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

Three different doses of bleomycin (BLM) (2,1, and 0.01 mg/animal) were injected ip into groups of hairless mice. Cell kinetic alterations in the basal layer of the epidermis were studied up to 10 days after BLM administration. The two highest doses of BLM affected the epidermal cell kinetics in a similar way but with different time courses. Only a moderate depression of the labeling index was observed during the first 24 hours. The results indicate that cells affected by BLM in the middle of the G1 phase are arrested in their subsequent S phase, and that thereafter an increase in the rate of DNA synthesis may occur in the arrested cells without increasing the number of cells in S phase. The percentage of cell accumulated in S and G2 phases as determined by flow cytofluorometry never exceeded 130% of control values with any of the doses. Phase durations were determined from percentage of labeled mitoses curves after the highest dose of BLM and were not significantly different from normal values, indicating that the accumulated cels are probably out of cycle and unable to proliferate again. Calculations based on cell counts and mitotic rate showed that the cells had a prolonged lifespan. No block and subsequent release of cells specifically caused by BLM were observed. BLM has a complex effect on the epidermis, and therefore does not seem to be a promising agent for cell synchronization as a basis for combination chemotherapy in vivo.
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PMID:Epidermla cell kinetics in hairless mice after bleomycin. I. Perturbations after different single doses. 7 87

Variations in epidermal chalones after a single surface application of methylcholanthrene have been described in previous papers. This paper reports a study of the effect of croton oil on epidermal growth regulators (G1 and G2 chalones). Hairless mice received a single topical application of 0.2 ml 0.25% acetone solution of croton oil. Control mice received only acetone. The short-term effect of croton oil on epidermal DNA synthesis and mitotic rate was studied. Other groups of croton oil-treated and acetone-treated mice were then killed at similar time intervals, and the treated area of skin was homogenized and extracted with water. The inhibitory effect of these extracts on normal epidermal DNA synthesis and mitotic rate was assayed in normal hairless mice. The resulting inhibition was interpreted as an expression of the concentration of G1 and G2 chalones, respectively, in the skin extracts. The first experiment confirmed that a single croton oil application provokes a short block in epidermal mitotic activity and probably also in DNA synthesis. This was followed by bimodal peaks of increased activity, the two maxima of mitotic rate on days 2 and 7. The concentration of the two chalones in the skins of treated animals varied in inverse proportion to the alterations in the DNA synthesis and the mitotic rate, with one exception. There was here initially a depression both of the mitotic rate and a low concentration of G2 chalone. This was interpreted as a short, initial direct effect of croton oil on the G2 chalone present at the time of application. It is concluded that croton oil application injures and kills epidermal cells, with subsequent alterations in the content of G1 and G2 chalones. This theory may explain the changes observed. The effects of croton oil on the amount of G1 and G2 chalones in the skin are probably related to the direct, toxic, cell-killing effect of croton oil, and not to its specific cancer promoting potency.
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PMID:Effects of croton oil on epidermal growth regulators (chalones). 13 13

Variations in epidermal chalones after a single surface application of methylcholanthrene and croton oil have been described in previous papers. This paper reports a study of the effect of adhesive tape stripping of the skin on epidermal growth regulators (G1 and G2 chalones). Pieces of adhesive tape were applied 6 times to the same area of skin in groups of mice. The short-term effects of tape stripping on epidermal DNA synthesis and on mitotic rate were studied at different intervals after stripping. Other groups of mice were killed at similar time intervals after stripping, and the treated area of skin was homogenized and extracted with water. The inhibitory effect of these extracts on normal epidermal DNA synthesis and mitotic rate was assayed in normal hairless mice. The resulting inhibitions were interpreted as an expression of the concentration of G1 or G2 chalone in the skin extracts. The first experiment confirmed that cellophane tape stripping gives rise to a short block in epidermal mitotic activity and probably also in DNA synthesis. This was followed by bimodal peaks of increased activity, the two maxima of labelling index being found on days 2 and 6, and the two maxima of mitotic rate on days 1-2 and 7. The concentrations of the two chalones in the skins of treated animals varied in inverse proportion to the alterations in the DNA synthesis and the mitotic rate, with one exception. Here there was initially a depression of the mitotic rate and a low concentration of G2 chalone. This was interpreted as a short reaction of the basel cells to the stripping trauma. It is concluded that adhesive tape stripping removes the differentiating cells and injures some basel cells, simultaneously altering the content of G1 and G2 chalones. The resulting increase in the rates of DNA synthesis and mitosis lasts only until the number of cells is high enough to produce growth-regulating substances (chalones) again. This theory may explain the changes observed. Since similar reactions are seen after both carcinogenic and co-carcinogenic chemical injury of the epidermis, the reaction pattern seems to be a general response to cell injury or cell removal.
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PMID:Effects of cellophane tape stripping of mouse skin on epidermal growth regulators (chalones). 14 79

