The distribution of infectivity in blood components and plasma derivatives in experimental models of transmissible spongiform encephalopathy

BACKGROUND: The administration of blood components from donors who subsequently develop Creutzfeldt-Jakob disease has raised the issue of blood as a possible vehicle for iatrogenic disease. STUDY DESIGN AND METHODS: We examined infectivity in blood components and Cohn plasma fractions in normal human blood that had been "spiked" with trypsinized cells from a scrapie-infected hamster brain, and in blood of clinically ill mice that had been inoculated with a mouse-adapted strain of human transmissible spongiform encephalopathy. Infectivity was assayed by intracerebral inoculation of the blood specimens into healthy animals. RESULTS: Most of the infectivity in spiked human blood was associated with cellular blood components; the smaller amount present in plasma, when fractionated, was found mainly in cryoprecipitate (the source of factor VIII) and fraction I+II+III (the source of fibrinogen and immunoglobulin); almost none was recovered in fraction IV (the source of vitamin-K-dependent proteins) and fraction V (the source of albumin). Mice infected with the human strain of spongiform encephalopathy had very low levels of endogenous infectivity in buffy coat, plasma, cryoprecipitate, and fraction I+II+III, and no detectable infectivity in fractions IV or V. CONCLUSION: Convergent results from exogenous spiking and endogenous infectivity experiments, in which decreasing levels of infectivity occurred in cellular blood components, plasma, and plasma fractions, suggest a potential but minimal risk of acquiring Creutzfeldt-Jakob disease from the administration of human plasma protein concentrates.     

Antisickling effects of 2,3-diphosphoglycerate depletion

Elevation of 2,3-bisphosphoglycerate (2,3-DPG) in sickle erthrocytes (SS RBCs) and concomitant acidification of the cell interior promote polymerization by decreasing the solubility (csat) of deoxyhemoglobin S. The antisickling effect of 2,3-DPG depletion was evaluated after activation of the 2,3-DPG phosphatase activity of bisphosphoglycerate mutase by glycolate-2-phosphate, leading to rapid loss of intracellular 2,3-DPG. To ensure its maximal reduction in a physiologic medium, isosmotic CO2/bicarbonate-buffered saline, pH 7.0, was used. Substitution of K+ for Na+ as the major extracellular cation suppressed K:Cl cotransport, prevented cell shrinkage, and allowed demonstration of the full antisickling effect of 2,3-DPG depletion. The modest effect on solubility per se of removing intraerythrocytic 2,3-DPG (delta Csat = 1.6 g/dL) was amplified into a much larger antisickling effect by interaction with three other cellular variables affecting solubility and polymer content (intracellular pH, O2 saturation, and mean cell hemoglobin concentration). Acting in concert, these four antisickling effects (three solubilizing, one osmotic) reduced polymer fraction of glycolate-treated SS RBCs by 32% to 63%, with a concomitant decrease in sickling of 46% to 95% at the nominal pO2 of the microcirculation (20 mm Hg). A decrement in sickling of this magnitude should significantly ameliorate the vasoocclusive severity of sickle cell disease.     

Induction of apoptotic cell death in chronic lymphocytic leukemia by 2- chloro-2'-deoxyadenosine and 9-beta-D-arabinosyl-2-fluoroadenine

2-Chloro-2'-deoxyadenosine (CldAdo) and 9-beta-D-arabinosyl-2- fluoroadenine (F-ara-A) have shown marked activity in the treatment of indolent lymphoid malignancies. Based on the susceptibility of various lymphocyte populations to apoptosis, we investigated whether CldAdo or F-ara-A would induce this process in lymphocytes from patients with chronic lymphocytic leukemia (CLL). In vitro exposure of leukemic lymphocytes to CldAdo or F-ara-A for 24 to 72 hours elicited features of apoptosis visible by light and electron microscopy. Analysis of DNA integrity showed DNA cleavage into nucleosomal-sized multimers. Using a quantitative assay, drug-induced DNA fragmentation was both time and dose dependent. Inhibition of active macromolecular synthesis did not prevent drug-induced fragmentation; however, both drug-induced and spontaneous DNA fragmentation were prevented by intracellular calcium chelation. In vitro culture with phorbol ester generally decreased drug- induced DNA cleavage. After prolonged incubation, CLL cells exhibited spontaneous cleavage; albeit, at significantly lower rates than drug- treated cells. Heterogeneity was observed for spontaneous and drug- induced DNA fragmentation and was significantly lower in B-leukemic cells obtained from patients with high-risk and refractory disease. We conclude that CldAdo and F-ara-A are potent inducers of apoptotic death in CLL and that this feature correlates with the disease status.     

Dynamic imaging of the stomach by real-time ultrasound--a method for the study of gastric motility.

