Flow cytometric method for detecting thiazole orange-positive (reticulated) platelets in thrombocytopenic horses

OBJECTIVE: To evaluate a method for detecting thiazole orange-positive (TO+, reticulated) platelets in equine blood, using flow cytometry. ANIMALS: 16 healthy, equine infectious anemia virus (EIAV)-negative horses and ponies; 9 thrombocytopenic, EIAV-positive horses and ponies; and 2 thrombocytopenic, EIAV-negative horses. PROCEDURE: Blood from healthy and thrombocytopenic horses was collected by jugular venipuncture. Appropriate sample requirement and incubation time for the assay were evaluated, using blood anticoagulated with EDTA or sodium citrate, or platelet-rich plasma in sodium citrate. The sample of blood or platelet-rich plasma was incubated with thiazole orange, and flow cytometric analysis was performed. Percentage of circulating TO+ platelets was determined from fluorescence (FL-1) logarithmic histograms. RESULTS: Healthy ponies (n = 9) had 1.28 to 2.83% (mean +/- SD, 2.03 +/- 0.50%) and horses (n = 7) had 0.9 to 3.44% (2.12 +/- 1.14%) TO+ platelets in circulation. Thrombocytopenic ponies (n = 7) had 11.14 to 48.41% (26.51 +/- 11.99%) and thrombocytopenic horses (n = 4) had 2.33 to 8.52% (6.19 +/- 2.68%) TO+ platelets in circulation. Mean platelet counts for the thrombocytopenic ponies and horses were 24,400 +/- 20,500 and 39,300 +/- 13,500 platelets/microliters, respectively (reference range, 94,000 to 232,000 platelets/ microliters). CONCLUSION: Thiazole orange-positive platelets can be detected in equine blood and percentages of TO+ platelets are increased in thrombocytopenic horses. CLINICAL RELEVANCE: Enumeration of TO+ platelets may prove to be a helpful noninvasive clinical measurement of bone marrow platelet production and aid in the assessment of platelet kinetics in thrombocytopenic horses.     

Cloning, characterization and identification of the gene encoding phosphatidylinositol 4-kinase

The vast majority of AIDS-related deaths are associated with opportunistic infections. For fungal infections, there are few effective antifungals, particularly for systemic use. The discovery that very low doses of the bleomycin family of anticancer chemical congeners compromise the integrity of fungal cell walls led to our approach to identify genes that complement-cell wall defects, and develop methods to facilitate the identification of new antifungals targeted to fungal cell walls. This report describes one of the genes cloned by complementation of the blm1-1 mutation of S. cerevisiae using a YCp50-based yeast genomic library. Characterization and identification of the gene were carried out using drug screening tests, Southern hybridization analyses, DNA sequencing and DNA sequence similarity searches in databases. The gene STT4, is essential for viability and encodes a phosphatidylinositol 4-kinase that plays an important role in the phosphatidylinositol-mediated signal transduction pathway required for cell wall integrity. Like blm1-1 mutant strains, stt4 cells arrest mostly in the G2/M phase of the cell cycle. Further studies using this approach should help us understand the role of PI4-K in maintaining fungal cell-wall integrity, identify additional genes affecting potential target structures in cell walls of opportunistic fungal pathogens in AIDS patients, and assist in drug discovery and antifungal drug design.     

Induction cisplatin/vinblastine and irradiation vs. irradiation in unresectable squamous cell lung cancer: failure patterns by cell type in RTOG 88-08/ECOG 4588. Radiation Therapy Oncology Group. Eastern Cooperative Oncology Group

