CO2 dissociation curves of oxygenated whole blood obtained at rest and in exercise

Summary In vitro CO₂ dissociation curves for oxygenated whole blood were determined in 19 healthy male subjects at rest and during submaximal and maximal bicycle work. Hemoglobin concentration and blood lactate increased with increasing work load and accordingly buffer value of the whole blood increased while bicarbonate and Base Excess (BE) decreased, resulting in a downward shift of the CO₂ dissociation curve during exercise. Despite the marked increase in buffer values of the blood, the slopes of the CO₂ dissociation curves during exercise were found to be about the same as those obtained at rest. It was inferred that the increasing effect of increased buffer value, on the dissociation slope, was essentially compensated by the decreasing effect of diminished bicarbonate content. The advantages of this relatively constant CO₂ dissociation slope for the indirect measurement of cardiac output by the Fick principle are discussed.     

CORRELATION OF SKIN POTENTIAL AND SKIN RESISTANCE MEASURES

Simultaneous measurements of skin potential (SP) and skin resistance (SR) obtained from 20 male and 20 female adult subjects during 2 sessions held 2 to 9 days apart were used in studying (1) the correlation of change measurements and prestimulus level in the two measures, and (2) the amount of correlation between SP and SR using both simple difference and residual change scores in which the regression of poststimulus values on initial level (prestimulus) has been controlled. Correlations within Ss and correlations among Ss showed large individual variability, correlation differences between males and females, and high correlation between SP and SR change scores. Although the law of initial value (LIV) seemed to have little applicability to the measurement of electrodermal responses, the results underscored the need to control for contamination of change measures by initial level regardless of direction.     

汉族男女七对显、隐性性状及基因频率的研究

目的探讨汉族男女在正常性状表现及基因频率的差异.方法调查湖南境内汉族男女7对正常遗传性状,并用Hardy-Weinberg定律和分离定律计算男女每一性状的基因频率.结果眼睑、拇指末关节的性状在汉族男女之间差异较大,而卷舌、耳垂、前额发际、发式、发旋无明显差异.结论同一民族不同性别在性状表现及基因频率方面存在差异,为中国人群体遗传学研究提供资料.     

Andrology: Acrosome reaction inducibility predicts fertilization success at in-vitro fertilization

We prospectively studied the ability of acrosome reaction (AR)inducibility to predict fertilization success in a group of232 infertile patients presenting sequentially for in-vitrofertilization (IVF). The median percentage of eggs fertilizedfor the overall patient population was 25% (interquartile range5–58%), with one to 29 oocytes available for insemination(median, five oocytes). The median percentage of eggs fertilizedat IVF increased as the percentage of spermatozoa able to undergoAR became greater: spermatozoa with a failed AR (5%) fertilizedonly 12% of eggs, while spermatozoa with AR values>9% fertilized50% of eggs. The assay had a specificity of 0.75, a sensitivityof 0.55 and an odds ratio of 2.9; thus, AR-positive patientsare 2.9 times more likely to achieve fertilization than patientswith a failed AR. Receiver operator characteristic (ROC) curveswere constructed for AR, sperm concentration and percentageof normal forms in semen. All three parameters proved to bepotentially useful in predicting the occurrence of fertilization,although AR and morphology appeared to be better than spermconcentration by ROC analysis. Patients were divided into fourclearly defined subgroups according to their traditional semencharacteristics, including morphology. The median percentageof eggs fertilized decreased as traditional semen characteristicsdeteriorated, from a median of 46% for patients with excellentsperm concentration, motility and morphology, to a median of29% for patients with suboptimal semen quality and a medianof 0% for patients with severely impaired semen. Within eachpatient subgroup, the median percentage of eggs fertilized was3-to 4-fold higher for individuals with a positive AR than forthose with a failed AR, indicating that AR has a greater effecton fertilization rate than traditional semen parameters includingmorphology. We now recognize that some men with good semen characteristicshave an unexpectedly poor AR and a markedly reduced fertilizationrate, while other men with poor traditional semen characteristicsunexpectedly retain AR and perform relatively well at IVF. Bycontrast to AR, morphology seemed to have little effect on fertilizationsuccess (two-way analysis of variance not significant). Thewife's age and oocyte quality were evenly distributed amongthe different patient subgroups, indicating that differencesin fertilization rate could not be attributed to either parameter.Our data indicate that AR has a much higher predictive valuefor IVF success than traditional semen parameters includingmorphology. We propose that AR assessment is a clinically usefuldiagnostic tool in determining a patient's likelihood of achievingfertilization at IVF.     

