Biomedical subjects

D Pee

Publications and source records attributed to D Pee.

27 records · Page 2Linked to original sources

PubMed1991

Evaluation of serum sialic acid and carcinoembryonic antigen for the detection of early-stage colorectal cancer.

Various expressions of elevated serum sialic acid (total sialic acid, TSA: lipid-associated sialic acid, LASA; LASA/TSA; TSA normalized to total protein, TSA/TP) have been evaluated and compared with increased serum carcinoembryonic antigen (CEA) levels for the detection of early-stage colorectal cancer. This evaluation was done blindly on a coded panel of 320 sera from staged colorectal cancer patients and controls provided by the Mayo Clinic--National Cancer Institute Diagnostic Bank. Unlike the findings of a previous preliminary study (Tautu et al., JNCI 80:1333-1337, 1988), the ratio of LASA/TSA was not useful for detecting early-stage (Dukes A and B) colorectal cancer. However, TSA and TSA/TP values were significantly elevated in each colorectal cancer subgroup compared with normal controls. TSA and TSA/TP values displayed a marginally better discriminatory power than CEA values in the case of Dukes A subgroup with respect to normal controls. CEA still appears to be the best single overall marker for discriminating between colorectal cancers and controls. However, multiple marker analysis using CEA and TSA (and related markers) appears to be more sensitive than CEA alone for detecting colorectal cancer.

Adult↗

PubMed1991

Mean square error of estimates of HIV prevalence and short-term AIDS projections derived by backcalculation.

We simulated multinomial AIDS incidence counts from 27 'representative' AIDS epidemics that spanned a period corresponding to previous applications of backcalculation (1 January 1977 to 1 July 1987) and assessed mean square error for several back-calculated estimators of HIV prevalence and short-term AIDS projections. Estimators were based on flexible model selection procedures that chose the best-fitting non-negatively constrained model of the infection curve from a family of possible step-function models. Selection of the best-fitting model from a family of four-step models each with a long last step of width of 4 or 4.5 years offered a favourable tradeoff between bias and variance when compared with selection from families of models with three steps or from families with a short last step. Five-step models performed as well as four-step models. Three-step models had substantially larger mean square error in some epidemic situations. Percentage root mean square error (PRMSE) for estimates of cumulative HIV prevalence as of 1 January 1985 was less than 14 per cent over a range of hypothetical epidemics of N = 50,000 infected individuals. PRMSE for short-term projections was less than 18 per cent. Estimates of cumulative HIV prevalence as of 1 July 1987 were substantially more uncertain and had a PRMSE of 33 per cent in the unfavourable case of a rapidly rising HIV epidemic. Estimates of cumulative HIV prevalence as of 1 July 1987 were positively biased in HIV epidemics with a rapidly decreasing recent HIV incidence rate and negatively biased in rapidly increasing HIV epidemics. Despite these uncertainties, we obtained useful estimates even for HIV epidemics with as few as 5000 infected individuals.

Acquired Immunodeficiency Syndrome↗

PubMed1991

Selecting an efficient design for assessing exposure-disease relationships in an assembled cohort.

We develop approximate methods to compare the efficiencies and to compute the power of alternative potential designs for sampling from a cohort before beginning to collect exposure data. Our methods require only that the cohort be assembled, meaning that the numbers of individuals Nkj at risk at pairs of event times tk and tj greater than or equal to tk are available. To compute Nkj, one needs to know the entry, follow-up, censoring, and event history, but not the exposure, for each individual. Our methods apply to any "unbiased control sampling design," in which cases are compared to a random sample of noncases at risk at the time of an event. We apply our methods to approximate the efficiencies of the nested case-control design, the case-cohort design, and an augmented case-cohort design, compared to the full cohort design, in an assembled cohort of 17,633 members of an insurance cooperative who were followed for mortality from prostatic cancer. The assumptions underlying the approximation are that exposure is unrelated both to the hazard of an event and to the hazard for censoring. The approximations performed well in simulations when both assumptions held and when the exposure was moderately related to censoring.

Biometry↗

PubMed1990

Fruit and vegetables in the American diet: data from the NHANES II survey.

Twenty-four hour dietary recall data from the Second National Health and Nutrition Examination Survey (1976-80) were used to estimate the numbers of servings of fruit and vegetables consumed by Black and White adults, to examine the types of servings (e.g., potatoes, garden vegetables, fruit, and juice), and to estimate the mean intake of calories, fat, dietary fiber, and vitamins A and C by number of servings. An estimated 45 percent of the population had no servings of fruit or juice and 22 percent had no servings of a vegetable on the recall day. Only 27 percent consumed the three or more servings of vegetables and 29 percent had the two or more servings of fruit recommended by the US Departments of Agriculture and of Health and Human Services; 9 percent had both. Consumption was lower among Blacks than Whites. The choice of vegetables lacked variety. Diets including at least three servings of vegetables and two servings of fruit contained about 17 grams of dietary fiber. Although caloric and fat intake increased with increasing servings of fruit and vegetables, the percent of calories from fat remained relatively constant. Although these data are 10 years old, more recent surveys have shown similar results. The discrepancy between dietary guidelines and the actual diet suggests a need for extensive public education.

Adult↗

PubMed1990

Application of DNA fingerprints for cell-line individualization.

