New method of evaluating sublethal damage to erythrocytes by blood pumps

We recently proposed a new concept, the total destruction time of erythrocytes, to indicate sublethal damage to erythrocytes by blood pumps. In this article, results of additional experiments concerning this new concept are reported. Five paired in vitro hemolysis tests with bovine blood were conducted using a cone-type centrifugal pump (Group A) and an impeller-type pump (Group B). A total pressure head of 100 mm Hg was applied. The factors evaluated were the normalized index of hemolysis and the total destruction time, or the pumping duration, required to raise the level of the plasma-free hemoglobin to 50% of the total hemoglobin. The morphologic change of the erythrocytes also was analyzed. The percentage of crenated cells was calculated from blood smear specimens 1 min after starting the pumps and 2 h before the total destruction time of Group A in each experiment. Although there was no statistical difference in the normalized index of hemolysis between the two groups, the total destruction time of Group A erythrocytes was significantly shorter than that of Group B (18.9 +/- 4.5 h and 33.7 +/- 9.9 h in Group A and Group B, respectively; p < 0.02). The rate of crenated erythrocytes was higher in Group A than in Group B at a point 2 h before the total destruction time of Group A. The total destruction time values seem to define a good method for establishing sublethal traumatic damage to erythrocytes in blood pumps.     

Adenosine triphosphate causes vasospasm of the rat femoral artery

OBJECTIVE: Adenosine 5'-triphosphate (ATP) causes vasoconstriction by activation of P2-purinoceptors on vascular smooth muscle cells. Erythrocytes contain ATP at a concentration (1.6 mmol/L) that contracts smooth muscle. Previous studies of hemoglobin solutions did not assess whether the vasoactivity was caused by ATP rather than or in addition to hemoglobin. It was hypothesized that the hemolysis of erythrocytes that occurs after subarachnoid hemorrhage releases ATP in concentrations that cause vasospasm. METHODS: Thirty-eight rats were randomly assigned to undergo placement of one of the following compounds in a silastic elastomer cuff around each femoral artery: 1) agarose gel (n = 8); 2) dog erythrocyte hemolysate (n = 8); 3) purified human hemoglobin (Hemolink; Hemosol, Inc., Toronto, Canada; n = 8); 4) ATP (n = 8); or 5) clotted autologous blood (n = 6). The amounts of hemoglobins and adenine nucleotides in the compounds were measured by spectrophotometry and high pressure liquid chromatography. Hemolysate, purified hemoglobin, and ATP were mixed with agarose gel to create an artificial clot. Rats were killed and fixed by perfusion at physiological blood pressure 7 days after perivascular cuff and spasmogen placement. Vasospasm was assessed by image analysis of cross sections of fixed femoral arteries. Arteries were assessed for histopathological changes on 3-point scales. RESULTS: There was significant variance in arterial diameters among groups (mean diameter +/- standard deviation: agarose gel, 0.29 +/- 0.06; purified hemoglobin, 0.28 +/- 0.04; hemolysate, 0.24 +/- 0.05; ATP, 0.25 +/- 0.05; clotted blood, 0.24 +/- 0.01; P < 0.05, analysis of variance, n = 11-20). Animals exposed to clotted blood, hemolysate that contained ATP, or ATP, developed vasospasm, whereas purified hemoglobin and agarose did not cause vasospasm. Endothelial proliferation and perivascular inflammation were more severe (P < 0.05) in arteries exposed to clotted blood, purified hemoglobin, and hemolysate. CONCLUSION: These results suggest that ATP may be a vasospastic substance released by erythrocyte hemolysis. The concentration of ATP in impure solutions of hemoglobin is too low to account for the vasoactivity of these solutions. The discrepancy between arterial narrowing and histopathological changes suggests that either histopathological changes may not be an important correlate of arterial vasospasm or that other substances are important in vasospasm.     