Clinically-based determination of safe DNAemia cutoff levels for preemptive therapy or human cytomegalovirus infections in solid organ and hematopoietic stem cell transplant recipients

Transplantation Centers using human cytomegalovirus (HCMV) antigenemia-based preemptive therapy will need to replace in the near future the antigenemia assay with a more standardized and automatable assay, such as a molecular assay quantifying HCMV DNA in blood (DNAemia). Thus, in view of replacing antigenemia with clinically safe cutoff values, DNAemia levels corresponding to antigenemia cutoffs guiding HCMV preemptive therapy were determined retrospectively in solid organ and hematopoietic stem cell transplant recipients (HSCTR) using an "in-house" quantitative PCR (QPCR) method. Since preemptive therapy had prevented appearance of HCMV disease in all patients tested, DNA cutoffs determined retrospectively had to be considered as safe clinically as antigenemia cutoffs used prospectively. However, in solid organ transplant recipients (SOTR), initiating preemptive therapy upon an antigenemia cutoff of 100 pp65-positive leukocytes, a DNAemia cutoff of 300,000 copies/ml blood had positive and negative predictive values of >90%, indicating that a DNAemia cutoff could achieve, in terms of prevention of HCMV disease, the same clinical results as the antigenemia cutoff. In HSCTR, initiating preemptive therapy upon first antigenemia positivity, a DNAemia cutoff of 10,000 copies/ml blood had a positive predictive value of >90%, indicating that the great majority of patients treated under the antigenemia guidance would have been treated also using this DNA cutoff. On the other hand, the negative predictive value of 28.6% indicated that two out of three HSCTR had been treated under the antigenemia guidance having the same levels of viral DNA as the untreated patients. The data suggest that a quantitative cutoff could be adopted as a guiding criterion for preemptive therapy also in HSCTR. Regression analysis allowed to determine the DNAemia (corresponding to QPCR) cutoff values for two commercial assays tested both in solid organ and HSCTR. Retrospective DNAemia cutoff values will be verified for safety in prospective trials.     

Unrestricted principal components analysis of brain electrical activity: Issues of data dimensionality,artifact, and utility

Summary Principal components analysis (PCA) was performed on the 1536 spectral and 2944 evoked potential (EP) variables generated by neurophysiologic paradigms including flash VER, click AER, and eyes open and closed spectral EEG from 202 healthy subjects aged 30 to 80. In each case data dimensionality of 1500 to 3000 was substantially reduced using PCA by magnitudes of 20 to over 200. Just 20 PCA factors accounted for 70% to 85% of the variance. Visual inspection of the topographic distribution of factor loading scores revealed complex loadings across multiple data dimensions (time-space and frequency-space). Forty-two non-artifactual factors were successful in classifying age, gender, and a separate group of 60 demented patients by linear discriminant analysis. Discrimination of age and gender primarily involved EP derived factors, whereas dementia primarily involved EEG derived factors. Thirty-eight artifactual factors were identified which, alone, could not discriminate age but were relatively successful in discriminating gender and dementia. The need to parsimoniously develop real neurophysiologic measures and to objectively exclude artifact are discussed. Unrestricted PCA is suggested as a step in this direction.Acknowledgements: This work was supported in part by NIA program project PO1AG049853 to M. Albert and the Mental Retardation Program Project P30HD18655 to J.J. Volpe. We thank our qEEG technologists Adele Mirabella, Susan Katz, Ellen Belles, and Marianne McGaffigan as well as our research secretaries for their unflagging support.     

