Monitoring data quality through comparisons between data systems

Since its creation in 1960, the National Center for Health Statistics (NCHS) has placed a high value on the quality of the information and statistics collected and published by its data systems. An important component of a comprehensive data quality monitoring system for a statistical agency such as NCHS is the comparison of statistics between data systems. Between-data-systems comparisons are used to monitor the consistency and comparability of statistics across data systems and between NCHS data systems and outside sources of data. This paper focuses on between-data-systems comparisons and describes a number of methodological analyses that can be used to evaluate data quality. The methodological analyses presented include the evaluation of time trends, the estimation of survey method effects, the evaluation of response error, the measurement of definitional and concept effects, and the detection of inconsistencies between data systems. The paper concludes with a discussion of the complexities of the between-data-systems comparisons and an assessment of the net benefits from such comparisons.     

In vivo-like growth of human tumors in vitro.

We show that diverse human tumors obtained directly from surgery or biopsy can grow at high frequency in vitro for long periods of time and still maintain many of their in vivo properties. The in vivo properties maintained in vitro include three-dimensional growth; maintenance of tissue organization and structure, including changes associated with oncogenic transformation; retention of differentiated function; tumorigenicity; and the growth of multiple types of cells from a single tumor.     

Peritoneal tuberculosis, large ovarian thecoma, and an elevated serum CA 125 level mimicking ovarian cancer

Laparotomy revealed peritoneal tuberculosis in a 32-year-old woman with pulmonary tuberculosis, ascites, a large pelvic mass, and an elevated serum CA 125 level. Postoperatively, after further treatment with antituberculosis agents, the CA 125 returned to normal and the patient has been well for 22 months.     

Expression of class I and class II major histocompatibility complex antigens on epithelial cells in recurrent aphthous stomatitis

The concept of an immunopathogenesis in the establishment and progression of the recurrent aphthous stomatitis (RAS) lesion is well accepted. In this study the expression of Class I and Class II major histocompatibility complex (MHC) antigens on the epithelial cells in the preulcerative, ulcerative and healing phases of RAS lesions was investigated using monoclonal antibodies in an immunohistological technique. Both Class I and Class II MHC antigens were found on the basal cells in preulcerative lesions. As the lesions progressed to the ulcerative phase, antigen expression occurred on the cell membranes throughout the entire thickness of the epithelium. With healing, the expression of both Class I and Class II MHC antigens on epithelial cells declined to a stage where there was little or no detectable antigen on the cell membranes. Although cytotoxicity of epithelial cells in RAS lesions is accepted, the role of MHC antigen expression on these cells is uncertain and remains to be ascertained. Nevertheless, the results of the present study indicate that MHC antigens are expressed by epithelial cells in RAS and their expression follows a defined sequence.     

Serum lipoprotein profile in children with celiac disease

Jejunal mucosa is responsible for the absorption of triglycerides and the production of lipoproteins [chylomicrons, very-low-density lipoprotein (VLDL), high-density lipoprotein (HDL)] and apolipoproteins (B-48, A-I, A-II, A-IV, C-II). Mucosal damage is known to cause fat malabsorption and probably also affects the serum lipid profile. To determine lipoprotein production in states of enterocyte dysfunction, we compared the serum lipid profiles in a group of 12 children with untreated celiac disease (flat jejunal mucosa) with the profiles in a control group of 10 children suffering from other intestinal diseases. Statistically significant differences were found in the following parameters (celiac versus control): plasma levels of triglycerides (70 versus 119 mg/dl), cholesterol content in LDL (107 versus 67.7 mg/dl), protein content in VLDL (6 versus 10 mg/dl), and level of apoprotein A-I (112 versus 140 mg/dl). No significant differences were found between the two groups in the serum levels of total cholesterol, the cholesterol content in VLDL and HDL, the protein content in LDL and HDL, and the level of apoprotein B. Following institution of a gluten-free diet, the lipoprotein profile reverted to normal. These data suggest that the changes in the serum lipoprotein profile in celiac disease are secondary to alterations in enterocyte function and not only a reflection of fat malabsorption.     

Effect of prazosin treatment on HDL kinetics in patients with hypertension

The effect of prazosin treatment on blood pressure, plasma HDL-cholesterol concentration, and apoprotein-AI/HDL (apoAI/HDL) kinetics was studied in 11 patients with mild hypertension. Blood pressure (mean +/- SEM) fell from 143 +/- 1/96 +/- 1 to 134 +/- 1/86 +/- 1 mm Hg after 4 to 5 months of prazosin treatment (P less than .001), associated with an increase in plasma HDL-cholesterol concentration from 38 +/- 2 to 46 +/- 2 mg/dL (P less than .001). Both the fractional catabolic rate (FCR) and total synthetic rate of apoAI/HDL, which were higher than previous reported values for normal individuals, decreased from 0.36 +/- 0.02 to 0.30 +/- 0.02 L/day and 17.4 +/- 1.1 to 13.8 +/- 1.1 mg/kg/min, respectively. These changes were statistically significant, and the post-treatment values for both variables were now within the normal range. When the decay curve was further analyzed by nonlinear curve fitting, it was shown that the return to normal of the FCR of apoAI/HDL in patients treated with prazosin was accounted for by the decrease of the decay constants of the second [p(2)] and third [p(3)] components of the 125I-AI/HDL disappearance curve. In conclusion, abnormalities in HDL concentration and HDL kinetics exist in patients with very mild hypertension. These defects were significantly improved with prazosin treatment, and this may render the compound of particular clinical benefit in the treatment of patients with mild hypertension.