Transmission of human immunodeficiency virus (HIV) by blood transfusions screened as negative for HIV antibody

Steady-state calculation of the risk of HIV infection from transfusion of screened blood from repeat donors

All blood donations in the United States are screened for human immunodeficiency virus (HIV), the virus that causes AIDS; in spite of this, potentially infectious donations are still made by donors who are infectious but have not yet developed detectable HIV antibodies. A steady-state model for blood donations is used to calculate the expected number of potentially infectious blood donations made by repeat blood donors in a specified time interval. The expected number of potentially infectious donations made by each infectious blood donor who subsequently becomes HIV positive is calculated, and estimators of this quantity are presented. The relative risks due to donations from repeat and first-time donors is discussed. Estimates of the proportion of all blood donations made at 19 American Red Cross regional blood centers that are potentially infectious are presented.

Lumbar percutaneous endoscopic interbody fusion

Since 1982, percutaneous endoscopic control has been found to be a fundamental help for selective posterior subligamentary decompression in lumbar contained disc herniations. After the first clinical experience in 1986 with percutaneous intervertebral bone grafting, the need for sufficient percutaneous preparation of the adjacent vertebral plates and postoperative immobilization of the operated on segment became evident. So in 1988, the original eccentrically abrasive end plate cutter for application under discoscopy was introduced. For a preoperative trial and postoperative stabilization, the complementary use of the external pedicle fixation device was standardized in 1988. The use of percutaneous autologous bone interposition was found essential for optimal bony interbody consolidation. The indications were limited strictly to monosegmental lumbar dysfunctions without a need for peridural decompression. In a series of 37 patients with standardized procedure and a mean followup of 33 months, bony interbody consolidation was achieved in 30 cases. The technique desists from any need for blood transfusion, and functional rehabilitation is facilitated because of the very limited percutaneous approach.

Using existing health care systems to respond to the AIDS epidemic: research and recommendations for Chile

Chile is a country with a relatively low prevalence of HIV infection, where successful prevention has the potential to change the future course of the epidemic. A controversial national prevention strategy based upon public education has emerged in response to characterizations of the epidemic as well-dispersed with a growing involvement of heterosexuals. This characterization is not consistent with the observed facts. There is a comparatively well-organized health care system in Santiago that is doing a good job of detecting HIV infection and already has in place the elements of a targeted intervention scheme. Chile should place priority on the use of the existing health care infrastructure for implementing both the traditional public health interventions for sexually transmitted diseases (contact tracing and partner notification) and the AIDS-necessitated strategy of focused counseling and education.

Plateletpheresis before redo CABG diminishes excessive blood transfusion

BACKGROUND

Blood conservation remains an important element for patients undergoing cardiac operations with cardiopulmonary bypass. Preoperative platelet-rich plasma (PRP) harvest is an autologous blood conservation method. The efficacy of preoperative PRP harvest and post-cardiopulmonary bypass reinfusion on postoperative bleeding and need for postoperative blood transfusion was evaluated in patients undergoing redo coronary artery bypass grafting in a prospective, randomized manner.

METHODS

All adult patients admitted for redo coronary artery bypass grafting entered into the study. The PRP harvest aim was 20% or more of the total estimated circulating platelets. Immediately preoperatively three sequestration cycles were performed. The PRP was reinfused after weaning from cardiopulmonary bypass. One hundred seven parameters/patient were recorded. There were 20 patients in the RPR group and 20 controls (without PRP harvest).

RESULTS

Patient characteristics, operative data, and preoperative hematologic parameters did not differ between the groups. In the PRP group, the mean platelet count in the PRP was 864 +/- 139 x 10(3)/microL, and the platelet yield was 27% +/- 5% (range, 20% to 37%). The average total chest tube blood loss was 423 mL (PRP) compared with 1,462 mL (controls; p < 0.001). Fourteen patients in the control group required blood transfusions postoperatively compared with only 1 patient in the PRP group (p < 0.001). Postoperative fluid requirements were also significantly greater in the control group (p < 0.001). Postextubation gas exchange was significantly better in the PRP group compared with controls (p < 0.01). Postoperative ventilation time and intensive care stay were significantly shorter in patients in the PRP group.

CONCLUSIONS

A preoperative PRP harvest of 20% or more of the total platelets and reinfusion of the PRP after cardiopulmonary bypass resulted in significantly less postoperative blood loss and decreased fluid and blood transfusion requirements compared with controls. Postextubation gas exchange, ventilation time, and time required in the intensive care unit were also better, and the method was found cost-effective.