The value of C-reactive protein for the differentiation of bacterial meningitis from viral meningitis

In order to differentiate bacterial meningitis versus viral meningitis, we have comparatively tested the efficacy of the following tests: C-reactive protein (CRP), erythrocytes sedimentation rate (ESR), fever, level of glucose in cerebro-spinal fluid (CSF), glucose in CSF/glycemia ratio, number of white blood cells in peripheric blood, percentage of neutrophils in peripheric blood, level of proteins in CSF and number of nucleated cells in CSF for a group of 49 patients, both children and adults with central nervous system infection (37 patients with bacterial meningitis and 12 with viral meningitis) hospitalised between May 1993 and July 1994 in Clinical Hospital for Infectious Diseases in Ia?i. The mean value of CRP in bacterial meningitis patients was 8.78 mg%, contrasting with the mean value of CRP = 1.92 mg% recorded in patients with viral meningitis. Ten out of 37 bacterial meningitis patients presented a CRP concentration < 1.85 mg%. All these 10 patients have already had an antibiotic treatment at the moment of the assay. One out of 12 cases of viral meningitis had a value of CRP = 3.3 mg%, all the remainder cases having values under 1.85 mg%. We recorded highly significant differences between the two patient groups for CRP (p < 0.001), ESR (p < 0.01), protein concentration in CSF (p < 0.001) and number of nucleated cells in CSF (p < 0.001). Differences recorded for fever, concentration of glucose in CSF, glucose in CSF/glycemia ratio, number of leucocytes in peripheric blood and percentage of neutrophils in peripheric blood, were not significant (p > 0.5). Data were analysed also by box-plot method which facilitates the visual appraisal of the differences recorded between the two aetiological groups. In conclusion, assays of CRP and ESR may be used as differentiation tests for bacterial meningitis versus viral meningitis, when assay is done before the antibiotic treatment, being sufficient sensitive, and easy to perform.     

Membrane versus bubble oxygenator in hyperthermic regional perfusion: a prospective randomized clinical study

In a prospective randomized clinical study a routinely used bubble oxygenator (Bentley-5) was compared with a hollow fiber membrane oxygenator (D 701 Masterflo 34) during hyperthermic isolated extremity perfusion. This was done to find out whether there were differences between the two oxygenators in hemolysis, cellular damage, oxygenation and temperature achieved during extremity perfusion. In 30 perfusions blood samples were obtained at defined times: plasma hemoglobin (Hb), serum lactate dehydrogenase (s-LDH), number of erythrocytes, mean corpuscular volume (MCV), hemoglobin and bilirubin were determined for hemolysis, leukocyte count (neutrophils, lymphocytes, monocytes) and platelets as a check for cellular damage, and PO2, PCO2, O2 saturation and pH to define blood oxygenation and CO2 elimination. Maximal increase in temperature after 30 min and perfusion time until maximum tissue temperature were also recorded. The membrane oxygenator yielded better results from the aspect of hemolysis: s-LDH and plasma Hb were significantly different (p < 0.001). Cellular damage was less with the membrane oxygenator: platelet differences were significant (p < 0.01). Oxygenation and hyperthermia were obtained more quickly and were better controllable in membrane oxygenator. Further advantages for the patient were the smaller volume of blood needed for priming in a membrane oxygenator (750 vs. 1,200 ml) and improved safety resulting from a 'closed' perfusion system. On the basis of the clinical prospective randomized trial conducted, we conclude that membrane oxygenators must be adopted as the new standard in isolated hyperthermic extremity perfusion.     

Method of noninvasive and continuous hemolysis/thrombogenesis measurement by laser photometry during artificial heart development

The purpose of this research is to propose and develop a method to measure hemolysis and thrombogenesis non invasively and continuously to aid in development of an artificial heart. Generally, the optical absorption rate of hemoglobin is influenced by oxygen saturation except at the isosbestic point, which is not influenced by oxygen saturation. The authors, therefore, used an 805 nm laser diode, an optical spectrum analyzer to obtain greater accuracy. An experimental blood circuit system was constructed using a Bio-Pump, Tygon tubing, a soft shell reservoir, and an optical measurement system. Experimental settings for monitoring hemolysis were as follows; blood volume 200 ml, blood flow 6 L/min, and afterload 200 mmHg. Blood was sampled six times (0, 30, 60, 120, 180, and 240 min), and hemolysis in each sampled was measured using a colorimetric method. Comparing continuous laser measurement data with the sample data, an adequate correlation is obtained, proving that the dynamic trend of hemolysis could be continuously measured. Furthermore, to analyze the process of thrombogenesis, simple experiments were performed using blood neutralized by protamine. As a result, the authors could see the process of thrombogenesis as it occurred and could confirm that this method is able to dynamically detect hemolysis and thrombogenesis.     

