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Biomedical subjects

S O'Brien

Publications and source records attributed to S O'Brien.

At least 181 records · Page 10Linked to original sources
PubMed1996

The multidomain protein Trio binds the LAR transmembrane tyrosine phosphatase, contains a protein kinase domain, and has separate rac-specific and rho-specific guanine nucleotide exchange factor domains.

rho-like GTP binding proteins play an essential role in regulating cell growth and actin polymerization. These molecular switches are positively regulated by guanine nucleotide exchange factors (GEFs) that promote the exchange of GDP for GTP. Using the interaction-trap assay to identify candidate proteins that bind the cytoplasmic region of the LAR transmembrane protein tyrosine phosphatase (PT-Pase), we isolated a cDNA encoding a 2861-amino acid protein termed Trio that contains three enzyme domains: two functional GEF domains and a protein serine/threonine kinase (PSK) domain. One of the Trio GEF domains (Trio GEF-D1) has rac-specific GEF activity, while the other Trio GEF domain (Trio GEF-D2) has rho-specific activity. The C-terminal PSK domain is adjacent to an Ig-like domain and is most similar to calcium/calmodulin-dependent kinases, such as smooth muscle myosin light chain kinase which similarly contains associated Ig-like domains. Near the N terminus, Trio has four spectrin-like repeats that may play a role in intracellular targeting. Northern blot analysis indicates that Trio has a broad tissue distribution. Trio appears to be phosphorylated only on serine residues, suggesting that Trio is not a LAR substrate, but rather that it forms a complex with LAR. As the LAR PTPase localizes to the ends of focal adhesions, we propose that LAR and the Trio GEF/PSK may orchestrate cell-matrix and cytoskeletal rearrangements necessary for cell migration.

Amino Acid Sequence↗
PubMed1996

Total hip replacement: a study of customized prostheses.

The majority of widely used hip prostheses offer a limited range of offset sizes, including 35, 37, 40, 44 and 45mm. These sizes are provided to match the mean population offset which has been reported as 43.0mm (Noble et al 1988). The variability of proximal femoral geometry in terms of offset is consistent with the theory that the geometry of the femur is determined by a large number of genetic and environmental factors (Ericksen 1979). This paper suggests that the range in offset sizes offered by off-the-shelf hip protheses is not sufficient to match the extremes of anatomical offset variability of the Northern Ireland sample studied and that a custom stem that matches more accurately key femoral dimensions such as offset, may be more desirable.

Clinical Nursing Research↗
PubMed1996

Older adults. An 11-year longitudinal study of adult protective service use.

BACKGROUND: Little is known about the epidemiology of adult protective services agency (APS) utilization, the state entities charged with assessment and advocacy for disenfranchised older adults. OBJECTIVE: To determine the prevalence of utilization by older adults and risk factors for APS. METHODS: A longitudinal study using the New Haven Established Population for Epidemiologic Studies in the Elderly population, a cohort of 2812 community-dwelling adults who were older than 65 years in 1982. The main outcome measure was referral to the state ombudsman on aging for protective services. RESULTS: Over the 11-year follow-up period, 209 cohort members (7.4%) were referred to the ombudsman 302 times as protective service cases for a community prevalence of 6.4% after adjusting for the sampling strategy of the cohort. Self-neglect was the most common indication for referral (73% of the cases). While in bivariate analyses a variety of baseline sociodemographic features, functional impairments, medical conditions, and social network factors were associated with APS use, in multivariable analysis only sociodemographic variables remained independent risk factors including low income (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.8 to 3.9), nonwhite race (OR, 2.2; 95% CI, 1.3 to 3.7), and age older than 75 years at cohort inception (OR, 1.9; 95% CI, 1.1 to 3.0). CONCLUSIONS: Prevalence of APS use by older adults is substantial, and sociodemographic features were the most compelling risk factors in our cohort. As the population ages, the number of older adults at risk for abuse, neglect, self-neglect, exploitation, and abandonment will increase; physicians will need to become familiar with APS referral pathways and mandatory reporting laws in their states.

Aged↗
PubMed1996

Characterization of GMP-17, a granule membrane protein that moves to the plasma membrane of natural killer cells following target cell recognition.

