Abstract P4-01-12: Optical imaging of breast density correlates with magnetic resonance imaging in patients undergoing neoadjuvant chemotherapy

Background: In addition to being a strong risk factor for breast cancer, data from recent studies suggests that breast density changes correlate with response to preventative or adjuvant tamoxifen treatment for breast cancer. Breast density may be a surrogate biomarker for survival and indication of the need for additional treatments such as radiotherapy. However, quantitative methods to assess breast density in the clinic are limited. In this study, we assess how Diffuse Optical Spectroscopic Imaging (DOSI) may be used to evaluate and understand changes in breast density in patients undergoing neoadjuvant chemotherapy.

Methods: DOSI was used to measure hemodynamic and metabolic information from the contralateral normal breast of 28 breast cancer patients undergoing neoadjuvant chemotherapy. DOSI uses near-infrared light to determine absolute tissue molar concentrations of oxyhemoglobin (ctO2Hb), deoxyhemoglobin (ctHHb), water, and lipid content without requirement of an exogenous contrast agent. DOSI measurements were compared to 3.0T MRI measured fibroglandular density before and during therapy.

Results: Water (r = 0.843; P<0.001), ctHHb (r = 0.785; P = 0.003), and lipid (r = -0.707; P = 0.010) concentration measured with DOSI correlated strongly with MRI-measured density before therapy. During neoadjuvant treatment measured at ∼90 days after treatment commenced, significant reductions were observed in ctO2Hb for pre- (-20.0%; 95% confidence interval (CI), -32.7 to -7.4) and postmenopausal subjects (-20.1%; 95% CI, -31.4 to -8.8), and water concentration for premenopausal subjects (- 1.9%; 95% CI, -17.1 to -6.7) compared to baseline. Lipid content increased slightly in premenopausal subjects (3.8%; 95% CI, 1.1 to 6.5) and water increased slightly in postmenopausal subjects (4.4%; 95% CI, 0.1 to 8.6). Percentage change in water at the end of therapy compared with baseline correlated strongly with percentage change in MRI-measured density (r = 0.864; P = 0.012).

Discussion: For this patient cohort, non-invasive optical measurement may provide an assessment of breast density and yield additional information that complements MRI and mammography techniques. We demonstrate a strong baseline correlation between water and ctHHb with breast density, reflecting the increased water content and rate of metabolism in fibroglandular breast tissue. Significant changes in optical markers for vascular density and supply (ctO2Hb and water) are observed during treatment. A significant decrease in ctO2Hb is observed in both menopausal groups. The steady reduction of ctO2Hb without a corresponding decrease in ctHHb suggests that chemotherapy agents act directly on the normal breast tissue, perhaps by causing a reduction of perfusion. The greater reduction in breast-tissue water in premenopausal subjects suggests that chemo-reduced ovarian hormone levels may exert a role in reducing breast-tissue density. Although from a limited patient dataset, these results suggest that DOSI may provide new functional indices of breast density based on hemoglobin and water that could be used at the bedside to assess response to therapy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-01-12.

Correlation of endogenous hormonal levels, fibroglandular tissue volume and percent density measured using 3D MRI during one menstrual cycle

BACKGROUND

We measured breast density (BD) on MRI and correlated with endogenous hormonal levels.

PATIENTS AND METHODS

Twenty-four premenopausal women received four weekly breast MRI. A blood sample was collected on the same day of MRI. BD was measured using a computer-based algorithm. The generalized estimation equation method was applied to model mean fibroglandular tissue volume (FV) and mean percent density (PD) from predictor variables including estradiol, progesterone, and week during a cycle.

RESULTS

In week 3, a borderline significant correlation between estradiol and PD (r = 0.43, P = 0.04), estradiol and FV (r = 0.40, P = 0.05) and between progesterone and FV (r = 0.42, P = 0.04) was noted. The FV and PD measured in weeks 4 and 1 were higher than in weeks 2 and 3, adjusted for variation in endogenous estradiol and progesterone, indicating that the hormone change could not account for the changes in density. No lag effect of endogenous hormone on the change of FV or PD was noted (all P-values > 0.05).

CONCLUSIONS

Our results showed that BD is not strongly associated with the endogenous hormone. Their association with breast cancer risk was likely coming from different mechanisms, and they should be considered as independent risk factors.

Role of dietary polyamines in a phase III clinical trial of difluoromethylornithine (DFMO) and sulindac for prevention of sporadic colorectal adenomas

Background:

The polyamine-inhibitory regimen difluoromethylornithine (DFMO)+sulindac has marked efficacy in preventing metachronous colorectal adenomas. Polyamines are synthesised endogenously and obtained from dietary sources. Here we investigate dietary polyamine intake and outcomes in the DFMO+sulindac colorectal adenoma prevention trial.

Methods:

Dietary polyamine data were available for 188 of 267 patients completing the study. Total dietary polyamine content was derived by the sum of dietary putrescine, spermine and spermidine values and categorised into two groups: highest (>75–100%) vs the lower three quartiles (0–25, 25–50 and 50–75%). Baseline tissue polyamine concentration and ODC1 genotype were determined. Logistic regression models were used for risk estimation.

Results:

A significant interaction was detected between dietary polyamine group and treatment with regard to adenoma recurrence (P=0.012). Significant metachronous adenoma risk reduction was observed after DFMO+sulindac treatment in dietary polyamine quartiles 1–3 (risk ratio (RR) 0.19; 95% confidence interval (CI) 0.08–0.42; P<0.0001) but not in quartile 4 (RR 1.51; 95% CI 0.53–4.29; P=0.44). However, a lower number of events in the placebo group within dietary quartile 4 confound the aforementioned risk estimates.

Conclusion:

These preliminary findings reveal complex relationships between diet and therapeutic prevention, and they support further clinical trial-based investigations where the dietary intervention itself is controlled.

Role of obesity in a randomized placebo-controlled, double-blind trial of difluoromethylornithine plus sulindac for the prevention of sporadic colorectal adenomas

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Background: Chemoprevention with difluoromethylornithine (DFMO) plus sulindac markedly reduces risk of recurrence in colorectal adenoma (CRA) patients. Obesity is associated with risk of CRA and colorectal cancer (CRC). This study investigates how obesity influences CRA characteristics at baseline and risk of recurrence after treatment with DFMO plus sulindac vs. placebo.

Methods: Our analysis included subjects enrolled in a phase III CRA prevention clinical trial investigating DFMO plus sulindac vs. placebo. Patients were classified by obesity (BMI > 30 kg/m2) status at baseline. Pearson's χ2 statistic or Fisher's exact test and Mann-Whitney U test were used to compare baseline characteristics with regard to obesity status. Log-binomial regression analysis was used to determine the relative risk of metachronous adenoma, adenoma with advanced histology, or multiple adenomas, adjusted for covariates.

