Biomedical subjects

A I Goldman

Publications and source records attributed to A I Goldman.

At least 19 recordsLinked to original sources

PubMed2005

In situ high-energy x-ray diffraction study of the local structure of supercooled liquid Si.

Employing the technique of electrostatic levitation, coupled with high-energy x-ray diffraction and rapid data acquisition methods, we have obtained high quality structural data more deeply into the supercooled regime of liquid silicon than has been possible before. No change in coordination number is observed in this temperature region, calling into question previous experimental claims of structural evidence for the existence of a liquid-liquid phase transition.

Journal Article↗

PubMed2002

Optimization of gene transfer into primitive human hematopoietic cells of granulocyte-colony stimulating factor-mobilized peripheral blood using low-dose cytokines and comparison of a gibbon ape leukemia virus versus an RD114-pseudotyped retroviral vector.

Primitive human hematopoietic cells in granulocyte-colony stimulating factor (G-CSF)-mobilized peripheral blood (MPB) are more difficult to transduce compared to cells from umbilical cord blood. Based on the hypothesis that MPB cells may require different stimulation for efficient retroviral infection, we compared several culture conditions known to induce cycling of primitive hematopoietic cells. MPB-derived CD34(+) cells were stimulated in the presence or absence of the murine fetal liver cell line AFT024 in trans-wells with G-CSF, stem cell factor (SCF), and thrombopoietin (TPO) (G/S/T; 100 ng/ml) or Flt3-L, SCF, interleukin (IL)-7, and TPO (F/S/7/T; 10-20 ng/ml), and transduced using a GaLV-pseudotyped retroviral vector expressing the enhanced green fluorescence protein (eGFP). Compared to cultures without stroma, the presence of AFT024 increased the number of transduced colony-forming cells (CFC) by 3.5-fold (with G/S/T), long-term culture-initiating cells (LTC-IC) by 4.6-fold (with F/S/7/T), and nonobese diabetic/severe immunodeficiency disease (NOD/SCID)-repopulating cells (SRC) by 6.8-fold (with F/S/7/T). Similar numbers of long-term culture-initiating cells (LTC-IC) and SRC could be transduced using AFT024-conditioned medium (AFT-CM) or a defined medium that had been supplemented with factors identified in AFT-CM. Finally, using our best condition based on transduction with the gibbon ape leukemia virus (GaLV)-pseudotyped vector, we demonstrate a 33-fold higher level of gene transfer (p < 0.001) in SRC using an RD114-pseudotyped vector. In summary, using an optimized protocol with low doses of cytokines, and transduction with an RD114 compared to a GaLV-pseudotyped retroviral vector, the overall number of transduced cells in NOD/SCID mice could be improved 144-fold, with a gene-transfer efficiency in SRC of 16.3% (13.3-19.9; n = 6).

Animals↗

PubMed2002

Absolute structure-factor measurements of an Al-Pd-Mn quasicrystal.

A number of X-ray reflections from an icosahedral quasicrystal Al-Pd-Mn have been measured with great accuracy on an absolute basis by making use of Bragg-case diffraction. Since the specimen had high crystal quality, the dynamical theory was used for analyzing the results and to extract structure factors from measured integrated intensities. Good agreement was found between theory and experiment for strong reflections. Anomalous transmission was found to be strong in the 'good' regions of the quasicrystalline specimen and it was measured on an absolute basis, but the small residual strains present in the specimen prevented an accurate comparison between theory and experiment. A detailed discussion is presented on the parameters that mostly affect anomalous transmission in relationship to the adopted structural model.

Journal Article↗

PubMed2001

Optimal continuous sequential boundaries for monitoring toxicity in clinical trials: a restricted search algorithm.

