Release of platelet-activating factor in human leukemia.

Cellular release of platelet-activating factor (PAF) was assessed in a series of human acute and chronic lymphoid and myeloid leukemias at presentation or in an active phase of the disease. PAF-like material, showing physicochemical properties similar to those of synthetic PAF and of PAF released from IgE-sensitized rabbit basophils, was found in cultures of cells from 5 of 6 acute lymphoblastic leukemias (ALL) (2 of 2 T-ALL and 3 of 4 common ALL) and from 13 of 24 B-cell chronic lymphocytic leukemias after stimulation with ionophore A23187 with or without phytohemagglutinin in the presence of acetyl coenzyme A. On the other hand, PAF was released only from 2 of 10 acute myeloblastic leukemias; both of them were of the more mature monoblastic subtype or M5 according to the French-American-British classification. Cells from all three cases of chronic myeloid leukemia studied were also capable of producing PAF. In eight cases of acute lymphoid and myeloid leukemia, the in vivo release of PAF was assessed by testing the plasma levels of this mediator. Only in two cases (one ALL and one acute myeloblastic leukemia) could detectable levels of circulating PAF be demonstrated; it is of interest that both of these cases showed clinical and hematological features of disseminated intravascular coagulation. No PAF was documented in the plasma of the five chronic leukemias tested (four B-cell chronic lymphocytic leukemias and one chronic myeloid leukemia). These findings indicate that lymphoid and myeloid leukemic cells have a different capacity of releasing PAF, possibly related to the level of cell differentiation rather than to an intrinsic property of the neoplastic cells. Furthermore, in some cases, an intravascular release of PAF may occur.

Heparin neutralizes serum antiplasmin inhibition of peripheral blood leukocyte fibrinolytic activity.

Serum inhibition of peripheral blood fibrinolytic activity has been evaluated with the 125I-fibrin coated well method. The inhibitory activity was found in a 140,000 d serum fraction that contained alpha 2-antiplasmin. Addition of heparin to cell cultures at concentrations in the range of values obtained during anticoagulant therapy has been demonstrated to counteract such inhibitory activity. The phenomenon has been shown to be linked with plasminogen activation in the presence of fibrin, to lead to a weakening of antiplasmin activity. By clarifying an important aspect of the mechanism of heparin action, our findings support the view that heparin can be usefully employed in treating thrombotic syndromes, not only as an anticoagulant, but also as a "profibrinolytic" agent.

[Use of nuclear magnetic resonance in cranio-facial pathology. Preliminary study]. / Impiego della risonanza magnetica nucleare nella patologia cranio-facciale. Studio preliminare.

The use of MRT in craniofacial pathology has been evaluated above all as regards the possibility offered by this technique for studying the soft parts with better results than already sophisticated investigations like the CT scan. The technique's limitations are the long duration of the investigation, the impossibility of carrying it out in carriers of pacemakers, the inadequate visualisation of the bone and calcifications, the fairly high cost; the advantages are the fact that ionising radiation is not employed, the ureter sensitivity for the soft parts, the good vessel evaluation and the possibility of obtaining oriented sections in every space plane without moving the patient. The use of MRT is therefore rich in prospects.

Benign transient blueberry muffin baby.

In this case-report a case of severe fetal anemia of unknown origin is presented. Diagnosis of fetal anemia was made at 24 weeks of gestational age, when fetal ascites was identified. Doppler sonography of medium cerebral artery showed a high systolic speed velocity (ACM-PSV), of 65 cm/s (>1.55 MoM). This value predicts a severe fetal anemia. Funicolocentesis confirmed hyporegenerative anemia, low reticulocytosis and low erythroblastosis. A fetal transfusion was performed. At birth anemia was still present and the baby presented blueberry muffin and liver erythropoietic foci. The blueberry muffin morphology presents as non-blanching, blue-red macules or firm, dome-shaped papules (2-8 mm in diameter). The eruption is often generalized but favors the trunk, head, and neck. Infectious (Toxoplasmosis, Cytomegalovirus, Rubella, Herpes, Parvo, Coxackievirus, Ebstein Barr, Syphilis), hematologic (sferocytosis, alloimmunization, foeto-maternal transfusion), metabolic, neoplastic (congenital leukemia, neuroblastome, congenital rhabdomyosarcome) and systemic (histiocytosis, lupus) pathologies indicated until now as possible disease causes were excluded. In the first day of life the neonate received a RBC transfusion for anemia (Hb=5.1 g/dL; Hct 15,7% at birth), followed within 48-72 hours by rapid disappearance of the rash, that wasn't then histologically examined. During two weeks of hospitalization reticulocytes raised spontaneously from 0.8% to 3.17%. Until two years of age the auxologic and clinical course was regular and the child is now in good health conditions. Due to the absence of systematic disease and the complete regression, no exact diagnosis and prognosis could be established in this case.

