Structural invariance of constitutively active and inactive mutants of acanthamoeba myosin IC bound to F-actin in the rigor and ADP-bound states

The three single-headed monomeric myosin I isozymes of Acanthamoeba castellanii (AMIs)-AMIA, AMIB, and AMIC-are among the best-studied of all myosins. We have used AMIC to study structural correlates of myosin's actin-activated ATPase. This activity is normally controlled by phosphorylation of Ser-329, but AMIC may be switched into constitutively active or inactive states by substituting this residue with Glu or Ala, respectively. To determine whether activation status is reflected in structural differences in the mode of attachment of myosin to actin, these mutant myosins were bound to actin filaments in the absence of nucleotide (rigor state) and visualized at 24-A resolution by using cryoelectron microscopy and image reconstruction. No such difference was observed. Consequently, we suggest that regulation may be affected not by altering the static (time-averaged) structure of AMIC but by modulating its dynamic properties, i.e., molecular breathing. The tail domain of vertebrate intestinal brush-border myosin I has been observed to swing through 31 degrees on binding of ADP. However, it was predicted on grounds of differing kinetics that any such effects with AMIC should be small [Jontes, J. D., Ostap, E. M., Pollard, T. D. & Milligan, R. A. (1998) J. Cell Biol. 141, 155-162]. We have confirmed this hypothesis by observing actin-associated AMIC in its ADP-bound state. Finally, we compared AMIC to brush-border myosin I and AMIB, which were previously studied under similar conditions. In each case, the shape and angle of attachment to F-actin of the catalytic domain is largely conserved, but the domain structure and disposition of the tail is distinctively different for each myosin.     

Does pelvic irradiation play a role in the management of prostate cancer?

The optimal management of patients with lymph node-positive prostate cancer remains controversial. The role of pelvic irradiation in patients at high risk for nodal involvement continues to be debated. Studies of prostate irradiation with and without inclusion of the pelvic lymph nodes show poor outcomes for node-positive patients, supporting the concept that many of these patients have systemic disease at presentation. Although no randomized trial has examined the role of pelvic irradiation in pathologically node-positive patients, available data fail to reveal any significant benefit of this approach over prostate-alone irradiation. More promising therapeutic approaches involve the combination of local therapy and sustained hormonal therapy. Series comparing prophylactic irradiation of the pelvis and prostate to irradiation of the prostate alone have shown no clear benefit of pelvic irradiation. Pelvic irradiation may play a role in the treatment of early-stage or occult nodal disease, although this has yet to be examined. Until prospective, randomized trials demonstrate the efficacy of pelvic irradiation in the management of prostate cancer, its use cannot be routinely recommended. Data support the use of lymphadenectomy in high-risk patients to identify those with positive nodes, since these patients require androgen withdrawal therapy.     

Working in addictions treatment services: some views of a sample of service providers in Ontario

Respondents in a survey of specialized addiction treatment providers indicated a strong commitment to the addictions field. In a multivariate analysis, intention to stay in the addictions field was positively related to a measure of attitudes toward staying or leaving, to age, involvement in an addictions studies program, working in a residential service, and job satisfaction. Intention to stay was negatively related to education and working in a nonresidential setting. Attention to factors that create positive attitudes to the addictions field, especially among younger, more educated people and those working in nonresidential services, is necessary to ensure a healthy future for addictions treatment.     

Glutathione metabolism and glutathione S-conjugate export ATPase (MRP1/GS-X pump) activity in cancer. II. Cell-to-cell variability, relation with cellular activation state and functional absence of GS-X pump in lymphocytes

A severe complication in late-stage cancer patients is host immunosuppression. It is suggested that overproduction of the highly cytostatic and cytotoxic antiproliferative cyclopentenone prostaglandins (CP-PGs) within the plasma of cancer-bearing subjects may contribute to immunosuppression. Lymphoid tissues of Walker 256 tumor-bearing rats accumulate large amounts of CP-PGs while the tumor tissue itself does not. Moreover, tumor cells may present differential sensitivity to CP-PGs due to the expression of the multidrug resistance-associated protein (MRP1) gene product which shows a Mg(2+)-dependent vanadate-sensitive glutathione S-conjugate export ATPase (GS-X pump) activity that extrudes CP-PGs from cells as glutathione S-conjugates. In this study, the possibility that deficient GS-X pump activity in immune cells that may be involved in the accumulation of CP-PGs is investigated. Rat lymph node lymphocytes do not exhibit any notable activity even when mitogen-stimulated. Conversely, although rat peritoneal resident (quiescent) or thioglycollate-stimulated (inflammatory) macrophages exhibit low GS-X pump activity, Bacillus Calmette-Guérin (BCG)-activated macrophages show a notable rise in the activity of the ATPase, suggesting that the cellular activation state may modulate GS-X pump activity/expression and that, under appropriate stimuli (e.g., during immune response) macrophages may provide a self-defense against electrophilic CP-PGs by forming GS-conjugates that can be extruded from cells through the GS-X pump. ras oncogene expression may be linked with MRP1/GS-X pump expression/activity, since C2C12 promyoblasts transformed by v-H-ras transfection doubled GS-X pump activity. These results support the proposition that the accumulation of CP-PGs and the immunosuppression of tumor-bearing subjects may be attributed to a lack of GS-X pump activity/expression in lymphocytes.     