Osteogenesis imperfecta: the distinction from child abuse and the recognition of a variant form

Inactivation of glutathione peroxidase correlates with the rate of hemoglobin chain oxidation. The enzyme inactivation is mainly present in those conditions where the autoxidation of the oxygenated chains is followed by transformation of the oxidized molecule into a hemichrome. Free hemoglobin chains have been encapsulated in human red blood cells by a dialysis technique that involves transient hypotonic hemolysis followed by isotonic resealing. Chain-loaded erythrocytes represent a good in vitro model of thalassemia. The presence of free human chains in the cell alters the intraerythrocytic glutathione peroxidase activity (alpha chains are more effective in the inactivation of the enzyme with respect to the beta chains).     

Endoscopists, polyp size, and post-polypectomy surveillance: making a mountain out of a molehill?

Hemolytic properties of human erythrocytes in hereditary spherocytosis (HS) were examined under hydrostatic pressure or hypotonic conditions. In the hypotonic buffer, HS erythrocytes were more fragile than normal erythrocytes, and the osmotic fragility was similarly enhanced if both erythrocytes were treated with 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS), an anion transport inhibitor. On the other hand, the hemolysis of HS erythrocytes at 200 MPa was almost the same degree as that of normal cells. Upon DIDS treatment, the hemolysis of normal erythrocytes at 200 MPa was suppressed by about 35%, whereas that of HS erythrocytes was not affected. The absence of a suppressive effect of DIDS on high-pressure-induced hemolysis is likely to be HS-specific and may be a reflection of the underlying defects of band 3-cytoskeleton interactions in HS erythrocytes.     

Intraoperative autotransfusion: equipment, protocols, and guidelines

Blood obtained by intraoperative autotransfusion is: 1) readily available 2) sterile 3) compatible 4) normothermic 5) inexpensive and may be infused rapidly for volume support. We have made extensive modifications to commercially available equipment in order to provide a safe, effective IAT. The effects of IAT in our series of 85 patients are outlined below. Red Cell Mass is reduced after IAT because of irretrievable blood loss and hemolysis, and may be controlled by homologous transfusion when necessary. Red Cell Survival is normal after IAT. Hemolysis. Plasma free hemoglobin is consistently elevated after IAT, but clears within 24 hours. Platelets are normal for patients autotransfused less than 3,500 ml; micropore filters should not be used in cases where greater than 3,500 ml blood is expected to be reinfused; in cases where greater than 3,500 ml is reinfused, 10 units of platelets are recommended for every 3,000 ml of blood reinfused; IAT does effect platelets function; however, platelets circulating within the patient function normally. Coagulation. We use local ACD to eliminate extracorporeal surface clotting. Even with massive IAT we have never demonstrated any clinical or laboratory evidence of intravascular coagulopathy. "Dilutional coagulopathy" may be procuced when greater than 5,000 ml are reinfused, and may be controlled with fresh frozen plasma and platelet concentrates. Bilirubin levels were normal after IAT despite gross hemoglobinuria. Fat emboli were not noted after IAT. Air emboli must be a concern in IAT; HOWEVER, PROPER OPERATION AND EQUIPMENT MODIFICATION MAY ELIMINATE EMBOLI. Renal Failure was not noted after IAT. Alveolar-arterial Oxygen Difference and Blood Gases were normal after IAT. We feel IAT is not necessary if a blood loss less than 1,000 ml is expected. Also, if greater than 3,500 ml is expected additional backup (i.e. homologous transfusions, platelets, fresh frozen plasma) may be required. As banked donor blood reserves become more limited, IAT may become a routine part of general surgical procedures.     

