Theragnostics for tumor and plaque angiogenesis with perfluorocarbon nanoemulsions.

Molecular imaging agents are extending the potential of noninvasive medical diagnosis from basic gross anatomical descriptions to complicated phenotypic characterizations based upon the recognition of unique cell-surface biochemical signatures. Although originally the purview of nuclear medicine, "molecular imaging" is now studied in conjunction with all clinically relevant imaging modalities. Of the myriad of particles that have emerged as prospective candidates for clinical translation, perfluorocarbon nanoparticles offer great potential for combining targeted imaging with drug delivery, much like the "magic bullet" envisioned by Paul Ehrlich 100 years ago. Perfluorocarbon nanoparticles, once studied in Phase III clinical trials as blood substitutes, have found new life for molecular imaging and drug delivery. The particles have been adapted for use with all clinically relevant modalities and for targeted drug delivery. In particular, their intravascular constraint due to particle size provides a distinct advantage for angiogenesis imaging and antiangiogenesis therapy. As perfluorocarbon nanoparticles have recently entered Phase I clinical study, this review provides a timely focus on the development of this platform technology and its application for angiogenesis-related pathologies.

Neurovirulence and host factors in flavivirus encephalitis--evidence from clinical epidemiology.

Japanese encephalitis virus (JEV) and West Nile virus (WNV) provide some of the most important examples of emerging zoonotic viral encephalitides. For these flaviviruses, only a small proportion of those infected develop clinical features, and these may range from a non-specific flu-like illness to a severe fatal meningoencephalitis, often with Parkinsonian features, or a poliomyelitis-like flaccid paralysis. The factors governing the clinical presentations, and outcome of flavivirus infections are poorly understood, but studies have looked at viral virulence determinants and the host immune response. Previous studies on JEV have suggested that the distribution of the four genotypes across Asia may relate to the differing clinical epidemiology (epidemic disease in the north, endemic disease in the south). However, new data based on the complete nucleotide sequence of a virus representing one of the oldest lineages, and phylogenetic analyses of all JEV strains for which genetic data are available, suggest that the distribution is best explained in terms of the virus' origin in the Indonesia-Malaysia region (where all genotypes have been found), and the spread of the more recent genotypes to new geographical areas. Clinical studies have shown that innate immunity, as manifested by interferon alpha levels, is important in JEV and other flaviviruses, but treatment with interferon alpha did not improve the outcome. A failure of the humoral immune response, is associated with death from encephalitis caused by JEV and WNV. Cellular immunity has been less well characterized, but CD8+ and CD4+ T cells are thought to be important.

Triple-quantum-filtered (23)Na NMR spectroscopy of subcutaneously implanted 9l gliosarcoma in the rat in the presence of TmDOTP(5-1).

The utility of triple-quantum (TQ)-filtered (23)Na NMR spectroscopy for discriminating between intra- and extracellular Na(+)(Na(i)(+) and Na(e)(+), respectively) in a solid tumor in vivo was evaluated using TmDOTP(5-) as a (23)Na shift reagent. Infusion of 80 mM TmDOTP(5-) without added Ca(2+) produced baseline-resolved Na(i)(+) and Na(e)(+) peaks in both single-quantum (SQ) and TQ-filtered (23)Na spectra. The Na(i)(+) signal represented 22+/-4% of the SQ spectrum, but 59+/-10% of the TQ-filtered spectrum. Therefore, the Na(i)(+) contribution in TQ-filtered spectra is much higher than in SQ spectra. Both SQ and TQ-filtered Na(i)(+) signals increased by about 75% 1 h after sacrificing the animal. The TQ-filtered relaxation times did not change during this time, indicating that changes observed in TQ-filtered spectra collected with a preparation time of 3 ms represent changes in the concentration of sodium ions contributing to the TQ-filtered signal. Similar experiments were conducted without TmDOTP(5-) to determine changes in the Na(e)(+) signal in the absence of the shift reagent. The changes in total SQ and TQ-filtered signals 1 h after sacrificing the animal showed that the SQ Na(e)(+) signal decreased by approximately 35%, while the TQ-filtered Na(e)(+) signal did not change significantly. This demonstrates that the TQ-filtered (23)Na signal is relatively insensitive to changes in Na(e)(+) content. To our knowledge, this work represents the first evaluation of multiple-quantum-filtered (23)Na spectroscopy to discriminate between intra- and extracellular Na(+) in a solid tumor in vivo.

