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M Lau

Publications and source records attributed to M Lau.

At least 73 records · Page 4Linked to original sources
PubMed1995

Effect of increased intra-abdominal pressure on hepatic extraction and clearance of fentanyl in neonatal lambs.

Fentanyl, an opioid metabolized by hepatic mixed function oxidases, is commonly administered as the primary anesthetic for neonates undergoing surgery. Pharmacokinetic studies have suggested that abdominal surgery in neonates decreases fentanyl clearance, contending that this results from increases in intra-abdominal pressure (IAP) decreasing hepatic blood flow. To examine the effects of IAP on hepatic blood flow and fentanyl clearance, we infused fentanyl to eight neonatal lambs, measured regional blood flows by using the radionuclide-labeled microsphere technique and determined hepatic fentanyl extraction and clearance and hepatic oxygen extraction and consumption at three levels of IAP: 0, 12 and 18 mm Hg. Increased IAP did not affect portal or hepatic blood flow or ductus venosus shunt. Fentanyl extraction was 16.5 +/- 3.0% (mean +/- S.E.) at 0 mm Hg of IAP. Increased IAP decreased hepatic extraction of fentanyl, thereby decreasing fentanyl clearance. Increased IAP did not affect hepatic oxygen extraction or consumption. In two additional animals in which serial measurements of hepatic blood flow were obtained, increased IAP (15 mm Hg) transiently decreased hepatic blood flow with recovery to control values at 2 hr. The authors conclude that fentanyl is poorly extracted by neonatal livers, in contrast to its large extraction ratio in adults. The decrease in fentanyl clearance with increased IAP is consistent with pharmacokinetic studies demonstrating decreased clearance in neonates undergoing abdominal surgery. However, the present study suggests that the mechanism of decreased clearance is decreased hepatic function (decreased fentanyl extraction) rather than decreased hepatic blood flow.

Abdomen↗
PubMed1994

Comparison of twitch depression of the adductor pollicis and the respiratory muscles. Pharmacodynamic modeling without plasma concentrations.

BACKGROUND: Although the respiratory muscles (the diaphragm and the laryngeal adductors) recover from paralysis more rapidly than does the adductor pollicis, patients can develop complete paralysis of the respiratory muscles, but not of the adductor pollicis, after bolus administration of vecuronium. The authors used a pharmacodynamic model not requiring muscle relaxant plasma concentrations to reconcile these findings. METHODS: The pharmacodynamic model is based on the traditional model, in which: (1) vecuronium concentration at the neuromuscular junction (C(effect)) is a function of the plasma concentration versus time curve and a rate constant for equilibration between plasma and the neuromuscular junction (k(eo)); and (2) effect is a function of C(effect), the steady-state plasma concentration that produces 50% effect (C50), and a factor to explain the sigmoid relationship between concentration and effect. In the absence of vecuronium plasma concentrations, an empiric model (rather than the usual effect compartment model) can be used to mimic the time delay (proportional, but not identical, to 1/k(eo)) between dose and effect. The model can be used to estimate the steady-state infusion rate that produces 50% effect (IR50), equal to the product of C50 and vecuronium plasma clearance; IR50 for different muscle groups then can be compared to assess relative sensitivity. The authors applied this model to published effect data for subjects given 40-70 micrograms/kg vecuronium in whom paralysis of three muscle groups was measured during opioid/propofol anesthesia. RESULTS: For IR50, the ratio of values for the larynx:diaphragm:adductor pollicis was 1.4:1.2:1; for the equilibration constant (inversely proportional to the time delay), the ratio for the respiratory muscles to the adductor pollicis was 2.5:1. CONCLUSIONS: Vecuronium concentrations peak earlier at the respiratory muscles than at the adductor pollicis, possibly the result of greater perfusion to these organs, leading to earlier onset of paralysis. The observation that bolus injection of vecuronium produces greater paralysis of the respiratory muscles than of the adductor pollicis, despite greater resistance of the respiratory muscles, can be explained by differential rates of equilibration between plasma and various muscles.

Humans↗
PubMed1994

Is intramuscular mivacurium an alternative to intramuscular succinylcholine?

