Evidence for interaction between platelet fibrinogen receptors

Previous analysis of fibrinogen binding to human aspirin-treated gel- filtered platelets yielded upwardly concave Scatchard plots. To ascertain whether this was due to the presence of independent heterogeneous receptor populations binding fibrinogen with different affinities, the dissociation of purified 125I-fibrinogen from ADP- treated gel-filtered platelets was evaluated as a function of receptor occupancy. Dissociation of bound labeled fibrinogen was measured after 50-fold dilution with buffer containing O, 0.2, 0.8, and 2.0 mg/ml unlabeled fibrinogen. Dissociation of labeled fibrinogen increased with increasing receptor occupancy and was biphasic. With buffer alone, 76.0% +/- 5.8% (SD) of labeled fibrinogen dissociated in 30 min, with an initial rate of 0.392 +/- 0.175 min-1; with 0.2 mg/ml fibrinogen, 83.7% +/- 3.9% dissociated, with an initial rate of 0.589 +/- 0.044 min- 1; with 0.8 mg/ml, 91.8% +/- 1.3% of the labeled fibrinogen dissociated, with an initial rate of 0.910 +/- 0.028 min-1; and with 2.0 mg/ml fibrinogen, 97.3% +/- 2.3% of label dissociated, with an initial rate of 1.06 +/- 0.257 min-1 (n=5). The final rates of fibrinogen dissociation were unaffected by unlabeled fibrinogen in the dilution buffer and were not statistically different from the final dissociation rate of 0.015 +/- 0.10 min-1 observed following dilution with buffer alone. These results were neither an artifact of aspirin treatment or gel filtration, as similar observations were made using non-aspirin-treated washed platelets, nor were they an artifact of the purified fibrinogen preparations, because binding studies using whole plasma as the major source of fibrinogen also yielded upwardly concave Scatchard plots. Since the data demonstrate that the initial rate and extent of fibrinogen dissociation are dependent on fibrinogen receptor occupancy, they suggest receptor interactions possibly resulting from receptor clustering or crosslinking. Because the dissociation was biphasic, the results also suggest some heterogeneity among platelet- fibrinogen interactions.     

成都市新都区餐饮具消毒效果监测

为了解餐饮具消毒现状,采用纸片检验法对新都区饮食单位餐饮具消毒效果进行了监测。结果,抽检餐饮单位297户,餐饮具样本1914份,总合格率为73.51％;抽检全部合格的单位占43.43％,全部不合格的单位占8.08％。结果显示,新都区餐饮业消毒效果和卫生状况整体水平较低,其中以中餐业和中等规模餐饮店卫生状况最差。因此,必须加强管理,加大监督监测力度,全面落实消毒和卫生管理制度,改进餐饮业卫生质量。     

Bioavailability of Soil-Bound TCDD: Dermal Bioavailability in the Rat

Bioavailability of Soil-Bound TCDD: Dermal Bioavailability inthe Rat. SHU, H., TEITELBAUM, T., WEBB, A. S., MARPLE, L., BRUNCK,B. DEI ROSSI, D., MURRAY, J., AND PAUSTENBACH, D. (1988). Fundam.Appl. Toxicol. 10, 335-343. 2,3,7,8-Tetrachlorodibenzo-p-dioxin(TCDD), an unwanted by-product formed during the manufactureof hexachlorophene and phenoxyherbicides, has been found asan environmental contaminant in many U.S. and Western Europeansites. This study examines in the rat the degree of dermal absorptionof TCDD bound to soil. Such information would assist regulatoryagencies in evaluating the degree of exposure of humans whocome in contact with TCDD-contaminated soil. Several parameterswhich may influence dermal absorption were studied, includingTCDD dose, duration of contact, presence of crankcase oil asa co-contaminant, and environmentally contaminated vs laboratory-preparedsoil. The dermal penetration of TCDD following 4 hr of contactwith skin was approximately 60% of that following 24 hr of contact(P 0.05). Following 24 hr of contact with the skin, the degreeof dermal uptake of TCDD contaminated soil was approximately1% of the administered dose. Under the conditions of the presentstudy, the degree of uptake does not appear to be influencedto any significant extent by the concentration of TCDD on soil,the presence of crankcase oil as co-contaminants, or by environmentallyvs laboratory-contaminated soil. Although a number of parametersexamined in this study did not significantly influence the degreeof dermal absorption of TCDD in the rat following 24 hr of contactwith the contaminated soil, the unqualified use of the 1% valueto estimate human exposure would overestimate human exposure,since there is general agreement among researchers that ratskin tends to be more permeable than human skin to highly lipid-solublecompounds such as TCDD.     

