Bone marrow metastases

This article discusses the clinical significance of bone marrow metastases and the current methods being used to detect tumor cells in marrow. The strategies being investigated for eradicating cancer cells from marrow in patients receiving hematopoietic cell autografts also are reviewed.

Patient access to experimental drugs and AIDS clinical trial designs: ethical issues

Today's clinical AIDS research is in trouble. Principal investigators are confronted with young and frequently highly knowledgeable patients. Many of these people with AIDS (PWAs) are often unwilling to adhere to the trial protocols. These PWAs believe they are ethically justified in breaching trial protocols because they do not consider themselves true volunteers in such trials. PWAs argue that they do not really volunteer because existing legislation prevents them from buying and using experimental drugs or from testing alternative treatment strategies. Their only access to such agents is participation in clinical trials.

Post-war trauma

One of the great delights of general practice is the way we are allowed to share people's lives. Another facet is the humbling experience of having a patient intuitively grasp a concept that you have found difficult to understand. As regular readers of these pages are aware, I am no stranger to emergencies and trauma. Consequently I see and experience critical incident stress at first hand. This gives me some understanding of others' experiences and, I hope, might help me prevent critical incident stress developing into the more severe post-traumatic stress disorder (PTSD) in those under my care. How well I recall that it was only the fall of a marble that prevented me from being conscripted for service in Vietnam. Kerry is a long-standing patient and an old friend (in a small community, if your patients aren't your friends, you do not have too many patients!). He was seeing me for something or other when he told me the following story. I was so impressed that I asked him to write it down. It speaks eloquently of the aftermath of war and how mates help each other deal with it. It also reminds us that there continue to be new crops of returned service-men who need our help.

Stem cell isolation

High-dose chemotherapy with autologous hematopoietic progenitor cell support is increasingly used to treat a variety of malignant diseases. A drawback of this technique is the potential for infusing clonogenic tumor cells with the autograft, producing relapse of the disease in the patient. The use of positive selection techniques to isolate stem cells and thus reduce or eliminate tumor cell contamination has been extensively studied over the past few years. Preliminary clinical results have demonstrated that these procedures deplete 2 to 7 logs of tumor cells and do not impair engraftment. It is too early to assess the ultimate clinical benefit of this strategy. Additional applications of CD34-selection include ex vivo expansion of and gene transfer into hematopoietic progenitor cells and T-cell depletion of allogeneic grafts to reduce the incidence of graft-versus-host disease.

Optimization of gene transfer using cationic lipids in cell lines and primary human CD4+ and CD34+ hematopoietic cells

Cationic lipids offer several advantages for gene delivery, both in vitro and in vivo. However, high-efficiency gene transfer has been demonstrated only for limited cell types. Here, we examine the level of expression of a luciferase reporter gene, delivered using cationic lipids, in both cell lines and primary human cells including peripheral blood mononuclear cells and CD34(+)-enriched hematopoietic cells. Variables shown to affect the efficiency of gene expression included the type of lipid, the amounts of DNA and lipid, the day of assay following transfection, the media used for lipid:DNA complex formation, the cell number, the promoter driving expression of the reporter gene and the physiological state of the cells (e.g., whether or not cells were differentiated). The maximal luciferase expression observed with the primary cells was one to two orders of magnitude lower than that seen in cell lines. Further studies, possibly involving altering the growth conditions for the cells, or using episomal vectors that will allow extrachromosomal maintenance of the DNA, are required to improve the level of transgene expression in the primary human cell types used here.

Neutralising antibodies after streptokinase treatment for myocardial infarction: a persisting puzzle

OBJECTIVE

To determine the development of titres of streptokinase (SK) neutralising antibodies after a single dose of SK, to establish when titres decrease to levels at which a second dose might be effective.

DESIGN

Analyses of blood samples taken from patients at intervals after SK administration.

SETTING

Australian public hospital.

PATIENTS

104 patients with acute myocardial infarction who were treated with SK and 27 controls who were not.

OUTCOME MEASURE

SK neutralising antibodies were measured once in each of the 27 controls and on 166 occasions in the 104 treated patients.

RESULTS

Titres of SK neutralising antibodies rose after SK administration but returned to control levels by 2 years.

CONCLUSIONS

SK might be effective again as a thrombolytic agent as early as 2 years after a single dose. These results are at variance with most previously published data and the reasons for this are not clear. Data evaluating patency rates after standard doses of streptokinase in patients with increased titres of neutralising antibodies are necessary before re-exposure to streptokinase can be recommended.