The potent skin tumor promoter (12-O-tetradecanoyl phorbol-13-acetate (TPA) stimulates epidermal macromolecular synthesis as well as proliferation, but little is known of specific functional aberrations produced by TPA. This report presents results of a study on the effects of TPA on epidermal histidase (L-histidine ammonia lyase), an enzyme found in normal epidermis but not in dermis or in mouse squamous cell carcinomas. Histidase activity was assayed on postmitochondrial supernatants obtained from hairless mouse epidermis after removal by keratotome. Topical TPA treatment at doses active in tumor promotion (1.7 to 17.0 nmoles/application) produced dose-dependent decreases in epidermal histidase specific activity at 19 hr posttreatment. The onset of the decrease occurred at 12 hr with recovery to control level specific activity by 5 days, showing kinetics similar to those obtained for stimulation of DNA synthesis. This decrease in histidase could not be attributed to a general inhibition of soluble protein synthesis or to the appearance of an inhibitor of histidase activity. The strong promoter TPA produced a greater histidase decrease than did the moderate promoter and mitogen 12,13-didecanoyl phorbol at equimolar dose, while phorbol, a nonpromoter and nonmitogen, produced no effects on histidase. The relationship of this histidase depression to tumor promotion and not initiation is further indicated by the finding that (a) Tween 60, a structurally unrelated tumor promotor, also produced a decrease in histidase; and (b) the tumor initiator urethan and an initiating dose of 9,10-dimethybenz(a)anthracene showed no effects on histadase activity.
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PMID:Decrease of epidermal histidase activity by tumor-promoting phorbol esters. 118 5

1. The respiratory-related modulation of activity in neurones of the lumbar sympathetic outflow to skeletal muscle, skin and pelvic organs was investigated in anaesthetized, paralysed and artificially ventilated cats, using single- and multi-unit recordings. The activity of the neurones was analysed with respect to the phrenic nerve discharge under various experimental conditions. 2. Neurones tentatively classified as muscle vasoconstrictor and visceral vasoconstrictor neurones exhibited two activity peaks, one caused by baroreceptor unloading during the declining phase of the second order blood pressure waves and a respiratory drive-dependent peak in parallel with inspiration. The two peaks were separated by depressions of activity in early inspiration and post-inspiration. After cutting vagus and buffer nerves the activity peak during inspiration remained and was followed and sometimes preceded by a depression of activity. 3. The majority of the neurones tentatively classified as cutaneous vasoconstrictor neurones exhibited no respiratory modulation in their activity. Others exhibited an activity peak in expiration, an activity peak in inspiration, or a respiratory profile similar to that in muscle vasoconstrictor neurones. During increased respiratory drive (induced by hypercapnia) some neurones with unmodulated activity changed to an inspiratory or an expiratory pattern. Neurones discharging predominantly in inspiration projected preferentially to hairless skin. 4. Neurones which were tentatively classified as sudomotor neurones discharged predominantly in early expiration. 5. Some preganglionic neurones which were tentatively classified as motility-regulating neurones discharged during expiration. The majority of these neurones disclosed no respiratory modulation of their activity. 6. The study shows that different types of neurone of the lumbar sympathetic system exhibit distinct patterns of respiratory modulation in their activity. We conclude that the type and degree of central coupling between respiratory system and sympathetic nervous system may vary according to the destination of the sympathetic neurones.
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PMID:Respiratory modulation of the activity in sympathetic neurones supplying muscle, skin and pelvic organs in the cat. 152 12

Keratinocytes from mouse skin were cultured for a short period in vitro following single or multiple treatments at low dose levels in vivo with the known chromosome-damaging agent triethylenemelamine (TEM). The chemical was applied to the skin of HRA/Skh hairless mice at concentrations corresponding to those reported to initiate cancer in initiation-promotion assays. A significant dose-related depression in keratinocyte cell recovery occurred over the dose range 0.3-1 mg TEM/mouse (single or multiple treatments). Under the same conditions, a dose-related induction of micronuclei was observed using the cytokinesis-block method with cytochalasin B. A similar frequency of micronuclei was detected in binucleate cells from mice treated with single or multiple applications of TEM. Mice held for 12-48 h post-treatment, before removal of skin for in vitro culture, yielded highest micronuclei frequencies. These results indicate that the same target cell population, skin keratinocytes, can be used to investigate both genotoxicity and carcinogenesis, and that micronucleus induction in these cells may be a sensitive signal of skin cancer initiation.
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PMID:Initiating carcinogen, triethylenemelamine, induces micronuclei in skin target cells. 275 23