The use of real-time ultrasonic imaging of the stomach for the study of gastric contractions in response to a liquid test meal is described. Gastric contractions in the pyloric antrum and distal body of the stomach were observed on closed circuit television, recorded on to cassette tape and also imaged on polaroid and ciné film. Gastric contractions were recorded from the pyloric antrum by longitudinal scanning in the lower epigastrium and reproducible motility tracings were obtained on a fibreoptic chart recorded. Intravenous metoclopramide enhanced the magnitude and frequency of antral movement, which was abolished by intravenous propantheline. Real-time ultrasonic imaging permits the non-invasive study of gastric contractions. It is safe, may be repeated as required, and provides a method for the study of the effect of drugs and disease states on gastric motility.     

White cells in fresh-frozen plasma: evaluation of a new white cell- reduction filter

BACKGROUND: Fresh-frozen plasma (FFP) has generally been regarded as an acellular component. Recently, viable lymphocytes have been detected in this component and the question of irradiation of FFP for certain patients has been raised. Whether the numbers of white cells (WBCs) in FFP are sufficient to require WBC-reduction of acellular components for patients receiving WBC-reduced cellular components has not been determined. WBC numbers in FFP were examined, and the performance of a new commercial WBC-reduction filter for FFP was assessed. STUDY DESIGN AND METHODS: WBC numbers in plasma processed for use as FFP and in thawed FFP were counted before and after WBC-reduction filtration by the use of flow cytometry Fast and slow filtration was used to simulate laboratory and bedside filtration, respectively. Three different methods for plasma harvesting (soft-spin, hard-spin, and second-spin methods) were assessed. The filter capacity was also examined. RESULTS: The numbers of WBCs in plasma covered a three-log10 range (soft-spin method, 0.04-3.6 × 10(6); hard-spin method, 0.47-45.4 × 10(6); second- spin method, 0.4–37.2 × 10(6)). For the hard-spin and second-spin methods which produced the greatest plasma yields, 92 percent and 85.7 percent of bags, respectively, had counts>1 × 10(6) and 43 percent (hard-spin method) and 45.7 percent (second-spin method) had counts>5 × 10(6). There was no significant difference between the counts obtained in plasma and thawed FFP. The filter reduced WBC numbers to <1 × 10(5) in all but 3 of 49 bags. In the remaining three, there were <2 × 10(5) WBCs. Five bags of plasma could be processed effectively through each filter. CONCLUSION: FFP may contain WBC numbers above the threshold at which the use of WBC-reduction filters for cellular components in some patients is necessary. Confirmation of these findings and similar investigations on plasma prepared by other methods may help in defining a role for the use of WBC-reduction filters for FFP     

A motion artefact in real-time ultrasound scanners

Motion observed in real-time ultrasound images may be very misleading. The speckle pattern in images of soft tissue is an artefact and it may move in a way which bears no simple relationship to the motion of the tissues. The physical origin of this anomaly is described.     

The presence and distribution of carcinoembryonic antigen in tumors of human minor salivary glands

Abstract Using an immunoperoxidase method we have demonstrated carcinoembryonic antigen (CEA) in more than half of a series of 62 tumors of minor salivary glands. CEA was present in both benign and malignant tumors. Its presence was related mainly to the formation of well differentiated ductal tissue in the neoplasms rather than to the histologic type of tumor. Although of only limited diagnostic value, the histologic presence of CEA in a particular tumor may indicate the possibility of postoperative monitoring of saliva and plasma, particularly where residual tumor, metastases or recurrences arc considered likely.     

Heartrate variation of umbilical artery Doppler waveforms

Umbilical artery Doppler waveforms from 20 patients were used to investigate the dependence of resistance index and pulsatility index on beat to beat pulse length over short time periods for individual patients, and on the usefulness of a common normalisation formula. For individual patients the resistance index and pulsatility index were only partially correlated with pulse length. Changes in both indices occurred independently of pulse length. Use of a common normalisation formula resulted in no significant reduction of the coefficient of variation of the resistance index (p greater than 0.1), and a reduction in the coefficient of variation of the pulsatility index of 10% (p greater than 0.001). It is concluded that short term changes in resistance index and pulsatility index cannot be corrected by a common normalisation formula.     

Blood flow detection by an intersecting zone ultrasonic Doppler unit

A continuous wave Doppler system has been constructed with which a localised region may be studied by arranging for the transmission zone and the reception zone of the beam to intersect at the selected region. This intersecting zone technique overcomes the problem of lack of localisation normally associated with continuous wave Doppler devices while retaining the low noise and high velocity measurement features of these instruments. The variable intersecting zone Doppler unit has been linked with a real-time ultrasonic scanner to study blood flow in the pregnant uterus. Sites studied include the placenta, the cord, the foetal aorta and umbilical vein.