BACKGROUND: Mivacurium's rapid onset and short duration of action in children suggests that intramuscular administration might treat laryngospasm and facilitate tracheal intubation without producing prolonged paralysis. Accordingly, the authors measured the neuromuscular effects of intramuscular mivacurium in anesthetized infants and children. METHODS: Twenty unpremedicated infants and children (3 months to 5 yr of age) were anesthetized with nitrous oxide and halothane and permitted to breathe spontaneously. When anesthetic conditions were stable, mivacurium was injected into the quadriceps or deltoid muscle. Minute ventilation and adductor pollicis twitch tension were measured. The initial mivacurium dose was 250 micrograms/kg and was increased (to a maximum of 800 micrograms/kg, at which dose the trial was ended) or decreased according to the response of the previous patient, the goal being to bracket the dose producing 80-90% twitch depression within 5 min of drug administration. RESULTS: No patient achieved > 80% twitch depression within 5 min of mivacurium administration. Peak twitch depression was 90 +/- 13% (mean +/- SD) for infants and 88 +/- 15% for children at 15.0 +/- 4.6 min and 18.4 +/- 6.4 min, respectively. Ventilatory depression (a 50% decrease in minute ventilation or a 10-mmHg increase in end-tidal carbon dioxide tension) occurred at 9.0 +/- 4.4 min in nine infants and 13.6 +/- 7.5 min in 10 children; ventilatory depression did not develop in one infant given a dose of 350 micrograms/kg. Time to peak twitch depression or ventilatory depression was not faster with larger doses. CONCLUSIONS: Although ventilatory depression preceded twitch depression, both occurred later with intramuscular mivacurium than would be expected after intravenous mivacurium or intramuscular succinylcholine. The authors speculate that the onset of intramuscular mivacurium is too slow to treat laryngospasm or to facilitate routine tracheal intubation in infants or children, despite administration of large doses.

Anesthesia, Inhalation↗
PubMed1994

HLA-B15: a widespread and diverse family of HLA-B alleles.

HLA-B15 embraces a multiplicity of antigenic specificities which vary in their distribution amongst human populations. To correlate B15 molecular structure with the serological picture we have sequenced alleles encoding the various subspecificities of the B15 antigen: B62, B63, B75, B76 and B77, and a number of "variants" of these antigens including the 8w66 split of B63. HLA-B63 (B*1517) and 8w66 (B*1516) heavy chains have sequence identity to B17 in the alpha 1 helix correlating with the antigenic crossreactivity of these molecules. HLA-B77(B*1513) and B75 (B*1502) heavy chains differ solely in segments determining the Bw4 and Bw6 public epitopes, consistent with the serological description of the B77 and B75 antigens. One allele encoding the B76 antigen (B*1512) appears to be the product of gene conversion between the HLA-A and -B loci and differs from B*1501 in codons 166 and 167. In contrast, a second allele encoding the B76 antigen (B*1514) differs from B*1501 by an unrelated substitution in codon 167 which confers similarily with B45, an antigen crossreactive with B76. A third allele encoding B76, B*1519, differs from B*1512 by a unique point substitution in exon 4. Three alleles encoding variant B15 and B62 antigens (B*1508, B*1511 and B*1515) differ from B*1501 by localized clusters of substitutions that probably result from interallelic conversion. The B15 sequences described in this paper, in combination with those previously determined, define a family of 22 alleles, including those encoding the B46 and B70 antigens. Within this family the patterns of allelic substitution are analogous to those of other HLA-A and -B families, in that pairwise differences almost always involve functional positions of the antigen recognition site and recombination is the major agent of diversification.

Alleles↗
PubMed1994

Gray scale and color flow Doppler characterization of uterine tumors.