Photochemical and photophysical studies of 3-amino-6-iodoacridine and the inactivation of lambda phage

The photochemistry and photophysics of 3-amino-6-iodoacridine (Acr-I) was studied. Photolysis (350 nm) of Acr-I (free base) generates products consistent with a free radical intermediate in methanol, benzene and carbon tetrachloride. The Acr-I hydrochloride is shown to bind to calf thymus DNA and to the self-complementary dinucleotide cytidylyl-(3'-5')-guanosine (CpG) miniduplex in a manner similar to that of proflavine (Acr-NH2), a known DNA intercalator. The Acr-I is shown to more efficiently nick supercoiled plasmid DNA pBR322 upon 350 nm or 420 nm photolysis than Acr-NH2. The efficiency of Acr-I-sensitized DNA nicking is not oxygen dependent. Photolysis of the Acr-I/(CpG)2 complex leads to cleavage of the dinucleotide and to cytidine base release by selective damage to a specific ribose moiety. Dinucleotide cleavage occurs equally well in the presence or absence of oxygen, thereby eliminating a singlet oxygen- or peroxyl radical-mediated process. Photolysis of Acr-I in the presence of a mononucleotide (GMP) or a non-self-complementary dinucleotide (uridylyl-[3'-5']-cytidine-UpC) does not lead to fragmentation and base release. Similarly, photolysis of the Acr-NH2/(CpG)2 complex does not lead to fragmentation and base release. The data indicate that photolysis of an iodinated intercalator bound to CpG or plasmid DNA generates an intercalated aryl radical and that the reactive intermediate initiates a sequence of reactions that efficiently nick nucleic acids. The inactivation of lambda phage sensitized by Acr-I with UV (350 nm) light is oxygen independent but with visible (420 nm) light is strongly oxygen dependent. The Acr-I fluoresces more intensely when excited at 446 than at 376 nm. Thus, UV photolysis may lead to C-I bond homolysis and free radical formation, a process that is not energetically feasible with visible light. The results demonstrate the difficulty of extrapolating model studies involving simple molecules and DNA to understanding the mechanism of viral inactivation with a particular sensitizer.

Effectiveness of very low doses of subcutaneous recombinant human erythropoietin in facilitating autologous blood donation before orthopedic surgery

BACKGROUND

Clinical and pharmacokinetic data suggest that very low doses of subcutaneous recombinant human erythropoietin (rHuEPO) may be effective in a preoperative autologous blood deposit program.

STUDY DESIGN AND METHODS

Fifty-two patients, scheduled for orthopedic surgery, were enrolled in a double-blind and placebo-controlled study. Patients were randomly assigned to the placebo group or to receive 30, 60, or 100 IU per kg of rHuEPO subcutaneously twice a week for 2 weeks before surgery. The dose of rHuEPO that was effective in facilitating the collection of 4 units of blood in the 2 weeks before surgery and that prevented a sharp decrease in hematocrit was determined.

RESULTS

Only in patients receiving 100 IU per kg of rHuEPO did the outcome measurements differ significantly from those in the placebo group. With a higher (p < 0.01) cumulative increase in red cell volume during the study period (297 +/- 127 vs. 121 +/- 44 mL), 64 percent of those receiving 100 IU per kg of rHuEPO were able to donate 4 units of blood for autologous use, as compared with 23 percent of the placebo group (p < 0.05). Allogeneic transfusion was avoided, and the preoperative hematocrit and reticulocyte count were significantly higher in the patients receiving 100 IU per kg of rHuEPO (p < 0.05 and p < 0.01, respectively).

CONCLUSION

Subcutaneously administered rHuEPO at a dose of 100 IU per kg twice a week for 2 weeks is effective in facilitating the collection of blood for autologous use and may improve the cost-benefit ratio of blood conservation interventions. Doses < or = 60 IU per kg are ineffective in facilitating such collections in this surgical setting.

[Proposals for a strategy for evaluation and utilization of screening tests for hepatitis C]

New assays for the screening of anti-HCV antibodies are regularly proposed for registration. The evaluation of new tests is based on the measurement of their intrinsic value: sensitivity and specificity. To assess the sensitivity of a test, it is very important to be able to obtain sera samplets tested with a "Gold Standard", which is, for HCV, RNA detection. Sensitivity is defined as the ratio of the number of true positive to the number of true positive added to the number of false negative samples. The problem is to define the samples to be tested. It is methodologically impossible to use a serological test for samples selection. The Gold Standard might be performed on samples from the general population or more easily from risk groups. The estimation of the precocity is more difficult. The constitution of an acute hepatitis panel is of interest an the follow up of risk groups has to be encouraged. The estimation of the number of samples needed depends on the required precision in the sensitivity measurement. The confidence interval (CI) decreases when the number of samples tested increases and when the sensitivity is high. The important questions are opposite: if the test is positive what is the probability for the patient to be really positive? (positive predictive value PPV), and, if the test is negative, what is the probability for the patient to be non-infected? (negative predictive value: NPV). The NPV depends on the prevalence of HCV infection in the tested population and on the sensitivity of the test. PPV increases with the prevalence rate and the specificity. Regarding these results, one may suggest that donor screening assays and tests used for diagnose HCV infection in patients may be evaluated with different strategies. Regarding blood donors screening, sensitivity is the most important parameter, the best strategy is to eliminate risk groups, and then, to perform very sensitive assays on negative samples. On the other hand, for patients diagnosis, specificity (avoid false positive results) is more important. The best strategy is to select patients at risk from clinical findings and then, to perform a specific test. Screening strategies for the general population have to take into account these two different strategies.