Continuous monitoring of severe adverse experiences can ensure the timely termination of a clinical trial if the therapy is shown to be harmful. In this paper we present methods for choosing a stopping rule for continuous monitoring of toxicity in small trials. They are especially useful for small phase II trials of about 30 patients for monitoring a binary toxicity event that is observed relatively quickly compared to the efficacy outcome. In 1987 Goldman described an algorithm for computing the exact type I error rate (alpha) and power (1-beta) of a specified discrete stopping boundary for sequential monitoring of a study with a fixed maximum number of patients (N) to be enrolled on the experimental therapy. Only an upper boundary was used since trials are only terminated for an excess frequency of toxicity and not for a low rate. By repeated use of this algorithm a stopping rule can be identified which has nearly the chosen level of (alpha) and a reasonable power depending on the design parameters of the study. The work reported here embeds this earlier algorithm as a subroutine in a larger FORTRAN program which searches all boundaries that fulfil constraints on size and power, as specified by the user. The search is restricted so that only those boundaries with size in a small neighbourhood of the chosen alpha are examined and displayed if the power is above a set minimum. These restrictions reduce the number of boundaries examined to only 0.4 per cent of all possible boundaries, thus reducing running time to a practical few seconds. Many such boundaries exist, the one with the largest power can then be chosen for monitoring the trial. The average sample number (ASN) and the expected relative loss (ERL) are also computed. The criterion for choosing may also be based on small ASN or low ERL in addition to power and appropriate alpha.

Algorithms↗

PubMed1999

Effects of phenytoin on cocaine self-administration in humans.

The goal of this pilot study was to determine the effects of phenytoin on cocaine self-administration in a human laboratory model. Subjects were randomized to either phenytoin (n = 6) or placebo (n = 7). Those assigned to phenytoin treatment received a single oral loading dose of 20 mg/kg. The phenytoin and placebo treatment groups did not differ in the number of tokens valued at $5, exchanged for cocaine. Similarly, the cardiovascular and subjective response to cocaine administration did not show a statistically significant treatment effect. In this laboratory model, phenytoin did not alter either the self-administration or effects of cocaine.

Adult↗

PubMed1997

Weekly fluconazole for the prevention of mucosal candidiasis in women with HIV infection. A randomized, double-blind, placebo-controlled trial. Terry Beirn Community Programs for Clinical Research on AIDS.

BACKGROUND: Candidiasis is a frequent complication of infection with the human immunodeficiency virus (HIV); however, few data exist about the natural history, prevention, and treatment of mucosal candidiasis in women. OBJECTIVE: To evaluate the safety and effectiveness of weekly fluconazole prophylaxis for mucosal candidiasis in women infected with HIV. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: 14 sites participating in the Community Programs for Clinical Research on AIDS (CPCRA). PATIENTS: 323 women with HIV infection and CD4+ cell counts of 300 cells/mm3 or less. INTERVENTION: 200 mg of fluconazole per week or placebo. Open-label fluconazole for candidiasis prophylaxis was permitted after two oropharyngeal or vaginal episodes or one esophageal episode. MEASUREMENTS: Development of mucosal candidiasis, clinical and in vitro resistance of Candida species to fluconazole, survival, and adverse events. RESULTS: After a median follow-up of 29 months, 72 of 162 patients receiving fluconazole and 93 of 161 patients receiving placebo had at least one episode of candidiasis (relative risk [RR], 0.56 [95% Cl, 0.41 to 0.77); P < 0.001). Weekly fluconazole was effective in preventing oropharyngeal candidiasis (RR, 0.50 [Cl, 0.33 to 0.74]; P < 0.001) and vaginal candidiasis (RR, 0.64 [Cl, 0.40 to 1.00]; P = 0.05) but not esophageal candidiasis (RR, 0.91 [Cl, 0.48 to 1.72]; P > 0.2). Relative risks were similar for women who had a history of mucosal candidiasis (RR, 0.5 [Cl, 0.35 to 0.75]) and those who did not (RR, 0.69 [Cl, 0.35 to 1.34]). Absolute risk reduction for patients with a history of infection was 25.6 per 100 person-years, which is more than twice the reduction of 11.2 per 100 person-years seen in patients with no history of infection. This difference reflects the higher risk of patients who previously had an infection. Candida albicans was not usually resistant to fluconazole in vaginal specimens in clinical or in vitro settings; such resistance occurred in less than 5% of patients in each group. CONCLUSIONS: Weekly fluconazole (200 mg) seems to be safe and effective in preventing oropharyngeal and vaginal candidiasis. This regimen has a useful role in the management of HIV-infected women who are at risk for recurrent mucosal candidiasis.