Normalization of affine gap costs used in optimal sequence alignment

The ionophore A23187 was used to facilitate release and continued development of Anaplasma marginale in short-term erythrocyte cultures. Addition of 10 microM A23187 to the cultures resulted in significant decrease in percentage of parasitized erythrocytes (PPE) by 24 hours after treatment; further development and increase in PPE was not observed. In contrast, the PPE of untreated cultures, those treated with dimethyl sulfoxide (DMSO) only and with 1 microM A23187 increased slightly during that time. Total erythrocyte count decreased in treated cultures in excess of that expected after samples of the medium were taken for analysis. The greatest cell loss and increased hemoglobin concentration in culture medium was observed in cultures treated with 10 microM A23187 and with an equivalent volume of DMSO. The DMSO appeared to cause hemolysis of some erythrocytes, but not of infected cells selectively. Release of A marginale inclusion bodies was seen by electron microscopy in samples from the 10 microM A23187-exposed cultures. At 30 minutes after treatment, free initial bodies were frequently seen. Inclusion body membranes and individual A marginale were associated with membranes of adjacent erythrocytes. Individual rickettsiae were seen in cell depressions and appeared to be entering erythrocytes. However, neither further invasion nor development of the parasite in erythrocytes was observed. Ionophore A23187 appeared to promote release of A marginale from erythrocytes, but did not enhance infection of erythrocytes or development of organisms in vitro.     

Morphology of immune destruction of the erythrocytes in fetuses and newborn infants

In the second half of pregnancy destruction of erythrocytes as a result of immunological aggresion in the fetus may occur in different manners: hemolysis in the vessel bed, fragmentation of erythrocytes, phagocytosis of intact erythrocytes and their fragments. Intravascular hemolysis occurs in immature fetuses. At that, the products of erythrocyte decomposition (hemosiderin and lipofuscin) are accumulated in the epithelial cells of the liver and the kidneys, the pancreas, the thyroid and the thymus. Fragmentation of erythrocytes (anuclear forms alone) occurs in the red splenic pulp and less in the vessels of the other organs. This process has been observed in fetuses after 7 months of gestation. Phagocytosis of erythrocytes and their fragments is done mainly by macrophages of the red splenic pulp as well as macrophages of the bone marrow, lymph nodes, and the Kupffer cells of the liver. Massive and long-term effect of iso (rhesus) antibody results in inhibition of the phagocytary activity of macrophages. In such cases, destruction of erythrocytes occurs in the vessel bed by lysis.     

The prognostic value of the lactate concentration and lactate/pyruvate ratio in cerebrospinal fluid following acute cerebral circulatory disorders

The study was conducted in 80 patients with ischaemic and 29 with haemorrhagic cerebral stroke. Lactate, pyruvate, the lactate/pyruvate ratio and glucose were determined in the arterial blood and lumbar CSF. A high prognostic value of the CSF lactate content was found in cases of ischaemic stroke. According to the data obtained, an elevation of the CSF lactate concentration above 4.0 mEq/l should be considered life-threatening. Haemorrhagic stroked was found to be accompanied by a reduced CSF glucose level and an elevated lactate content, as well as by a significant proportional elevation of the lactate and red blood cells count in the CSF. The conducted calculations demonstrated that 1/4 to 1/3 of the CSF lactate is formed at the expense of the glycolytic metabolism in the CSF erythrocytes. This constitutes the main reason of the discordance between the CSF lactate content in haemorrhagic stroke and the routine criteria of prognosis in ischaemic stroke. The lactate/pyruvate ratio in the CSF is of no prognostic importance in both forms of cerebral stroke.     

Automation in the hematology laboratory

In the routine laboratory for hematology conflicting results may be obtained for the red blood cell parameters with the Coulter Counter Model S. These parameters2) are: mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC). When the values of the MCHC are above 36 g/dl something must be wrong with the blood sample of the patient. One of the reasons can be agglutination e.g. by cold agglutinins. The blood sample should be reanalysed before and after heating for 1 hour at 37 degrees C. If the values change: cold agglutinins are present; if no change occurs paraproteins, or other disturbing factors, such as bilirubin or high leucocyte levels, will be found. MCH values may also be high in some cases e.g. if the red blood cells are coated with antibodies (Coombs test positive) or after ingestion of medicines like Azathioprine. These examples show that it is possible in some cases to correlate immunological findings with the red blood cell parameters. In addition to the results with the Coulter Counter Model S, some observations on the Hemalog (Technicon) are also presented.     