Estimated risk of transmission of the human immunodeficiency virus by screened blood in the United States

BACKGROUND

In the United States, transmission of the human immunodeficiency virus (HIV) by blood transfusion occurs almost exclusively when a recently infected blood donor is infectious but before antibodies to HIV become detectable (during the "window period"). We estimated the risk of HIV transmission caused by transfusion on the basis of the window period associated with the use of current, sensitive enzyme immunosorbent assays and recent data on HIV incidence among blood donors.

METHODS

We analyzed demographic and laboratory data on more than 4.1 million blood donations obtained in 1992 and 1993 in 19 regions served by the American National Red Cross, as well as the results of HIV-antibody tests of 4.9 million donations obtained in an additional 23 regions.

RESULTS

We estimated that, in the 19 study regions, 1 donation in every 360,000 (95 percent confidence interval, 210,000 to 1,140,000) was made during the window period. In addition, it is estimated that 1 in 2,600,000 donations was HIV-seropositive but was not identified as such because of an error in the laboratory. We estimated that 15 to 42 percent of window-period donations were discarded because they were seropositive on laboratory tests other than the HIV-antibody test. When these results were extrapolated to include the additional 23 Red Cross service regions, there was a risk of one case of HIV transmission for every 450,000 to 660,000 donations of screened blood. If the Red Cross centers are assumed to be representative of all U.S. blood centers, among the 12 million donations collected nationally each year an estimated 18 to 27 infectious donations are available for transfusion.

CONCLUSIONS

The estimated risk of transmitting HIV by the transfusion of screened blood is very small and nearly half that estimated previously, primarily because the sensitivity of enzyme immunosorbent assays has been improved.

Blood transfusion in beta thalassaemia major

Conventional treatment of beta thalassaemia major is based on regular blood transfusion from early childhood. Maximum effectiveness of transfusion therapy depends on the following. (1) Availability of safe blood. Donation programmes should aim at retaining repeat donors, who carry decreased risk of transmitting blood-borne infections. Donors should be screened with laboratory tests performed to the highest possible standard of quality. Selection of safe donors can be improved by the adoption of questionnaires containing direct questions on risk factors for transfusion transmissible infections. (2) Use of good quality red blood cells, which should be leucodepleted, preferably by filtration, that can be carried out at the bedside. (3) Regular evaluation of blood transfusion indices, including mean level of haemoglobin maintained, annual blood requirement, daily haemoglobin fall, mean transfusion interval, transfusion reaction rate. This can be assisted by the use of a computerized patient record. (4) Maintenance of a permanent record of the patient's blood group genotype (including at least Rh, Kell, Kidd and Duffy systems) and any red cell antibodies that develop. This is mandatory to ensure optimal survival of transfused red cells. (5) Continuous monitoring of transfusion transmissible infections. (6) Vaccination against hepatitis B of all suitable patients. (7) Intensive iron chelation. This should be done by regular subcutaneous administration of desferrioxamine B. Oral chelators, which are currently under laboratory and clinical evaluation, are not yet available for general use.

Aspirin, a silent risk factor in urology

Aspirin is a widely used drug for its analgetic, antiinflamatory and antipyretic effects as well as for prophylactic effect in cardiovascular diseases. However, an increased number of operative hemorrhagic complications in patients on daily aspirin have been reported, an adverse effect highly relevant in urology. In this review the normal hemostatic mechanism and the chief pharmacological effect of aspirin on hemostasis is described. The literature is reviewed for hemorrhagic complications to aspirin in urology. Few reports indicate that aspirin increases bleeding and need for transfusion following prostatectomy, but no placebo-controlled clinical trials with large patient groups have been carried out. Following prostate biopsy and extracorporeal shock wave lithotripsy aspirin-induced hemorrhagic complications have been reported. Cessation of aspirin ingestion one week prior to invasive urologic procedures and correction of bleeding complications with desmopressin, platelet concentration or fresh whole blood is described.

Aprotinin versus desmopressin for patients undergoing operations with cardiopulmonary bypass. A double-blind placebo-controlled study

BACKGROUND

Aprotinin reduces blood loss in operations done with cardiopulmonary bypass, whereas the use of desmopressin remains controversial. We compared aprotinin, desmopressin, and placebo in a double-blind, randomized trial to evaluate bleeding and transfusion requirements.

