La Ricerca in clinica e in laboratorio最新文献

The detection of serum hepatitis B virus (HBV) DNA in 32 chronic HBsAg carriers was performed by spot hybridization technique using both biotinylated and radiolabeled probes, in order to compare their specificity and sensitivity. Our results show that both assays are specific since neither evidence of cross-hybridization between HBV DNA and sera from patients with chronic non-A, non-B (NANB) hepatitis was found, nor HBV DNA was detected both in patients with chronic anti-HBs/anti-HBc-positive hepatitis and in patients negative for all HBV markers. An agreement between the two assays was observed in 94% of the tested sera. Even though in 5 serum samples (6%) low levels of HBV DNA (0.1-1 pg/100 microliter) remained undetected using the biotin-labeled probe, the lower detection limit of the two assays (0.1 pg of HBV DNA) was the same using purified Dane particles as control. This study indicates that the enzymatic detection of HBV DNA is suitable for routine and rapid monitoring of HBV replication in both HBeAg- and anti-HBe-positive patients, as well as for a semiquantitative analysis of serum HBV DNA.

The international normalized ratios (INR) system allows valid comparisons in results and quality of performance to be made between users of different thromboplastin reagents. In the international quality control surveys currently over 80% of the 53 countries participating report INR. Stated local international sensitivity index (ISI) values show fair agreement with values calculated from quality control returns obtained with local and reference reagents. The coefficient of variations (CV) of the INR in these surveys are between 11-22% depending upon INR values. In comparison, CV of the UK national scheme are currently 7-13%. However, analysis of UK results has shown high CV with high ISI reagents. This is due to the ISI effect as CV of INR is CV of prothrombin ratio (PR) multiplied by the ISI. Ideal thromboplastins should show good precision of PR and a low ISI to prevent this apparent deterioration when PR results are transformed into the INR scale. Instrumentation has a further effect on the INR result. Unfortunately, the effect is not uniform even within instrument type and model or even between normal and therapeutic results. Local instrument adjustment or local calibration is therefore necessary. Thus, quality control surveys continue to highlight problems in prothrombin time standardization.

Persistent generalized lymphadenopathy (PGL) is a reactive lymphadenitis affecting HIV-positive patients; furthermore, PGL is often a prodrome of AIDS-related complex and AIDS. In the present review the authors describe the histology and the immunohistochemistry of lymph nodes of patients affected by PGL. Histologic alterations of lymph nodes with PGL are classified according to three main types: follicular hyperplasia without or with follicular fragmentation, follicular involution and follicular depletion. Immunohistology demonstrates a peculiar infiltration of CD3+/CD4+ and CD3+/CD8+ lymphocytes in germinal centers; CD3+/CD8+ are often grouped in small clusters centered by a newly formed small blood vessel. Accessory follicular dendritic reticulum cells (FDRCs) of germinal centers are characterized by a positive staining for p24 and p19 HIV major core antigens. In germinal centers, FDRCs undergo progressive lysis in follicular involution and in follicular depletion. Other viral antigens, such as EBV, are infrequently seen in lymph nodes from HIV-positive patients. Paracortical areas of lymph nodes are often characterized by prominent postcapillary venule proliferations and by hyperplasia of the endothelial cells which are HLA-DR positive, often p19 and p24 positive, and occasionally express HIV genome. In conclusion, in PGL the histologic changes correlate well with the immunohistologic features; accordingly, PGL might be considered the result of abnormal immune reactions to several stimuli still incompletely known.

Since the clinical diagnosis of deep vein thrombosis (DVT) of the lower limbs is nonspecific, a confirmation by objective tests is mandatory. Recently, three new simple and reproducible methods of detecting DVT have been developed: computerized impedance plethysmography, standardized Doppler ultrasound, and compression ultrasonography. In three large prospective studies including consecutive outpatients with clinically suspected DVT, these tests were blindly evaluated versus phlebography, to determine diagnostic criteria and accuracy. The sensitivity for proximal DVT was 91% for computerized impedance plethysmography, 91% for standardized Doppler ultrasound and 100% for compression ultrasonography; sensitivity for all thrombi (including calf-vein thrombi) was 86, 85 and 91%, respectively; the specificity was 94% for computerized impedance plethysmography, and 99% for both standardized Doppler ultrasound and compression ultrasonography. The results of these studies demonstrate that all the three tests are highly specific and sensitive methods for the diagnosis of proximal DVT in symptomatic outpatients. However, isolated calf thrombi could not be detected adequately. Before these simple tests can be recommended as substitutes for phlebography, the safety of withholding anticoagulant therapy in patients with repeated normal tests should be assessed.