AIDS-Related Opportunistic Infections↗

PubMed1996

Response of CD4 lymphocytes and clinical consequences of treatment using ddI or ddC in patients with advanced HIV infection.

The value of CD4 lymphocyte counts as a surrogate marker in persons with advanced human immunodeficiency virus infection during antiretroviral treatment was assessed using longitudinal models and data from the Terry Beirn Community Programs for Clinical Research on AIDS didanosine/zalcitabine trial of 467 HIV-infected patients. Patients with AIDS or two CD4 counts of < or = 300 who fulfilled specific criteria for zidovudine intolerance or failure were randomized to receive either 500 mg didanosine (ddl) daily or 2.25 mg zalcitabine (ddC) per day. Absolute CD4 counts were recorded at study entry and at as many as four visits. Patients were followed for clinical disease progression and survival. At 2 months, the difference in mean CD4 count from baseline was +15.4 cells/mm3 in the ddI group but -1.3 cells/mm3 in the ddC group. Patients assigned to ddI had a greater chance of a CD4 response at 2 months than those on ddC, yet only those in the ddC group with a response showed significant improvement in progression of disease or survival compared with ddC nonresponders, ddI responders, and ddI nonresponders (p = 0.03). We conclude that a CD4 response does not necessarily correlate with improved outcome and is therefore not a useful surrogate marker in these patients.

Antiviral Agents↗

PubMed1994

A comparative trial of didanosine or zalcitabine after treatment with zidovudine in patients with human immunodeficiency virus infection. The Terry Beirn Community Programs for Clinical Research on AIDS.

BACKGROUND: Both didanosine and zalcitabine are commonly used to treat patients with human immunodeficiency virus (HIV) infection who cannot tolerate zidovudine treatment or who have had disease progression despite it. The relative efficacy and safety of these second-line therapies are not well defined. METHODS: In this multicenter, open-label trial we randomly assigned 467 patients who previously received zidovudine and had 300 or fewer CD4 cells per cubic millimeter or a diagnosis of the acquired immunodeficiency syndrome (AIDS) to treatment with either didanosine (500 mg per day) or zalcitabine (2.25 mg per day). RESULTS: After a median follow-up of 16 months, disease progression or death occurred in 157 of 230 patients assigned to didanosine and 152 of 237 patients assigned to zalcitabine, for a relative risk of 0.93 for the zalcitabine group as compared with the didanosine group (P = 0.56), which decreased to 0.84 (P = 0.15) after adjustment for the CD4 count, Karnofsky score, and presence of AIDS at base line. There were 100 deaths in the didanosine group and 88 in the zalcitabine group, for a relative risk of 0.78 (P = 0.09) and an adjusted relative risk of 0.63 (P = 0.003). A majority of patients in each group (66 percent) had at least one adverse event during treatment (153 patients taking didanosine and 157 taking zalcitabine). Peripheral neuropathy and stomatitis occurred more often with zalcitabine and diarrhea and abdominal pain more frequently with didanosine. CONCLUSIONS: For patients with HIV infection who have not responded to treatment with zidovudine, zalcitabine is at least as efficacious as didanosine in delaying disease progression and death.

Acquired Immunodeficiency Syndrome↗

PubMed1992

Exemplary data: sample size and power in the design of event-time clinical trials.