METHODS AND RESULTS

One hundred forty-nine patients (48 received aprotinin, 50 desmopressin, 51 placebo) were included. Blood loss and transfusion requirements were recorded and levels of Factor VIII coagulant activity, von Willebrand's factor, thrombin-antithrombin complexes, and D-dimer were measured. Overall blood loss was 195 +/- 146 ml/m2 in the aprotinin group, 400 +/- 192 ml/m2 in the desmopressin group, and 489 +/- 361 ml/m2 in the placebo group (95% confidence intervals: difference between desmopressin and aprotinin 98 to 312 ml/m2, p < 0.001; difference between placebo and aprotinin 190 to 398 ml/m2, p < 0.001). Twenty-six percent of patients treated with aprotinin, 66% of those treated with desmopressin, and 56% of those treated with placebo were given transfusion (95% confidence intervals: difference between aprotinin versus placebo plus desmopressin 51% to 71%, p < 0.001). Fibrinolytic activation throughout cardiopulmonary bypass was markedly higher with placebo or desmopressin administration. D-dimer level correlated with overall blood loss in patients receiving desmopressin or placebo, but not in those receiving aprotinin.

CONCLUSION

Aprotinin administration reduces blood loss and transfusion requirements in cardiopulmonary bypass. This benefit may be explained by a lower activation of fibrinolysis.

Effect of glycerol on intracellular virus survival: implications for the clinical use of glycerol-preserved cadaver skin

Glycerol has long been used for the preservation of skin allografts. The antimicrobial activity of glycerol has not been fully documented. This paper reports the results of an investigation of a model studying the effect of glycerol on the inactivation of intracellular viruses. Two viruses--herpes simplex type I (HSV-1) and poliovirus--were cultured within human dermal fibroblasts. These intracellular viruses were incubated with 50 per cent, 85 per cent and 98 per cent glycerol at 4 degrees C and 20 degrees C for 4 weeks. Each week, the cultures in glycerol and controls in fibroblast maintenance medium were assayed for virus infectivity by examining the ability of harvested viruses to infect further fibroblasts. At 4 degrees C, 85 per cent glycerol could not fully inactivate intracellular HSV-I or poliovirus even after 4 weeks; 98 per cent glycerol inactivated intracellular HSV-I (after 3 weeks) but could not fully inactivate intracellular poliovirus after 4 weeks. At 20 degrees C, 85 per cent glycerol inactivated intracellular HSV-I (within 1 week) but could not fully inactivate intracellular poliovirus after 4 weeks; 98 per cent glycerol inactivated intracellular HSV-I (within 1 week) and inactivated intracellular poliovirus (after 2 weeks). It is suggested that, on the basis of this study, glycerol can reduce intracellular virus infectivity but that its effects are very dependent on concentration, time and temperature such that we would recommend that allograft skin be exposed to 98 per cent glycerol for a minimum of at least 4 weeks at a minimum temperature of 20 degrees C before clinical use.

The potential for HIV transmission through allogeneic bone. A review of risks and safety

Over the past two decades, oral and maxillofacial surgeons have gained a greater appreciation for the biology of allogeneic bone healing, resulting in a dramatic increase in its indications and use. Unfortunately, this time period has also ushered in near epidemic proportions of HIV-infected persons, some of whom might be considered as potential donors of allogeneic bone. As this article will discuss, surgeons and tissue bank teams alike must be aware of the clinical and serologic criteria associated with an acceptable donor. Only in this way can contamination-free specimens be obtained and surgically implanted.

Risk of human immunodeficiency virus (HIV) transmission by anti-HIV-negative blood components in Germany and Austria

In order to estimate the residual risk of transfusion-transmitted HIV infection we have analyzed the data from two transfusion centers in Austria (Vienna) and Germany (Göttingen) from 1985 to 1994. In Vienna, an incidence of 1:42,000 positive anti-HIV tests in repeat donors and a prevalence of 1:7000 in first-time donors were found in 1993. In Göttingen, the indicence was 1:67,000 and the prevalence 1:7900 from 1985 to 1993. Based on a mathematical model which takes (a) the window period and (b) the false-negative rate of anti-HIV tests, as well as (c) human and operational errors into consideration, we have calculated the residual risk of HIV infection. The residual risk (third generation anti-HIV test) was found to be 1:520,000 (95% confidence interval 1:1340,000-1:210,000), and 1:900,000 (95% confidence interval 1:2340,000-1:380,000) for Vienna and Göttingen, respectively, in 1993. Look-back studies from 1985 till 1994 revealed transfusion-transmitted HIV infections in three recipients (for 1.9 million donations in Vienna) and one recipient (for 160,000 donations in Göttingen) of blood components. Based on our model, as well as on prevalence and incidence rates of HIV infection, it is also possible to predict the efficacy of additional measures introduced to further decrease the risk of transfusion-transmitted HIV infection through blood components.

Confidential unit exclusion: the North London Blood Transfusion Centre's experience

A 'Confidential AIDS Questionnaire' has been used at North London Blood Transfusion Centre (NLBTC) donor sessions since July, 1985. The aim of the questionnaire is to encourage self-exclusion by those donors whose behaviour puts them at risk of HIV infection. In a situation where such individuals cannot avoid donating they can indicate, in confidence, that their blood should not be used for transfusion. Since the introduction of this procedure, an average of 10 donors per month, who admitted relevant risk behaviour, have been permanently excluded and a number of prospective donors have excluded themselves when faced with the questionnaire. We have found the questionnaire to be well accepted by donors. It is a useful adjunct to routine donor selection and microbiological testing of donations in our efforts to minimize transfusion-transmitted infection.

