Identification and quantification of anti-D, -C and -G in alloimmunized pregnant women

Our objectives were to investigate possible overestimation of maternal anti-D due to co-existing anti-C and/or anti-G, and to confirm the presence of anti-D in plasma presumed to contain anti-D+C. We investigated 96 samples (from 22 antenatal patients and 74 blood donors) initially identified as containing anti-D+C using routine investigation procedures. Anti-D quantification was performed using an Astoria Pacific International 300 (API 300) continuous flow analyser with R1R1 and R2R2 reagent red cells. Where possible, samples were tested manually using a rare D+, C-, G- cell, to confirm the presence of anti-D. Fifty-two of 96 samples (11/22 antenatal patients and 41/74 blood donors) gave >50% higher anti-D quantification results with R1R1 cells than with R2R2 cells. Anti-D was not detected using manual techniques in 16 of 73 samples tested (10/22 antenatal patients and 6/51 blood donors). Anti-D quantification using R1R1 reagent red cells may cause inaccurate estimation of anti-D levels, when anti-C and/or anti-G are present. Indeed, a significant number of cases, where apparent anti-D+C is identified, may contain only anti-C+G and lack an anti-D component. This may in turn lead to a failure to administer prophylactic anti-D immunoglobulin to RhD negative patients in cases where anti-D is not present, putting these patients at risk from immunization with possible consequences to future pregnancies.     

The frequency of anti-C + anti-G in the absence of anti-D in alloimmunized pregnancies

Anti-D+C are often initially identified in sera from alloimmunized women. Anti-G may be present in these samples, mimicking anti-D+C, and therefore the differentiation of anti-D, -C and -G may be important. Sera from 27 alloimmunized women, initially identified as containing anti-D + anti-C, were analysed by adsorption/elution studies in the presence of polyethylene glycol (PEG) using R(0)r (D+C-G+) and r'r(D-C+G+) red blood cells (RBC). Additionally, 15/27 samples were tested by adsorption in the presence of PEG and subsequently warm elution, using rGr (D-C-G+) RBC. Anti-G + anti-C, without anti-D, were identified in 4/27 samples (14.8%) and none of the newborn children needed postpartum treatment. The combination of D+G, D+C and D+C+G antibodies occurred in 25.9%, 11.1% and 48.1% of the women, respectively. Overall, anti-G was detected in 24/27 samples (88.9%). Pregnant women shown to have anti-G+C but not anti-D should receive Rh immune globulin. Additionally, the finding of apparent anti-D+C during pregnancy in D-negative spouses may lead to paternity testing and therefore a correct antibody identification is necessary.     

An enzyme-linked immunosorbent assay for the quantitation of IgG anti-D and IgG subclasses in the sera of alloimmunized patients

BACKGROUND: IgG subclass composition of maternal alloantibodies to the D antigen seems to play a role in the severity of hemolytic disease of the newborn.The subclassing of IgG anti-D is usually performed by hemagglutination techniques, but the results are not quantitative and sometimes are difficult to interpret. Thus, there is a need for quantitative methods. STUDY DESIGN AND METHODS: The aim of this study was to develop an enzyme-linked immunosorbent assay (ELISA) for the quantitation of specific IgG anti-D and IgG subclasses in the sera of alloimmunized patients. Group O R1R2 red cells were sensitized with anti-D. Red cell membranes were solubilized with nonionic detergent. IgG and IgG subclasses were measured by a sensitive and reproducible immunocapture ELISA. A serum calibrated for its IgG subclass content was used as a reference, and the anti-D preparation 68/419 was used as an internal control. Optimal conditions for the detection of IgG anti-D and IgG subclasses by ELISA were studied. The absolute concentration and the proportions of IgG subclasses were determined in the sera of 14 pregnant women. RESULTS: A close parallelism was observed between dilutions of the IgG reference serum and the IgG anti-D solubilized from sensitized RBCs. The sum of IgG anti-D subclass concentrations, determined by the ELISA, correlated well with other quantitative methods. CONCLUSION: The method described is sensitive and can be used routinely for the quantitative determination of specific IgG anti-D and IgG subclasses in sera.     