Results: At baseline, obesity was associated with increased adenoma number (p =0.017), size (p =0.003), advanced histology (p =0.042), high-risk adenomas (p =0.0002), and distal adenomas (p =0.038). Obesity did not modify adenoma recurrence after treatment with DFMO plus sulindac or placebo (p =0.80).

Conclusions: Our results provide supporting evidence for the association of obesity with high-risk adenoma features at baseline; however, obesity does not substantially modify CRA risk reduction after treatment with DFMO plus sulindac vs. placebo.

[Table: see text]

[Table: see text]

A genome-wide linkage scan for iron phenotype quantitative trait loci: the HEIRS Family Study

Iron overload phenotypes in persons with and without hemochromatosis are variable. To investigate this further, probands with hemochromatosis or evidence of elevated iron stores and their family members were recruited for a genome-wide linkage scan to identify potential quantitative trait loci (QTL) that contribute to variation in transferrin saturation (TS), unsaturated iron-binding capacity (UIBC), and serum ferritin (SF). Genotyping utilized 402 microsatellite markers with average spacing of 9 cM. A total of 943 individuals, 64% Caucasian, were evaluated from 174 families. After adjusting for age, gender, and race/ethnicity, there was evidence for linkage of UIBC to chromosome 4q logarithm of the odds (LOD) = 2.08, p = 0.001) and of UIBC (LOD = 9.52), TS (LOD = 4.78), and SF (LOD = 2.75) to the chromosome 6p region containing HFE (each p < 0.0001). After adjustments for HFE genotype and other covariates, there was evidence of linkage of SF to chromosome 16p (LOD = 2.63, p = 0.0007) and of UIBC to chromosome 5q (LOD = 2.12, p = 0.002) and to chromosome 17q (LOD = 2.19, p = 0.002). We conclude that these regions should be considered for fine mapping studies to identify QTL that contribute to variation in SF and UIBC.

Initial screening transferrin saturation values, serum ferritin concentrations, and HFE genotypes in Native Americans and whites in the Hemochromatosis and Iron Overload Screening Study

We compared initial screening transferrin saturation (TfSat) and serum ferritin (SF) phenotypes and HFE C282Y and H63D genotypes of 645 Native American and 43,453 white Hemochromatosis and Iron Overload Screening Study participants who did not report a previous diagnosis of hemochromatosis or iron overload. Elevated measurements were defined as TfSat >50% in men and >45% in women and SF >300 ng/ml in men and >200 ng/ml in women. Mean TfSat was 31% in Native American men and 32% in white men (p = 0.0337) and 25% in Native American women and 27% in white women (p < 0.0001). Mean SF was 153 microg/l in Native American and 151 microg/l in white men (p = 0.8256); mean SF was 55 microg/l in Native American women and 63 microg/l in white women (p = 0.0015). The C282Y allele frequency was 0.0340 in Native Americans and 0.0683 in whites (p < 0.0001). The H63D allele frequency was 0.1150 in Native Americans and 0.1532 in whites (p = 0.0001). We conclude that the screening TfSat and SF phenotypes of Native Americans are similar to those of whites. The allele frequencies of HFE C282Y and H63D are significantly lower in Native Americans than in whites.

Relationship between transferrin saturation and iron stores in the African American and US Caucasian populations: analysis of data from the third National Health and Nutrition Examination Survey

In previous analyses of transferrin saturation data in African Americans and Caucasians from the second National Health and Nutrition Examination Survey (NHANES II), subpopulations were found consistent with population genetics for common loci that influence iron metabolism. The goal of this new study was to determine if these transferrin saturation subpopulations have different levels of iron stores. Statistical mixture modeling was applied to transferrin saturation data for African Americans and Caucasians from the third National Health and Nutrition Examination Survey (NHANES III), and then the mean serum ferritin concentrations were determined for the transferrin saturation subpopulations that were identified. After adjustment for diurnal variation, 3 subpopulations of transferrin saturation were identified in each racial group. Satisfying Hardy-Weinberg conditions for major locus effects, in both racial groups the sum of the square roots of the proportion with the lowest mean transferrin saturation and the proportion with the highest mean transferrin saturation was approximately 1. When weighted to reflect the US adult population as a whole, these subpopulations of increasing transferrin saturations had progressively increasing mean age-adjusted serum ferritin concentration values in each ethnic grouping as stratified by sex (trend test, P <.002 for all). These results are consistent with the concept that population transferrin saturation subpopulations reflect different levels of storage iron.

Effects of difluoromethylornithine chemoprevention on audiometry thresholds and otoacoustic emissions

OBJECTIVES

To determine the effects of long-term, low-dose difluoromethylornithine (DFMO) on audiometric thresholds and distortion product otoacoustic emission (DPOAE) levels in humans.

DESIGN

A prospective, randomized, placebo-controlled phase 2 clinical trial of DFMO in participants with a prior adenomatous colonic polyp.

SETTING

Academic tertiary care referral center.

PARTICIPANTS

One hundred twenty-three volunteer subjects with colorectal polyps and normal hearing for the frequencies 250 through 2000 Hz.

INTERVENTIONS

Subjects were randomized to receive placebo or oral DFMO at daily dosages between 0.075 and 0.4 g/m(2) of body surface area for 12 months.

OUTCOME MEASURES

Pure-tone audiometric thresholds for the frequencies 250, 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz and DPOAE levels were measured at baseline and 1, 3, 6, 9, and 12 months after starting treatment with DFMO or placebo and 3 months after cessation of treatment if there was a suggestion of possible changes at the 12-month measurement.

RESULTS

At these low dosages, there was little evidence for shifts in auditory pure-tone thresholds, and there were no statistically significant shifts in DPOAE levels. For auditory pure-tone thresholds, there was a subtle, approximately 2- to 3-dB hearing level decrease in hearing sensitivity for the 2 higher DFMO dosages, but only at the 2 lowest frequencies, 250 and 500 Hz.

CONCLUSIONS

Administration of low-dose DFMO for 12 months did not produce hearing loss, in contrast to prior studies that used higher dosages.

Estrogen replacement therapy in endometrial cancer patients: a matched control study

OBJECTIVE

To determine if estrogen replacement therapy, in women with a history of endometrial cancer, increases the risk of recurrence or death from that disease.

METHODS

Two hundred forty-nine women with surgical stage I, II, and III endometrial cancer were treated between 1984 and 1998; 130 received estrogen replacement after their primary cancer treatments and 49% received progesterone in addition to estrogen. Among this cohort, 75 matched treatment-control pairs were identified. The two groups were matched by using decade of age at diagnosis and stage of disease. Both groups were comparable in terms of parity, grade of tumor, depth of invasion, histology, surgical treatment, lymph node status, postoperative radiation, and concurrent diseases. The outcome events included the number of recurrences and deaths from disease.

RESULTS

The hormone users were followed for a mean interval of 83 months (95% confidence interval [CI] 71.0, 91.4) and the nonhormone users were followed for a comparable mean interval of 69 months (CI 59.1, 78.7). There were two recurrences (1%) among the 75 estrogen users compared with 11 (14%) recurrences in the 75 nonhormone users. Hormone users had a statistically significant longer disease-free interval than nonestrogen users (P =.006).