The effects of ultraviolet irradiation (UVI) (290-400 nm) and/or systemic immunosuppressive drug therapy (azathioprine and prednisolone) on the immunocompetence of the skin of hairless (HRA/Skh-1) mice were investigated. Mice were studied for the density of ATPase+, Ia+ and Thyl X 2+ cells in the dorsal epidermis and contact hypersensitivity (CH) of skin to dinitrofluorobenzene (DNFB). Prednisolone therapy alone and UVI alone each reduced the densities of the three skin immune cell markers and CH responsiveness; azathioprine therapy alone had no such effects. When a suberythemal dose of UVI that induced a moderately depressive effect on these two skin parameters was used, additional azathioprine therapy produced no further depression; additional prednisolone therapy further depressed the densities of ATPase+ and Ia+ cells and CH responsiveness; additional therapy with combined azathioprine and prednisolone induced profound depression of the incidences of the three immune cell markers and of CH responsiveness. These data point to interaction between azathioprine/prednisolone therapy and UVI in depressing local immune function within skin which may contribute to the increased susceptibility of the sun-exposed skin of immunosuppressed kidney transplant recipients to infective and carcinogenic processes.
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PMID:Effects of therapy with azathioprine and prednisolone and ultraviolet irradiation on mouse skin immune function and immune cell markers. 295 83

Groups of hairless (hr/hr) mice were given a single, topical skin application of either 50, 5 or 0.5 micrograms 7,12-dimethylbenz[a]anthracene (DMBA). At different times up to 3 days after treatment epidermal DNA distribution patterns were determined by flow cytometry, and sp. act. of DNA and labeling indices were obtained based on incorporation of [3H]thymidine. Mitotic rates were determined by the Colcemid method, and the number of basal and suprabasal cells were scored in histological sections. All three doses of DMBA led to an early depression in the uptake of [3H] thymidine, associated with an accumulation of cells with S phase DNA content peaking at 16 h. By combining the methods for studying DNA synthesis, it can be concluded that the alterations observed probably were due to a slow rate of DNA synthesis in the S phase cells, rather than to a block at the entrance of cells into the S phase. Three days after the application, DMBA still maintained an effect on the cell cycle progression, at least in the S phase. There was an obvious dose-response relationship in the inhibition of epidermal DNA synthesis. Six hours after application of the two highest doses of DMBA an early increase in the mitotic rate was observed. This short-lasting high mitotic rate was followed by a transient, very brief increase in the number of suprabasal cells. Thereafter a decrease in both the mitotic rate and the number of suprabasal cells occurred, probably caused by the alterations in DNA synthesis. After the lowest dose there was no such early increase in the mitotic rate and no initial, short-lasting increase in the number of suprabasal cells. Hence, this study shows that decreasing doses of DMBA provoke decreasing degrees of the same type of cell kinetic perturbations in the epidermal cell cycle.
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PMID:Cell kinetic effects of low doses of the skin carcinogen 7,12-dimethylbenz[a]anthracene on hairless mouse epidermis. 311 12

A technique for in situ harvesting of the outer table of the skull using a "guided" osteotome is presented. While guards have been placed to control the depth of the blade, additional steps are advised to ensure the highest level of safety in clinical use: Before harvesting the graft, a full set of anteroposterior and lateral x-rays should be examined to determine which areas of the skull are thin and should be avoided. All areas with cranial sutures should be avoided because here the dura is more firmly attached to the inner table making perforation more dangerous. Bone should not be harvested under the hairless forehead region because this results in a visible depression. The surgeon should use the guards as guides to visually monitor the depth of the blade. The surgeon should not attempt the procedure without having a set of three different depths (1 mm, 2 mm, and 3 mm) available. Different skulls have different thicknesses of the outer table, and the technique loses the advantage of safety if an inappropriate depth is used.
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PMID:The harvesting of cranial bone grafts: a guided osteotome. 403 86

Hairless (hr/hr) mice segregating for SJL/J and HRS/J genes (SJL-HRS) were compared to their haired counterparts with respect to immune responsiveness, tumour development and ecotropic murine leukemia virus (MuLV) expression. Homozygosity at the hairless locus did not affect expression of MuLV. There was however, a significant depression of the cellular immune response of these mice as characterized by depressed reactions in phytohemagglutinin, concanavalin A and mixed leukocyte assays. Haired and hairless mice did not differ significantly in response to B-cell mitogens or in production of cytotoxic antibody. The depressed cellular immune response in hr/hr mice is associated with a distinctive histologic type of spontaneous reticulum cell sarcomas. The importance of these results in relation to previous studies of HRS/J hairless mice is discussed.
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PMID:Immunodeficiency and reticulum cell sarcoma in mice segregating for HRS/J and SJL/J genes. 629 51


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