Morphometrics of rapidly frozen goose lungs.

To understand the structural basis of avian gas exchange better, we made a morphometric study of domestic and Canada goose lungs. The volume of glutaraldehyde-fixed domestic goose lungs (30 cm3/kg body weight) was similar to that determined from silicone casts of Canada goose lungs by Duncker (33 cm3/kg). To examine finer structures, we rapidly froze goose lungs under physiologic conditions, fixed tissue samples by a freeze substitution procedure and analyzed samples with stereological methods. From light micrographs we determined that about 55% of the lung is parabronchi in both species. Volume densities of air capillaries, blood capillaries and tissue and surface:volume ratios of these same structures were determined from electron micrographs. Our measurements agree with those from glutaraldehyde-fixed Canada goose lungs from other laboratories. Gas exchange surface area was largest in the good flier (Canada goose) but both birds had larger surface areas than comparably sized mammals. The harmonic mean blood-gas barrier thickness is smaller in both species of birds (0.3 microns) than in mammals. Thus, membrane diffusing capacities for gases should be larger in birds than in mammals. Pulmonary blood capillary transit time, as calculated from blood capillary volume and normal levels of cardiac output, are longer in birds than in mammals and should allow more time for blood-gas equilibrium. Pleats and folds were frequently observed in air and blood capillaries, suggesting that the avian lung may not be as rigid as was previously thought and that capillary volumes and surface areas may change under physiologic conditions.

Influence of vascular and transpulmonary pressures on endothelial vesicles in nonedematous and edematous lungs.

We examined the effects of vascular and transpulmonary (Ptp) pressures on endothelial vesicles in nonedematous and edematous dog lungs by transmission electron microscopy (TEM). Edema was defined as a 30% increase in lung weight. Lungs were prepared for TEM by rapid freezing followed by freeze substitution. Using a random sampling procedure, the size and numerical density (Nv) of vesicles was obtained by standard morphometric techniques and the percentage of cytoplasm occupied by vesicles (Vv) calculated. Results show that at Ptp = 5 cm H2O, vascular pressure has no influence on the variables examined in nonedematous and edematous lungs. At Ptp = 25 cm H2O, increases in vascular pressure were associated with significant decreases in the percent cytoplasm occupied by vesicles for both series of experiments. When nonedematous lungs were compared to edematous lungs, we found increases in vesicle size, Nv, and the percentage of endothelial cell cytoplasm occupied by vesicles. The results confirm the increase in vesicles associated with edema. This result does not appear to be due to increased vascular pressure per se, although time related influences could be involved.

Size of pores of Kohn: influence of transpulmonary and vascular pressures.

We investigated the influence of transpulmonary (Ptp) and vascular pressures on the size of the pores of Kohn in primary alveolar septa. Dogs lungs, perfused and ventilated in situ, were rapidly frozen with Freon 22 in zone II or III conditions following deflation to Ptp of 5, 15, or 25 cmH2O. Frozen samples were freeze-substituted for transmission electron microscopy. Five fields containing at least one pore each were selected randomly from each section of tissue, and the minimum diameter visible in the cut section was measured. For both zone II and III conditions, as Ptp increased, mean pore size increased. The mean pore size under zone III conditions was 1.2015, 1.788, and 2.249 micrometer for Ptp of 5, 15, and 25 cmH2O, respectively. For zone 2 conditions, the corresponding values were 1.1438, 1,8757, and 2.08 micrometer. For both zones II and III, increasing capillary hydrostatic pressure had no significant effect on pore size. The results support the notion that alveolar pores can increase collateral ventilation by dynamically stretching as Ptp increases. Capillary pressure does not influence pore size probably because of collagen fibers, which surround the pore lumen. Presumably, these fibers resist encroachment of capillaries on the pore lumen as vascular pressures increase.