Assessment of CMV load in solid organ transplant recipients by pp65 antigenemia and real-time quantitative DNA PCR assay: correlation with pp67 RNA detection

After bone marrow (BM) or solid-organ (SO) transplantation viremic Cytomegalovirus (CMV) infection is observed frequently. Quantitative assay of CMV in blood helps the management of this clinical condition. In the present report, 83 samples from 39 solid organ recipients, three CMV assays were compared simultaneously for the first time: the Nuclisens CMV pp67 assay (nucleic acid sequence-based amplification, NASBA), an "in-house" quantitative real-time PCR assay (TaqMan) for CMV DNA, and pp65 antigenemia. The relation between CMV DNA and pp65 antigenemia, the quantitative assays, was evaluated on a larger group including 251 blood samples from 118 solid organ recipients. Real-time PCR provided the best results; > or =130 CMV DNA copies/2 x 10(5) peripheral blood leukocytes (PBLs) predicted > or =1 pp65 antigen positive (Ag+) cell/2 x 10(5) PBLs. By taking pp65 antigenemia as the "gold standard," the sensitivity of CMV DNA quantitation and of the pp67 RNA assay were 0.95 and 0.20, respectively, while the corresponding specificity values were 0.50 and 0.93. When real-time PCR was considered as the "gold standard," the sensitivity and specificity of the pp65 antigenemia were 0.65 and 0.91, respectively. Among the three tests examined, the sensitivity of the pp67 RNA assay was the lowest. On the other hand, the pp67 RNA assay was highly specific and effective in pinpointing high viremia patients. The present report, by providing predictive values for all three diagnostic profiles, DNA load, antigenemia, and pp67RNA, is a contribution for validation of real-time PCR as a new standard for quantitative assessment of CMV viremia in clinical settings.     

Infrared spectroscopy: A new diagnostic tool in Alzheimer disease

Biological markers play an evolving role in the diagnosis of Alzheimer disease (AD). We compare conventional measurements of cerebrospinal fluid (CSF) tau and β-amyloid_1–42 proteins to a novel approach – Fourier transformed infrared (FT-IR) spectroscopy – a simple technique derived from chemical and physical sciences that characterizes intramolecular bonds. For automatic diagnostic analysis, we developed an artificial neural network (ANN). We examined 71 patients with a clinical diagnosis of AD and 66 controls. β-Amyloid_1–42 was decreased (sensitivity 80% and specificity 78%); tau was elevated (sensitivity 76% and specificity 88%) in CSF of AD patients. The combined tau/β-amyloid_1–42 quotient was able to distinguish healthy from diseased subjects with 99% sensitivity and 86% specificity. The ANN could separate FT-IR spectroscopy data with 88.5% sensitivity and 80% specificity. FT-IR spectroscopy proved to be cost-effective and simple to perform. Diagnostic sensitivity and specificity is in the range of CSF tau and β-amyloid_1–42 protein analysis. Larger sample numbers for ANN training and validation could increase diagnostic accuracy and thus prove to be a useful screening tool.     

CSS-Ⅱ型ECG微机自动诊断与临床金标准在1160例中的比较研究

作者自行设计的CSS-Ⅱ型心电图微型计算机自动诊断系统试用于临床,受试者1160例,其中波形异常和心律失常共247份心电图,从913份正常心电图中随机抽样106份,两者共计353份图纸,用本研究诊断确定的“金标准”(Gold standard)与该系统的自动诊断结论进行比较。结果:波形诊断及心律失常的诊断一致率均在90％以上,排除了机遇诊断一致率,其波形为90％,心律失常为88％。     

842例工人、农民和战士最大呼气流量-容积曲线的测定

作者用“点值法”对成都市内和郊区842例从事轻、中、重劳动的健康工人、农民和战士作了MEFV曲线和常规肺功能测定,发现工人和农民在低肺容积时流量增加,在高、中肺容积时流量下降,并以农民最明显,重劳动工人次之,轻、中劳动工人较不明显,战士则相反。揭示不同的体力活动方式及生活条件可导致不同肺容积时的流量改变,以适应其代谢增强时的耗氧需求。