Effects of chemotherapy by 1,3-bis(2-chloroethyl)-1-nitrosourea on single-quantum- and triple-quantum-filtered 23Na and 31P nuclear magnetic resonance of the subcutaneously implanted 9L glioma.

The effects of chemotherapy [25 mg/kg 1,3-bis(2-chloroethyl)-1-nitrosourea administered with a single i.p. injection] on cellular energetics by 31P nuclear magnetic resonance (NMR) spectroscopy, total tissue sodium by single-quantum (SQ) 23Na NMR spectroscopy, and intracellular sodium by triple-quantum-filtered (TQF) 23Na NMR spectroscopy were studied in the s.c. 9L glioma. Animals were studied by NMR 2 days before therapy and 1 and 5 days after therapy. Destructive chemical analysis was also performed 5 days after therapy to validate the origin of changes in SQ and TQF 23Na signals. One day after treatment, there was no significant difference between control and treated tumors in terms of tumor size or 23Na and 31P spectral data. Five days after therapy, treated tumors had 28 +/- 16% (P < 0.1) lower SQ 23Na signal intensity, 46 +/- 20% (P < 0.05) lower TQF 23Na signal intensity, 125 +/- 51% (P < 0.05) higher ATP:Pi ratio, 186 +/- 69% (P < 0.05) higher phosphocreatine:Pi ratio, and 0.17 +/- 0.06 pH units (P < 0.05) higher intracellular pH compared with control tumors. No significant differences in TQF 23Na relaxation times were seen between control and treated tumors at any time point. Destructive chemical analysis showed that the relative extracellular space of control and treated tumors was identical, but the treated tumors had 21 +/- 8% (P < 0.05) lower total tissue Na+ concentration and 60 +/- 24% (P < 0.05) lower intracellular Na+ concentration compared with the controls. The higher phosphocreatine:Pi and ATP:Pi ratios after 1,3-bis(2-chloroethyl)-1-nitrosourea treatment indicate improved bioenergetic status in the surviving tumor cells. The decrease in SQ and multiple-quantum-filtered 23Na signal intensity was largely attributable to a decrease in Na(i)+ because the treatment did not change the relative extracellular space. The improved energy metabolism could decrease the intracellular concentration of Na+ by increasing the activity of Na+-K+-ATPase and decreasing the activity of Na+/H+. Although both 23Na and 31P spectra were consistent with improved cellular metabolism in treated tumors, the 23Na methods may be better suited for monitoring response to therapy because of higher signal:noise ratio and ease of imaging the single 23Na resonance.

TmDOTP(5-) as a (23)Na shift reagent for the subcutaneously implanted 9L gliosarcoma in rats.

The use of TmDOTP(5-) as an in vivo (23)Na NMR shift reagent (SR) for subcutaneously implanted 9L gliosarcoma was evaluated. TmDOTP(5-) produced a single sharp extracellular peak after about 50-60 min of infusion, and did not cause any changes in the (31)P resonance areas or chemical shifts, suggesting that the SR is homogeneously distributed in the extracellular space and does not alter tumor bioenergetic status. TmDOTP(5-) and CoEDTA(-) as extracellular space markers gave identical results for relative extracellular space (0.25 +/- 0.03 and 0.25 +/- 0.04, respectively) and intracellular Na(+) concentration (19.3 +/- 4.0 mM and 18.6 +/- 3.9 mM, respectively), indicating that the biodistribution of the SR is the same as the well-accepted extracellular space marker. The in vivo T(1) and T(2) relaxation times of intra- and extracellular Na(+) were also measured. Our results indicate that TmDOTP(5-) promises to be an effective shift reagent and extracellular space marker in the 9L gliosarcoma and perhaps other tumors. Magn Reson Med 45:436-442, 2001.

Quantitation of intracellular [Na+] in vivo by using TmDOTP5- as an NMR shift reagent and extracellular marker.