DNA fingerprints of 46 human cell lines were derived using minisatellite probes for hypervariable genetic loci. The incidence of 121 HaeIII DNA fragments among 33 cell lines derived from unrelated individuals was used to estimate allelic and genotypic frequencies for each fragment and for composite individual DNA fingerprints. We present a quantitative estimate of the extent of genetic difference between individuals, an estimate based on the percentage of restriction fragments at which they differ. The average percent difference (APD) among pairwise combinations from the population of 33 unrelated cell lines was 76.9%, compared with the APD in band sharing among cell lines derived from the same individual (less than or equal to 1.2%). Included in this survey were nine additional cell lines previously implicated as HeLa cell derivatives, and these lines were clearly confirmed as such by DNA fingerprints (APD less than or equal to 0.6%). On the basis of fragment frequencies in the tested cell line population, a simple genetic model was developed to estimate the frequencies of each DNA fingerprint in the population. The median incidence was 2.9 X 10(-17), and the range was 2.4 X 10(-21) to 6.6 X 10(-15). This value approximates the probability that a second cell line selected at random from unrelated individuals will match a given DNA fingerprint. Related calculations address the chance that any two DNA fingerprints would be identical among a large group of cell lines. This estimate is still very slight; for example, the chance of two or more common DNA fingerprints among 1 million distinct individuals is less than .001. The procedure provides a straightforward, easily interpreted, and statistically robust method for identification and individualization of human cells.

Alleles↗

PubMed1985

The effect of intravenous hyperalimentation on the dietary intake of patients with small cell lung cancer. A randomized trial.

In a randomized trial of 119 patients with small cell cancer of the lung, the effects of a 30-day course of central intravenous hyperalimentation (IVH) on dietary intake were evaluated. All patients underwent the same aggressive chemotherapy and radiation therapy; 57 patients received IVH and 62 served as controls. Median caloric intake prior to antineoplastic therapy was less than 1.2 times basal energy expenditure, below the maximum necessary to maintain weight. While receiving IVH, patients had increased caloric and protein intake. Once the IVH was stopped, oral intake was transiently depressed and thereafter similar to control patients. Baseline nutritional parameters, age, sex, and immediate toxicity from chemotherapy did not predict subsequent caloric insufficiency. Direct estimation of dietary intake is likely the most valuable measure in selecting patients who will need adjunctive nutritional support.

Adult↗

PubMed1985

Effects of intravenous hyperalimentation during treatment in patients with small-cell lung cancer.

One hundred nineteen patients were entered onto a randomized trial of the role of intravenous hyperalimentation (IVH) in patients with small-cell lung cancer. IVH was given during the first 30 days of induction chemotherapy to 54 patients. IVH did not effect any improvement in response or survival from therapy. In view of the lack of benefits from IVH, an analysis was made of the toxicities suffered by the 54 patients receiving IVH as well as any effects IVH might have made on chemotherapy-induced toxicity. Toxicities observed included mechanical difficulties with the catheter leading to temporary or permanent discontinuation of the IVH (11 patients), subclavian vein thrombosis (one patient), sepsis in nine patients v none of the 62 control patients, fluid overload (27 patients), hyponatremia (25 patients), and hyperglycemia requiring insulin (13 patients). Patients receiving IVH had higher granulocyte counts on days 14 and 21 of the first cycle of chemotherapy. Analysis shows that this difference is likely caused by fever and infection associated with IVH rather than any nutritional effect on granulopoiesis. In this population of patients, IVH had significant complications but did not ameliorate chemotherapy-induced toxicity and it did not effect any clinical benefit. Future studies of adjunctive nutritional therapy must consider the significant risk in this older population and must limit IVH volume or exclude patients with even mild compromise in cardiovascular functions. Further, any new trial must have a significant rationale for adjunctive use to justify the potential risks.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1983

Quantitative criteria for prediction of the results after displaced fracture of the ankle.

In a series of 146 displaced ankle fractures, the effects of age, sex, side of injury, mechanism of injury, severity as determined by the Lauge-Hansen classification, type of injury (open or closed), open or closed treatment, and internal fixation of one or both malleoli were analyzed using subjective, objective, and radiographic parameters. Statistically significant prognostic features were identified and a prognostic scale was developed using multiple linear-regression analysis. The significant parameters were age, adequacy of the post-reduction positions of the medial and lateral malleoli, and completeness of the restoration of the deltoid ligament and distal tibiofibular syndesmosis. Open reduction proved superior to closed reduction, and in bimalleolar fractures open reduction of both malleoli was better than fixing only the medial side. Using the data on the first 109 fractures, a multiple linear-regression equation was formulated and used to predict the outcomes of the last thirty-seven fractures in the study. The accuracy of the predictions in them was 81 per cent.

Adolescent↗

PubMedDate not supplied

The partial questionnaire design for case-control studies.

We propose an alternative to a long questionnaire that may increase quality while reducing the cost and effort of participants and researchers. In the 'partial questionnaire design', information about the exposure of interest is obtained from all subjects, while zero, one, or more disjoint subsets of questions about possible confounders are asked to randomly selected subgroups. The proposed analyses exploit the fact that the uncollected data can be considered to be missing at random. We show that it is possible to obtain high efficiency for estimating the effect of exposure of interest, adjusted for confounding, while substantially shortening average questionnaire length.

Bias↗