The aim of this study was to investigate gray scale and color flow characteristics of a group of patients with a suspected uterine pathologic condition. One hundred and twenty-two consecutive patients at the Women's Cancer Center, University of Minnesota, undergoing transvaginal sonography and color flow Doppler imaging for suspected uterine corpus abnormality made up the study group. After gray scale morphologic assessment, color flow Doppler imaging of the tumor and uterus was performed, including the ipsilateral uterine artery. Malignant tumors were confirmed pathologically in all 35 patients who had them. In comparing patients with benign versus malignant tumors, gray scale morphologic assessment confirmed that malignant uterine tumors (31 endometrial cancers and four sarcomas) were more likely to have a thickened echoic endometrium (P = < 0.0001), be enlarged (P = 0.004), to be retroverted (P = 0.02), and to lack a subendometrial halo (P < 0.0001). Patients with four benign and 13 malignant tumors demonstrated increased flow when assessed by CFD. The calculated sensitivity of increased color flow in predicting malignancy was 39%, with a specificity of 92%, a positive predictive value of 77%, and a negative predictive value of 71%. No difference existed between the benign and malignant groups for the systolic, diastolic, and mean velocities and for the calculated pulsatility index and resistive index in both sampled uterine and intramyometrial or tumor vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

International Cell Exchange, 1994.

1. We summarize typings of 40 cells for Class I antigens and 20 cultured cell lines for Class II antigens through the International Cell Exchange in 1994. Serologic Class II typings were compared with DNA typings for the same 20 cells. Two hundred eighty-one laboratories participated in the monthly Class I Serum Exchange. One hundred nineteen serology laboratories and 74 DNA laboratories reported Class II specificities on a monthly basis. 2. The average detection levels, as well as the high detection levels, were determined for 16 A-locus and 27 B-locus antigens. Mean detection rates of 95% or greater average detection were obtained for 12 A-locus and 10 B-locus antigens. Lower than 80% agreement was calculated for one A-locus antigen (A74) and 7 B-locus (B46, B48, B61, B67, B73, B75, B77) antigens. 3. We compared discrepancy rates of 10 A-locus and 7 B-locus antigens typed 3 times or more. The false-negative discrepancy rates, i.e. how often the antigen was missed, were greater for more of the B-locus specificities than for the A-locus antigens. B62, having the highest false-positive rate, tended to be overassigned. The discrepancy rates, especially the false-negative rate, for B70 were shown to decrease over a 7-year period. 4. In 1994, 8 laboratories attained records of total no misses for all analyzed antigens. Twelve laboratories had final records of only one discrepancy, and 5 laboratories had impressive perfect records (zero false negatives and false positives) for their yearly antigen reports. 5. Retyping of 12 Class I and 8 Class II reference cells showed improved detection of antigens. Results of a donor typed 4 times over 11 years demonstrated marked improvement, nearly doubling for A33, B38, and B75. Two cells first typed in 1991, then retyped in 1994, showed improved detection for Class II splits by serology and DNA typing. 6. We updated the list of sequenced Class I Exchange cells. Seven new cells were added as well as confirmatory sequence data for A*2403 to the A9.3 (cell 762) and a new B*0705 (cell 715) for previously listed cells. Variants detected in the exchanges for Class I (DT/B7x40, B15, B16, B5x53) and Class II (DRB1*1111, DQB1*02, DR1, DR2) specificities were discussed. Eleven rare or unusual Class II haplotypes were studied in 1994. 7. The mean detection levels were determined for 9 broad DR and 4 DQ specificities by serology and compared to those attained for the respective generic (low resolution) DNA typing.(ABSTRACT TRUNCATED AT 400 WORDS)

Alleles↗
PubMed1994

International sera exchange analyses in relation to DNA sequences: summary report from 1990 to 1994.

One hundred ninety-five sera were tested against over 7,000 cells originating from approximately 100 laboratories in the world during the past 5 years. This collaboration was useful to compare local data with data from other laboratories, although the local panel of cells varied from 30 to 200. In analyzing the reactions of the sera, it was noted that antibodies that react cleanly to well-defined antigens can usually be defined by a single unique amino acid residue. Antisera which appear to be definable by several amino acids (a motif) have reactivities which are more variable.

Amino Acid Sequence↗
PubMed1994

Cumulative characteristics of atracurium and vecuronium. A simultaneous clinical and pharmacokinetic study.