A case of mild HDFN caused by anti-C,anti-D,and anti-G: Diagnostic strategy and clinical significance of distinguishing anti-G from anti-D and anti-C

Anti-G is commonly present with anti-D and anti-C and can confuse serological investigations. The differentiation of anti-G from anti-D and anti-C is particularly essential for the accurate diagnosis of hemolytic disease of the fetus and newborn (HDFN) and appropriate administration of anti-D immunoglobulin prophylaxis in Rhesus (Rh) negative women. We reported a rare case of anti-G together with anti-D and anti-C in a pregnant woman and her female neonate. The titers of IgG anti-D, anti-C, and anti-G in the woman were 256, 128, and 32, respectively. While the titers of IgG anti-D, anti-C, and anti-G in the neonate were 16, 8, and 4, respectively. The neonate experienced mild HDFN and only received phototherapy during hospitalization. This report discusses the diagnostic strategy and clinical significance of differentiating anti-G from anti-D and anti-C.     

Arterial stiffness: clinical relevance, measurement and treatment

Most traditional cardiovascular risk factors alter the structure and/or function of arteries. An assessment of arterial wall integrity could therefore allow accurate prediction of cardiovascular risk in individuals. The term 'arterial stiffness' denotes alterations in the mechanical properties of arteries, and much effort has focused on how best to measure this. Pulse pressure, pulse wave velocity, pulse waveform analysis, localized assessment of blood vessel mechanics and other methods have all been used. We review the methodology underlying each of these measures, and present an evidence-based critique of their relative merits and limitations. An overview is also given of the drug therapies that may prove useful in the treatment of patients with altered arterial mechanics.     

Macro enzymes: prevalence, composition, detection and clinical relevance

The presence of a macro enzyme, i.e. an enzyme with an abnormally high molecular weight, frequently leads to a genuinely increased serum activity or an interference in laboratory assays. This may thereby result in false positive diagnoses, such as acute myocardial infarction or pancreatitis. The various forms of macro enzymes are reviewed. In the case of immune complexes the immunoglobulins and (iso)-enzymes involved are discussed, as well as the specificity of the interaction, the prevalence and clinical relevance, associations with autoimmune or other diseases, and their behaviour in laboratory assays.     

The metabolic syndrome: pathophysiology, clinical relevance, and use of niacin

OBJECTIVE: To review the pathophysiology and clinical relevance for using niacin to treat the metabolic syndrome. DATA SOURCES: Primary articles were identified through a MEDLINE search (1966-January 2003), and recommendations for treatment were obtained from the National Cholesterol Education Program Adult Treatment Panel (NCEP-ATP) III guidelines. STUDY SELECTION AND DATA EXTRACTION: Published studies showing the effects of the metabolic syndrome, atherogenic dyslipidemia, and niacin were evaluated and reviewed. DATA SYNTHESIS: The metabolic syndrome is a highly prevalent condition that affects 24% of American adults and significantly increases the risk of coronary heart disease (CHD). Most patients with metabolic syndrome have atherogenic dyslipidemia characterized by elevated triglycerides, low high-density-lipoprotein cholesterol (HDL-C), and small, dense low-density-lipoprotein cholesterol (LDL-C) particles. The NCEP-ATP III identifies patients with the metabolic syndrome as candidates for intensified therapy. Lifestyle modifications and drug therapy are recommended. Niacin represents a good option for treating the triad of lipid abnormalities seen in the metabolic syndrome because it raises HDL-C, lowers triglycerides, and increases LDL-C particle size. CONCLUSIONS: Treatment of the metabolic syndrome is recommended by NCEP-ATP III to further reduce CHD risk after the LDL-C target has been met. Prospective clinical studies are needed to define the impact of niacin and other lipid-modifying agents on CHD morbidity and mortality in patients with the metabolic syndrome.     