Analysis of tumor-infiltrating lymphocytes in cutaneous squamous cell carcinoma

OBJECTIVE: To characterize tumor-infiltrating lymphocytes (TILs) within lesions of cutaneous squamous cell carcinoma (SCC) and related disorders. DESIGN: Case series with 1- and 2-color immunohistologic, molecular biological analysis of T-cell clonality and in vitro cytotoxicity assays. SETTING: Academic medical center. PATIENTS: Twenty-one patients, including 6 with actinic keratoses, 4 with SCC in situ, and 11 with invasive SCC. RESULTS: CD8+ TILs were present within lesions of cutaneous SCC and AK. These cells constituted a variable minority of the total T-cell infiltrate, and many expressed a phenotype consistent with major histocompatibility complex-restricted cytotoxic T lymphocytes: CD3+, TIA1+, CD16-, CD56-, CD57-. They also expressed HLA-DR, suggesting their activation in vivo. Virtually all T cells were T-cell receptor (TCR)-beta + delta, indicating that they expressed the TCR-alpha beta protein heterodimer. Molecular biological analysis of TCR-gamma gene rearrangements by the polymerase chain reaction and denaturing gradient gel electrophoresis technique indicated that the TILs were polyclonal. Functional studies suggested that TILs derived from SCC lesions were cytotoxic for autologous tumor cell targets. CONCLUSION: Tumor-infiltrating lymphocytes within cutaneous SCC lesions contain a subpopulation of polyclonal, major histocompatibility complex-restricted cytotoxic T lymphocytes expressing the TCR-alpha beta heterodimer.     

Sequential steps in hematogenous metastasis of cancer cells studied by in vivo videomicroscopy

Understanding metastatic spread of cancer is of upmost importance to developing successful strategies to treat this disease. In this review, we present a picture of the process of hematogenous metastasis from the initial arrest of cancer cells, their extravasation, postextravasation migration, and their replication to form tumors, based on experimental results using in vivo videomicroscopy. The cancer cells are initially arrested by size constraints within minutes of entering the circulation and with little hemodynamic destruction. Within 24-48 h >80% of these cancer cells extravasate as single cells by adhesion to and spreading along the vessel wall, often using pseudopodial projections to move into the surrounding tissue without disrupting the microcirculation. Some of the extravasated cells also use pseudopodial projections to migrate to specific structures in the tissue where they can replicate. Many cancer cells can persist as dormant cells, neither dividing nor undergoing apoptosis. Only a small fraction of extravasated cells begin to divide to form micrometastases, and only a very small fraction of these micrometastases continue to grow to form tumors. Possible clinical implications are that (1) initial arrest and extravasation may be difficult to prevent and thus may be poor therapeutic targets; (2) dormant single cells will not be affected by conventional cancer therapies which are designed to treat actively growing cells; and (3) regulation of growth of cells after extravasation is key to determining whether clinically evident metastases form - this stage of metastasis thus offers promising targets for new antimetastasis drugs.     

Late reopening of successfully treated macular holes

We report on preoperative estimation of operative risk, principally rating liver injury in chronic liver disease, c.g., chronic hepatitis and cirrhosis, for liver resection and general surgery. Regarding general surgery, elective and standard operation are possible in Child A and operations with measures to lessen intraoperative blood loss and lymphadenectomy in Child B, but in Child C, surgery is limited to emergency palliative operations, and conservative treatment methods must chosen. In liver resection and major surgery it is important to estimate extent of liver resection and operative risk, primarily by R15 and KICG, and make an overall judgment based on fibronectin, hyaluronic acid, sinusoidal endothelial cell function measured by thrombomodulin, sigma IRI in the 75g OGTT, Fischer's ratio and other indices of lipid metabolism. Generally, surgery limits are: KICG, 40%. Conventional indices of hepatic reserve should be reviewed. Indices recently attracting interest in liver resection cases are quantitative 99mTC-galactosyl human serum albumin scintigraphy using liver cell surface asialoglycoprotein receptor, and functional hepatic resection rate using 99mTC-GSA SPECT images, which is important in estimating liver regeneration after percutaneous trashepatic portal embolization.     

5-HT1A receptor activation: short-term effects on the mRNA expression of the 5-HT1A receptor and galanin in the raphe nuclei

Systemic administration of the 5-HT1A receptor agonist 8-OH-2-(di-n-propylamino)-tetralin (8-OH-DPAT; 0.3 mg/kg, s.c.) was used to explore the effects of activation of 5-HT1A receptors on expression of mRNA coding for 5-HT1A receptor, tryptophan hydroxylase (TPH) and galanin in the ascending raphe nuclei. 8-OH-DPAT increased the hybridization signal of the 5-HT1A receptor by 105% in the dorsal raphe nucleus (B7) 30 min after the injection. No effects were seen at the later time points (2-8 h). In the median raphe nucleus (B8) and the B9 cell group in the medial lemniscus, 8-OH-DPAT induced a marked decrease in labeling 30 min after injection. At 8 h following 8-OH-DPAT injection, the effect had shifted to an increase in 5-HT1A receptor labeling by 68% in the B8 area. Importantly 8-OH-DPAT had no significant effects on the expression of mRNA coding for TPH and galanin. The results suggest an important and differential mechanism for the regulation of 5-HT1A receptor mRNA levels in the dorsal and median raphe nuclei. This regulation may be of importance for the differential control of the activity of the ascending 5-HT neurons, and hence for mood regulation. The results also indicate a dissociation between the effects mediated by 5-HT1A receptor functions and those regulating the coexisting peptide galanin in the dorsal raphe.