CONCLUSION

Estrogen replacement therapy with or without progestins does not appear to increase the rate of recurrence and death among endometrial cancer survivors.

Breast cancer survival and in vitro tumor response in the extreme drug resistance assay

PURPOSE

To determine whether in vitro extreme drug resistance (EDR) assay results for patients with breast carcinoma were associated with clinical outcome after chemotherapy.

PATIENTS AND METHODS

EDR assays were performed on tumor tissue obtained from 103 newly diagnosed breast cancer cases. EDR scores of 2 for low, 1 for intermediate, or 0 for extreme drug resistance were determined for each agent tested. In vitro EDR scores for 4-hydroxycyclophosphamide (4HC) and doxorubicin were summed for patients treated with AC, or for 4HC and 5-FU for patients treated with CMF. Treatment selection was blinded to assay results.

RESULTS

Median time to progression was significantly shorter for patients with extreme or intermediate in vitro resistance (n = 55, 48 months), compared to patients with low in vitro resistance, (n = 41, 100 months, p = 0.022). Patients demonstrating extreme to intermediate drug resistance also showed poorer survival than the low resistance group (49.5 months vs. not reached, median follow-up 48 months, p =0.011). Summed EDR scores, stage, and number of lymph nodes were significantly associated with survival in univariate and multivariate analysis. Compared to EDR scores of 4, summed EDR scores of 0-1 and summed EDR scores of 2-3 were associated with a relative risk of death of 3.09 (95%, CI 1.05-9.06, Cox proportional hazards model, p = 0.040) and 2.35 (95%, CI 1.07-5.15, Cox proportional hazards model, p = 0.033), respectively.

CONCLUSION

Extreme drug resistance testing identified patients with individual patterns of drug resistance prior to therapy. In this cohort of breast cancer patients treated with chemotherapy, summed EDR scores were significantly associated with time to tumor progression and overall survival. EDR results may offer a method for optimizing treatment selection.

Racial and ethnic colorectal cancer patterns affect the cost-effectiveness of colorectal cancer screening in the United States

BACKGROUND & AIMS

Colorectal cancer screening beginning at age 50 is recommended for all Americans considered at "average" risk for the development of colorectal cancer.

METHODS

We used 1988-1995 California Cancer Registry data to compare the cost-effectiveness of two 35-year colorectal cancer screening interventions among Asians, blacks, Latinos, and Whites.

RESULTS

Average annual age-specific colorectal cancer incidence rates were highest in blacks and lowest in Latinos. Screening beginning at age 50 was most cost-effective in blacks and least cost-effective in Latinos (measured as dollars spent per year of life saved), using annual fecal occult blood testing (FOBT) combined with flexible sigmoidoscopy every 5 years and using colonoscopy every 10 years. A 35-year screening program beginning in blacks at age 42, whites at age 44, or Asians at age 46 was more cost-effective than screening Latinos beginning at age 50.

CONCLUSIONS

Colorectal cancer screening programs beginning at age 50, using either FOBT and flexible sigmoidoscopy or colonoscopy in each racial or ethnic group, are within the $40,000-$60,000 per year of life saved upper cost limit considered acceptable for preventive strategies. Screening is most cost-effective in blacks because of high age-specific colorectal cancer incidence rates.

Independent association of angiogenesis index with outcome in prostate cancer

New molecular factors have been characterized that are associated with the prognosis of prostate carcinoma patients, including p53 status and angiogenesis. We reported recently that mutant p53 (mp53) was associated with decreased expression of an endogenous inhibitor of angiogenesis, thrombospondin-1 (TSP-1), and increased microvessel density in melanoma and breast cancer. In this study, we performed a similar analysis on primary prostate carcinoma to determine whether these factors were associated with each other or patient outcomes. Paraffin-embedded specimens of 98 cases of primary prostate carcinoma were obtained and examined to confirm tissue diagnosis and Gleason scores. Carcinoma-specific levels of p53, TSP-1, and tumor angiogenesis were determined using semiquantitative immunohistochemistry (IHC) methods. Acquisition of mp53 was significantly associated with decreased TSP-1 (P = 0.002) and increased angiogenesis (P < 0.0001). An angiogenesis index integrating mp53, TSP-1, and angiogenesis (CD31) scores was found to be an independent predictor of survival in univariate and multivariate analyses that included Gleason score, clinical stage, and patient age. Further validation of the angiogenesis index in prostate carcinoma may provide a new tool to stratify patient risk.

Hepatic iron concentration and total body iron stores in thalassemia major

BACKGROUND AND METHODS

We tested the usefulness of measuring the hepatic iron concentration to evaluate total body iron stores in patients who had been cured of thalassemia major by bone marrow transplantation and who were undergoing phlebotomy treatment to remove excess iron.

RESULTS

We began treatment with phlebotomy a mean (+/-SD) of 4.3+/-2.7 years after transplantation in 48 patients without hepatic cirrhosis. In the group of 25 patients with liver-biopsy samples that were at least 1.0 mg in dry weight, there was a significant correlation between the decrease in the hepatic iron concentration and total body iron stores (r=0.98, P<0.001). Assuming that the hepatic iron concentration is reduced to zero with complete removal of body iron stores during phlebotomy, the amount of total body iron stores (in milligrams per kilogram of body weight) is equivalent to 10.6 times the hepatic iron concentration (in milligrams per gram of liver, dry weight). With the use of this equation, we could reliably estimate total body iron stores as high as 250 mg per kilogram of body weight, with a standard error of less than 7.9.

CONCLUSIONS

The hepatic iron concentration is a reliable indicator of total body iron stores in patients with thalassemia major. In patients with transfusion-related iron overload, repeated determinations of the hepatic iron concentration can provide a quantitative means of measuring the long-term iron balance.

Prostate needle biopsy infection after four or six dose ciprofloxacin

OBJECTIVE

This retrospective analysis is to determine rates of clinical infection after prostate needle biopsy with four versus six doses of ciprofloxacin to previous literature.

MATERIALS AND METHODS

Two groups were treated with pre and post biopsy 500 mg of ciprofloxacin twice daily by either six doses (n=337) or four doses (n=288) with the first dose given 24 or 12 hours prior to the procedure respectively.

RESULTS

Six (0.96%) of the 625 patients had symptomatic urinary tract infections with a positive urinalysis and/or culture. One (0.3%) infection occurred among patients receiving six doses of ciprofloxacin, and five infections (1.7%), were identified among four dose patients. Two febrile episodes occurred in the four dose group, one requiring hospitalization.

CONCLUSION

A low infection rate associated with prophylactic regimens. Six doses of ciprofloxacin appears more effective than four doses in reducing the clinical and febrile infection rate following ultrasound guided biopsy of the prostate. No obvious financial benefit was observed.