In planning a complex clinical trial with time to event as the outcome, it is difficult to derive the power of the test statistic analytically. In this paper we describe an algorithm for generating exemplary data from an alternative hypothesis that can be used to compute the expected value of a logrank test statistic and its power under that alternative. Exemplary data are nonrandomly computer-generated data that are constructed from a complex stochastic process and have desirable characteristics such as distributional moments similar to those of the process. An algorithm for generating exemplary timed events data is presented and its use in evaluating power for the planning of clinical trials demonstrated. These data represent "expectations" of outcome, data censoring, and censoring event times. A test statistic, z, such as the logrank can be computed from the data. It is distributed asymptotically, N(mu A, 1), under the alternative hypothesis and its value is used to estimate mu A and the power of the test for a given trial scenario. The results compare favorably to results from analytical methods and Monte Carlo simulations published in the literature. The advantages of the method lie in the degree of flexibility in study design, choice of models that describe the timing of events, and the range of testing methods that can be used. Although Monte Carlo methods may appear to have similar flexibility, the exemplary algorithm is more practical because only one data set need be analyzed and the modifications can be achieved without reprogramming.

Algorithms↗

PubMed1991

The cure model and time confounded risk in the analysis of survival and other timed events.

The use of the Kaplan-Meier estimator for the analysis and testing of cure model data is discussed and results are compared with the more commonly used logrank test. The Kaplan-Meier estimator is particularly appropriate for describing the shape of the underlying survival distribution of data from bone marrow transplantation but is also relevant for different types of timed events data from other chronic diseases. The estimate of the event-free fraction by the product limit, may have a bias depending on the extent of follow-up, the parameters of the model, and confounding by competing risk events. The test based on the product limit has appropriate size and is more powerful as long as follow-up is sufficient to minimize the bias. On the other hand, the logrank test, which is optimal for testing differences in time-to-event curves under proportional hazard assumptions, may be inappropriate and misleading for evaluating the difference in event-free fractions under the cure model.

Bias↗

PubMed1991

Matrix engineering.

Matrix engineering is a technology that utilizes hyaluronan (HA, hyaluronic acid) based matrices to control, direct or augment tissue regenerative processes. Hyaluronan and the concept of matrix engineering have become established tools in ophthalmic and orthopaedic medicine. The clinical indications for HA are limited by the physical properties and short residence time of the natural HA molecule. To expand and improve upon its current medical applications, a family of HA derivatives was prepared by chemical modification and cross-linking. Relative to the non-modified HA molecule, the hylan family of polymers provides more versatile physical forms, improved mechanical properties and an extended residence time. Hylan can also be used as a surface coating to improve blood compatibility. The chemical, physical and biological properties of hylans will be reviewed, focusing on the specific therapeutic indications they enable.

Animals↗

PubMed1989

Six-year follow-up of the clinical significance of karyotype in acute lymphoblastic leukemia.

To evaluate the importance of pretreatment karyotype in predicting long-term outcome in acute lymphoblastic leukemia (ALL), we performed a follow-up study of the 329 patients from the Third International Workshop on Chromosomes in Leukemia. Living patients have now been followed a minimum of 6 years. Patients were divided into ten groups according to pretreatment karyotype: no abnormalities, one of the following structural abnormalities [the Philadelphia chromosome, rearrangements involving 8q24, t(4;11), 14q+, 6q-] or, in the remaining cases, modal number (less than 46, 46, 47-50, greater than 50). As previously reported for achievement and duration of complete remission, and overall survival, disease-free survival differed significantly (p less than 0.001) among chromosome groups for both adults and children. Among children, karyotype was an independent prognostic factor for predicting disease-free survival. Because of the long follow-up, we now have been able to utilize statistical models to estimate the percentage of patients cured, according to karyotype alone and combined with other risk factors. Adults with the highest likelihood of cure (21-33%) were those patients with FAB-L1, a leukocyte count of 50,000/microliters or less, and one of the following chromosome groups: greater than 50, 47-50, 6q-, or normal. In children these same characteristics were associated with the highest percentage of cure (58-71% cured). In addition, we identified several groups of children with less than 15% chance of cure who clearly need to be treated as high-risk patients at diagnosis. Future studies of patients who have received risk-adapted therapy based on these chromosome data are needed to determine if more intensive treatment will improve the outlook of patients with cytogenetically unfavorable types of ALL.