Cytotoxic lymphocytes are characterized by their inclusion of cytoplasmic granules that fuse with the plasma membrane following target cell recognition. We previously identified a cytotoxic granule membrane protein designated p15-TIA-1 that is immunochemically related to an RNA-recognition motif (RRM)-type RNA-binding protein designated p40-TIA-1. Although it was suggested that p15-TIA-1 might be derived from p40-T1A-1 by proteolysis, N-terminal amino acid sequencing of p15-TIA-1 immunoaffinity purified from a natural killer (NK) cell line by using monoclonal antibody (mAb) 2G9 revealed that p15-T1A-1 is identical to the deduced amino acid sequence of NKG7 and GIG-1, cDNAs isolated from NK cells and granulocyte-colony-stimulating factor-treated mononuclear cells, respectively. Epitope mapping revealed that mAb 2G9 recognizes the C terminus of p15-T1A-1 and p40-T1A-1. The deduced amino acid sequence of p15-T1A-1/NKG7/GIG-1 predicts that the protein possesses four transmembrane domains, and immuno-electron microscopy localizes the endogenous protein to the membranes of cytotoxic granules in NK cells. Given its subcellular localization, we propose to rename-this protein GMP-17, for granule membrane protein of 17 kDa. Immunofluorescence microscopy of freshly isolated NK cells confirms this granular localization. Target cell-induced NK cell degranulation results in translocation of GMP-17 from granules to the plasma membrane, suggesting a possible role for GMP-17 in regulating the effector function of lymphocytes and neutrophils.

Amino Acid Sequence↗
PubMed1996

Result of interferon-alpha therapy in patients with chronic myelogenous leukemia 60 years of age and older.

PURPOSE: To determine the response rate to interferon-alpha (IFN-alpha) in patients with chronic myelogenous leukemia (CML) aged 60 years and older. PATIENTS AND METHODS: Patients with CML aged 60 years and older included in all protocols with INF-alpha therapy for chronic phase CML at the M.D. Anderson Cancer Center were analyzed. They were treated with human leukocyte or recombinant human IFN-alpha 5x10(6) U/m2 daily alone or in combination with hydroxyurea or IFN gamma. The clinical characteristics of the patients were analyzed and their hematologic and cytogenetic responses to IFN-alpha and survival from the initiation of therapy were determined. Results were compared with those of younger patients treated in the same protocols. Treatment-related toxicity was also analyzed. RESULTS: Thirty-five of 274 (13%) patients included in trials of IFN-alpha-based regimens for CML were 60 years and older. Older patients had a higher percentage of bone marrow blasts (P = 0.04) and basophils (P = 0.09) than younger patients. Sixty-nine percent achieved a complete hematologic remission with IFN-alpha therapy, and 51% had a cytogenetic response, which was major in 26% and complete (Philadelphia chromosome-positive cells = 0%) in 20%, Their median survival was 64 months, and the estimated 5-year survival rate was 62%. These results were not different from those in younger patients. Twenty-two patients (63%) had at least grade 2 toxicity requiring dose adjustment. The most frequent side effects were neurotoxicity in 31% and chronic fatigue in 29%. CONCLUSIONS: Patients with CML 60 years of age and older respond well to IFN-alpha therapy, but experience more toxicity. This therapy should be considered for these patients if they are otherwise in good condition, with careful attention to IFN-alpha toxicity and its management.

Age Factors↗
PubMed1996

Purine analogs in chronic lymphocytic leukemia and Waldenström's macroglobulinemia.