A method is presented to measure the absolute concentration of intracellular Na+ ([Na+]i) in vivo by using interleaved 23Na- and 31P-nuclear magnetic resonance (NMR) spectroscopy and TmDOTP5- as shift reagent and chemical marker of tissue extracellular space (ECS). The technique was used to determine [Na+]i and relative ECS in livers of control rats (21 +/- 3 and 0.11 +/- 0.02 mM, respectively) and in rats exposed to carbon tetrachloride (103 +/- 29 and 0.23 +/- 0.03 mM, respectively). The NMR measurements were confirmed independently on excised tissue samples by using atomic absorption spectroscopy. The results confirm that TmDOTP5- can be used as a combined cation shift reagent and ECS marker, thereby allowing quantitation of [Na+]i in vivo by NMR.

In vivo imaging of nitrous oxide-induced changes in cerebral activation during noxious heat stimuli.

BACKGROUND: Although previous studies have provided some insight into the pharmacologic aspects of nitrous oxide analgesia, the neural circuits mediating its antinociceptive effect remain relatively unexplored. Position emission tomography was used in nine volunteers to identify the loci of nitrous oxide-modulated cerebral responses to a peripheral noxious stimulus. METHODS: Nitrous oxide-pain interactions were studied by comparing regional cerebral blood flow responses to a 48 degrees C tonic heat stimulus, applied to each volunteer's left forearm, during room air inhalation with those obtained while 20% nitrous oxide was administered. Two cerebral blood flow scans were obtained with the 15O-water technique during each condition. Locations of specific regional activation related to pain, and nitrous oxide, were identified using the statistical parametric mapping method, with a significance level of P < 0.01. Pain was rated by visual analog scale and the values were compared using Wilcoxon rank sum analysis. RESULTS: Pain produced cerebral activation in the contralateral thalamus, anterior cingulate, and supplementary motor area. Adding nitrous oxide during pain stimulation abolished activation in these areas but was associated with activation in the contralateral infralimbic and orbitofrontal cortices. In parallel, mean visual analog scale scores decreased significantly from 67 +/- 4 (SEM) to 54 +/- 5 (P < 0.05). CONCLUSIONS: Nitrous oxide, at 20% concentration, appears to modulate pain processing in the brain's medial pain system, and also activates the infralimbic and orbitofrontal cortices. The potential contribution of the affected brain areas to nitrous oxide analgesia is discussed.

Regional brain activity changes associated with fentanyl analgesia elucidated by positron emission tomography.

Recent positron emission tomography (PET) studies have demonstrated areas of pain processing in the human brain. Given the inhibitory effects of opioids on neuronal activity, we predicted that fentanyl's analgesic effects would be associated with suppression of pain-evoked responses in these distinct brain areas. To test this, PET was used to measure cerebral blood flow responses, as reflections of regional neuronal activity, to painful and nonpainful thermal stimuli both in the absence and presence of fentanyl in humans. During each PET scan in nine healthy volunteers a tonic heat source was placed against the subject's left forearm, delivering a preset temperature of either 40 degrees C (nonpainful) or 47-48 degrees C (painful). Subjects underwent eight blood flow studies, each consisting of 50 mCi [15O]water injection and a PET scan. The first four studies were performed during placebo administration in the stimulus sequence: nonpainful, painful, painful, nonpainful. This sequence was then repeated during intravenous (i.v.) administration of fentanyl 1.5 micrograms/kg [corrected]. Significant differences in regional cerebral blood flow (rCBF) between the placebo and the fentanyl conditions during nonpainful and painful stimuli were identified using statistical parametric mapping. It was found that pain increased rCBF in the anterior cingulate, ipsilateral thalamus, prefrontal cortex, and contralateral supplementary motor area. Fentanyl increased rCBF in the anterior cingulate and contralateral motor cortices, and decreased rCBF in the thalamus (bilaterally) and posterior cingulate during both stimuli. During combined pain stimulation and fentanyl administration, fentanyl significantly augmented pain-related rCBF increases in the supplementary motor area and prefrontal cortex. This activation pattern was associated with decreased pain perception, as measured on a visual analog scale. In contrast to our hypothesis, these data indicate that fentanyl analgesia involves augmentation of pain-evoked cerebral responses in certain areas, as well as both activation and inhibition in other brain regions unresponsive to pain stimulation alone.

Anesthetics modulate phospholipase C hydrolysis of monolayer phospholipids by surface pressure.