Adult↗

PubMed1988

Four- and five-year follow-up results from four seventh-grade smoking prevention strategies.

Recent studies have suggested that a prevention program that addresses the social influences that encourage smoking can be effective in deterring cigarette use by adolescents. This study presents 4- and 5-year follow-up results from two studies which evaluated three variations of this social influences model and compared them to a health consequences program and an existing-curriculum condition. The results suggest that a seventh-grade program, built around the social influences model and taught jointly by same-age peer leaders and local classroom teachers, may reduce 4-year weekly- and daily-smoking cumulative incidence rates, providing the first evidence for any long-term effects for the social influences model. However, the results also suggest that any long-term effects from such interventions are probably limited and may depend heavily on the manner in which the social influences model is translated during the intervention. Additional follow-up studies are needed to clarify the long-term effects of these intervention programs.

Adolescent↗

PubMed1988

Smokeless tobacco use among ninth graders in a north-central metropolitan population: cross-sectional and prospective associations with age, gender, race, family structure, and other drug use.

Smokeless tobacco use was analyzed in relation to demographic factors and to past and current use of tobacco, alcohol, and marijuana in 4,249 ninth graders in the Twin Cities metropolitan area. Smokeless tobacco use was found to be more common among males, particularly whites; among whites relative to blacks; among adolescents from one-parent households; and among those who reported current or prior use of cigarettes, alcohol, or marijuana. Smokeless tobacco use was also very common among the Native Americans and Hispanics sampled. The results suggest that smokeless tobacco may be joining the list of common recreational drugs that have potential for both short and long-term danger to the adolescent user.

Adolescent↗

PubMed1988

Allogeneic bone marrow transplantation for acute leukaemia: comparative outcomes for adults and children.

Advances in both allogeneic marrow transplantation and conventional therapy for acute leukaemia have complicated the choice between bone marrow transplantation (BMT) and other remission treatment options. Because older patients may be more susceptible to BMT-related complications, this study analysed the effect of age on clinical outcome for 149 patients with acute leukaemia in remission receiving allogeneic BMT. Overall projected relapse-free survival at 3 years post-transplant is equivalent for 48 adults (18 years or older) and 101 children (less than 18) at 45.4% (31.1-59.6; 95% confidence interval) and 39.9% (30.1-49.7; 95% C.I.), respectively. Among 73 patients with acute lymphocytic leukaemia (ALL) 35.3% of adults and 30.1% of children survive relapse-free at 3 years. Cox multiple regression analysis demonstrated that higher diagnostic white count, but not pre-transplant extramedullary leukaemia, remission number, or age, was important as an independent adverse clinical prognostic factor for patients with ALL. Overall outcome was better for 76 patients with acute myeloid leukaemia (AML) with 51.6% of adults and 52.9% of children surviving relapse-free at 3 years post-transplant. Cox multivariate regression analysis identified first remission status and lower white cell count, but not patient age, as independent predictors of improved relapse-free survival for AML patients. Adults had greater transplant morbidity, predominantly related to a higher incidence of acute graft-versus-host disease (GVHD), resulting in longer hospital stay. Survival at 100 d, long-term survival and clinical performance status were similar in both age groups. These data suggest that results of allogeneic BMT for adults with acute leukaemia compare favourably with those found in children and are superior to most reports of conventional chemotherapy. Allogeneic BMT remains a reasonable option for remission acute leukaemia patients up to the age of 45.

Adolescent↗

PubMed1987

Comparison of autologous and allogeneic bone marrow transplantation for treatment of high-risk refractory acute lymphoblastic leukemia.