BACKGROUND: Cumulative effects (increased 25-75% recovery time with increasing dose) are evident with vecuronium but not with atracurium. Pharmacokinetic simulations suggest that vecuronium's cumulation occurs as recovery shifts from distribution to elimination whereas atracurium's recovery always occurs during elimination. The purpose of this study was to examine this pharmacokinetic explanation. METHODS: We assigned 12 volunteers to receive atracurium of vecuronium on three occasions during nitrous oxide-isoflurane anesthesia. Evoked adductor pollicis twitch tension was monitored. On occasion 1, the dose expected to produce 95% block (ED95) was estimated for each subject. On occasions 2 and 3, 1.2 or 3.0 multiples of ED95 were given as a bolus. Plasma was sampled for 128 min to determine muscle relaxant concentrations; pharmacodynamic modeling was used to determine effect-compartment drug concentrations (Ce). For each drug, recovery time, recovery phase half-life (rate of decrease in Ce during recovery), and Ce at 25% and 75% recovery were compared between doses. RESULTS: Atracurium's recovery time increased 2.4 +/- 2.2 min (mean +/- SD) with the larger dose, less than the increase with vecuronium (8.2 +/- 3.8 min). Atracurium's recovery phase half-life was 14.6 +/- 1.7 and 20.1 +/- 2.3 min with the small and large doses (P < 0.05); vecuronium's recovery phase half-life increased similarly from 13.5 +/- 2.3 to 18.5 +/- 5.0 min (P < 0.05). At 75% recovery, vecuronium's Ce decreased from 65 +/- 18 ng/ml with the small dose to 55 +/- 15 ng/ml with the large dose (P < 0.05). Assuming that neuromuscular junction sensitivity was constant, this difference could be explained by considering neuromuscular effects of vecuronium's metabolite, 3-desacetylvecuronium. CONCLUSIONS: Although vecuronium was cumulative (as predicted), atracurium was also slightly cumulative. Inconsistent with our hypothesis, recovery phase half-lives for both drugs increased similarly between doses; therefore, differences in cumulation were not solely explained by pharmacokinetics of the muscle relaxant. It appears that 3-desacetylvecuronium contributes to vecuronium's cumulative effect, even after usual clinical doses.

Adult↗
PubMed1993

Strategy and implementation of a system for protein engineering.

This paper describes an overall view of an industrial protein engineering project from conception to successful completion. The choice of rational design was determined by the availability of an excellent three-dimensional crystal structure and the availability of information in the literature to define a strategy. The design strategy was refined extensively during the course of the project. The development of methods for mutagenesis, expression, verification, purification, and characterization of mutant enzymes is dictated in part by the enzyme property one chooses to modify and must be rapid yet accurate. Such an approach would be applicable to improve the stability of any other protein or enzyme. Using this approach, we successfully increased the stability of subtilisin BL over 10-fold at 50 degrees C with an overall success rate greater than 60%.

Bacillus↗
PubMed1993

The 1993 cell typings of the International Cell Exchange.

1. This is a summary of the typings for 40 cells for Class I antigens and 20 cultured cell lines for Class II antigens through the International Cell Exchange. Serological typings were compared with DNA typing reports for Class II specificities. Presently, 283 laboratories participate in the monthly Class I exchange. Class II results were received from 124 serology labs and 81 DNA labs on a monthly basis. 2. In 1993, 12 A-locus antigens were typed and 8 specificities reached levels of 95% or greater average detection. Thirteen of the 33 B-locus antigens showed 95% or better mean agreement levels. There was an improvement in detection of B76 and B7801. 3. Discrepancy rates of 7 A-locus and 9 B-locus antigens typed 3 or more times were compared with the overall rates for each respective locus. The discrepancy rate of false negatives, ie, how often the antigen was missed for the recognized B-locus specificities, continued to be greater than those for the A-locus antigens. The discrepancy rates, especially the percent false-positive, decreased for A33 during the recent 6-year period. 4. We showed the number of labs with their total of false-negatives and false-positives. Twelve labs attained a final total of no misses for all antigens. In 1993, 11 labs achieved impressive perfect records (zero false negative and false positive) for all analyzed antigens. 5. Retyping results of 2 donors showed improved antigen detection, particularly of A2403, B70, and B76. 6. Eleven cells typed in previous cell exchanges as having new or rare variants were sequenced recently. The B*5102 and B*5901 cells were retyped as reference cells. A new A-locus variant detected in previous exchanges was recently confirmed by sequence work as A*8001. New variants of B5 and B22 were discussed. 7. In addition to the mean detection rates, the low and high levels were determined for 15 broad (11 DR & 4 DQ) specificities by serology and compared with those attained for the respective generic (low-resolution) DNA typing. Only 2 broad antigens (DR10 and DQ4) had less than a 90% agreement level by serology. All of the generic types reached over 95% average detection levels, with the exception of DQB1*04, which reached 90% mean detection. 8. Detection of 8 Class II splits (4 DR & 4 DQ) continued to pose problems in serology, ranging from as low as 15% for DQ5 and DQ9 to an average detection level of 61% for DR15.(ABSTRACT TRUNCATED AT 400 WORDS)