Protein glycation: measurement and clinical relevance

This review of protein glycation deals with the biochemical background of glycated blood proteins, their methods of determination and their clinical significance. General reaction principles for determination of glycated proteins are discussed with special emphasis on the determination of glycated serum proteins in the clinical laboratory. Binding methods like boronate affinity, immunoassay, phenylhydrazine binding and ion exchange chromatography leave the analyte intact, whereas chemical methods like strong or mild hydrolysis or reduction in alkaline medium (fructosamine assay) results in destruction of the glycated protein. As most reactions are nonstoichiometric (except ion exchange chromatography and periodate oxidation), varying results are obtained from laboratory to laboratory. Up to now boronate affinity chromatography, mild hydrolysis yielding hydroxymethylfurfural and the fructosamine assay have been mostly used for determination of glycated serum proteins. The fructosamine assay appears to be most practical, because it is quick, economic and precise, but it suffers from unspecific side reactions. Although other methods like immunoassays or boronate ester formation in solution appear promising, there is currently no commercially available assay for the economic, precise and accurate determination of glycated serum protein. The clinical relevance of glycated serum protein determination is difficult to evaluate because the assays are based on different reaction principles and hence yield variable results. Nevertheless, the following conclusion may be drawn from the reports now available. i) The possibility that glycated serum proteins may discriminate better than glycated haemoglobin between "normal" and "diabetic" is still controversial. ii) Glycated serum proteins are formed faster than glycated haemoglobin, reflecting the changes in glycaemia for shorter periods of time (medium-term control). iii) It has not been yet established, using large cohorts, whether the glycated serum proteins allow the detection or exclusion of diabetes. iv) Determination of glycated serum proteins should not be considered as a substitute for the determination of glycated haemoglobin, but rather as a complementary determination, leading to the improved laboratory control of the diabetic patient.     

Hibernating myocardium, stunning, ischemic preconditioning: clinical relevance.

Hibernation is a chronic condition that can be due to either chronic low perfusion or repetitive stunning. When oxygen demands increase, prolonged periods of ischemia occur, resulting in multiple episodes of stunning. Because hibernation may play a significant role in refractory failure, the diagnosis of hibernation followed by reperfusion can be life saving. Myocardium that has sustained a transient sublethal injury but has the potential for recovery with time is referred to as stunned myocardium. Myocardial stunning is commonly seen after coronary artery bypass surgery: variable periods of myocardial ischemia are sustained during coronary artery bypass graft surgery, and when these patients return to the intensive care unit, their ventricular function is severely impaired because of the prolonged anoxia during bypass. With the support of artificial assist devices, counterpulsation or temporary use of catecholamines, these patients improve and have a favorable prognosis. Similarly, recovery occurs with time in stunning that follows AMI or cardiac transplantation because in either case the heart had been temporarily anoxic. Clinical observations of ischemic preconditioning include the following: (1) first-effort angina or "warm-up phenomenon," i.e., angina with exercise early, but similar or greater effort the rest of the day does not cause any angina and (2) mortality of AMI is lower in patients with a history of angina preceding AMI. Angina 1 to 2 hours before AMI is the most effective time window for ischemic preconditioning. A less potent "second window" is observed when angina occurs during the second to fourth day before AMI. Adenosine possesses marked cardioprotective properties and has been used to pharmacologically induce ischemic preconditioning with some success. Work is still in progress.     

Headache and psychiatric comorbidity: historical context, clinical implications, and research relevance

The comorbidity of headache and psychiatric disorders is a well-recognized clinical phenomenon warranting further systematic research. Affective disorders occur with at least three-fold greater frequency among migraineurs than among the general population, and the prevalence increases in clinical populations, especially with chronic daily headache. When present, psychiatric comorbidity complicates headache management and portends a poorer prognosis for headache treatment. However, the relationship between headache and psychopathology has historically been misunderstood, and measures of psychopathology have not always met the standard of formal Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV) criteria. In some cases, headache has been inappropriately attributed to psychological or psychiatric features, based on anecdotal observations. The challenge for future studies is to employ research methods and designs that accurately identify and classify the subset of headache patients with psychiatric disorders, evaluate their impact on headache symptoms and treatment, and identify optimal behavioral and pharmacologic treatment strategies. This article offers methodological considerations and recommendations for future research including: (i) ascribing dual-International Classification of Headache Disorders, 2nd ed. (ICHD-2) headache and DSM-IV psychiatric diagnoses according to reliable and valid diagnostic criteria, (ii) differentiating subclinical levels of depression and anxiety from major psychiatric disorders, (iii) encouraging validation studies of the recently published ICHD-2 diagnoses for "headache attributed to psychiatric disorder," (iv) expanding epidemiological research to address the range of DSM-IV Axis I and II psychiatric diagnoses among various headache populations, (v) identifying relevant psychiatric and behavioral mediator/moderator variables, and (vi) developing empirically based screening and treatment algorithms.     

Spigelian hernia: CT findings and clinical relevance

Objective

The purpose of our study was to evaluate the clinical relevance of preoperative CT in distinguishing between the two subtypes of spigelian hernia (SH).