Ventilation-perfusion relationships during hemorrhagic hypotension and reinfusion in the dog.

The inert gas elimination technique was used to estimate pulmonary ventilation-perfusion (VA/Q) mismatching in heparinized, ventilated, anesthetized dogs during a 90-min period of hemorrhagic hypotension (mean arterial pressure 40 Torr) and subsequent reinfusion of the shed blood. Systemic and pulmonary arterial pressures, as well as cardiac output, were similar to those in previously reported studies using this protocol. Mean arterial O2 partial pressure (PO2) fell from 86 to 75 Torr after hemorrhage and rose to a mean value of 78 Torr after reinfusion. The VA/Q distributions showed that a mean of 56.7% of the ventilation was associated with unperfused or poorly perfused (VA/Q greater than 10) regions during hypotension (control 33.7%). After reinfusion, a mean of 47.8% of the ventilation was still directed to lung with little or no perfusion. This could not be explained on a hydrostatic basis, since pulmonary arterial pressure after reinfusion was greater than the control value. Shunt or blood flow to low VA/Q regions did not increase at any time during hemorrhagic hypotension or reinfusion. Microscopic examination of lung tissue revealed extensive leukocyte aggregation that was not seen in control animals. The mean diameter of obstructed pulmonary vessels was 35 microns (range 13.8-59.8 microns). Storing the shed blood in acid-citrate-dextrose instead of heparin had no significant effect on the extent of leukocyte aggregation. We suggest that leukocyte aggregation and margination may be related to the high VA/Q regions seen in these animals.

Shrinkage of lung after chemical fixation for analysis of pulmonary structure-function relations.

Glutaraldehyde is widely used to chemically fix lungs for analysis of pulmonary structure-function relations. Accurate interpretation of observations on fixed tissue requires a clear definition of any artifacts, such as tissue shrinkage, resulting from fixation with glutaraldehyde. Two experimental procedures were used in this study to examine possible shrinkage artifacts resulting from fixation of lung by glutaraldehyde. In the first, isolated perfused dog lungs were rapidly frozen at different transpulmonary pressures. Samples were then freeze substituted at -50 degrees C using 70% ethylene glycol with and without fixatives present. In the second series of experiments, the left lungs of mongrel dogs were fixed by vascular perfusion with glutaraldehyde at different transpulmonary pressures. In both series of experiments any changes in linear dimensions resulting from the fixation procedure were measured. Also, the presence of aldehyde was demonstrated by a positive reaction with Schiff reagent. The results demonstrate that lung tissue fixed either by vascular perfusion or freeze substitution tends to shrink to about the same extent. This shrinkage is reasonably constant at about 9% for transpulmonary pressures of 5 and 15 cmH2O and increases to about 15% when the transpulmonary pressure reaches 25 cmH20.

Identification of functional lung unit in the dog by graded vascular embolization.

To study the dimensions of the functional gas exchange unit, spherical polystyrene beads (diam 50-500 micrometers) were injected intravenously into 12 normal anesthetized paralyzed dogs (15-24 kg wt). We argued that beads small enough to lodge within gas exchange units would not give rise to a population of high ventilation-perfusion ratio (VA/Q) areas, whereas embolization of larger vessels supplying these units would. Each dog received only one bead size in cumulative 0.25-g doses up to a maximum of 2.25 g. Multiple inert gas elimination data were obtained after each dose to monitor the development of high VA/Q regions. Injection of 50- and 100-micrometers beads never gave rise to high VA/Q regions, whereas 150-, 250-, and 500-micrometers beads consistently induced a high VA/Q mode comprising up to 45% of the ventilation. Histological examination of lungs from five additional dogs injected with small (approximately 0.5 g) doses revealed that beads rarely formed clusters and appeared in vessels of their own diameter in over 90% of instances. By the above criterion, the functional gas exchange unit in these lungs is that volume of tissue subtended by 150- micrometers-diam arteries (vessels associated with respiratory bronchioles).