Population screening for hemochromatosis: a comparison of unbound iron-binding capacity, transferrin saturation, and C282Y genotyping in 5,211 voluntary blood donors

Early diagnosis and treatment of hemochromatosis is essential to prevent organ damage. Screening strategies to detect early hemochromatosis include testing for iron overload and/or genetic testing. Voluntary blood donors numbering 5,211 were screened with unbound iron-binding capacity (UIBC), transferrin saturation (TS), and genetic testing for the C282Y mutation of the HFE gene. The study found 16 C282Y homozygotes (1 in 327), 69 compound heterozygotes, 371 simple heterozygotes, and 4,755 normals. There were 5 men and 11 women homozygotes with a mean age of 42, range 28 to 57. Mean UIBC (24 +/- 7 microL) and TS (48% +/- 17%) in homozygotes were significantly different from compound heterozygotes, simple heterozygotes, and normals (ANOVA). Only 3 homozygotes had an elevated serum ferritin. Family studies found an additional 4 iron-loaded homozygotes. Optimal thresholds were < or =28 micromol/L for UIBC and > or =46% for TS. Receiver operating characteristic (ROC) curve analysis showed an area under the curve for UIBC of 0.93 (0. 85-1.0, 95% confidence interval), and for TS of 0.83 (0.7-0.95). Screening with UIBC to preselect those for genotyping is a cost-efficient strategy for population screening for hemochromatosis.

Patient-specific analysis of sequential haematological data by multiple linear regression and mixture distribution modelling

Automated storage and analysis of the results of serial haematologic studies are now technically feasible with present-day laboratory instruments and devices for data storage and processing. In current practice, physicians mentally compare a laboratory result with previous values and use their clinical judgement to determine the significance of any change. To provide a statistical basis for this process, we describe a new approach for the detection of changes in patient-specific sequential measurements of standard haematologic laboratory tests. These methods include hierarchical multiple regression modelling, with a weighted minimum risk criteria for model selection, to choose models indicating changes in mean values over time. This study is the first to analyse sequential patient-specific distributions of laboratory measurements, utilizing mixture distribution modelling with systematic selection of starting values for the EM algorithm. To evaluate these statistical methods under controlled conditions, we studied 11 healthy human volunteers who were depleted of iron by serial phlebotomy to iron-deficiency anaemia, then treated with oral iron supplements to replete iron stores and correct the anaemia. Application of sequential patient-specific analyses of haemoglobin, haematocrit, and mean cell volume showed that significant departures from past values could be identified, in many cases, even when values were still within the population reference ranges. Additionally, for all subjects sequential alterations in red blood cell volume distributions during development of iron-deficiency anaemia could be characterized and quantified. These methods promise to provide more sensitive techniques for improved diagnostic evaluation of developing anaemia and serial monitoring of response to therapy.

Single-dose administration of Bowman-Birk inhibitor concentrate in patients with oral leukoplakia

The Bowman-Birk inhibitor (BBI) is a soybean-derived serine protease inhibitor and a potential cancer chemopreventive agent for humans. In this Phase I clinical trial, BBI concentrate was administered as a single oral dose to 24 subjects with oral leukoplakia. Pharmacokinetics of BBI was analyzed, and subjects were monitored clinically for toxic effects. Subjects received between 25 and 800 chymotrypsin inhibitor units (CIU) of the compound in a dose escalation trial. BBI was taken up rapidly, and a metabolic product of BBI was excreted in the urine within 24-48 h. No clinical or laboratory evidence of toxicity was observed in the study. Protease activity was also measured in buccal cells to evaluate usefulness as a biomarker. Single-dose BBI concentrate administered up to 800 CIU was well tolerated and appeared to be nontoxic. Further investigation in Phase II clinical trials is being done.

T cell numbers relate to bone involvement in Gaucher disease

The major elements of bone pathology in Gaucher disease are a failure of osteoclast and osteoblast function, resulting in osteopenia and also osteonecrosis. T lymphocytes have recently been found to be involved in the regulation of osteoblast/osteoclast activity in vitro. In the present report the peripheral blood T major lymphocyte subsets were investigated in a group of genotyped type 1 Gaucher disease patients. A total of 31 patients were studied: 21 non-splenectomized (5 N370S homozygotes) and 10 splenectomized (of whom 1 was a N370S homozygote). The results show that non-splenectomized patients present a decrease in absolute numbers of peripheral blood T lymphocytes, specially the CD4+ T subset. However, when patients were analyzed with respect to the presence of bone disease, the number of CD8+ T lymphocytes was found to be statistically significantly lower in patients presenting bone involvement. Furthermore, lower numbers of CD8+ T lymphocytes were significantly correlated with higher levels of plasma tartrate resistant acid phosphatase (TRAP) activity, a putative marker of osteoclast cell activity. These in vivo findings are in agreement with the results reached in vitro by others. They provide an additional marker of disease severity in Gaucher disease. In the group of genotyped Gaucher disease patients, the majority of the N370S homozygous patients presented a clinically milder phenotype, including the absence of bone involvement, confirming earlier reports predicting that a number of these patients may remain undiagnosed. Collectively the homozygosity for the N370S mutation and normal T cell numbers may provide additional markers for the clinical heterogeneity of Gaucher disease.

Long-term safety and effectiveness of iron-chelation therapy with deferiprone for thalassemia major

BACKGROUND

Deferiprone is an orally active iron-chelating agent that is being evaluated as a treatment for iron overload in thalassemia major. Studies in an animal model showed that prolonged treatment is associated with a decline in the effectiveness of deferiprone and exacerbation of hepatic fibrosis.

METHODS

Hepatic iron stores were determined yearly by chemical analysis of liver-biopsy specimens, magnetic susceptometry, or both. Three hepatopathologists who were unaware of the patients' clinical status, the time at which the specimens were obtained, and the iron content of the specimens examined 72 biopsy specimens from 19 patients treated with deferiprone for more than one year. For comparison, 48 liver-biopsy specimens obtained from 20 patients treated with parenteral deferoxamine for more than one year were similarly reviewed.

RESULTS

Of the 19 patients treated with deferiprone, 18 had received the drug continuously for a mean (+/-SE) of 4.6+/-0.3 years. At the final analysis, 7 of the 18 had hepatic iron concentrations of at least 80 micromol per gram of liver, wet weight (the value above which there is an increased risk of cardiac disease and early death in patients with thalassemia major). Of 19 patients in whom multiple biopsies were performed over a period of more than one year, 14 could be evaluated for progression of hepatic fibrosis; of the 20 deferoxamine-treated patients, 12 could be evaluated for progression. Five deferiprone-treated patients had progression of fibrosis, as compared with none of those given deferoxamine (P=0.04). By the life-table method, we estimated that the median time to progression of fibrosis was 3.2 years in deferiprone-treated patients. After adjustment for the initial hepatic iron concentration, the estimated odds of progression of fibrosis increased by a factor of 5.8 (95 percent confidence interval, 1.1 to 29.6) with each additional year of deferiprone treatment.