Infectious disease markers in blood donors in northern Thailand

BACKGROUND

A major epidemic of human immunodeficiency virus type 1 (HIV-1) infections that are primarily due to heterosexual transmission has developed in Thailand since 1988. The epidemic has been most severe in northern Thailand. The blood banks in Chiang Mai began screening donors for HIV-1 antibodies in February 1988 and for p24 antigen in April 1992.

STUDY DESIGN AND METHODS

The trends of HIV-1 antibody prevalence were analyzed by type of donor (i.e., paid, replacement, and voluntary) for the period of 1988 through 1993. In addition, the prevalence of HIV-1 p24 antigen and of antibodies to syphilis, hepatitis B surface antigen, and hepatitis C virus was evaluated among blood donors at Chiang Mai University Hospital and the Thai Red Cross blood banks in Chiang Mai.

RESULTS

The prevalence of HIV-1 antibodies increased from 0.84 percent in 1988 to 4.04 percent in 1991. Seropositivity was highest in paid professional donors. After discontinuation of the use of paid donors in 1993, HIV-1 antibody prevalence decreased to 3.34 percent. Antibody prevalence in replacement donors increased from 0.56 percent in 1988 to 5.82 percent in 1991. Among 44,446 donors tested, 7 (0.016%) were HIV-1 p24 antigen positive but antibody negative.

CONCLUSION

The exclusion of paid donors and the use of p24 antigen testing are justified in northern Thailand. Additional strategies to exclude donors at very high risk and to attract those at low risk for infection should be developed and evaluated to increase blood transfusion safety in this and other, similar populations.

Testing blood donors for HIV: current controversies

Despite an estimated risk of HIV infection from anti-HIV screened blood transfusions of less than one in 225,000 per unit, there continues to be strong pressure to implement additional donor screening and viral inactivation procedures. Decisions to implement such procedures must be based on analyses that incorporate accurate estimates of residual risk, and data-based projections for the reduction in risk that would result from each measure. Since the residual risk of HIV is primarily due to donations given in the infectious pre-seroconversion window, effort must be directed at: reducing donations by persons in this window; employing tests that narrow the window; and development and implementation of procedures that inactivate viral compartments that predominate during the window. Unfortunately, as the risk of HIV has declined to near-undetectable levels, the challenge of generating appropriate data to evaluate new measures, and thereby support rational policy decisions, has increased inversely. To meet this challenge, we must refine our understanding of the virological characteristics of early HIV seroconversion, and of the types of donors who present in the seroconversion window. Thoughtful application of a thorough understanding of the seroconversion window, in the context of accurate HIV incidence data in the donor settings, should enable us to assure the public of a safe blood supply while resisting inappropriate implementation of unnecessary and usually non-specific procedures.

Viral contamination of blood components and approaches for reduction of infectivity

Currently, the United States blood supply offers a relatively low risk of viral infection. This is a result of careful selection of donors and extensive laboratory testing using sensitive procedures. Epidemiologic data show that there is some room for improvement in donor selection, but such improvements cannot be expected to entirely eliminate the collection of blood from infectious donors. Similarly, increased numbers of tests, along with improvements in the analytic sensitivity of these tests, may further reduce risk, but again, complete safety cannot be assured. Consequently, there is continuing interest in the development of safe and effective procedures for viral inactivation of single donor blood components. In order to establish appropriate expectations for such inactivation procedures, it is necessary to understand the titers and distributions of viral contaminants in blood components. Viruses may variously occur free in the plasma, as replicative forms in actively infected leukocytes, as integrated proviral DNA and perhaps, nonspecifically associated with cellular surfaces.

Infections and immunological hazards of allogeneic bone transplantation

Allogeneic transplantation of human cancellous and cortical bone is a controversially discussed concept in trauma and orthopaedic surgery. Biological and immunological arguments support transplantation of autologous material whenever this is technically possible. On the other hand, synthetic alloplastic materials for bone substitution are available free of immunological and hygienic hazards. In this context the value of allogeneic bone grafts is discussed, especially considering the problem of AIDS. If autologous corticospongious bone is to be used its supply is limited. On the other hand, alloplastic synthetic artificial bone does not meet all the requirements demanded for substitution of large osseous defects up to now. The problems of geometric and mechanical stability of these alloplastic materials still remain. Therefore, no alternative to allografting of large, stable, corticospongious fragments exists in some cases. Bone transplantation is performed without vital indication in nearly every case. Thus an optimum of hygienic security has to be claimed for recipients of allogeneic bone. The "Munich model" for bone transplantation is presented and discussed.