Mixing in flowing gas.

We used a mass spectrometer to analyze continuously from a flow stream after changeover of one gas to a mixture of other gases. At the end of a straight cylinder (length = 100 cm, inner diameter = 1/2 inch), light-weight gases appeared later but reached full-scale deflection earlier than heavy gases. Apparently gases with high molecular diffusivity tended to diffuse radially so that they were not carried forward axially in rapidly moving streams. This blunting of the profile of mean concentration vs distance as fresh gas move down a tube, plus spreading of a gradient region of transition between fresh gas and stale gas, are the fundamental processes of diffusion/convection interactions in the lung. Turbulence and molecular diffusion are similar in that they limit the penetration of inspired gases that could occur if laminar flow were the only process acting. However, turbulence and molecular diffusion cause true irreversible mixing of fresh and stale gases, whereas dispersion by laminar flow does not.

Electron micropscopic appearances of rapidly frozen lung.

Analysis of pulmonary structure-function relationships by microscopy requires that the lung be fixed under carefully controlled physiological conditions, since lung structure is extremely responsive to the relationship between airway and vascular pressures. Unfortunately, standard post-mortem fixation techniques leave some doubt as to the exact relationship between these pressures during fixation. This problem can be circumvented by stabilizing lung structure by rapid freezing under carefully controlled physiologic conditions. Using ethylene glycol in a freeze substitution technique we have developed procedures which yield a degree of preservation compatible with the high degree of resolution of the electron microscope. These can be used to obtain a more detailed understanding of pulmonary structure-function relationships under well-defined physiological conditions.

Interaction of convection and diffusion in pulmonary gas transport.

Normal human subjects inspired various volumes of a normoxic argon mixture containing low concentrations of several biologically inert tracer gases with markedly different diffusivities (helium, neon, and sulfur hexafluoride). The behavior of Ne, Ar, and SF6 could be predicted on the basis of axial dispersion due to differences in diffusivity. For example, neon, having the highest diffusivity of the three, was more uniformly distributed within the bronchial tree than either argon or SF6. The behavior of helium, however, was not consistent with predictions based solely on axial diffusion. Contrary to expectation, the early portion of expiration was helium enriched while gas assumed to come from the alveolar regions contained relatively less helium than the other gases. Results of this study suggest that radial diffusion during convective bulk flow may play a significant role in intrapulmonary gas transport if relative diffusivity is extremely large. We conclude that diffusion gradients do exist within the bronchial tree during normal quiet breathing and that these gradients become less significant as inspired volume increases.

Electron microscopy of lung rapidly frozen under controlled physiological conditions.

Light microscopy of lung rapidly frozen under controlled physiological conditions has been very successful in correlating pulmonary structure and function. However, to study some aspects of pulmonary capillary morphology, the higher resolution of electron microscopy (EM) is necessary. To date, most EM of lung has involed the instillation of a fixative through the airways or vascular system, techniques that probably alter the normal pressure relationships of the capillaries and therefore their morphology. We describe here a technique for rapidly freezing lung to a depth of 1--2 mm below the pleural surface and preparing sections for EM. Lungs from open-chest rats were frozen at various transpulmonary pressures with cold (--80 degrees C) 70% ethylene glycol. Small pieces were then fixed with a solution containing glutaraldehyde and paraformaldehyde for 24 h at --50 degrees C. Staining was with osmium tetroxide and uranyl acetate. Lung frozen at high volumes showed marked stretching of the alveolar septa with severe deformation of the capillaries. Lung frozen at low inflation pressures revealed open capillaries containing numerous red blood cells; in addition, infolding of the alveolar wall was frequently seen. We conclude that this technique gives a level of preservation of rapidly frozen lung suitable for electron microscopy.

Pulmonary vascular resistance during unilateral pulmonary arterial occlusion in ducks.

