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At least 397 records · Page 22Linked to original sources
PubMed1999

Acute cerebral redistribution in response to invasive procedures in the human fetus.

OBJECTIVES: We sought to investigate the fetal hemodynamic response to the acute stress of invasive procedures. STUDY DESIGN: The middle cerebral artery pulsatility index was measured by Doppler ultrasonography before and after 136 invasive procedures (fetal blood sampling, transfusion, shunt insertion, tissue biopsy, and ovarian cyst aspiration). The response of fetuses submitted to invasive procedures involving transgression of the fetal body, such as intrahepatic vein blood sampling, was compared with that of control procedures at the placental cord insertion. RESULTS: The middle cerebral artery pulsatility index value fell with fetal blood sampling performed at the intrahepatic vein (median, -0.26; 95% confidence interval, -0.35 to -0.15) but not at the placental cord insertion (median, 0.05; 95% confidence interval, -0.04 to 0.19). With transfusions, the middle cerebral artery pulsatility index also fell with procedures at the intrahepatic vein (mean, -0.51; 95% confidence interval, -0.66 to -0.35) but not at the placental cord insertion (mean, -0.04; 95% confidence interval, -0.23 to 0.14). The magnitude of the response was greater with transfusions than with blood sampling alone. The middle cerebral artery pulsatility index value also fell with non-fetal blood sampling procedures involving transgression of the fetal body (mean, -0.32; 95% confidence interval, -0.56 to -0.09) but not with control non-fetal blood sampling procedures. The change in the middle cerebral artery pulsatility index was not related to gestational age, with the youngest fetus showing a fall in the middle cerebral artery pulsatility index value being at 16 weeks' gestation. Although the degree of response was weakly correlated with the duration of needling (y = -0.21 - 0.00014x; R (2) = 0.08; P =.02), multiple logistic regression demonstrated that this was instead a function of the type of the procedure. A response was seen within 70 seconds of fetal puncture. The fetal heart rate did not change significantly with procedures in any of the above-mentioned groups. CONCLUSIONS: The human fetus mounts a cerebral hemodynamic response to invasive procedures involving transgression of the fetal body, which is consistent with the brain-sparing effect.

Biopsy↗
PubMed1996

Screening potential corneal donors for HIV-1 by polymerase chain reaction and a colorimetric microwell hybridization assay.

PURPOSE: Current screening of potential corneal donors for human immunodeficiency virus type 1 (HIV-1) involves serologic detection of antibodies to the virus. However, this approach cannot detect infection during the seronegative window period of the disease. We therefore evaluated the polymerase chain reaction (PCR) assay for viral nucleic acid as a possible alternative to screening cadaveric blood for HIV-1. METHODS: Blood specimens from cadavers diagnosed at autopsy with acquired immunodeficiency syndrome (AIDS) (n = 21), at high risk for HIV-1 infection (n = 47), and at no known risk (n = 350) were screened by PCR for HIV-1 proviral DNA and human leukocyte antigen (HLA)-DQ alpha sequences, and for HIV antibodies. RESULTS: All AIDS group samples were seropositive; of these, 18 (86%) and 20 (95%) of 21 were positive for HIV by PCR of proteinase K- and Chelex-extracted pellets, respectively. The seropositive samples negative by PCR testing were shown to inhibit PCR amplification. Nine (19%) of 47 high-risk specimens were HIV-positive. The no-known-risk group yielded negative results. The overall sensitivities for PCR in the proteinase K- and Chelex-treated groups were 90% and 97%, respectively, compared with Western blot reactivity. If PCR-inhibitory samples and HLA-DQ alpha-negative samples had been eliminated, sensitivity would have been 100%. Specificity was 100% for each group. CONCLUSIONS: Screening cadaveric blood by PCR may be feasible, but further refinement of the assay and blood specimen collection practices will be necessary for it to become routine. Future studies should focus on optimizing specimen procurement and preparation to reduce or eliminate specimens that inhibit PCR.

AIDS Serodiagnosis↗
PubMed2001

Nucleic acid testing: update and applications.

Nucleic acid testing (NAT) holds the promise of closing the window of infectiousness for hepatitis C virus (HCV) and the human immunodeficiency virus (HIV) in the general blood supply. Pioneering work by the source plasma industry with NAT for hepatitis A virus (HAV), hepatitis B virus (HBV), and parvovirus B19 suggests that, in the future, the risk of other viral infections may be reduced using similar technology. The European Commission decree that, by July 1999, all source plasma for fractionation should be NAT nonreactive for HCV at a sensitivity of 100 viral IU/mL, has driven the implementation of NAT in the United States. It is estimated that more than 95% of the US blood supply is currently tested by one of two investigational tests for HCV and HIV, and many institutions restrict the release of red blood cell (RBC) and plasma products prior to the release of NAT results. NAT implementation has been hampered by a lack of fully automated, low-cost technologies; the absence of Food and Drug Administration (FDA)-approved and validated clinical tests; and lagging turnaround times. Results from US investigational trials of the Procleix Transcription Mediated Amplification (TMA) HCV/HIV (Chiron Corp, Emeryville, CA) and the COBAS AmpliScreen (Roche Diagnostics, Indianapolis, IN) polymerase chain reaction (PCR) assays have begun to substantiate their value. While NAT assays will not replace serologic tests, they lay the groundwork for further reducing the already low risk of infection transmission through transfusion of blood components and their factor derivatives.