Anesthetics are believed to produce anesthesia through the reversible inhibition of synaptic transmission but how this is accomplished is unknown. Based on earlier studies of anesthetic-enzyme-phospholipid interaction, we surmised that anesthetics may inhibit synaptic transmission by increasing synaptic membrane lateral pressure thereby inhibiting phospholipid hydrolysis, membrane transduction and synaptic transmission. As a first approximation towards investigating this concept, we hypothesized that anesthetics modulate the rate of phospholipase C hydrolysis of a lipid monolayer through its effects on surface pressure. The relationship between the hydrolysis rate of a monolayer of dipalmitoylphosphatidylcholine [14C-choline] (DPPC) by phospholipase C (Plase C) and monolayer surface pressure (SP) as altered by either halothane, isoflurane, or by physical compression at 37 degrees C was studied. The decline in surface 14C-activity as the [14C]choline diffuses into the Krebs-Ringer bicarbonate buffer aqueous subphase is estimated as the rate of DPPC hydrolysis measured by the initial slope method. DPPC hydrolysis was about 300 cpm/min and constant between SP of 0 to 20 dynes/cm. Higher SP between 25 and 30 dyne/cm, whether induced by halothane, isoflurane or physical compression, increased the rate of hydrolysis by 5-fold to a peak rate of about 1600 cpm/min at 25-30 dynes/cm. At a SP above 32 dynes/cm, DPPC hydrolysis abruptly ceased. We conclude that anesthetics can reversibly inhibit synaptic transmission through their effects on synaptic membrane lateral pressure. We also speculate that membrane lateral pressure may be a highly sensitive means of controlling membrane function through alteration in membrane lipid composition, membrane enzyme activity, receptor affinity and ion channel permeability.

In vivo imaging of human limbic responses to nitrous oxide inhalation.

Human behavioral studies have shown that nitrous oxide, in subanesthetic concentrations, impairs psychomotor function, cognitive performance, and learning and memory processes. However, the cerebral mechanisms of such effects remain unknown. Positron emission tomography (PET) was used to map the brain areas associated with nitrous oxide effects. Regional cerebral blood flow (rCBF) was measured in eight volunteers, during room air (control) or 20% nitrous oxide (nitrous oxide) inhalation using 15(O)-water, to reflect regional neuronal activity. To control for the possibility that 20% nitrous oxide uncoupled cerebral blood flow and metabolism, in four of the subjects, regional cerebral metabolic rate (rCMR) was also measured using 18F-deoxyglucose during the two experimental conditions. Results of rCBF and rCMR scans were compared between conditions using the statistical parametric mapping method, and areas of nitrous oxide-related activation or deactivation were identified at a significance level of 0.005. Percent changes in rCBF scan pixels from these activated or deactivated areas were then compared with those of stereotactically corresponding rCMR scan pixels with t statistics (P < 0.05 was defined as a significant difference). It was found that cerebral blood flow and metabolism were not uncoupled by 20% nitrous oxide, since percent changes in rCBF and rCMR, detected during nitrous oxide inhalation, did not differ significantly from each other (P < 0.05). Nitrous oxide inhalation was associated with significant activation in the anterior cingulate cortex, a limbic area known to mediate psychomotor and cognitive processes. Deactivation was found in the posterior cingulate, hippocampus, parahippocampal gyrus, and visual association cortices in both hemispheres; the former two regions are known to mediate learning and memory. These areas identified by PET in vivo may provide the neuroanatomical basis for the behavioral responses associated with subanesthetic nitrous oxide inhalation.

Human brain activity response to fentanyl imaged by positron emission tomography.

Positron emission tomography (PET) is a noninvasive imaging technique that can be used to observe drug actions on human brain in vivo. We used 15O-water PET scanning in six volunteers to examine the effects on regional cerebral activity as reflected by regional cerebral blood flow (rCBF) of a small intravenous bolus of fentanyl. rCBF was compared between scans obtained after fentanyl or a placebo using three separate statistical criteria including a pixel-by-pixel t statistic; significance was stringently defined at P values < 0.01. Anatomic locations of regional cerebral activity changes were verified by aligning rCBF PET scans with cranial magnetic resonance images using mathematical coregistration. Fentanyl administration was associated with significant increases in rCBF consistent with regional neuronal activation in both cingulate and orbitofrontal and medial prefrontal cortices, as well as caudate nuclei. These areas are responsive to nociceptive stimuli and are involved in avoidance learning, reward and addiction, visceromotor control, maintenance of attention, and pain-related affective behavior. Significant decreases were noted in both frontal and temporal areas and the cerebellum, a distribution far less extensive than that of opiate receptors in general. These data indicate that fentanyl's effects are highly localized and specifically affect cerebral regions associated with a range of pain-related behaviors.