PURPOSE: To analyze disease failure patterns by pretreatment characteristics and treatment groups in a prospective randomized trial. METHODS AND MATERIALS: Patients with medically inoperable Stage II, unresectable IIIA and IIIB nonsmall cell lung cancer with KPS > or =70 and weight loss < or =5% were randomized to one of three treatment groups: standard radiation therapy with 60 Gy at 2.0 Gy per day (STD RT), induction chemotherapy with cisplatin 100 mg/m2 days 1 and 29 with vinblastine 5 mg/m2 weekly for 5 weeks followed by 60 Gy at 2.0 Gy per day (CT + RT), or hyperfractionated radiation therapy with 69.6 Gy at 1.2 Gy b.i.d. (HFX RT). Of 490 patients enrolled, 458 were evaluable. Minimum and median periods of observation for this analysis were 4 years and 6 years, respectively. RESULTS: Pretreatment characteristics were equally distributed. Toxicities were previously reported. Median survival rates were 11.4, 13.6, and 12.3 months for STD RT, CT + RT, and HFX RT, respectively (log rank p = 0.05, Wilcoxon p = 0.04). Survivals were 20, 31, and 24% at 2 years, and 4, 11, and 9% at 4 years in the STD RT, CT + RT, and HFX RT groups, respectively. There were no differences in local tumor control rates among the treatments. Patterns of first failure showed less distant metastasis (DM) (other than brain) for CT + RT compared to the RT alone arms (p = 0.04). Within squamous cell carcinoma (SCC), DM (other than brain) rates were 43%, 16%, and 38% in SCC for STD RT, CT + RT, and HFX RT, respectively (p = 0.0015). Patients with peripheral/chest wall lesions were significantly more likely to fail first in the thorax when treated on STD RT compared to CT + RT and HFX RT (p = 0.009). Survival rates were similar among the treatment arms for patients with squamous cell carcinoma. Among patients with nonsquamous cell carcinoma, failure patterns did not differ by treatment group, but survival was significantly better in those who were treated by induction chemotherapy (p = 0.04). CONCLUSION: Patients with squamous cell carcinoma treated on the CT + RT arm had a significant reduction of first DM other than brain, but there was difference in survival. Survival favored CT + RT in nonsquamous carcinoma despite similar failure patterns. Reasons for improved survival with CT + RT in NSCLC are not yet available.     

X-ray structures of the MgADP, MgATPgammaS, and MgAMPPNP complexes of the Dictyostelium discoideum myosin motor domain

The three-dimensional structures of the truncated myosin head from Dictyostelium discoideum myosin II (S1dC) complexed with MgAMPPNP, MgATPgammaS, and MgADP are reported at 2.1, 1.9, and 2.1 A resolution, respectively. Crystals were obtained by cocrystallization and were isomorphous with respect to those of S1dC. MgADP.BeFx [Fisher, A. J., et al. (1995) Biochemistry 34, 8960-8972]. In all three structures, the electron density for the entire nucleotide was clearly discernible. The overall structures of all three complexes are very similar to that of the beryllium fluoride complex which suggests that the differences in the physiological effects of ATPgammaS and AMPPNP are due to the changes in the equilibrium between the actin-bound and actin-free states of myosin caused by the lower affinity of AMPPNP for myosin. In S1dC.MgAMPPNP, the presence of the bridging nitrogen prompts the side chain of Asn233 to rotate which disrupts the hydrogen bonding pattern in the nucleotide binding pocket and alters the water structure surrounding the ribose hydroxyl groups. It appears that this change is responsible for the reduced affinity of AMPPNP for myosin relative to ATPgammaS. In contrast to the G-proteins, there is no major change in the conformation of the ligands that coordinate the nucleotide in S1dC.MgADP. This is due to three water molecules that adopt the approximate positions of the three oxygens on the gamma-phosphate and maintain the interactions with the Mg2+ ion and protein molecule. Interestingly, the thiophosphate group is evident in S1dC.MgATPgammaS even though it is slowly hydrolyzed by myosin. This suggests that the conformation observed here and in chicken skeletal myosin subfragment-1 [Rayment, I., et al. (1993) Science 261, 50-58] is unable to hydrolyze ATP and represents the structure of the prehydrolysis weak binding state of myosin.     

CD28 engagement and proinflammatory cytokines contribute to T cell expansion and long-term survival in vivo

To mount a productive response to Ag, CD4+ T cells in mice must divide, differentiate, and survive at least until the Ag has been eliminated. It has been suggested that to accomplish this, T cells must receive two signals, one through their TCRs and a second through CD28. The second signal through CD28 has been thought to fulfill two roles, to stimulate T cell proliferation and to promote T cell survival. In this paper we confirm that CD28 engagement can contribute to vigorous T cell expansion in mice injected with superantigens. However, CD28 engagement does not protect T cells produced during a superantigen-specific proliferative response from undergoing subsequent deletion. Even if CD28 is bound, 4 days after superantigen exposure, the majority of T cells produced in response to superantigen exposure are eliminated in vivo. In contrast, this loss of superantigen-stimulated T cells can be prevented by the inflammatory stimuli created by injection of bacterial LPS. This protection does not require engagement of CD28 by its ligands, B7-1 and B7-2. These data suggest that productive T cell responses in mice involve a number of signals, including those initiated through TCR and CD28, which are primarily involved in the activation and expansion of T cells, and others delivered by proinflammatory cytokines that protect an activated T cell from subsequent deletion.     