We measured mean pulmonary arterial pressure (Ppa) during temporary unilateral pulmonary arterial occlusion (TUPAO) in 10 ducks. Ppa increased from 11.4 +/- 0.8 mmHg during control conditions to 18.8 +/- 1.8 during TUPAO. In 5 of the 10 ducks we also measured mean left atrial pressure (Pla) and cardiac output (Q). In these ducks Ppa significantly increased with TUPAO from 13.9 +/- 0.4 to 22.0 +/- 1.2 mmHg, whereas Pla and Q did not change significantly. Pulmonary vascular resistance (PVR) increased from 10.6 +/- 1.3 to 24.1 +/- 5.3 mmHg X min X 1(-1) on TUPAO. By assuming equal vascular resistance in either lung it can be calculated that the vascular resistance in only one lung was 22.5 +/- 3.5 mmHg X min X 1(-1) during control conditions. Thus doubling flow resulted in no significant change in one lung's vascular resistance. A morphometric study of both lungs of a domestic goose that were rapidly frozen during TUPAO indicated very little compliance in pulmonary blood capillaries. The relative volume of exchange tissue occupied by blood capillaries was 0.28 in the occluded lung and 0.36 in the perfused lung. Surface-to-volume ratios of blood capillaries were 12,524 cm-1 in the occluded lung and 11,056 cm-1 in the perfused lung. We conclude that PVR in birds is relatively insensitive to changes in Q, in contrast to mammals.

Redistribution of pulmonary blood flow in the dog with PEEP ventilation.

The effects of positive end-expiratory pressure (PEEP) at 20 cmH2O on the distribution of pulmonary blood flow was studied in intact dogs and isolated lung preparations. Measurements were made of a) the continuous distribution of ventilation-perfusion ratios (VA/Q), b) the vertical distribution of pulmonary blood flow, and c) the dimensions of the microvasculature. Without PEEP the distributions of ventilation and perfusion were unimodal and centered on a VA/Q close to one. Dependent regions received 5-10 times more of cardiac output than uppermost regions. With PEEP the distribution showed a bimodal character, one mode of normal VA/Q and the other comprising one-third of ventilation, lying between VA/Q of 10 and 100. Cardiac output was reduced two- to threefold and blood flow in the uppermost regions was grossly reduced but not eliminated. Bimodal distributions were also found in isolated lungs with PEEP, and histological examination of rapidly frozen lung tissue showed that alveolar capillaries were closed in the uppermost, poorly perfused regions, whereas alveolar corner vessels remained open. We suggest that the blood flow through these corner vessels is responsible for the additional, high VA/Q mode during PEEP.

Screening for fetal Down's syndrome with maternal serum markers--an experience in Italy.

The effectiveness of maternal serum alpha-fetoprotein, unconjugated oestriol, and human chorionic gonadotrophin in screening for Down's syndrome (DS) was evaluated on 840 women who underwent amniocentesis for fetal karyotype on account of their age. The risk of a DS pregnancy was established using the method of Wald et al. (1988b), which combines the age-specific risk with that indicated by the levels of the three serum markers. In women over 35, at cut-off risk levels of 1:250 and 1:380, the false-positive rate was 24 and 34 per cent, respectively. In all nine cases of DS, the estimated risk was higher than 1:250. The best screening strategy with the lowest false-positive rate was obtained by combining the three serum markers. The results suggest that this kind of screening can be proposed during genetic counselling for women under 35 and older women wishing to avoid the risk of miscarriage induced by amniocentesis.

[Lymphocyte subpopulations in idiopathic dilatational cardiomyopathy]. / Sottopopolazioni linfocitarie nella cardiomiopatia dilatativa idiopatica.

Lymphocyte subsets have been examined in 23 patients affected by idiopathic dilated cardiomyopathy (IDCM). Patients were divided according to their functional class showing that compromised subjects exhibited high T-lymphocyte helper/suppressor ratio whereas the contrary was observed in the other patients. It has therefore suggested that IDCM is characterized by 2 distinct phases, each of them with different helper/suppressor ratio.