Funding resuscitation research.

The present trend in managed care has meant downsizing expectations concerning the availability of support for resuscitation research. This trend applies to funding possibilities from industry, governmental agencies, and nongovernmental agencies (Table 1). There will be increasing barriers to making innovations. Truth, science, and good patient care alone will not make potential donors give grants. Investigators must also understand the potential donors' expectations and be persuasive. "Delight your donor". Industries' concerns include intellectual property rights and publications. The National Institutes of Health, recently favoring molecular biology over lifesaving therapies or integrated physiologic research, is an anomaly. The current peer review system propagates itself without having advocates for resuscitation research. This system has become a self-fulfilling prophecy. The American Heart Association is only recently, after 30 yrs of educational activities concerning cardiopulmonary resuscitation, considering putting some basic research money into resuscitation research. In university hospitals, where clinical departments have made significant contributions to innovative, clinically relevant life-support research, funded with incomes from patient care, the sky is beginning to fall. Resuscitation researchers need persuasive advocates with clout and hard data to convince funding agencies to give support to multilevel research and development in areas of pathophysiology and reversibility of terminal states and clinical death--to give these topics a higher priority than is currently available.

Fluorine-19 nuclear magnetic resonance imaging and spectroscopy of sevoflurane uptake, distribution, and elimination in rat brain.

BACKGROUND: Determination of macroscopic and microscopic distribution of general anesthetics can facilitate identification of anatomic, cellular, and molecular loci of anesthetic action. Previous attempts to measure brain anesthetic distributions with fluorine-19 (19F) nuclear magnetic resonance (NMR) imaging were conducted at magnetic field strengths lower than 2 Tesla. All have produced only silhouettes of brain tissue. Difficulties intrinsic to NMR imaging of anesthetics include higher anesthetic solubility in extracranial tissues and the lower limits to spin-echo delay times that can be used in conventional NMR imaging methods. So far, such methods have been unable to capture rapidly decaying brain 19F NMR signals. METHODS: 19F NMR imaging and spectroscopy were conducted at 4.7 Tesla using a specially developed NMR probe and new imaging methods. With the new techniques, it was possible to observe directly the uptake, distribution, and elimination in brain of sevoflurane, a fluorinated general anesthetic with special advantages for NMR investigations. RESULTS: 19F NMR images, acquired at different times after sevoflurane administration, clearly showed the distribution of a fluorinated general anesthetic within the brain. Based on continuous transverse relaxation time measurements, sevoflurane signals could be separated into two components, attributable respectively to sevoflurane in a mobile or immobile microenvironment. During washin, there was a delayed accumulation of anesthetic in the mobile microenvironment. During washout, there was a rapid elimination from the immobile microenvironment. CONCLUSIONS: At anesthetizing concentrations, sevoflurane distributes heterogeneously in the brain. Sevoflurane in the brain tissue contributes mostly to the immobile component of the 19F signal, whereas that in the surrounding adipose and muscle tissues contributes mostly to the mobile component. Imaging and spectroscopic results suggest that the immobile component of sevoflurane is associated with the general anesthetic effects of the agent.

Volatile anesthetic requirements differ in mice selectively bred for sensitivity or resistance to diazepam: implications for the site of anesthesia.

One approach to elucidating the general anesthetic target has used genetic selection procedures, wherein animals are bred for sensitivity or resistance to general anesthetics and correlations are sought with a specific neuronal structural or functional defect. For example, murine strains have been developed that are either sensitive or resistant to the obtunding effects of diazepam, as assessed by their ability to maintain balance on a rotating rod. The present study explored whether diazepam-sensitive (DS) and diazepam-resistant (DR) mice might also be similarly divergent in the obtunding response to general anesthetics, by testing the requirements for halothane and enflurane in these strains. Using a carousel enclosed in a chamber, the end-point of loss-of-righting reflex was defined. For both anesthetics, the DS groups had a lower median effective dose (ED50, %atm) than did the DR group, and the reductions paralleled diazepam susceptibility. For example, with halothane, the ED50 for the DS group was 0.72 +/- 0.022 (SE); the ED50 for the DR group was 0.87 +/- 0.030 (P < 0.0001). Similar results were obtained with enflurane. Such findings associate an inbred difference in response to diazepam with altered volatile anesthetic requirement, suggesting that these two phenotypes are mediated by a common underlying mechanism.