The prevalence of early postpartum psychiatric morbidity in Dubai: a transcultural perspective

The surface roughness of artificial blood contacting devices is an important surface property that is closely related to blood cell trauma. The present study investigated the effect of the surface roughness of a pump housing on hemolysis in an impeller-type centrifugal blood pump, a pivot bearing supported Gyro C1E3 pump. The purpose of the study was to determine which part of a housing has the greatest surface roughness effect on hemolysis in a centrifugal pump. Seven Gyro C1E3 pumps were prepared, each with a smooth surface impeller and a housing with differing areas of altered surface roughness. Both top and bottom housings were divided into half subregions, each with the same area. Seven test pumps were produced by subjecting various subregions of the housings to vapor polishing and sandblasting. The treated surfaces were then examined by a surface profile instrument. Using these 7 pumps with different areas of altered housing roughness, in vitro hemolysis tests were performed simulating cardiopulmonary bypass (5 L/min, 350 mm Hg). The results of this study are as follows. First, the surface roughness of the top housing had a greater effect on hemolysis than that of the bottom housing. Second, on the surface of the top housing, the surface roughness of the outer half area had a greater effect on hemolysis than that of the inner half area. Third, on the surface of the bottom housing, the surface roughness of the inner half area had a greater effect on hemolysis than that of the outer half area. These findings concur with previous studies of flow patterns in pumps. Thus, it is expected that the method in this study, comparative in vitro hemolysis tests of the pumps with surfaces of the same roughness but different locations, can be used to detect the high shear area inside a pump.     

Poly-N-acetyllactosaminyl saccharide chains of band 3 as determinants for anti-band 3 autoantibody binding to senescent and oxidized erythrocytes

Natural IgG antibodies to band 3 glycoprotein of erythrocyte membrane (anti-band 3 IgG) are known to bind to senescent erythrocytes, and believed to initiate antibody-dependent phagocytic removal of the senescent cells from blood circulation. Anti-band 3 antibodies also bind to the erythrocytes with hereditary hemoglobin abnormalities such as sickle, beta-thalassemic and hemoglobin K?ln erythrocytes. Oxidative stress appears to be responsible for the generation of senescent cell antigen on erythrocytes, to which anti-band 3 antibodies bind, since erythrocytes oxidized in vitro bind anti-band 3 IgG, and various oxidative modifications are observed in senescent erythrocytes as well as the erythrocytes with abnormal hemoglobin. Major antigenic sites of band 3 for anti-band 3 IgG autoantibodies are its sialylated poly-N-acetyllactosaminyl saccharide chains. The poly-N-acetyllactosaminyl saccharide chains on senescent erythrocytes are indeed involved in the antigenic sites on senescent erythrocytes. The finding of the carbohydrate epitopes and possible involvement of oxidative mechanism are compatible with the band 3 clustering hypothesis, in which clustering of band 3 molecules in erythrocyte membrane is supposed to be responsible for effective binding of anti-band 3 IgG to the cell surface, because the carbohydrate epitopes of band 3 can form multivalent epitopes on cell surface when band 3 molecules cluster, and oxidative stress can induce such clusters. Interestingly, poly-N-acetyllactosaminyl chains of band 3 on oxidized erythrocytes are also recognized by macrophages directly. Thus, poly-N-acetyllactosaminyl chains may play dual roles as determinants for recognition by anti-band 3 IgG and by macrophages.     

Evaluation of myocardial protection in open heart surgery - with special reference to local cardiac hypothermia

Erythrocyte-granulocyte rosettes (EGR) were found in the capillary blood of two cases of autoimmune haemolytic anemia, the first caused by an IgM non-I antibody and the second by an IgG. Both antibodies activated complement, and C3b was demonstrated on the erythrocytes. The rosettes appeared as arrangements of 6-10 red cells adhering to a central granulocyte; phagocytosis was most generally absent. The finding of EGR in the capillary blood may be useful for the recognition of complement activation up to the C3b stage in some cases of autoimmune haemolytic anemia.     