Neuroprotective effects of pramipexole against tunicamycin‐induced cell death in PC12 cells

• 1 Pramipexole (PPX), a dopamine D2 and D3 receptor agonist, exerts neuroprotective effects via both dopamine receptor‐mediated and non‐dopaminergic mechanisms. In the present study, we demonstrate that PPX reduces the toxicity of tunicamycin, a typical endoplasmic reticulum (ER) stressor, in PC12h cells, a subline of PC12 cells.
• 2 The PC12h cells were treated with 300 μmol / L PPX in the presence of 0.5 μmol / L tunicamycin for 24 h. The neuroprotective effects of PPX against tunicamycin‐induced cell death were evaluated using 3‐(4,5‐dimethyl‐2 thiazoyl)‐2,5‐diphenyl‐2H‐tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) release assays, Hoechst 33258 staining and western blot analysis.
• 3 Tunicamycin (0.2, 0.3 and 0.5 μg / mL) dose‐dependently decreased MTT activity and increased LDH release from PC12h cells. Treatment with 300 μmol / L PPX rescued the tunicamycin‐induced decrease in cell viability.
• 4 Spiperone (10 μmol / L), a dopamine D2 and D4 receptor antagonist, had no effect on PPX neuroprotection against tunicamycin in these cells. Marker proteins of ER stress and apoptosis are known to be upregulated by tunicamycin, but we detected no significant effects of PPX on these factors.
• 5 In conclusion, we speculate that a combination of several mechanisms may be involved in PPX‐induced neuroprotection.

     

Primary Ewing sarcoma: follow-up with Ga-67 scintigraphy

While avid accumulation of gallium-67 citrate and technetium-99m methylene diphosphonate (MDP) occurs initially in most cases of primary Ewing sarcoma, uptake after therapy is less well defined. Thirty patients with Ewing sarcoma who underwent Ga-67 and bone scintigraphy at diagnosis, at completion of therapy, and at relapse from 1978 to 1988 were evaluated. All 30 patients showed less primary site Ga-67 activity following therapy. Twenty-three of 28 patients who underwent corresponding bone scintigraphy showed less uptake, but residual activity was usually more intense than with Ga-67. Avid reaccumulation of Ga-67 occurred in four of five patients with primary site relapse, while patients who underwent bone scintigraphy showed less change. It was concluded that a greater decrease in Ga-67 than in Tc-99m MDP uptake often occurs in patients successfully treated for primary Ewing sarcoma. Information obtained at Ga-67 scintigraphy is most likely to be helpful if results of bone scintigraphy remain abnormal or if occult relapse is suspected.     

Effects of Cardiomyoplasty on Cardiac Growth in Rats

A bstract Background and aim of the study : Cardiomyoplasty (CMP) has been proposed as a treatment for pediatric patients, but restriction of cardiac growth by the muscle wrap is a potential source of concern. This possibility was investigated in an immature animal model. Methods : Six-week-old rats (body weight 203.8 ± 5.4 g, mean ± SEM) underwent either left thoracotomy with CMP (group I, n = 7), or thoracotomy without CMP (group II, n = 8). A third group (group III, n = 7) served as untreated controls. Final measurements were made 20 weeks later after body weights had reached a plateau. Results : Preoperative body weights were not significantly different between the groups. At elective sacrifice, the body weights of animals that underwent surgery did not differ significantly (group I, 558.0 ± 21.5 g and group II, 617.3 ± 20.3 g), but were significantly less than those of control animals (727.6 ± 13.3 g, p < 0.001 and p < 0.01, respectively). Cardiac ventricular weights in the CMP group were significantly less than those of control animals (group I, 1.21 ± 0.06 g; group III 1.45 ± 0.04 g; p < 0.01), but were not statistically different from those of the sham thoracotomy group (group II, 1.36 ± 0.05 g). Mean left ventricular end-diastolic volumes were similar in all groups (group I, 0.67 ± 0.07 mL; group II, 0.66 ± 0.07 mL; and group III, 0.69 ± 0.10 mL; p = ns). Conclusions : A major surgical procedure impairs growth in juvenile rats. No evidence emerged from this study for additional restriction of cardiac development due to cardiac wrapping. However, studies that include stimulated muscle wraps are needed before CMP should be considered for the pediatric age group.     

Immunological effect of aqueous extract of Vernonia amygdalina and a known immune booster called immunace® and their admixtures on HIV/AIDS clients: a comparative study

Objective

To investigate the immunological effect of Vernonia amygdalina (V. amygdalina) leaf extract and immunace^® on HIV infected patients taking highly active antiretroviral therapy.

Methods

Fresh V. amygdalina leaves were collected within Nsukka area in Enugu State. The leaves were rinsed with distilled water. Two handful of cleaned fresh leaves were soaked in 200 mL water and squeezed gently by hand to a mixture. Clients were divided into four groups and each group was given different combination. They took the medication for four weeks. The immune effect was tested against marketed immune booster in some retroviral clients.

Results

The mean absolute CD4 count was increased in the client who took the extract or supplement. And the clients who took both the extract and supplement had a greater increase in the CD4 count. The increased CD4 was significant as compared with the control group (P<0.05). The skin rashes were also improved in the entire groups.

Conclusions

It can be concluded that the aqueous extract of V. amygdalina and immunace or both have immunological effect on HIV infected patients. Therefore, we suggest that the V. amygdalina extract or immunace or both could be used as adjuvant in the management of HIV/AIDS clients.