzene, chloroform, and ether.
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PMID:Toxicity of Kalanchoe spp to chicks. 671 83

Respiratory symptoms and spirometric pulmonary function data [i.e., first-second forced expiratory volume (FEV1.0) and forced vital capacity (FVC)] for 128 (30%) males who were exposed to alkyl benzene sulphonate in a detergent factory and for 56 (76%) unexposed workers in the same factory are reported herein. Exposed subjects had been employed for 1 month to 15 yr, and they generally complained of cough and mucus secretions, nasal catarrh, chest pain, and breathlessness. Unexposed workers had been employed for 1 month to 13 yr and had a significantly lower (P less than .001) frequency of symptoms, as well as significantly higher (.01 greater than P greater than .001) FEV1.0 and FVC than the exposed workers. The reduction in pulmonary function of exposed subjects from the predicted was significantly higher (.01 greater than P greater than .001) than that experienced by the unexposed subjects. There was a significant 8-hr workshift depression in lung function. There was radiological evidence of pulmonary fibrosis, but lack of pre-employment chest radiographs renders this inconclusive. Respiratory symptoms in exposed subjects decreased with duration of employment, which probably indicates the exodus from the work force of those who could not tolerate the nonsoapy detergent.
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PMID:Pulmonary function of exposed and control workers in a Nigerian nonsoapy detergent factory. 672 84

Chronic exposure of animals to benzene results in lymphocytopenia and bone marrow depression. A highly sensitive microculture system was developed to amplify and characterize marrow mitogen response which depended on the isolation of cells by Percoll continuous density gradient centrifugation and strict adherence to optimal culture conditions. Maximal mitogen responses to phytohemagglutinin (PHA) and concanavalin A (con A), as assessed by (3H)-thymidine uptake, occurred at later times in rat bone marrow cultures (days 5-7 of culture) compared with spleen and thymus (days 2-3). Compared with spleen and thymus, the PHA: con A stimulation ratio was inverted for marrow, yet the responsive cells were morphologically identical to those of peripheral lymphoid organs. Populations enriched in lymphoid precursors were inhibited from responding to PHA stimulation at noncytotoxic concentration (less than microM) of the benzene metabolites, p-benzoquinone or 1, 2, 4-benzenetriol. Pretreatment with less than microM concentrations of metabolite resulted in a modulation of lectin-induced responses such the blastogenesis was induced at higher concentrations of lectin relative to untreated cells. These changes indicate that known metabolites of benzene induce a concentration dependent modulation of differentiation and proliferation in lectin-stimulated cells from rat bone marrow in vitro.
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PMID:Effect of benzene metabolites on phytohemagglutinin-stimulated lymphopoiesis in rat bone marrow. 706 19

The chemical and biological properties of several lipophilic derivatives of 99mTc(Sn)pyridoxylidenephenylalanine were investigated, and some clearcut structure distribution relationships (SDRs) were derived from the results: (i) An increase in total lipophilicity of the complex molecule decreases its urinary excretion after intravenous administration. (ii) A lipophilic substituent in the para position of the benzene ring of the phenylalanine moiety decreases the urinary excretion of the complex, but it delays the hepatobiliary transit. (iii) A lipophilic substituent in the ortho position accelerates the hepatobiliary transit along with the depression of the urinary excretion. (iv) When both para and ortho positions are occupied by lipophilic substituents, the ortho-effect (acceleration) is predominant over the para-effect (inhibition) on the hepatobiliary transit. These SDRs are discussed in terms of the chemical structure of the complex molecules, and guide-lines for designing new 99mTc-labeled hepatobiliary agents are proposed.
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PMID:Lipophilic derivatives of 99mTc(Sn)pyridoxylidenephenylalanine: a structure distribution relationship (SDR) study on technetium-99m complexes. 715 10


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