Comparison of RhD Typing Results by Serology and Molecular Methods

OBJECTIVE

Molecular testing determines D antigen status when abnormal serologic results are observed. Molecular testing is routinely batched, resulting in longer turnaround time for abnormal D status resolution. During the interim, obstetric patients with questionable/uninterpretable and weak D typing results by serology, per the immunohematology reference laboratory (IRL) policy, will receive RhD negative blood. This study aimed to determine whether serology results achieved a concordance.

METHODS

Six hospitals provided samples to the IRL (first IRL) for RhD status by DNA. De-identified samples were sent for serology RhD (second IRL). A concordance of ≥80% was acceptable.

RESULTS

Forty-nine samples were evaluated. Results were concordant (65.3% [32/49]) and discordant (34.7% [17/49]). This is significantly lower than clinically acceptable 80% (z = 2.57, P < .05). The turnaround-time was 3.0 hours for serology and 4.4 days for molecular evaluation.

CONCLUSION

Due to a low concordance, serology could not be used in place of molecular testing.

Mutator/Hypermutable fetal/juvenile metakaryotic stem cells and human colorectal carcinogenesis

Adult age-specific colorectal cancer incidence rates increase exponentially from maturity, reach a maximum, then decline in extreme old age. Armitage and Doll (1) postulated that the exponential increase resulted from "n" mutations occurring throughout adult life in normal "cells at risk" that initiated the growth of a preneoplastic colony in which subsequent "m" mutations promoted one of the preneoplastic "cells at risk" to form a lethal neoplasia. We have reported cytologic evidence that these "cells at risk" are fetal/juvenile organogenic, then preneoplastic metakaryotic stem cells. Metakaryotic cells display stem-like behaviors of both symmetric and asymmetric nuclear divisions and peculiarities such as bell shaped nuclei and amitotic nuclear fission that distinguish them from embryonic, eukaryotic stem cells. Analyses of mutant colony sizes and numbers in adult lung epithelia supported the inferences that the metakaryotic organogenic stem cells are constitutively mutator/hypermutable and that their contributions to cancer initiation are limited to the fetal/juvenile period. We have amended the two-stage model of Armitage and Doll and incorporated these several inferences in a computer program CancerFit v.5.0. We compared the expectations of the amended model to adult (15-104 years) age-specific colon cancer rates for European-American males born 1890-99 and observed remarkable concordance. When estimates of normal colonic fetal/juvenile APC and OAT gene mutation rates (∼2-5 × 10(-5) per stem cell doubling) and preneoplastic colonic gene loss rates (∼8 × 10(-3)) were applied, the model was in accordance only for the values of n = 2 and m = 4 or 5.

Evidence of flexible coding in visual word recognition

In 3 visual word recognition experiments, the authors examined Ss' differential dependence on phonological versus orthographic information in accessing the lexicon. The critical manipulation was the presence or absence of pseudohomophones in the nonword context of a lexical decision task. Ss received a list with either no pseudohomophones (NPsH group) or 17%-30% pseudohomophones among the nonwords (PsH group). In the first 2 experiments Ss in the PsH group were faster and no less accurate on word trials than Ss in the NPsH group. Furthermore, performance in the NPsH group was adversely affected by phonological inconsistency in the target's orthographic neighborhood. In the final experiment, a double lexical decision paradigm was used, and performance on orthographically similar but phonologically dissimilar pairs differed in the 2 conditions.

Evidence of flexible coding in visual word recognition

In 3 visual word recognition experiments, the authors examined Ss' differential dependence on phonological versus orthographic information in accessing the lexicon. The critical manipulation was the presence or absence of pseudohomophones in the nonword context of a lexical decision task. Ss received a list with either no pseudohomophones (NPsH group) or 17%-30% pseudohomophones among the nonwords (PsH group). In the first 2 experiments Ss in the PsH group were faster and no less accurate on word trials than Ss in the NPsH group. Furthermore, performance in the NPsH group was adversely affected by phonological inconsistency in the target's orthographic neighborhood. In the final experiment, a double lexical decision paradigm was used, and performance on orthographically similar but phonologically dissimilar pairs differed in the 2 conditions.

Neighborhood effects in visual word recognition: effects of letter delay and nonword context difficulty

The role of a target's orthographic neighborhood in visual word recognition was investigated in 2 lexical decision experiments. In both experiments, some stimuli had 1 letter delayed relative to the presentation of the rest of the stimulus. Experiment 1 showed that delaying a letter position, which yielded a potentially competitive neighbor, was more costly to target recognition than delaying a position that yielded no neighbors. This effect was strongest when one of these neighbors was of higher frequency than the target itself. Additionally, the effect was reduced for words with a high friendly-to-unfriendly-neighbor ratio (friendly neighbors being those words containing the delayed letter). In Experiment 2 the difficulty of the word-nonword discrimination was manipulated by varying the density of the nonwords' neighborhoods. Only when the nonwords had many neighbors at several positions did the word responses show neighborhood competition effects.

Neighborhood effects in visual word recognition: effects of letter delay and nonword context difficulty

The role of a target's orthographic neighborhood in visual word recognition was investigated in 2 lexical decision experiments. In both experiments, some stimuli had 1 letter delayed relative to the presentation of the rest of the stimulus. Experiment 1 showed that delaying a letter position, which yielded a potentially competitive neighbor, was more costly to target recognition than delaying a position that yielded no neighbors. This effect was strongest when one of these neighbors was of higher frequency than the target itself. Additionally, the effect was reduced for words with a high friendly-to-unfriendly-neighbor ratio (friendly neighbors being those words containing the delayed letter). In Experiment 2 the difficulty of the word-nonword discrimination was manipulated by varying the density of the nonwords' neighborhoods. Only when the nonwords had many neighbors at several positions did the word responses show neighborhood competition effects.

The processing of inflected words

Is an inflected word identified by first decomposing it into stem plus suffix or, instead, is it recognized as a whole? Several lexical decision experiments studied the recognition of inflected words in English (a language with few inflections) and Serbo-Croatian (a heavily inflected language). If recognition depended on decomposition, preceding the inflection with a brief exposure of the stem (less than 100 ms) should have primed the lexical entry for the stem and, therefore, facilitated recognition of the whole inflected word that followed. It did not. It was also found that the speed of recognizing an inflected word was more strongly associated with the frequency of the whole inflected form than with the frequency of its stem. The results suggested that in word recognition, lexical contact is first made with the whole word form. Nevertheless, morphological decomposition may still occur in subsequent processing.