The observation of lymphopenia in children deficient in adenosine deaminase (ADA) led to exploration of an inhibitor of the enzyme in lymphoid malignancies; thus deoxycoformycin was the first purine nucleotide used in human trials. Fludarabine and 2-chlorodeoxyadenosine (2-CdA), agents resistant to deamination by ADA, have been utilized in the past decade. All of these drugs act as competitors for deoxyadenosine triphosphate at the A sites of the elongating DNA strand, terminating DNA synthesis. However, their remarkable efficacy in indolent lymphoid malignancies is not well explained by this mechanism of action. The induction of apoptosis and resultant cytotoxicity may be important in their activity. As a single agent, fludarabine has been associated with overall remission rates as high as 55% in previously treated patients and 79% in previously untreated patients. With this agent, a dosage regimen of 25-30 mg/m2 daily over 5 days seems to be the most effective to date. Fludarabine has shown more favorable remission rates than the traditional salvage regimens incorporating anthracyclines and alkylating agents. Regimens combining fludarabine with mitoxantrone and with doxorubicin have shown minimal therapeutic advantage in CLL, while combination with cyclophosphamide appears promising. Remission rates with deoxycoformycin have been lower than with fludarabine, but studies have been small in patient numbers. The agent 2-CdA, first successful in hairy-cell leukemia, has shown overall response rates in chronic lymphocytic leukemia similar to those seen with fludarabine. Whether or not cross-resistance occurs among the purine analogs has not been fully determined, but occasional patients with disease refractory to fludarabine have responded to 2-CdA. Cumulative myelosuppression and immunosuppression may be experienced however. In the B-cell neoplastic entity, Waldenström's macroglobulinemia, fludarabine therapy in patients previously treated with alkylating agents and/or steroids produced a 36% response rate. Only two previously untreated patients received fludarabine, and both responded. A similar response rate of 40% was seen when 2-CdA was administered to previously treated patients. This response rate increased to 85% in a study of 26 previously untreated patients, making this one of the most effective drugs yet investigated in this condition.

Antineoplastic Agents↗
PubMed1996

Significance of cytogenetic clonal evolution in chronic myelogenous leukemia.

PURPOSE: To describe the incidence and significance of clonal evolution patterns. PATIENTS AND METHODS: We analyzed 264 patients with Philadelphia chromosome (Ph)-positive chronic myelogenous leukemia (CML) who developed clonal evolution between 1967 and 1993. RESULTS: The median survival time following clonal evolution was 19 months. Factors associated with worse survival (P < .01) were as follows: chromosome 17 abnormality or chromosomal translocations other than Ph, high percentage of abnormal metaphases, longer time to clonal evolution, and presence of other accelerated-phase features. A recursive partitioning technique (CART) identified different risk groups. The best group (37 patients; no chromosome 17 abnormality, abnormal metaphases < 16%, and interval to clonal evolution < or = 24 months) had an estimated median survival time of 54 months. The worst two groups included 27 patients with chromosome 17 abnormalities and > or = 36% abnormal metaphases (estimated median survival time, 6 months), and 22 patients with other accelerated features and > or = 16% abnormal metaphases (estimated median survival time, 7 months). The intermediate group had an estimated median survival time that ranged from 13 to 24 months. Prior interferon therapy evaluated within risk groups showed a significant survival advantage only in the intermediate-risk group. A multivariate analysis showed similar results, and identified the following independent poor prognostic variables: chromosome 17 abnormality, percentage of abnormal metaphases (cutoff, 24%), longer time to clonal evolution (cutoff, 24 months), other accelerated-phase features, and no prior interferon therapy. Patients with none, one, two, three, or more of the first four features had median survivals times of 51, 24, 14, and 7 months, respectively. CONCLUSION: The prognostic significance of clonal evolution in CML is not uniform and is related to the specific abnormality, time to its development, its predominance in metaphases, and the presence of other accelerated features, and it may be modified by specific therapies.

Bone Marrow Transplantation↗
PubMed1996

Can one induce premenstrual symptomatology in women with prior hysterectomy and bilateral oophorectomy?

Nine women who had undergone hysterectomy and oophorectomy and who previously suffered from severe premenstrual syndrome (PMS) were given estrogen and progesterone in a naturalistic single-blind paradigm. The 13-item Beck Depression Inventory, Spielberger State Anxiety Inventory, Menstrual Distress Questionnaire and the Daily Ratings Form of the Premenstrual Assessment Form were all given daily. Estradiol and progesterone concentrations were estimated. When results from all subjects were considered together, these measures were not correlated with hormonal status. However, individual subjects showed correlations between some symptom scores and serum progesterone concentrations. We conclude that women diagnosed as having PMS do not respond in a uniform fashion to ovarian hormones. Further quantitative studies are needed to relate these individual differences to the syndrome of PMS.

Drug Therapy, Combination↗
PubMed1996

Practical guidelines for the management of chronic myelogenous leukemia with interferon alpha.