Bcl-2-family proteins: the role of the BH3 domain in apoptosis

Bcl-2-related proteins have come to occupy a prominent position in the realm of programmed cell death. Members of this fast-growing family are highly related in one or more specific regions, commonly referred to as Bcl-2 homology (BH) domains. BH domains contribute at multiple levels to the function of these proteins in cell death and survival. Particularly intriguing is the emergence of the BH3 domain as a potent 'death domain' and of a growing subclass of pro-apoptotic proteins with no similarity to Bcl-2 beyond their BH3 homology. Here, the authors classify proteins of the Bcl-2 family on the basis of function and domain organization, discuss the importance of the BH3 domain in protein-protein interactions and in cell death and provide possible explanations for the perceived redundancy in the expression of this subclass of death promoters.     

Venezuelan equine encephalitis and Oropouche virus infections among Peruvian army troops in the Amazon region of Peru

An outbreak of a febrile illness characterized by headache, ocular pain, myalgia, and arthralgia occurred during June 1994 among Peruvian army troops in Northern Peru. On June 14-16, 1994, clinical data and blood samples were obtained from eight soldiers with a febrile illness, and from 26 others who had a history of febrile illness during the past three months. A follow-up blood sample was obtained 107 days later from four of the febrile and seven of the afebrile soldiers. Serum samples were tested for dengue (DEN), Oropouche (ORO), and Venezuelan equine encephalitis (VEE) IgM and IgG antibodies by an enzyme-linked immunosorbent assay (ELISA). Virus isolation was performed by inoculation of newborn mice and Vero cell cultures. Viral isolates were identified by immunofluorescence, ELISA, and nucleotide sequencing. A VEE virus infection was confirmed in three of the eight febrile soldiers, two by virus isolation, and one by serology. Antigenic analysis indicated that one of the virus isolates was similar to VEE subtype I, variety ID, viruses previously isolated in Colombia and Venezuela. Nucleotide sequence data showed that both viral isolates were identical to one another and closely related to VEE ID viruses previously isolated in Peru, Colombia, and Venezuela. Serologic results showed that two of 26 afebrile soldiers had IgM antibody to VEE and four had IgG antibody to VEE; two febrile soldiers had IgG antibody in their first serum samples. Oropouche-specific IgM antibody was detected in one of the eight febrile and five of the afebrile soldiers, and 18 of the 34 soldiers had low titers of ORO IgG antibody titers, which did not meet the diagnostic criteria for confirmed cases. All soldiers were negative for DEN IgM antibody, and 10 had flavivirus IgG antibody that reacted with DEN antigens. These data indicated that VEE ID virus was one of the causes of illness among Peruvians soldiers and that this was the first association of this VEE subtype with human disease in Peru.     

Differential responses to chemoimmunotherapy in patients with metastatic malignant melanoma

An open, multicentre non-randomised study was performed to evaluate the activity and toxicity of combination chemoimmunotherapy, consisting of cisplatin, interleukin-2 and interferon-alpha, in metastatic malignant melanoma. Between March 1992 and September 1993, 28 patients with pathologically proven metastatic malignant melanoma, bidimensionally measurable disease and an Eastern Co-operative Oncology Group score < or = 1 were treated with the combination chemoimmunotherapy. The regimen consisted of cisplatin (100 mg/m2 on day 0), interleukin-2 (Proleukin, Chiron, Middlesex, U.K.) 18 x 10(6)IU/m2/d continuous intravenous infusion on days 3-7 and 17-22, with interferon-alpha (Roferon-A, Roche, Hertfordshire, U.K.) 9 x 10(6) U/d subcutaneously on days 3, 5, 7, 17, 19, 21 during the interleukin-2 infusions. The treatment cycle lasted 28 days. Among 27 assessable patients, 5 patients achieved partial responses, for an overall response rate of 18% (95% CI 6-37%). Median progression-free survival was 44 days (range 8-279) and median overall survival was 264 days (range 41-1432). Differential responses were noted in 41% of patients and responses were more frequent in non-visceral disease (skin, lymph node and soft tissue disease) (P = 0.04). These results indicate that differential responses to chemoimmunotherapy are common in patients with metastatic melanoma. This may account for the broad range of response rates reported in the literature.     

Identification/prediction algorithms for armax models with relaxed positive real conditions

Extended least squares (ELS) algorithms are proposed for ARMAX model identification with the objective of avoiding the positive real condition associated with standard equation error and output error algorithms. This is achieved by an overparametrization at the cost of additional richness requirements on excitation signals, but without introducing ill-conditioning or infinite-dimensional calculations as in earlier methods. Results for the case of D-step-ahead prediction ELS algorithms for ARMAX models are also explored in the paper. Some simulation studies are included to assess the relative performance characteristics of the proposed algorithms, and the nature of the relaxed positive real condition for different degrees of overparametrization N is investigated in detail for second-order noise models.