CONCLUSIONS

Deferiprone does not adequately control body iron burden in patients with thalassemia and may worsen hepatic fibrosis.

Guidelines for organisation and management of external quality assessment using proficiency testing. Expert Panel on Cytometry of the International Council for Standardization in Haematology

This document is intended to assist towards the WHO objective that external quality assessment (EQA) schemes be established at national and/or regional levels world-wide. Quality assurance is defined as all steps taken by the director of a laboratory to ensure reliability of laboratory results and to increase accuracy, reproducibility and between-laboratory comparability. This includes the use of internal quality control procedures and participation in external quality assessment. Internal quality control provides the means for evaluation of analytic test results at the time of testing in order to decide whether they are reliable enough to be released to the requesting clinicians. EQA, on the other hand, refers to a system of retrospective and objective comparison of results from different laboratories by means of proficiency testing (PT) organised by an external agency. The main purpose is to establish between-laboratory and between-method (including between-instrument) comparability, and agreement with a reference standard where one exists. Internal quality control and EQA complement each other and must never be considered as alternatives.

Loading dose of quinine in African children with cerebral malaria

The majority of deaths from cerebral malaria occur within 48 h after admission to hospital. Because of the possibility of inadequate treatment within this period, the use of a loading dose of quinine has been proposed. We reviewed clinical and laboratory data for 113 children with cerebral malaria, who were treated with intravenous quinine, 10 mg/kg every 8 h, at Macha Mission Hospital in rural Zambia. In 1990-1991, 39 children were not given a loading dose of quinine while, in 1992-1993, 74 children received a loading dose of 20 mg/kg. Elevated serum iron levels, as reflected in transferrin saturation, were strongly associated with higher mortality. A loading dose of quinine was associated with faster recovery from coma and enhanced clearance of parasitaemia and fever. The loading dose was also associated with trends to lower mortality and higher haemoglobin levels, but these differences were not statistically significant.

Distribution of transferrin saturations in the African-American population

To determine if transferrin saturations in African Americans may reflect the presence of a gene that influences iron metabolism, we analyzed the distribution of these values in 808 African Americans from the second National Health and Nutrition Survey. We tested for a mixture of three normal distributions consistent with population genetics for a major locus effect in which the proportion of normal homozygotes is p2; of heterozygotes, 2pq; of affected homozygotes, q2; and in which p+q = 1. Three subpopulations based on transferrin saturation were present (P < .0001) and the fit to a mixture of three normal distributions was good (P = .2). A proportion of .009 was included in a subpopulation with a mean +/- standard deviation transferrin saturation of 63.4% +/- 5.7% (postulated homozygotes for a gene that influences iron metabolism), while a proportion of .136 had an intermediate saturation of 38.0% +/- 5.7% (postulated heterozygotes) and .856 a saturation of 24.6% +/- 5.7% (postulated normal homozygotes). These proportions were consistent with population genetics because the sum of the square roots of the proportions with the lowest mean transferrin saturation (P = .925) and the highest (q = 0.093) was approximately 1 (1.018). The results are consistent with the presence in African Americans of a common locus that influences iron metabolism.

Distribution of transferrin saturation in an Australian population: relevance to the early diagnosis of hemochromatosis

BACKGROUND & AIMS

An elevated transferrin saturation is the earliest phenotypic abnormality in hereditary hemochromatosis. Determination of transferrin saturation remains the most useful noninvasive screening test for affected individuals, but there is debate as to the appropriate screening level. The aims of this study were to estimate the mean transferrin saturation in hemochromatosis heterozygotes and normal individuals and to evaluate potential transferrin saturation screening levels.

METHODS

Statistical mixture modeling was applied to data from a survey of asymptomatic Australians to estimate the mean transferrin saturation in hemochromatosis heterozygotes and normal individuals. To evaluate potential transferrin saturation screening levels, modeling results were compared with data from identified hemochromatosis heterozygotes and homozygotes.

RESULTS

After removal of hemochromatosis homozygotes, two populations of transferrin saturation were identified in asymptomatic Australians (P < 0.01). In men, 88.2% of the truncated sample had a lower mean transferrin saturation of 24.1%, whereas 11.8% had an increased mean transferrin saturation of 37.3%. Similar results were found in women. A transferrin saturation threshold of 45% identified 98% of homozygotes without misidentifying any normal individuals.

CONCLUSIONS

The results confirm that hemochromatosis heterozygotes form a distinct transferrin saturation subpopulation and support the use of transferrin saturation as an inexpensive screening test for hemochromatosis. In practice, a fasting transferrin saturation of > or = 45% identifies virtually all affected homozygous subjects without necessitating further investigation of unaffected normal individuals.

Effect of iron chelation therapy on mortality in Zambian children with cerebral malaria

To examine the effect of iron chelation on mortality in cerebral malaria, we enrolled 352 children in a trial of deferoxamine in addition to standard quinine therapy at 2 centres in Zambia, one rural and one urban. Entrance criteria included age < 6 years, Plasmodium falciparum parasitaemia, normal cerebral spinal fluid, and unrousable coma. Deferoxamine (100 mg/kg/d infused for a total of 72 h) or placebo was added to a 7 d regimen of quinine that included a loading dose. Mortality overall was 18.3% (32/175) in the deferoxamine group and 10.7% (19/177) in the placebo group (adjusted odds ratio 1.8; 95% confidence interval 0.9-3.6; P = 0.074). At the rural study site, mortality was 15.4% (18/117) with deferoxamine compared to 12.7% (15/118) with placebo (P = 0.78, adjusted for covariates). At the urban site, mortality was 24.1% (14/58) with deferoxamine and 6.8% (4/59) with placebo (P = 0.061, adjusted for covariates). Among survivors, there was a non-significant trend to faster recovery from coma in the deferoxamine group (adjusted odds ratio 1.2; 95% confidence interval 0.97-1.6; P = 0.089). Hepatomegaly was significantly associated with higher mortality, while splenomegaly was associated with lower mortality. This study did not provide evidence for a beneficial effect on mortality in children with cerebral malaria when deferoxamine was added to quinine, given in a regimen that included a loading dose.

African iron overload and hepatocellular carcinoma (HA-7-0-080)

Although HLA-linked hemochromatosis greatly increases the risk for hepatocellular carcinoma in people of European ancestry, iron overload in Africa is not thought to be etiologically related to this malignancy. To determine if African iron overload may be associated with hepatocellular carcinoma, we reviewed 320 consecutive diagnostic liver biopsies processed at the University of Zimbabwe from 1992 to 1994 and we selected for analysis 215 biopsies from adults that were suitable for the histological assessment of hepatocellular iron. Subjects were stratified according to hepatocellular iron grades of 0-2+ (normal levels to mild siderosis; n = 183) and grades of 3+ and 4+ (distinctly elevated levels consistent with iron overload; n = 32). Thirty-six subjects had hepatocellular carcinoma. Logistic regression modeling revealed a significant association between iron overload and hepatocellular carcinoma after adjustment for age, sex and and the presence of portal fibrosis or cirrhosis (p = 0.041). The odds of hepatocellular carcinoma in subjects with iron overload was 3.1 (95% confidence interval of 1.05-9.4) times that of subjects without iron overload. While we could not test for exposure to viral hepatitis or to aflatoxins in this study, our findings suggest that iron overload may be a risk factor for hepatocellular carcinoma in Africa.