Interferon-A (IFN-A) is an effective agent in the treatment of chronic myelogenous leukemia (CML). Hematologic remissions occur in the majority of patients with newly diagnosed disease, and cytogenetic remissions may occur in up to 50% of patients. Several studies have shown a correlation between the dose of IFN-A and achievement of a major cytogenetic response; this response has also been correlated with prolonged survival. However, IFN-A may be associated with significant side effects that reduce enthusiasm for the use of this drug, produce difficulties in patient compliance, and limit the dose delivered to the patient, thus resulting in ineffective use of IFN-A. Experience with this drug has led to a refinement in techniques for initiation of therapy as well as interventions to deal with side effects. These strategies are often not discussed in publications dealing with response rates and survival. In this review we discuss strategies to minimize toxicity and improve the effectiveness of IFN-A in the treatment of CML.

Antineoplastic Agents↗
PubMed1996

Hodgkin's disease variant of Richter's syndrome: experience at a single institution.

Patients developing Hodgkin's disease (HD) after a diagnosis of chronic lymphocytic leukemia (CLL), are frequently included in a series of patients with Richter's syndrome (RS). We sought to determine the natural history of the association of CLL and HD. Over a 21 year period, 1374 patients with CLL have been registered in our computer data base. Seven cases of CLL and HD have been documented and confirmed. The median age of these patients was 71 years (range 44-77) and clinical features included male gender (86%), B symptomatology (86%), rapidly progressive lymphadenopathy (71%), prior CLL therapy (71%), advanced Ann Arbor stage (86%), marrow involvement with HD (43%), and autoimmune hemolytic anemia (29%). HD was documented by excisional lymph node biopsy in six cases and splenectomy in one. Mixed cellularity HD was shown in six and nodular sclerosis in one. Five of the biopsies revealed intervening areas consistent with small lymphocytic lymphoma. The Sternberg-Reed (SR) cells were CD15+ in 6/7 cases, and Ki-1+ in the 6 patients tested. CD45 and CD20 staining of the SR cells was nonreactive. The median time to development of HD was 45 months (range 0 to 96). The overall responses to different chemotherapy regimens was approximately 25% with only one CR. Six patients have died at 3, 9, 10, 13, 15 and 36 months and one patient is alive with progressive disease at 11 months. Our data suggests that CLL patients have a heightened risk for HD, features of advanced HD on presentation, and a poor response rate with short survival.

Adult↗
PubMed1996

Disseminated intravascular coagulation in adult acute lymphoblastic leukemia: frequent complications with fibrinogen levels less than 100 mg/dl.

In order to establish the frequency and clinical complications of DIC during remission induction of untreated adults with acute lymphoblastic leukemia, we retrospectively reviewed the records of 125 consecutive patients treated with vincristine, doxorubicin, and dexamethasone but without L-asparaginase. DIC, defined as hypofibrinogenemia in the presence of elevated fibrin-fibrinogen degradation products, was detected at presentation in 10% of 99 and during remission induction in 67% of 58 patients who were screened for DIC. Elevated levels of D-dimers (DD) were seen in all eight patients with DIC in whom they were measured. All cases of DIC were diagnosed by the ninth day of induction and were associated with infection in 15 of 39 patients. DIC did not cause any deaths but was temporally associated with two thromboses and four hemorrhages in six of the 16 patients with fibrinogen levels < 100 mg/dl but with only one hemorrhage among 23 patients (4%) with fibrinogen levels > 100 mg/dl (P < 0.01). Heparin was not administered to any patient, whereas platelets were administered to all to maintain platelet counts > 20 x 10(9)/l. Fresh frozen plasma (FFP) and/or cryoprecipitate were administered 26 patients resulting in a contemporaneous correction of the coagulopathy and in control of hemorrhages and thromboses. We conclude that DIC is rare at presentation but common during induction of adult ALL and is frequently associated with clinical complications when fibrinogen levels are < 100 mg/dl. We recommend daily testing of fibrinogen, PT, and DD during the first 10 days of induction, and for the patients with DIC platelet transfusions to maintain counts > 20 x 10(9)/l, and when fibrinogen levels fall below 100 mg/dl transfusions of FFP and/or cryoprecipitate. Additional studies are needed to determine the optimal management of the DIC during remission induction of adult acute lymphoblastic leukemia.