B-Lymphocytes↗
PubMed1992

International Cell Exchange: 1992.

1. This is a review of 1992 typing of 40 cells for Class I antigens and 18 cultured cell lines for Class II antigens through the International Cell Exchange. Serological typings were compared with DNA typing reports for Class II specificities. Presently, 290 laboratories participate in the monthly Class I exchange. Class II results were received monthly from 166 serology laboratories and from 36 DNA laboratories. 2. In 1992, 11 of the 16 A-locus antigens attained 95% or greater average detection. Nine of the 27 B-locus antigens showed 95% or better mean agreement levels. Antigens such as B46 and B70 continued to show improvement in detection in a 5-year period. 3. We compared discrepancy rates of 7 A-locus and 8 B-locus antigens typed 3 times or more. The rates for the B-locus specificities, especially for percentages of false negatives (ie, how often the antigen assignment was missed), continued to be greater than those for the A-locus antigens. Nevertheless, the discrepancy rates of B35 and B70 decreased dramatically during the last 5 years. 4. We showed the number of laboratories with the total of false negatives and false positives. Nine laboratories achieved perfect records (0 false negatives and false positives) for all analyzed antigens in 1992. 5. Results of retyping of 3 donors over several years were shown to indicate improved antigen detection. 6. Recently recognized HLA-specificities, such as A2403 and B5102, were shown as cell variants studied in previous cell exchanges. Variants of B15, B16, and B40 families were presented, as well as several new A-locus antigens. 7. The low and high rates, in addition to the average detection levels, were indicated for a total of 27 (18 DR and 9 DQ) Class II specificities by serology and by DNA typings. Eight of the 15 DR/DRB1 specificities attained 90% or better average agreement by both serology and DNA. Three of the 9 DQ antigens achieved 90% or better average detection by both methods. 8. Confirmation by DNA typings was demonstrated for 8 Class II specificities with 60% or lower detection levels by serology; the average detection levels by DNA typing was 80% or greater. Confirmation of 2 splits of Class II antigens by DNA typing was shown in 3 cells. 9. The percent detection levels were calculated for 17 DRB1 alleles and 11 DQB1 alleles. Variation in agreement was observed for the Class II alleles. Two DRB1 and 3 DQB1 alleles had average detection levels of 80% or higher.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Line↗
PubMed1992

Morphologic scales and relative distances between lesions identified on Papanicolaou smears.