Mixture models in haematology: a series of case studies

Two specific applications of finite mixture distributions in haematology include (1) the analysis of the distribution of red blood cell volumes to characterize and quantify alterations in erythrocyte subpopulations in anaemia and (2) the analysis of the distribution of transferrin saturation to estimate subpopulation parameters based on individual genotype for haemochromatosis. For these applications, we describe the comprehensive approach that was taken to distribution modeling. The choice of distributions and the number of mixture components to be fit were based upon theoretical and physiological considerations and a variety of additional statistical problems were considered. These included fitting mixtures of doubly-truncated data and evaluating model fit in the presence of extremely large sample sizes. As a result of the comprehensive approach taken to statistical problem solving in haematology, methods developed for analysis of red blood cell volume distributions have now been adopted by the International Council for Standardization in Haematology. Additionally, analysis of population transferrin saturation distributions from the white population of the USA has led to an independent estimate of the prevalence of homozygotes for haemochromatosis, confirming that the gene for haemochromatosis is common.

Associations of iron overload in Africa with hepatocellular carcinoma and tuberculosis: Strachan's 1929 thesis revisited

We analyzed data from the first study of iron overload in Africans, conducted between 1925 and 1928, to determine whether this common condition is associated with death from hepatocellular carcinoma and/or tuberculosis. In the original study, necropsies were performed on 714 adult blacks from southern Africa. Hepatic and splenic iron levels were measured semiquantitatively in 604 subjects and one of five iron grades was assigned. We examined death from hepatocellular carcinoma or from tuberculosis and the variables of age, sex, the presence of cirrhosis or other diagnoses that might be influenced by iron status, and tissue iron grades. Nineteen percent of men and 16% of women had the highest grade of hepatic iron. After adjustment for the presence of cirrhosis, hepatic iron grade was the variable most significantly associated with death from hepatocellular carcinoma (P = .021). The odds of death from hepatocellular carcinoma in subjects with the highest grade of hepatic iron was 23.5 (95% confidence interval, 2.1 to 225) times the odds in subjects with the three lowest grades. Splenic iron was the variable most significantly associated with death from tuberculosis (P <.0001). The odds of death from tuberculosis with the highest grade of splenic iron was 16.9 (4.8 to 59.9) times the odds with the two lowest grades. These findings suggest that iron overload in black Africans may be a risk factor for death from hepatocellular carcinoma and for death from tuberculosis.

Prevalence of heterozygotes for hemochromatosis in the white population of the United States

In previous studies, the prevalence of HLA-linked hemochromatosis, thought to be the most common genetic illness in whites, has been estimated by identifying homozygotes in the population. Because not all homozygotes express the disease phenotypically, the accuracy of these estimates is uncertain. We analyzed the distribution of transferrin saturation values in the second National Health and Nutrition Examination Survey to estimate the prevalence of hemochromatosis heterozygotes in the US population. After removing values for possible homozygotes, two populations were present (P < .01 for each gender). When weighted to reflect the US adult white male population as a whole, a proportion of 850 per 1,000 (95% confidence interval, 0.81 to 0.89) were included in a population with a lower mean saturation of 29.7% (29.1% to 30.3%), whereas 150 per 1,000 (0.11 to 0.19) comprised a population with a higher mean saturation of 47.0% (45.1% to 49.0%). Similar results were found for the female population. The gene frequencies were estimated to be 0.081 from the male population and 0.070 from the female population corresponding to prevalences of homozygotes of 6.6 and 4.8 per 1,000, respectively. Our results confirm that the gene for hemochromatosis is common.

Transferrin saturation and recovery from coma in cerebral malaria

To determine if the elevated transferrin saturations found in some patients with severe malaria are associated with an adverse outcome in cerebral malaria, we retrospectively measured baseline saturations in stored serum samples from 81 Zambian children with strictly defined cerebral malaria. The children had been treated with quinine, sulfadox-ine-pyrimethamine, and intravenous infusions of either placebo (n = 39) or the iron chelator, desferrioxamine B (n = 42), in a previously reported trial (Gordeuk et al, N Engl J Med 327:1473, 1992). More than one-third of children in both the placebo- and iron chelator-treated groups had transferrin saturations exceeding 43%, which is 3 standard deviations above the expected mean for age. Among children receiving quinine and placebo, those with elevated transferrin saturations had a delayed estimated median time to recover full consciousness (68.2 hours) compared with those with saturations < or = 43% (25.4 hours; P = .006). The addition of iron chelation to quinine therapy in children with high saturations appeared to hasten recovery (P = .046). We conclude that increased transferrin saturations may be associated with delayed recovery from coma during standard therapy for cerebral malaria and that serum iron and total iron binding capacity should be measured in future studies.

Efficacy of deferoxamine in preventing complications of iron overload in patients with thalassemia major

BACKGROUND

To determine whether deferoxamine prevents the complications of transfusional iron overload in thalassemia major, we evaluated 59 patients (30 were female and 29 male; age range, 7 to 31 years) periodically for 4 to 10 years or until death.

METHODS

At each follow-up visit, we performed a detailed clinical and laboratory evaluation and measured hepatic iron stores with a noninvasive magnetic device.

RESULTS

The body iron burden as assessed by magnetic measurement of hepatic iron stores was closely correlated (R = 0.89, P < 0.001) with the ratio of cumulative transfusional iron load to cumulative deferoxamine use (expressed in millimoles of iron per kilogram of body weight, in relation to grams of deferoxamine per kilogram, transformed into the natural logarithm). Each increase of one unit in the natural logarithm of the ratio (transfusional iron load to deferoxamine use) was associated with an increased risk of impaired glucose tolerance (relative risk, 19.3; 95 percent confidence interval, 4.8 to 77.4), diabetes mellitus (relative risk, 9.2; 95 percent confidence interval, 1.8 to 47.7), cardiac disease (relative risk, 9.9; 95 percent confidence interval, 1.9 to 51.2), and death (relative risk, 12.6; 95 percent confidence interval, 2.4 to 65.4). All nine deaths during the study occurred among the 23 patients who had begun chelation therapy later and used less deferoxamine in relation to their transfusional iron load (P < 0.001).

CONCLUSIONS

The early use of deferoxamine in an amount proportional to the transfusional iron load reduces the body iron burden and helps protect against diabetes mellitus, cardiac disease, and early death in patients with thalassemia major.