Adult↗
PubMed1996

Secondary acute promyelocytic leukemia. Characteristics and prognosis of 14 patients from a single institution.

The aims of this study were to analyze the characteristics and outcome of patients with secondary acute promyelocytic leukemia (APL) and compare them to those with primary APL. One hundred and thirteen patients referred to our service with a diagnosis of APL were reviewed. Fourteen were classified as secondary APL. Nine were induced with chemotherapy, and five with all-trans retinoic acid plus chemotherapy. Pretreatment characteristics, response to therapy and outcome of primary vs secondary APL were compared by standard statistical methods. Secondary APL constituted 12% of all APL cases. Patients with secondary APL were significantly older (median age 56 vs 36 years; P < 0.01) and had a lower incidence of hypofibrinogenemia (P < 0.01) than those with primary APL. The complete response (CR) rates were similar with secondary vs primary APL (CR rates 79 vs 69%), as were CR duration and survival. The CR rates at 5 years were 57 and 45%, respectively(P not significant), and the survival rates 37 and 35%, respectively (P not significant). The incidence of secondary APL within APL disease (12%) was similar to the incidence of secondary acute myeloid leukemia (AML) in karyotypes not known to be therapy-related (diploid, t(8;21), inversion 16: incidences 9 to 12%), but was significantly lower than in karyotypes known to be therapy-related (chromosome 5 or 7 abnormalities, 11q; incidences 30 and 33%). We conclude that secondary APL has general characteristics and outcome similar to primary APL. it is more likely a second primary rather than therapy-related AML, and should be treated in a manner similar to primary APL.

Adult↗
PubMed1996

Causes of initial remission induction failure in patients with acute myeloid leukemia and myelodysplastic syndromes.

We analyzed 144 of 475 previously untreated patients with acute myeloid leukemia (AML, n = 87) and 'high-risk' myelodysplastic syndromes (MDS, n = 57) who failed to achieve a complete remission with fludarabine- and high-dose cytarabine-containing regimens between 1991 and 1994. The AML and MDS groups were comparable with regard to age, major prognostic indicators, supportive care received, type of antileukemia response and causes of death and were considered together. The causes of death of 118 evaluable patients were compared to a series of 123 AML initial remission induction failures previously reported from our institution. The induction failure rate was significantly lower (30 vs 43% P <0.001). We found a significant decrease in fatal infections (autopsied patients, P = 0.001) and a reduction in bacterial (autopsied and non-autopsied patients, P <0.005) but not fungal (non-autopsied patients, P = 0.93; autopsied patients P = 0.15) infections as causes of induction death. Pulmonary hemorrhage was twice as common in the present report (P < 0.005, with pulmonary hemorrhage almost three times as common as fatal cerebral hemorrhage. A comparison restricted to the AML patients in the present study yielded similar results. We conclude that the mortality profile in AML remission induction has undergone substantial changes at our institution since our last report, probably as a consequence of the introduction of new chemotherapy regimens and supportive care modalities.

Acute Disease↗
PubMed1996

Engraftment of chronic prolymphocytic and T cell leukemia in SCID mice.

Engraftment of human acute leukemia cells in immunocompromised (SCID) mice has resulted in in vivo models for exploration of human tumor biology. Attempts at engraftment of chronic leukemia cells have been generally unsuccessful. We have engrafted cells from three human chronic leukemias in SCID mice. Cell populations were from two patients with chronic lymphocytic leukemia (CLL) and either increased proolymphocytes (CLL-Pro; patient 1), or prolymphocytic transformation (PLL; patient 2) and from a third patient with newly diagnosed T cell CLL. Both fresh and cryopreserved cells were used and were injected intravenously, intraperitoneally, or both, after conditioning with cyclophosphamide. In addition, cells derived from a mouse spleen engrafted with human leukemia were passaged into another mouse. The animals were observed daily for signs of disease or appearance of tumors and sacrificed when terminally ill. At intervals blood samples were obtained and analyzed for the presence of human cells or DNA. Human leukemic cells were demonstrated by polymerase chain reaction (PCR) analysis of the human DQalpha gene or positive staining for human leukocyte common antigen (LCA). The presence of Epstein-Barr virus (EBV)-positive cells was also investigated by PCR analysis. Disseminated tumors developed in most mice inoculated with cells from the first patient, and this was associated with shortened survival times. The methods of administration, use of fresh or frozen samples, or the size of the inoculum had no effect on the development of leukemia. Survival of the mouse receiving passaged cells was similar to mice inoculated with fresh cells. Extensive histologic, immunophenotypic, and DNA studies were performed on organs from mice engrafting with cells from patient 1. PCR analysis for EBV sequences was negative in the mice engrafting from all three cases. The successful engraftment of human CLL-Pro PLL and T cell CLL in SCID mice, and the reproducibility of this effect using frozen cells, will provide a model for exploration of disease biology and for investigations of new drugs or combinations that may be useful in the treatment of CLL.