Existing problems in the testing for infectious diseases

Current methods for testing donated blood for presence of infectious viral agents in the USA differ from those used in other countries because of the USA Food and Drug Administration's (FDA) control which inhibits rapid introduction of testing methods or improvements. Delays in FDA approval may occur because of concerns about methodology or the state of knowledge about the disease it is intended to detect as well as due to variability between manufacturers. Despite strict FDA control, testing problems continue to occur in the USA. No approved method detects infectious agents during the "window period," and variations in detection, i.e., false positives and false negatives (even with confirmatory testing), continue to occur. The effect of physical and chemical changes (e.g., various anticoagulants) on samples has not been thoroughly evaluated. Test performance problems include lapses in sample identification, failure to use routine laboratory controls, improper calculation and reporting of results, improper acceptance of test runs and failure to properly detect and retest samples when carryover from very reactive samples occurs. For these reasons, transfusion-related disease transmission continues to occur. The current USA emphasis on good manufacturing practices should provide continuous improvements.

Construction of gag, pol, and env specific riboprobes for confirmation of HIV-1 specific polymerase chain reaction products

Conserved regions of the gag, pol, and env genes of HIV-1 pBH10 DNA (gag nucleotides(nt)1508-1652, pol nt 2811-3118, env nt 7792-7934; Ratner et al., 1985) were amplified by the polymerase chain reaction (PCR) using oligonucleotides complementary to the termini of these regions as primers. Primer areas of the amplified DNA were then removed by digestion with restriction endonucleases, and the internal fragments purified and cloned in both orientations into the 'riboprobe' transcription vector pGEM-5Z. Riboprobes made from these plasmids did detect the specific sequences of pBH10 DNA and of HIV-1 DNA amplified by PCR from clinical material. The riboprobes will be useful to confirm the specificity of PCR-amplified fragments of lymphocyte DNA obtained from infants of HIV-infected mothers and from high risk, but seronegative contacts of HIV-1 infected individuals.

Nosocomial infections in the pediatric intensive care unit

Pediatric intensive care units have contributed considerably to the management of children with severe diseases and life-threatening conditions. The use of mechanical ventilation, invasive monitoring, and indwelling catheters increase the risk for nosocomial infection. Improving infection control practices and surveillance can significantly reduce the incidence of nosocomial infections.

Blood safety in developing countries

This study, based on responses to a questionnaire, was undertaken to define problems in and formulate solutions for improving blood safety in developing countries as part of an effort to monitor the status of blood transfusion services globally. Despite improvements between 1988 and 1992, only 66% of developing countries (DGCs) and 46% of least developed countries (LDCs) screen all blood donations for antibodies to human immunodeficiency viruses; 72% DGCs and 35% LDCs test all donations for hepatitis B surface antigen and 71 and 48%, respectively, for syphilis. The antihuman globulin test is performed routinely in 62% DGCs and 23% LDCs, and inadequate quality assurance in all aspects of preparatory testing is a major weakness in many countries. The blood supply is usually insufficient: none of the LDCs and 9% of the DGCs collect 30 units or more per 1,000 of the population annually. Blood donor systems are totally voluntary and non-remunerated in 15% DGCs and 7% LDCs; 80% DGCs and 93% LDCs rely totally or partially on replacement donors and 25% of both groups on paid donations. The proportion of repeat donors is low (medians: 47% in DGCs, 20% in LDCs), and discard rates for collected blood are often high (up to 33%). Most of the blood collected is transfused as whole blood, and most DGCs and LDCs have inadequate supplies of plasma substitutes for management of acute haemorrhage. The reasons for these problems and suggested solutions are discussed.

The effectiveness of the confidential unit exclusion option

BACKGROUND

The confidential unit exclusion (CUE) option is intended to reduce human immunodeficiency virus (HIV) transmission by excluding donors newly infected with HIV who have not yet developed HIV antibody (window-period donors); however, its efficacy in excluding window-period donors has not been evaluated.

STUDY DESIGN AND METHODS

The use of the CUE option was studied among the donors of 3.7 million units at 18 American Red Cross blood services regions during 1991 and 1992 and among 322 previously HIV-1-seronegative donors who subsequently donated a seropositive unit between 1987 and 1990 at 40 United States blood centers. These seroconverting donors had previously been shown to be highly likely to donate during their window period.

RESULTS

On the basis of data from these two populations, it was estimated that only 3 to 5 percent of units donated by window-period donors were not transfused because of the CUE option, that 0.4 percent of all donations were from donors who confidentially excluded their blood from transfusion, and that donors who confidentially excluded their blood were 21 times more likely to be HIV antibody-positive than donors who did not use the CUE option. It is estimated that, if all US blood centers used the CUE option, a total of 2 to 17 otherwise acceptable units donated by window-period donors would not be transfused annually.

CONCLUSION

Although donors who confidentially exclude their blood from transfusion are 21 times more likely to have HIV antibody, the rarity of window-period donors and the infrequency of confidential exclusion by window-period donors cause the CUE option to have minimal impact on transfusion safety.