Blood Donors↗
PubMed1975

Fetal blood drawing.

A small sample of fetal blood suitable for studies of haemoglobin synthesis was obtained from a placental vessel under endoscopic visualisation in 23 of 26 patients in whom the procedure was attempted prior to second-trimester abortion. Fetal blood loss, calculated in 23 cases, was between 0-2 ml. and 2-5 ml., and fetal blood-volume depletion varied from 0-5% to 15%. No short-term ill-effects were demonstrated in mother or fetus in any of 16 patients in whom the injection of aborti-facient was postponed for between 16 and 24 hours after the procedure.

Abortion, Therapeutic↗
PubMed1979

Dried-blood spot screening for cystic fibrosis in the newborn.

Serum-immunoreactive-trypsin (I.R.T.) was measured in children with cystic fibrosis (C.F.) and a variety of controls. In the first few months of life all C.F. children had a raised serum-I.R.T. A dried blood-spot assay for I.R.T. was established and has potential as a screening test for C.F. in the newborn.

Antigens↗
PubMed1995

Feline transfusion medicine. Blood types and their clinical importance.

Anemia is the most common indications for a blood transfusion in cats and fresh whole blood is typically administered. Recent experimental studies and clinical reports have elucidated the importance of feline blood types in transfusion medicine. The AB blood group system, the only recognized feline blood group system, consists of three blood types: type A is most common, type B is frequently found in certain breeds, and type AB occurs rarely. The blood type frequently varies geographically among domestic shorthair cats and between breeds. Because of the presence of naturally occurring alloantibodies, only AB-matched transfusions are effective and safe. Blood typing is now readily available and incompatibilities are easily recognized with blood crossmatching tests. Owing to the general presence of strong anti-A alloantibodies in type B cats, type A blood given to a type B cat results in life-threatening acute hemolytic transfusion reactions. Immediate withdrawal of a transfusion and supportive care may save a patient. Other transfusion reactions, unrelated to AB mismatch, cause only mild and transient signs. Peculiarities of feline blood banking also are reviewed.

Animals↗
PubMed2000

Spurious metabolic acidosis in hemodialysis patients.

Metabolic acidosis with an increased anion gap (AG) is frequently seen among patients with end-stage renal failure that is corrected to a variable degree by chronic hemodialysis. The degree of acidosis is generally interpreted from the concentration of total carbon dioxide (tCO(2)) in blood drawn from the vascular access used for dialysis. As with many dialysis units in the United States, our laboratory studies for outpatients are performed in a central laboratory several hundred miles away and must be shipped there by air freight. We observed a consistent and clinically important difference between the tCO(2) content of samples reported from the central laboratory compared with results reported from a local university hospital chemistry laboratory. The central laboratory readings were always lower, resulting in an increase in the AG. Delays in centrifugation of the blood to separate the clot from the serum and in the initiation of analysis led to an increase in the lactate content of the samples. That increase, however, was insufficient to explain the difference in tCO(2) levels. These data suggest that something happens to the samples in transit to cause an artifactual reduction of the tCO(2) level. For many dialysis patients, the severity of their acidosis may be falsely represented by the tCO(2) content of blood samples reported from central laboratories.

Acidosis↗
PubMed1996

Screening for extreme postdialysis urea rebound using the Smye method: patients with access recirculation identified when a slow flow method is not used to draw the postdialysis blood.

To look for patients with extreme urea rebound, we drew intradialytic samples one third of the way into dialysis during routine modeling for 3 months. The samples taken postdialysis were obtained after stopping the blood pump, without any slow flow period. Using the Smye equations, the intradialytic urea level was used to predict urea rebound, expressed as Kt/V-equilibrated minus Kt/V-single pool (deltaKt/V). Results were averaged for the 3-month period in 369 patients. Mean estimated deltaKt/V was -0.20 +/- 0.13, which was similar to but slightly higher than the predicted value (-0.6 x K/V + 0.03) of -0.19 +/- 0.04. In 27 patients, extreme rebound (mean deltaKt/V < -0.40) was found. Sixteen of these patients consented to further study, but only after access revision in four patients. In these patients, additional slow flow samples after 15 seconds and 2 minutes of slow flow, respectively, were drawn one third of the way into dialysis and postdialysis, and a sample was drawn 30 minutes after dialysis. On restudy, postdialysis rebound was still high with full flow samples deltaKt/V = -0.40 +/- 25, but was much lower (-0.18 +/- 0.07) and similar to predicted rebound (-0.19 +/- 0.05; P = NS) when based on 15-second slow flow samples. Eight of the 16 had marked (>15%) access recirculation by urea sampling, and deltaKt/V based on full flow post samples correlated with access recirculation (r = -0.91). The results suggest that the Smye method is valuable for identifying patients with aberrantly large postdialysis rebound values. When the postdialysis samples are drawn without an antecedent slow flow period, most patients with extreme rebound values turn out to have marked access recirculation.

Blood Specimen Collection↗