Chemoradiotherapy and transplantation of bone marrow from matched sibling donors have been useful for the treatment of acute lymphoblastic leukemia in patients with a poor prognosis but are not available to some two thirds of patients who do not have a matched allogeneic donor. We undertook this study to compare autologous and allogeneic marrow transplantation in the treatment of such cases. We treated 91 patients with high-dose chemoradiotherapy and followed them for 1.4 to 5 years. Forty-six patients with an HLA-matched donor received allogeneic marrow, and 45 patients without a matched donor received their own marrow taken during remission and purged of leukemic cells with use of monoclonal antibodies. Bone marrow engraftment occurred earlier in patients who received autologous marrow. Recipients of autologous marrow had shorter hospital courses, with significantly fewer peritransplantation deaths than recipients of allogeneic marrow. Post-transplantation relapse of leukemia was the most frequent cause of treatment failure; relapses occurred in an estimated 37 percent of patients with allogeneic grafts in whom graft-versus-host disease developed, 75 percent of patients with allogeneic grafts in whom graft-versus-host disease did not develop, and 79 percent of patients who received autologous grafts. The interval before relapse was significantly shorter in the autologous-marrow group than in the allogeneic-marrow group. Recipients of autologous and allogeneic marrow whose first pretransplantation remissions were short (less than 18 months) had eventual outcomes similar to those whose first remissions were longer than 18 months. Patients with a first remission lasting less than 18 months had an outcome better than that expected with chemotherapy alone. The fractions of "cured" patients were estimated to be 20 percent in the autologous-marrow group and 27 percent in the allogeneic-marrow group--not a significant difference, but because of the limited statistical power of the study, the question of long-term disease-free survival must still be considered open.

Adolescent↗

PubMed1987

Central nervous system involvement in acute nonlymphocytic leukemia. A prospective study of adults in remission.

To identify adults with acute nonlymphocytic leukemia at risk for the development of central nervous system involvement, we performed periodic cerebrospinal fluid examinations on patients in remission. Among 58 consecutive patients monitored during first remission, central nervous system leukemia developed in nine (16 percent). Four patients, including one who was symptomatic, had central nervous system leukemia detected simultaneously with marrow relapse. Five additional patients were asymptomatic and continue to have bone marrow remission. Following central nervous system and systemic treatment, two of these five patients have never had relapse, and three had relapse in the bone marrow five, 10, and 21 months later. Factors at diagnosis associated with the subsequent development of central nervous system leukemia were elevated leukocyte count, serum lysozyme and lactate dehydrogenase, extramedullary infiltration including splenomegaly, and monocytic (FAB M4 or M5a) morphology. In six of 17 patients (35 percent) with monocytic morphology, central nervous system leukemia developed compared with only three of 41 patients (7 percent) with other subtypes (p = 0.02). Discriminant analysis identified leukocyte count, splenomegaly, and M4 or M5a morphology as the most important risk factors and led to a mathematical formula that correctly identified 90 percent of the patients. Although the risk of central nervous system leukemia in adults with acute nonlymphocytic leukemia is too low to justify routine prophylaxis, those patients recognized to be at a greater risk should receive prophylaxis or be monitored closely with periodic lumbar punctures.

Acute Disease↗

PubMed1987

Issues in designing sequential stopping rules for monitoring side effects in clinical trials.

In a clinical trial of a new treatment, severe side effects may be a problem, and the trial may have to be stopped if the incidence is too high. We need to anticipate the need for such a decision to halt the trial early, and possibly design formal stopping rules for an excess of untoward events. The work presented here discusses the issues involved in such monitoring in comparison with more conventional analysis of the outcome variable. Stopping rules are derived by application of the sequential probability ratio test (SPRT), followed by computation of the exact size and power and adjustments of the consequent rules to achieve chosen operating characteristics appropriate to a monitoring situation. Rules are also derived from a Bayesian approach. These rules are applied to an illustrative trial and compared to the actual conditions that lead to the closing the trial.

Bone Marrow Transplantation↗