We fit a Gaussian-type curve to a nonmonotonic transform of initial arbitrarily given scales (pseudoscalar transform) of a two-way discrete classification table by maximizing the likelihood (entropy) and computing morphologic scales of clusters of objects identified by visual judgments. The scales give the relative distance between pairs of categories or states. Morphologic scales of histologic lesions (states) identified on Papanicolaou smears were computed from a confusion matrix consisting of 3,545 matched pairs of observations on Papanicolaou smears and colposcopically directed biopsies available from the Gynecologic Cytology Laboratory, University of Minnesota, between 1985 and 1987. The original (uncollapsed) confusion matrix consisted of eight cytologic categories and histologic states: normal plus atypical benign, reactive atypia (including condylomatous changes); mild, moderate and severe dysplasia; squamous carcinoma in situ; invasive squamous cell carcinoma; and other malignancies. The morphologic scales are expressed numerically, which reflects a degree of confusion between two diagnostic categories or states. Except for malignancies other than squamous cell carcinoma, morphologic scales of histologic states seen from cytology retained the order of clinical severity. We detected a high degree of confusion between severe dysplasia and carcinoma in situ. Malignancies other than squamous cell carcinoma fell between moderate and severe dysplasia. Such a transposition of the scales in this group containing adenocarcinoma was likely due to frequent association of adenocarcinoma with cervical intraepithelial neoplasia. Morphologic scales of cytologic categories seen from histology showed high degrees of confusion and transpositions between mild and moderate dysplasia and between severe dysplasia and carcinoma in situ.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1992

Information, discrimination and divergence in cytology. V. General symmetry of total discrimination and total divergence.

Total discrimination and divergence are derived from Baye's theorem and based on backward (a posteriori) probabilities. Total forward (a priori) discrimination and divergence can be computed from a test matrix from which total backward discrimination and divergence were calculated for optimization of the classifications of gynecologic cytology (Papanicolaou smears) and quality control in a laboratory. The total forward discrimination and divergence appears to behave in parallel with the total backward discrimination and divergence, and the discrepancies in the backward and forward discrimination/divergence were the smallest near the optimum classification scheme. Conversely, the discrepancies between backward and forward discrimination and divergence may be helpful in finding the best classification scheme for gynecologic cytology. The general symmetries of the total backward and forward discrimination/divergence may be related to the human cognitive process of preferring symmetry and to the historic process in which cytologic classification followed histologic classification and continuously checked for matches in two directions--i.e., from histology to cytology and vice versa--thus resulting in the preservation of symmetry.

Bayes Theorem↗
PubMed1992

Information, discrimination and divergence in cytology. VI. Biases and errors of measurement in small samples.

Total discrimination and total divergence have been shown to be useful measures of performance in diagnostic cytology. The sample size, Ns (observed number of cytology-histology pairs, essential components of a confusion matrix), may be small for the comparison of two or more laboratories or periodic quality control using observed values. From actual data from previous reports in this series, the best estimation of the confusion matrix of a population was obtained by fitting a Gaussian-type curve after pseudoscalar transform of ranks (row and column numbers). Small sample confusion matrices were generated by Monte Carlo simulation to 2.5 x 10(-7) resolution. To keep measurement biases within +/- 0.5 decits, we found that 100-200 samples of cytology-histology pairs were required in the best classifications of three, four and five category-states. At these sample sizes, measurement errors (standard errors) were also contained within +/- 0.5 decits. This study also confirmed that previously reported overestimated propagated errors in small samples were in fact overestimation and that their use for testing a null hypothesis was valid. The number of samples with indefinable statistics due to a zero denominator can be as high as 30% when the sample sizes are 500 for three, four and five category-state classifications. Biases due to small samples were positive for most category-states except for the optimum three category-states, in which bias changed to negative ("bias inversion"), and observed errors of discrimination and divergence paradoxically decreased as Ns decreased ("error-sample paradox") for a small sample size (Ns less than 700).(ABSTRACT TRUNCATED AT 250 WORDS)

Cytodiagnosis↗
PubMed1991

International Cell Exchange, 1991.

1. During 1991, lymphocytes from 40 individuals of various races and 20 cultured B-cell lines were sent to 290 laboratories (listed in appendix) for typing. The results of the blind tests were analyzed and reported monthly. This is a summary of the year's 10 monthly exchanges. 2. Ten A-locus antigens showed 95% or greater agreement among laboratories, and 100% agreement was achieved for A2 and A3. Agreement of 95% or more was reached for 7 B-locus specificities. Both Bw54 and Bw73 showed marked improvement in detection during the last 3 years. 3. Six laboratories did not miss the assignment of any A- or B-locus antigens. The false-positive and false-negative assignment rates are given for the A- and B-loci. 4. The following variants were studied: B5-53 variants from various races, BN21, B7x40 (DT), and B7x27. 5. Aw66 assignment was found to be discrepant between the United States and European laboratories. 6. The A28 splits, Aw68 and Aw69, were studied, as were cells with different Aw68 splits. 7. Cell lines were typed by 150 laboratories, including 19 DNA laboratories. Six Class II antigens had 95% or higher detection levels, and 5 others had higher than 90% detection levels. 8. Both DNA and serology laboratories had difficulty in assigning the DRw6 splits, DRw13 and DRw14. The definition of the splits of DR3, DQw1, and DQw3 was clarified with the additional DNA typing results. 9. Amino acid sequencing confirmed a new variant of Bw53, as indicated by the assignments based on serology.