Materials and methods

We reviewed retrospectively the CT images of 35 patients. The patients were divided into two groups on the basis of the SH subtype: interstitial SH group (n = 15) and subcutaneous SH group (n = 20). Clinical characteristics of patients and CT findings were analyzed. Bowel ischemia on surgery was also noted.

Results

Sixteen right hernias and 19 left hernias were observed. Fifteen interstitial SH (43%) and 20 subcutaneous SH (57%) were found. No type of content showed a statistically significant association with one or other subtype of SH. Nine of the 26 patients presenting with SH with SB content showed signs of SBO on CT. Closed-loop SBO on CT was present in 5 of the 26 patients with SB content. An interstitial SH was observed in all of these 5 patients (p = 0.039). Surgery was performed on 10 patients. Bowel ischemia was found on surgery in 4 patients and showed no statistically significant association with a particular subtype of SH (p = 0.6).

Conclusion

Our study shows the importance of performing CT in SH. CT provides the diagnosis of SH, shows SH content, and demonstrates the presence of SBO or closed-loop SBO. Moreover, the distinction between the two subtypes of SH on CT appears to be of clinical relevance since closed-loop SBO is statistically associated with interstitial SH and the optimal surgical approach may differ.     

Intravenous nicardipine: cardiovascular effects and clinical relevance

Nicardipine hydrochloride is the first intravenous dihydropyridine calcium antagonist to become available in the United States. Its chemical structure makes it unique among its drug class and confers clinically useful properties for the treatment of acute cardiovascular conditions, such as ischemia, hypertension, congestive heart failure, cerebrovascular disease, and related disorders. For patients with coronary artery disease, IV nicardipine reduces myocardial oxygen demand by reducing afterload and increases myocardial oxygen supply through coronary vasodilatation. Preliminary data suggest that nicardipine also has cardioprotective and vascular antispastic effects. Nicardipine has been shown to be effective in the treatment of mild to moderate hypertension both as monotherapy and in combination with other antihypertensive agents. In congestive heart failure, nicardipine enhances left ventricular pumping activity and augments coronary blood flow beyond that required by increased myocardial oxygen consumption. Its lack of major effects on sinoatrial and atrioventricular conduction makes it safe for use in patients with certain types of conduction disturbances. Nicardipine's rapid onset and short duration of action are additional advantages for use in the management of acute cardiovascular disorders.     

Genomic diagnosis of thrombophilia in women: clinical relevance

The detection of the DNA-sequence of human coagulation factors and inhibitors has introduced the possibility of differentiated mutation analysis in patients with venous thrombosis. Since venous thromboembolism is a multifactorial disease, women are at an increased risk to develop venous thrombosis due to hormonal contraception, during pregnancy and the puerperium. In addition, pregnancy complications like early or late fetal loss, pregnancy-induced hypertensive disorders and very recently recurrent embryo implantation failure have been suspected to be associated with thrombophilia. Therefore, it is of major importance to define inherited thrombophilic disorders, in which genetic diagnosis is of clinical relevance. While most of the genetic defects described so far represent a risk factor for venous thrombosis, only a minority of these defects actually needs DNA analysis to be detected: mutation analysis is clinically relevant, when factor V Leiden mutation is suspected, because relative risks concerning venous thrombosis as well as pregnancy complications clearly differ between homozygote and heterozygote forms of this frequently observed mutation. Similarly detection of the prothrombin mutation G20210A is of clinical relevance, although data for the very rarely observed homozygote variant are not sufficiently available. In contrast, detection of the homozygote variant of the MTHFR-mutation C677T is not useful, since clinical relevance could not be proven in a majority of studies concerning women specific risk situations. Inherited deficiencies of antithrombin, protein C and protein S are rare with high rates of different mutations. Genetic analysis seems only useful in patients with wide intraindividual variations of coagulation inhibitor activities. Genetic analysis concerning the PAI-1 4G/5G polymorphism or the factor XIII Val34Leu polymorphism can not be recommended in women specific risk situations because of insufficient data.     

Steroid hormones: relevance and measurement in the clinical laboratory

Steroid hormones are synthesized in the adrenal cortex, the gonads, and the placenta; are all derived from cholesterol and many are of clinical importance. This article addresses the relevance and methods of measurement of steroid hormones in the clinical laboratory.