Construction of gag, pol, and env specific riboprobes for confirmation of HIV-1 specific polymerase chain reaction products

Conserved regions of the gag, pol, and env genes of HIV-1 pBH10 DNA (gag nucleotides(nt)1520-1665, pol nt 2326-2663, env nt 7192-7333; Ratner et al., 1985) were amplified by the polymerase chain reaction (PCR) using oligonucleotides complementary to the termini of these regions as primers. Primer areas of the amplified DNA were then removed by digestion with restriction endonucleases, and the internal fragments purified and cloned in both orientations into the 'riboprobe' transcription vector pGEM-5Z. Riboprobes made from these plasmids did detect the specific sequences of pBH10 DNA and of HIV-1 DNA amplified by PCR from clinical material. The riboprobes will be useful to confirm the specificity of PCR-amplified fragments of lymphocyte DNA obtained from infants of HIV-infected mothers and from high risk, but seronegative contacts of HIV-1-infected individuals.

Experience of autologous blood transfusion at a district general hospital in Zambia

An Autologous Blood Transfusion Programme has been in operation at Ndola Central Hospital (NCH) since April 1992. This paper describes a method of cell salvage and reviews the two types of autologous transfusion [acute isovolaemic haemodilution (AIH) and cell salvage] practised over the 6 month period November 1992 to April 1993. No complications or adverse effects were encountered and the benefits include reduction of immunological reactions and transmission of infection, which are risks associated with homologous transfusion. There is need to minimize homologous transfusions because of these risks and hospitals should develop reasonable, practical guidelines for safer transfusion, including the use of autologous blood whenever possible.

Donor insemination and human immunodeficiency virus: a risk/benefit analysis

In 1988 the American Fertility Society revised its guidelines for the use of semen in donor insemination by stating that "the use of fresh semen for donor insemination is no longer warranted." Although the consequences of this recommendation include an approximate doubling of the patient's cost of treatment, a 50% reduction in both cycle fecundity and 3-month life-table pregnancy rates, a reduction in the number of pregnancies because of patient dropout, and an ethically troubling increase in physician income as a direct result of the diminished efficacy of treatment, an analysis of the risk of transmission of human immunodeficiency virus through donor insemination has not been presented. All available data suggest that neither safety nor efficacy need be sacrificed in the current practice of donor insemination by offering patients the choice of appropriately screened fresh or frozen sperm.

Detection of human immunodeficiency virus type 1 by PCR before seroconversion in high-risk individuals who remain seronegative for prolonged periods

HIV-1 seronegative patients at high risk for HIV infection were followed up. In 1990 PCR was positive for HIV DNA sequences in samples of 17 seronegative patients who continued to report for surveillance of HIV infection. There was clear evidence of seroconversion in four of these 17 seronegative patients, while in one patient an indeterminate result for HIV was repeatedly obtained in different samples. The other 12 patients continue to be seronegative without any evidence of HIV infection except the presence of provirus in peripheral blood mononuclear cells. It is important to apply the PCR technique together with tests to detect other virological and immunological markers, in order to identify seronegative carriers and thus avoid HIV transmission by them.

Blood Conservation and Blood Salvage

Autologus blood transfusion has been recommended as the blood of choice for surgical patients. Procurement of autologus blood can be accomplished by utilizing one or more conservation interventions: preoperative autologous blood donation, acute preoperative hemodilution, and perioperative autologous salvage. Recent estimates of cost-effectiveness emphasize that blood conservation interventions need to be held accountable with regards to their costs as well as their benefits. Despite recent advances in blood safety, patients need to be informed of the relative risks of blood transfusion and blood conservation, so that a careful balance of the need for blood conservation along with an acknowledgment of the life-saving properties of blood can be maintained.

Changes in longevity and causes of death among persons with hemophilia A

To examine recent changes in longevity and the causes of death among persons with hemophilia A, we evaluated death certificate data for persons who died in the United States from 1968 through 1989 and had hemophilia A or congenital Factor VIII disorder (ICD code 286.0) listed on the death certificate as one of the multiple causes of death. Multiple-cause-of-death mortality data for the United States from 1968 to 1989 were examined to compare death rates by year, focusing on death rates and causes of death for 1979-1981, 1983-1985, and 1987-1989. Gender, age group, race, geographic region, and median age at death of persons with hemophilia A and human immunodeficiency virus (HIV)-related disease listed as a cause of death were compared with those with hemophilia A without HIV-related disease. From 1968 through 1989, 2,792 hemophilia A deaths were reported. The death rate increased from 0.5 to 1.3 per 1,000,000 persons. From 1979-1981 through 1987-1989, mortality increased in all age groups above 9 years of age and age at death shifted markedly to lower ages. Median age at death decreased from 57 years in 1979-1981 to 40 years in 1987-1989. The percentage of deaths due to hemorrhage or diseases of the circulatory system decreased markedly as the result of the increase in deaths associated with HIV infection or infections other than HIV infection. Spread of HIV-1 infection in persons with hemophilia A has disrupted the reduction in mortality seen with factor replacement therapy, implementation of home care, and use of comprehensive hemophilia treatment centers. It is hoped that advances in the care of HIV-infected persons will improve survival in the hemophilia community.