Amino Acid Sequence↗
PubMed1990

1990 cell typings in the International Cell Exchange.

1. A yearly summary of the previous year's cells typed through the International Cell Exchange allows a participating laboratory to compare its own performance with 292 currently participating exchange laboratories, inasmuch as each laboratory receives its individual antigen report. We present an annual summary for the 1990 typings of 40 cells sent for Class I and 20 cells sent for Class II antigens. 2. The mean detection percentages and the detection ranges for 21 WHO-designated (well-defined) and 21 WHO-provisional (with "w" designations, less well-defined) antigens were determined for the Class I cells typed in 1990. Seventeen WHO antigens showed 95% or greater detection levels. The remaining WHO antigens showed at least 90% agreement, with the exception of B38. More variation in detection is observed in the WHO-provisional antigens. Aw33, Bw50, Bw60, and Bw62 showed 90% or greater average detection percents. In recent years, antigens such as Bw46 and Bw70, have shown great improvement in detection. 3. The percent discrepancy rates of 8 HLA-A,B antigens typed 4 times or more in 1990 were presented as well as the total percent discrepancy rates for all Class I antigens. Comparison of 1990 figures with those of 1988 and 1989 shows a marked decrease in the total discrepancy rates. 4. The number of false negatives and false positives for the Class I antigens indicates that few laboratories have trouble typing the WHO antigens; as many as 115 laboratories had 0 misses. However, a greater number of laboratories missed the less well-defined WHO-provisional antigens: 7 laboratories had 0 misses for all the antigens and 4 laboratories had perfect records (0 false negatives and false positives) for cells typed in 1990. 5. In 1990, the cell exchange continued to study new cell variants. An A10 (A26x34) variant was detected in 4 cells and another possible variant, B7x40 (DT), was determined in 3 cells. 6. The average detection percentages and detection ranges were determined for 23 Class II antigens. Improved detection is indicated. At least 9 Class II antigens showed 90% or greater agreement level, of which at least 4 had 95% or greater mean detection. 7. Since the incorporation of DNA typing results in the B-cell line exchange reports in July 1990, the Class II antigen splits in 11 cells have been confirmed or clarified. Two Class II variants were also confirmed by the DNA laboratories. Presently, 145 serology and 7 DNA laboratories are in this exchange.(ABSTRACT TRUNCATED AT 400 WORDS)

DNA↗
PubMed1989

Fifteen-year overview of the International Cell Exchange.

1. Through the International Cell Exchange, 4 cells were shipped for blind typing to tissue typing laboratories on a monthly basis for the past 15 years. As many as 288 laboratories worldwide currently participate in this exercise. 2. The frequency of detection of a total of 85 HLA-A,B,C specificities by the laboratories has been determined. Each specificity has been classified as to the reliability of identification. 3. Lymphocytes from 27 donors were sent for retesting in as long as a 13-year interval. This provided an accurate picture of the advances in percent detection by the laboratories. 4. At least 5 variants were found by shipping cells to the laboratories: variants of A9, B21, B5, Bw52, and B40. 5. B cell lines were sent to investigate the HLA-DR antigens. At least 11 specificities had a concordance rate higher than 80% and 5 had a rate of more than 95%. 6. HLA-A,B antibodies sent for antibody characterization were classified by a new mass program for the likely epitope against which the sera were directed. As many as 28 different epitopes were detected by the sera sent in the serum exchange.

HLA Antigens↗