A method to examine the need for duplicate testing of common coagulation tests

A statistical protocol for evaluating the need for duplicate coagulation testing was developed. It requires at least 32 sets of duplicate prothrombin times or partial thromboplastin times over the expected range of results. In addition to the statistical procedures, clinical evaluation of the duplicates is required.

Pyridoxine responsive hereditary sideroblastic erythropoiesis and iron overload: two microcytic subpopulations in the affected male, one normocytic and one microcytic subpopulation in the obligate female carrier

Mild hepatic iron overload has been demonstrated by magnetic susceptibility measurements in a 22-year-old man with hereditary sideroblastic erythropoiesis despite hemoglobin levels in the normal range and a normal erythropoietin level. His grandfather's sideroblastic anemia has been found to be responsive to pyridoxine; his mother's hemoglobin has persisted in the normal range but red cell volume distribution analysis demonstrated two subpopulations; 30% with estimated geometric mean of 68 fl and 70% an estimated mean of 93 fl. Red cell distribution analysis of the grandson demonstrated two microcytic subpopulations; 46% with an estimated geometric mean of 45 fl and 54% an estimated mean of 70 fl. A therapeutic regimen is outlined to reduce to normal his iron stores and to prevent the future development of excessive iron overload.

Hepatic iron stores and plasma ferritin concentration in patients with sickle cell anemia and thalassemia major

To examine the relationship between hepatic iron stores and plasma ferritin concentration in individuals treated with red cell transfusion and iron chelation therapy, 37 patients with sickle cell anemia and 74 patients with thalassemia major were studied. In each patient, hepatic iron stores were measured by an independently validated noninvasive magnetic method, and plasma ferritin was determined by immunoassay. The correlation between hepatic iron and plasma ferritin was significant both in patients with sickle cell anemia (R = 0.75, P < 0.0001) and in those with thalassemia major (R = 0.76, P < 0.0001). Regression analysis showed no significant difference between the two groups in the linear relationships between hepatic iron stores and plasma ferritin. Considering all 111 transfused patients as a group, the coefficient of correlation between hepatic iron stores and plasma ferritin was highly significant (R = 0.76, P < 0.0001). Regression analysis found that variation in body iron stores, as assessed by magnetic determinations of hepatic iron, accounted for only approximately 57% of the variation in plasma ferritin, suggesting that the remainder was the result of other factors, such as hemolysis, ineffective erythropoiesis, ascorbate deficiency, inflammation, and liver disease. The 95% prediction intervals for hepatic iron concentration, given the plasma ferritin, were so broad as to make a single determination of plasma ferritin an unreliable predictor of body iron stores. Variability resulting from factors other than iron status limits the clinical usefulness of the plasma ferritin concentration as a predictor of body iron stores.

Detection of two-component mixtures of lognormal distributions in grouped, doubly truncated data: analysis of red blood cell volume distributions

We have examined the statistical requirements for the detection of mixtures of two lognormal distributions in doubly truncated data when the sample size is large. The expectation-maximization algorithm was used for parameter estimation. A bootstrap approach was used to test for a mixture of distributions using the likelihood ratio statistic. Analysis of computer simulated mixtures showed that as the ratio of the difference between the means to the minimum standard deviation increases, the power for detection also increases and the accuracy of parameter estimates improves. These procedures were used to examine the distribution of red blood cell volume in blood samples. Each distribution was doubly truncated to eliminate artifactual frequency counts and tested for best fit to a single lognormal distribution or a mixture of two lognormal distributions. A single population was found in samples obtained from 60 healthy individuals. Two subpopulations of cells were detected in 25 of 27 mixtures of blood prepared in vitro. Analyses of mixtures of blood from 40 patients treated for iron-deficiency anemia showed that subpopulations could be detected in all by 6 weeks after onset of treatment. To determine if two-component mixtures could be detected, distributions were examined from untransfused patients with refractory anemia. In two patients with inherited sideroblastic anemia a mixture of microcytic and normocytic cells was found, while in the third patient a single population of microcytic cells was identified. In two family members previously identified as carriers of inherited sideroblastic anemia, mixtures of microcytic and normocytic subpopulations were found. Twenty-five patients with acquired myelodysplastic anemia were examined. A good fit to a mixture of subpopulations containing abnormal microcytic or macrocytic cells was found in two. We have demonstrated that with large sample sizes, mixtures of distributions can be detected even when distributions appear to be unimodal. These statistical techniques provide a means to characterize and quantify alterations in erythrocyte subpopulations in anemia but could also be applied to any set of grouped, doubly truncated data to test for the presence of a mixture of two lognormal distributions.

Somatosensory evoked response and recovery from stroke

The purpose of this study was to evaluate median nerve short latency somatosensory evoked potentials (SEP) as prognostic indicators of functional outcome after right cerebral infarction. Twenty-six patients with right cerebral infarction were admitted to a rehabilitation unit and were classified into three groups based on the evoked potentials measured on admission. The SEP classification and nine other variables reported to predict recovery after stroke were evaluated for prediction of the final outcome measure, the Barthel Scale, using stepwise multiple regression analysis. Patients with normal SEP achieved a mean Barthel score of 95 +/- 3.9 SD, while patients with an amplitude asymmetry on SEP showed a mean Barthel score of 77.5 +/- 17.5 SD. The group with absence of cortical potentials had a mean Barthel score of 59.5 +/- 21.3 SD. Six predictors (Barthel admission score, SEP, electroencephalogram, Brunnstrom staging of the arm at the time of admission, joint position sense, and hemihypesthesia) were highly correlated with the Barthel outcome score (p less than 0.05 for all). The linear regression equation with three predictors (Barthel admission score, SEP, and homonymous hemianopsia) provided the best prediction of Barthel outcome score (p = 0.005). These data indicate that the Barthel admission score is the best predictor of functional level after stroke rehabilitation. Knowledge of the median SEP and homonymous hemianopsia improve this prediction.

Utilization of clover diets by sheep. 2. Intake, digestion and utilization of nitrogen and sulfur

Nine mature Merino wethers were fed three clover diets at 95% of previously measured intake under steady state conditions. The diets were mature subterranean clover (MSC), green subterranean clover (GSC) and persian clover (PC). The utilization of dietary N and S was studied for each feed.The ratios of digestible organic matter (DOM) to crude protein (CP) in the diets ranged from 3.9 to 5.5 : 1. The flow of microbial crude protein (MCP) from the abomasum was only 34 g day-1 in sheep given MSC compared to 77 g day-1 for GSC and 85 g day-1 for PC. However, the calculated efficiencies of MCP synthesis were 230-250 g MCP per kg OM apparently digested in the rumen for the three clovers. Despite the similar efficiencies of MCP synthesis, the ammonia-N (30 mg l-1) and sulfide-S (220 8g l-1) concentrations in the rumen of sheep fed MSC were low. The concentrations for the the other clovers were ammonia-N 90-110 mg l-1 and sulfide-S 730-1770 8g l-1. The amount of CP apparently digested in the intestines (DCPi) was only 31 g day-1 in sheep given MSC compared to 100 g day-1 and 81 g-1 in those fed GSC and PC, respectively. While this indicates that protein insufficiency in the tissues may have limited the intake of MSC, the DCPi values per unit of DOM intake were 150,210 and 150 g kg DOM-1 for MSC, GSC and PC, respectively. Sheep excreted more N and S (% of intake) in faeces when given MSC compared to GSC or PC.The sheep were in positive apparent balance for N and S when fed GSC or PC, but were mobilizing these nutrients from tissues at the low intakes of DOM, N and S with MSC. The wool growth rates and amounts of N and S incorporated into wool when MSC was fed were about half the other two feeds.These results are discussed in relation to other work on the utilization of N and S by sheep and likely effects of this on the intake of the feeds.