Authors report 6 cases of benign recurrent intrahepatic cholestasis (BRIC), a rare disease of unknown etiology first described 30 years ago by Summerskill and Walshe, and thought to represent a study model for human cholestasis. Clinical, biochemical and pathologic findings of BRIC are briefly summarized in this paper in order to emphasize some triggering factors of the cholestatic attack (e.g., flu-like episodes and pregnancy), the diagnostic problems and the importance to avoid a surgical procedure. Finally, the 'state of the art' of the pathogenesis of BRIC is briefly summarized.

Prothrombin time (PT) testing is used for monitoring oral anticoagulant therapy, its result being usually expressed as international normalized ratio (INR). This is done using the international sensitivity index (ISI) specific of thromboplastin employed to carry out the test. In this way a good PT standardization may be achieved although the instruments used to calibrate the thromboplastins might influence the ISI value.

Cholesterol determined by 4 different enzymatic commercial kits and by the dry chemistry Reflotron system was higher in serum stored at 4 degrees C and at -20 degrees C than in fresh serum. The effects of storage seem to be temperature-dependent. In fact, cholesterol values significantly increased only after 2h of freezing. The prolongation of freezing up to 2 weeks was not followed by further significant changes. In serum stored at 4 degrees C the increase in cholesterol was slower than in frozen serum. Both free and esterified cholesterol underwent an increase after storage. When cholesterol was determined by a chemical method (sulfuric acid-ferric chloride) after extraction with ethyl acetate and ethanol, no difference was observed in fresh and stored serum. Cholesterol, triglycerides and apoproteins A-I and B underwent parallel changes after storage both in whole serum and fractionated lipoproteins. Our findings strongly suggest that in serum stored at positive or negative temperature there is an alteration of the lipoprotein molecules which allows an easier availability of cholesterol for the enzyme-substrate reaction than in fresh serum. Current enzymatic methods underestimate (about 10%) cholesterol when the analysis is performed on fresh serum.

The activated partial thromboplastin time (APTT) is a commonly performed laboratory procedure which is used for multiple purposes including monitoring of heparin therapy, detection of coagulation factor deficiency, and detection of lupus anticoagulants. Among the hereditary coagulation deficiencies, factor VIII and factor IX are the most common. APTT reagents differ widely in both their sensitivity to factor VIII and factor IX deficiencies as well as their responsiveness. Sensitivity may be defined as the ability to identify a deficiency state while responsiveness is indicated by the degree of prolongation of the APTT result as compared to the upper limit of normal. Reagents may be both sensitive and responsive or alternatively sensitive and relatively nonresponsive. Consequently, it is extremely important for each laboratory to carefully identify the upper limit of the normal range. A variety of preanalytical variables will also effect the sensitivity of the APTT to factor deficiency states. These variables include specimen handling and the preparation of platelet poor plasma. The instrument effect is also of importance. Selection of the reagent tends to have the most impact on sensitivity and responsiveness while instrumentation affects the precision of a given APTT. The composition and concentration of phospholipid in APTT reagents does have an effect on reagent responsiveness and sensitivity. Sensitivity to factor deficiencies does not necessarily parallel sensitivity to lupus anticoagulants.

In hemostasis testing the development of chromogenic substrates provides an alternative to the traditional methods based on the detection of forming clots. The new technology has often replaced the clotting tests, especially in the area of single clotting factor and inhibitor assay, less frequently for global screening tests. We report studies of the validity and clinical application of two reagents for activated partial thromboplastin time (APTT) testing with chromogenic substrates in comparison with the conventional clotting method. Congenital deficiencies of the intrinsic coagulation pathway, other than hypo- and dysfibrinogenemia detected by chromogenic APTT, agreed with those detected by the clotting APTT. The results with the two methods for plasma under heparin treatment suggest a lesser responsiveness of the chromogenic methods to heparinization. The chromogenic methods demonstrated the presence of the lupus anticoagulant in the majority of tested samples of known lupus subjects, but with a lower responsiveness than the clotting method. In conclusion, we found chromogenic APTT suitable for hemostasis testing because it generally gives the same information as the conventional clotting method with the exception of heparin monitoring and lupus anticoagulant detection, where an improved sensitivity would be desirable.