Aged↗
PubMed1996

Evaluation of CI-973, a platinum analogue, in refractory or relapsed acute leukemia.

The purpose of the study was to define the maximally tolerated dose (MTD), major toxicities, and possible antitumor activity of CI-973 a new platinum analogue, in patients with refractory or relapsed acute leukemia. CI-973 was given as a 5-day continuous infusion every 3 to 4 weeks to patients with refractory or relapsed acute leukemia, at doses ranging from 150 mg/m2 to 1350 mg/m2 per course. Thirty-six patients were treated including 18 patients with acute myelogenous leukemia (AML), four with acute lymphocytic leukemia (ALL) and 14 with chronic myelogenous leukemia in blastic phase (CML-BP). Severe gastrointestinal and renal side-effects were the dose-limiting toxicities occurring in four of five patients treated with CI-973 1200 to 1350 mg/m2 per course. At the MTD of 1000 mg/m2 per course, three of 13 patients treated (23%) had moderate to severe nausea and vomiting, three (23%) had moderate diarrhea and one had moderate mucositis. Among 21 patients treated at > or = 1000 mg/m2 (15 AML, 6 CML-BP) no objective complete or partial responses were observed. Twelve of 18 patients (66%) with evaluable marrows on day 14 showed significant suppression of marrow blasts percentage and marrow leukemic infiltrate percentage. Tests for measurement of DNA adduct formation in leukemic cells in vivo after CI-973 therapy, and in vitro following exposure of leukemic cells to CI-973 were developed. This study defined the MTD of CI-973 to be 1000 mg/m2 by continuous infusion over 5 days every 3 to 4 weeks in patients with refractory or relapsed acute leukemia. Gastrointestinal and renal side-effects were dose-limiting. No objective responses were noted in this heavily resistant population. Correlations between CI-973-induced DNA adduct formation and individual patient response to CI-973 will help to define its role in leukemia subsets.

Acute Disease↗
PubMed1996

Factors predicting complete remission and subsequent disease-free survival after a second course of induction therapy in patients with acute myelogenous leukemia resistant to the first.

Patients with newly diagnosed acute myelogenous leukemia (AML) with persistent leukemia after their first course (CO1) of induction chemotherapy are generally given a second similar course, although their outcome is known to be worse than CO1 responders even when a complete remission (CR) is achieved. To identify specific patients who should or should not receive a second induction course identical to the first we analyzed outcome in 370 patients with persistent AML after CO1 who received a second identical course. One hundred and forty-two (38%) achieved CR on this course; median subsequent disease-free survival (DFS) in these 142 was 29 weeks and 10% were alive in CR at 5 years. The 5-year DFS of CO2 responders was significantly lower than that of CO1 responders (10 vs 24%, P < 0.001). Logistic regression identified pretreatment cytogenetic abnormalities (except inv 16, t(8;21), or t(15;17)), presence of an antecedent hematologic disorder or secondary AML as each having unfavorable prognostic import similar to the case in untreated patients. Treatment with "high-dose' rather than standard-dose cytarabine increased the probability of 2nd course CR. The occurrence of pneumonia, sepsis, or major hemorrhage were prognostically unfavorable, primarily in the high-dose cytarabine group, and, once in CR, DFS was shorter in this group. Equations predicting probability of 2nd course CR were derived. If validated prospectively these could be used to assign patients to either receive a second course of initial induction therapy or to change to salvage or investigational therapy after the first course. Alternatively, they could be used to stratify patients entering a prospective randomized trial comparing these two strategies.

Adult↗