Mechanisms of cerebrovascular O2 sensitivity from hyperoxia to moderate hypoxia in the rat.

Cerebrovascular dilation over PaO2 ranging from hyperoxia to moderate hypoxia is unexplained. We hypothesize that tissue acidosis is the cause. Local cortical cerebral blood flow (LCBF), tissue hydrogen ion concentration [H+]t, and tissue PO2 (PtO2) were measured with microelectrodes in the parietal cortex of 18 rats during a 30-min steady state on 60 to 10% inspired O2 (PaO2, 300 to 40 torr) during 40% N2O analgesia. Five rats kept on 60% O2/40% N2O served as controls. In 18 rats at a PaO2 of 275 +/- 7 torr (mean +/- SEM) and PaCO2 of 35 +/- 1 torr, cerebral values were: LCBF = 129 +/- 23 (mean +/- SEM) ml.100 g-1.min-1; [H+]t = 62 +/- 6 nM; and PtO2 = 25 +/- 3 torr. As PaO2 was reduced from about 300 to 40 torr, changes in these variables in percentage of control with respect to PaO2, were described by the following equations, all at P less than 0.0001: LCBF = 85.9 + 5,572/Pao2; [H+]t = 97.15 + 1,012/PaO2; and PtO2 = 108.8 - 3,492/PaO2. Simultaneous solution of the LCBF and [H+]t equations at various PaO2 revealed a slope of 8.82%/nM. Direct correlation between LCBF in ml.100 g-1.min-1 and [H+]t in nM revealed a linear relationship defined by the equation Y = -7.472 + 1.6705X (r = 0.6426) for [H+]t between 56 and 160 nM (pH = 7.25 and 6.80) but no correlation at [H+]t values between 56 and 32 nM (pH = 7.25 to 7.50). Cerebrovascular tone is directly correlated with [H+]t during progressive, 30-min steady-state reduction in PaO2 from 350 to 40 torr.

A method to increase recovery of fentanyl from urine.

Fentanyl, a highly lipophilic drug (pk(a) 7.7), is a common drug of abuse. The current standard techniques to detect fentanyl in urine have low recovery rates and poor sensitivity. We report a modified solvent extraction technique that can recover between 63 and 86% of the drug with a detection limit of 0.2 ng/10 ml of urine. In addition, we report the duration of urinary fentanyl excretion in 11 adolescent patients administered either low (less than 10 mg/kg) or high (20-40 mg/kg) doses of fentanyl as part of anesthesia. The mean duration of urinary fentanyl excretion was similar in the two groups, with duration ranging from 1 to 5 days, and urine fentanyl concentration ranging from 0.1 ng to 10.3 ng/10 ml of urine.

Febrile transfusion reaction caused by AB0-incompatible platelet transfusion.

A febrile transfusion reaction caused by strong isoagglutinins in the patients serum is reported. The reaction resulted from a transfusion of group A platelets in a group 0 patient; the recipients' serum contained high titered isohemagglutinin (Anti-A 1:8192) capable of lysing bloodgroup A1 red cells up to a titer of 1:8. Moreover, the serum showed a strong positive thrombocytotoxic reaction with the platelets of the donor and some other group A individuals, but remained negative with group 0, and turned to negative reaction with group A samples after neutralization with bloodgroup substance. We conclude that pretransfusion testing of group 0 donors and recipients for isohemolysins combined with platelet crossmatching may prevent febrile reactions.

The frequency of IgA-deficiency in the Austrian population. A protocol for large-scale screening by ELISA and a study on 3056 blood donors.

A protocol for large scale screening of blood donors for IgA-deficiency with the help of an ELISA is described. The ELISA method proved to be fast and reliable, the obtained data can be managed by electronic data processing. Donors were regarded as IgA-deficient when their serum level was below 10 mg/dl (normal values 90 to 450 mg/dl). At this concentration ELISA shows acceptable reproducibility (within +/- 15% limits). We found 8 deficient donors, i.e. one in 382 or 0.26%. Seven of these donors were totally deficient by ELISA, 2 of them having a strong anti-IgA in their serum. We conclude that ELISA is a simple, reliable, and inexpensive method for screening blood donors for IgA-deficiency.