Utilization of clover diets by sheep. 1. Intake and digestion of organic matter and cell wall constituents

Nine mature Merino sheep received three clover diets in a randomized block design experiment. The diets were mature subterranean clover (MSC), apparent organic matter digestibility (OMD) 60%; green subterranean clover (GSC), OMD 72%; persian clover (PC), OMD 67070, and were given at 95% of measured ad libitum intake. The voluntary consumption of the MSC was lower than the intakes of the CSC and PC. Consequently, the sheep given MSC lost weight, while those receiving the more digestible diets gained weight. Associated with the different intakes in these clover diets, there there were no differences in the levels of ruminal fill, but there were differences in ruminal loads of dry matter (DM) and neutral detergent fibre (NDF) in sheep given MSC, GSC and PC, respectively. The flows of DM and OM through the abomasum were lower for MSC, and with a tendency for the fractional outflow rate of NDF of this diet to be lower (2.3 v. 2.8% h-1) when compared to the GSC and PC hays. The proportions of apparent OM (0.65-0.71), of NDF (0.71-0.82) and of ADF (0.95-140) digestion occurring in the rumen were similar for the three clover hays. The fractional digestion rates of potentially digestible NDF were higher for the more digestible clovers (c. 8.6% h-1) than for the MSC (6.5% h-1). The intake of the higher digestibility clovers may have been more related to the capacity of the sheep to use absorbed nutrients than to constraints imposed by ruminal digesta load, rate of digestion in the rumen or rate of outflow to the omasum. With the MSC the level of ruminal or dry matter load was low. In addition, the fractional rates of digestion and of outflow of cell wall constituents were or tended to be lower for this diet than for the other clovers. Intake of MSC may have been limited not only by these factors, but also by the supply of essential nutrients to the tissues or by other characteristics of the hay influencing its acceptability to sheep.

Academic group practice. The physicians' view

In order to evaluate physician response to the reorganization of a traditional medical clinic into a group practice model, a randomized controlled trial was conducted using equivalent groups of patients and physicians. The group practice model, unlike the traditional clinic, provided decentralized registration, 5 days/week clinic coverage, and night/weekend phone coverage. Residents worked in small groups with an attending physician, nurse practitioner, staff nurse, and receptionist. A panel of 50 medical residents was interviewed prior to the reorganization and 1 year later. Residents in the experimental groups perceived improvements in the ancillary staff, placed a higher value on informal discussion of patient management problems, and were more satisfied with the outpatient experience. Moreover, residents in the group practices were more likely to voluntarily schedule additional clinic sessions to accommodate their patients. No change was noted in their career choices. We conclude that reorganization of a traditional medical clinic into a group practice model can result in increased physician satisfaction although it may not have a major impact on long-term career goals.

Uniformity of liver density and nonheme (storage) iron distribution

The extent of variation in tissue density and hepatic nonheme iron concentration has been examined at autopsy in 21 adult livers. Samples were taken from each liver at inferior and superior sites in the midaxillary, anterior axillary, and midclavicular lines. Histologic examination showed diffuse metastatic carcinoma, cirrhosis, fibrosis, necrosis, steatosis, or congestion in 19 livers; two livers were normal. Density was determined by saline displacement of 0.5- to 1.0-g specimens. Nonheme iron concentration was measured at each site in samples of the size obtained by wedge (0.5 to 1.0 g) and percutaneous needle (0.005 to 0.010 g) biopsy using specially developed chemical assays. Density was uniform within each liver. Despite the inclusion of diseased tissues, the variation in density among the 21 livers was small (coefficient of variation, 1.25%). The mean (+/- 1 SD) hepatic density was 1.051 +/- 0.013 g/mL (range, 1.017 to 1.077 g/mL). Within each liver, the nonheme iron also was uniformly distributed among the six sites. Chemical measurements of nonheme iron concentration were not significantly different in samples of the size obtained by wedge or percutaneous liver biopsy. All the hepatic nonheme iron determinations were below the upper 95% confidence limit of concentrations in adult males (480 micrograms/g). In the absence of focal lesions, the uniformity in hepatic density and nonheme iron distribution supports the assumption of several clinical methods for measuring liver storage iron (wedge and needle biopsy, determination of hepatic magnetic susceptibility, computed tomography, and magnetic resonance imaging) that one sample of liver tissue is representative of the whole organ.

A randomized controlled trial of academic group practice. Improving the operation of the medicine clinic

We conducted a controlled trial of the adoption of a group-practice model within an academic department of medicine. Ongoing randomization yielded similar groups of patients and residents. To determine the effect of the intervention on medicine-clinic operation, we monitored the hospital outpatient activity of 28 residents and 2299 patients during an 11-month study period. The group-practice clinics generated 20% more patient encounters per month than did the traditional, control clinics (328 vs 273 encounters), primarily because twice as many voluntary, overflow clinic sessions were scheduled (20.2 vs 9.7 sessions). Yet, because group-practice registration was decentralized, patients spent 15% less time in completing scheduled visits (93.2 vs 109.9 minutes). Regular utilizers of the group practices made 7% more scheduled clinic visits on average (3.27 vs 3.05 visits), but 39% fewer walk-in visits (0.14 vs 0.23 visits). Hospital-wide, continuity of care was not affected. We conclude that adoption of a group-practice model at our institution improved clinic productivity, enhanced patient flow, and decreased unscheduled clinic visits.

Statistical and graphical evaluation of erythrocyte volume distributions

A protocol for the statistical and graphical evaluation of erythrocyte volume distributions has been developed using expectation-maximization methods for distribution parameter estimation. In a reference sample group of 50 healthy individuals, none of the red cell volume distributions determined by an aperture impedance method differed significantly from a log normal model. Measurements in 211 patients with anemia provided evidence that similar statistical methods could be used for the characterization of abnormal red cell volume distributions. Graphical displays accurately summarize the quantitative information derived from the analysis of volume distributions and show a reference distribution fitted to the observed distribution against the range of distributions found in healthy individuals. This protocol provides a specific, statistically valid implementation of the general principles for the analysis of cell volume distributions proposed by the International Committee for Standardization in Hematology.