Considerations in choice of a clinical endpoint for AIDS clinical trials. Terry Beirn Community Programs for Clinical Research on AIDS (CPCRA)

In most clinical trials of antiretroviral therapy for patients infected with HIV, the major outcome variable has been the combined clinical endpoint of any new or recurrent AIDS defining event. We review features of combined endpoints and use data from the Terry Beirn Community Programs for Clinical Research on AIDS (CPCRA) to evaluate this outcome measure in terms of relevance, diagnostic certainty and sensitivity. We conclude that this endpoint is not relevant because: (i) the 19 different events constituting the combined endpoint are equally weighted in analyses even though they vary considerably in terms of risk of death; and (ii) events after the first are ignored, thus the event profile of patients is not taken into account in making treatment comparisons. We also conclude that power may be low with use of this endpoint if treatments under study do not have an immediate impact on disease progression, if some events which occur soon after randomization represent a disease process that has already begun to incubate, or if treatment differences for the various events constituting the combined endpoint are differentially effected by treatment. Since the ease and certainty of diagnosis of each of the 19 events also vary, we recommend that survival be the primary endpoint of antiretroviral trials, and that all opportunistic events experienced by patients, not just the first, be collected and summarized. Trial reports should include comparisons of incidence of each event by treatment group so that readers can rank events as they please. A single summary measure which considers severity and the entire event profile, as described here, would also be useful for assessing the impact of treatments on quality of life. Further research on approaches for weighting and combining multiple outcome measures is needed.

General practitioners and pharmacists interprofessional communication

This draft joint statement by the Royal Australian College of General Practitioners and the Pharmaceutical Society of Australia Ltd is published here for comment as a national initiative. All suggestions received will be considered before a final statement is adopted.

Management of collapse in general practice

In a general practice setting managing the emergency call for a collapsed patient begins with the doctor talking to the caller. This article reviews the steps taken and the equipment needed to ensure a successful outcome when managing a patient who has 'collapsed' outside a practice or hospital setting.

Access to needed follow-up services. Variations among different Medicare populations

BACKGROUND

We developed a new approach to measuring access to care that examines post-hospitalization follow-up care. It reveals differences in receipt of follow-up care among different subsets of the Medicare population.

METHODS

Medicare administrative databases from 1986, 1988, and 1990 were used to construct three retrospective cohorts. Each cohort consisted of patients from a random 1% sample of Medicare beneficiaries admitted with selected conditions that almost always require timely follow-up care. Various "vulnerable populations" within these cohorts were defined on the basis of age, sex, race, and other demographic factors. Merged outpatient records were used to determine receipt of postdischarge follow-up physician services, follow-up services in outpatient departments, and any follow-up care for these different Medicare populations.

RESULTS

Beneficiaries aged 85 years or older, black beneficiaries, Medicaid/Qualified Medicare Beneficiaries, residents of urban core counties, residents of the highest-poverty ZIP codes, and residents of Health Professional Shortage Areas were less likely to receive follow-up physician services. Beneficiaries aged 85 years or older, black beneficiaries, residents of the highest-poverty ZIP codes, and residents of Health Professional Shortage Areas were less likely to receive any follow-up care.

CONCLUSIONS

This method identified some Medicare populations who failed to receive needed follow-up services, suggesting problems with access to care. This method may be useful in tracking changes in access under the new Medicare fee schedule.

Physician incomes under an all-payer fee schedule

This DataWatch estimates physicians' net incomes under various scenarios for universal adoption of the Medicare fee schedule. American Medical Association (AMA) data on physicians' gross incomes by payer are adjusted for differences in fees across Medicare, Medicaid, and private payers. Net income (gross income net of practice costs) is shown under several alternatives. Average net incomes would range from roughly $100,000 to $200,000, depending on specialty and the particular assumptions used. General practitioners' incomes would typically rise, and income differences across specialties would be narrowed significantly. The Medicare fee schedule, as intended, would increase incomes of primary care physicians relative to specialists.

Posterior continuous curvilinear capsulorhexis. An experimental study with clinical applications

The posterior continuous curvilinear capsulorhexis technique has been advocated in cases of posterior capsule rupture during extracapsular cataract extraction. The authors compared posterior continuous curvilinear capsulorhexis with posterior capsular sharp-edged tears. Two different types of forces were experimentally created on the posterior capsule of 30 human eyes obtained after death: (1) implantation and dialing of posterior chamber intraocular lenses (PC IOLs) and (2) increased intravitreal pressure by injection of balanced salt solution. All posterior capsular tears extended toward the equator, causing major capsular defects. In contrast, the posterior continuous curvilinear capsulorhexis remained intact in all cases. This experimental study proves that in cases where an inadvertent posterior capsular tear occurs, a posterior continuous curvilinear capsulorhexis is useful in preventing further capsular damage. Also, in cases where a posterior capsulotomy is indicated, a smooth edge created by a posterior continuous curvilinear capsulorhexis may be useful to maintain the integrity of the capsular bag for PC IOL capsular implantation.