Absence of prolonged immunosilent infection with human immunodeficiency virus in individuals with high-risk behaviors

PURPOSE

The presence in some individuals of a prolonged phase of infection with human immunodeficiency virus type 1 (HIV-1) before seroconversion remains controversial. This study was undertaken to determine with a sensitive in vitro amplification technique, the polymerase chain reaction (PCR), whether seronegative individuals with high-risk behaviors could harbor HIV-1 sequences in their peripheral blood mononuclear cells (PBMCs) and remain seronegative for more than 6 months.

PATIENTS AND METHODS

Seronegative individuals who engaged in unprotected anogenital intercourse with HIV-1-infected partners or with more than 10 individuals per year, and seronegative individuals who shared needles with seropositive partners, were recruited prospectively over 18 months. HIV-1 DNA and RNA sequences were detected in PBMCs of these individuals with three PCR assays using SK38/SK39, SK145/SK431, and SK68/SK69. Seronegative but PCR-positive patients were also evaluated with p24 antigen capture assay, radioimmunoprecipitation assay, and Western blot. The latter patients were followed prospectively to reproduce PCR-positive results and monitor serologic responses.

RESULTS

Sixty-one men and 18 women, with an average age of 34.1 +/- 7.6 years, were recruited: 56 were homosexual men, 18 were heterosexual women, and 5 were heterosexual men. Amplification reactions for HIV-1 of 104 PBMC specimens from 79 patients with negative or indeterminate serologies revealed that 4 patients (5.1%) were positive with PCR for HIV-1 DNA and RNA at the time of enrollment. Positive amplification reactions could not be reproduced in prospective samples for one patient. The analysis of a variable human genomic locus in this patient's PBMCs demonstrated that the first PCR-positive sample and following PCR-negative samples originated from different patients, suggesting a specimen mix-up. Two of the three PCR-positive seronegative patients had symptoms suggestive of acute retroviral disease. Sera from all three patients contained p24 antigen. Two patients seroconverted within 1 month whereas one patient could not be followed prospectively.

CONCLUSION

Prolonged infection with HIV-1 without seroconversion was not found in our population of patients at very high risk for HIV-1 infection. All PCR-positive patients seroconverted in less than 1 month.

Amplification and detection of a single molecule of human immunodeficiency virus RNA

Detection of plasma viremia in human immunodeficiency virus type 1 (HIV-1)-infected people is indispensable for the diagnosis of seronegative infection as well as for the evaluation of virus activities in vivo. The direct detection of HIV-1 RNA in circulation has been performed by means of reverse transcription followed by polymerase chain reaction (RT-PCR). As an attempt to establish a highly sensitive assay, we evaluated the effects of two-step amplification with nested primers and double priming of reverse transcription on the sensitivity of RT-PCR. The sensitivity of two-step amplification was 100 times higher than that of one-step amplification. The double priming of reverse transcription further increased the sensitivity of the following two-step amplification 100 times, which appeared to be enough to detect HIV-1 RNA from as little as a 2.2 x 10(-4) TCID50 unit equivalent of culture supernatant of HIV-1-infected cells and a single molecule of HIV-1 gag complementary RNA synthesized by in vitro transcription. By use of this most sensitive assay, we successfully detected HIV-1 RNA in serum or plasma from all 22 patients with acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC) and 13 out of 14 untreated asymptomatic carriers. Of 43 asymptomatic carriers under the treatment with interferon-alpha or azidothymidine, 17 cases showed negative results, indicating that the virus activity was suppressed by the therapeutics. We also noted the inhibitory effect of heparin on RT-PCR.

Tissue banking safety: caveats and precautions for the oral and maxillofacial surgeon

Oral and maxillofacial reconstructive surgeons using allogeneic tissues have expressed justifiable concern over the safety of these tissues as they relate to the transmission of infectious disease. This report reviews cases of infectious disease transmission from inadequately screened donors of allogeneic tissues, as well as those related to improper sterilization and cataloging of these tissues. It is concluded that good judgment and attention to good science on the part of the tissue bank as well as the surgeon can maximize the ability to place contamination-free specimens, thereby avoiding complications similar to those described.

Blood transfusion practices after resection of intrathoracic neoplasms

A heightened awareness of the risks of blood transfusion and the previously reported common administration of blood products (31-55%) following thoracic surgery prompted us to evaluate our recent transfusion practices. Of 355 patients who underwent a thoracotomy or median sternotomy from July 1987 through September 1991, 91 (25.6%) were transfused a mean 3.1 units of blood within the first 30 postoperative days. Transfused and nontransfused patients were compared with respect to age, body surface area, preoperative hemoglobin, estimated operative blood loss, and estimated postoperative hemoglobin. Univariate analyses of variance indicate significant (P < 0.01) differences between the two groups of patients for preoperative hemoglobin, blood loss, and estimated postoperative hemoglobin. Transfusion frequencies by year of operation are: 1987, 36%; 1988, 31%; 1989, 33%; 1990, 23%; 1991, 15%. We conclude that our transfusion requirements are lower than reported rates and that clinical parameters may help predict the need for subsequent transfusion.