Etiopathogenesis of hemolytic reactions in total artificial heart recipients

Hemolysis in total artificial heart (TAH) recipients was analyzed. From a total of 66 long-term experiments lasting from 30-314 days performed in the Brno Research Center, in 53 animals, the total red blood cell (RBC) count, hematocrit, total hemoglobin, and free plasma hemoglobin were investigated. We could essentially divide the whole group of calves in 2 subgroups. The first subgroup was calves with hemolytic reactions, and the second subgroup was calves without any hemolytic reaction at all. In the first subgroup, hemolysis occurred in 47% of the overall number of animals during extracorporeal circulation (ECC), in 15% during ECC and later periodically during the experiment, in 8% during ECC and then continuously during the experiment, and finally in 10% not during ECC but repeatedly during the experiment. In 20% of the animals from the overall number, hemolysis did not occur at all (second subgroup). These results testify to the great individual differences within 1 breed (Bohemian with a substantial component of Holstein). These differences are further modified by exogenous and endogenous factors. First, the inborn resistance of the RBC membrane and also thrombi formation and the mineralization of the driving diaphragm are very important. The extreme situation of decreased RBC membrane resistance was proved using a calf from another breed, the slow growing Scottish Highland breed, which did not survive 22 days of pumping due to intractable lethal hemolysis. These factors are also indicated by the hemolytic action of some drugs (e.g., Dopegyt) used during the experiment for another reason. Also important are the mechanical forces of pumping, surface moieties of the biomaterial, mineralization of the driving diaphragms, thrombi formation, infection, etc. Essentially, the hemolytic reaction in the TAH recipient has a multifactorial character. Hemolysis is undoubtedly an important factor, which can have a profound impact on the length of survival. The experimental and clinical experiences must be continuously integrated, and conclusions valid for human TAH application must be considered as very important for further TAH experimental and clinical research.     

Quinone-dependent tertiary amine N-oxide reduction in rat blood

Rat blood exhibited a significant quinone-dependent N-oxide reductase activity towards imipramine N-oxide. The reduction mediated by the blood proceeded in the presence of both NAD(P)H and menadione under anaerobic conditions. When menadione was replaced with 1,4-naphthoquinone or 9,10-phenanthrenequinone, similar results were obtained. The reduction was also mediated by the combination of rat erythrocytes and plasma. The reducing activity was inhibited by dicumarol and carbon monoxide. When boiled plasma was combined with untreated erythrocytes, the N-oxide reducing activity was abolished. In contrast, when boiled erythrocytes were combined with untreated plasma, the activity was unchanged. These results suggest that the activity is caused by the heme of hemoglobin in erythrocytes and quinone reductase in plasma. In fact, erythrocytes and hemoglobin have the ability to reduce the N-oxide when supplemented with DT-diaphorase purified from rat liver in the presence of both NAD(P)H and menadione. Hemoglobin also exhibits N-oxide reductase activity with reduced menadione (menadiol). Furthermore, hematin exhibits a significant reducing activity in the presence of menadiol. The reduction appears to proceed in two steps. The first step is enzymatic reduction of quinones to dihydroquinones by quinone reductase(s) with NADPH or NADH in plasma. The second step is nonenzymatic reduction of imipramine N-oxide to imipramine by the dihydroquinones, catalyzed by the heme group of hemoglobin in erythrocytes. Cyclobenzaprine N-oxide and brucine N-oxide are similarly transformed to the corresponding amines by the above reducing system in blood. These results suggest that blood plays an important role in the reduction of tertiary amine N-oxides to tertiary amines.     

Analysis of the lytic activity of the Serpulina hyodysenteriae hemolysin

The hemolysins of Serpulina hyodysenteriae are active at 27 to 40 degrees C and pH 3 to 9 and are unaffected by enzymatic inhibitors. Pore formation was demonstrated by the inhibition of hemolysis with molecules of 2.0 to 2.3 nm in diameter and the release of 86rubidium from erythrocytes without hemoglobin release after exposure to native hemolysin.     

Organization of resuscitation care of children in a large region

The structure of a plate apparatus for detoxication of biological fluids has been described. The operation of the apparatus for cholesterol recovery from blood and artificial biological fluid by the extracting emulsions "water in oil" has been investigated. The parameters of the apparatus, such as the number of plates, the height of the apparatus, the volume of extracting emulsion, have been determined. The blood flow velocity which excludes the entry of extracting emulsion drops into biological fluid has been chosen. The values of cholesterol recovery (22.4%) and of red blood cell hemolysis when blood is present in the working apparatus chamber have been defined.     

Insulin, glucagon, portal systemic shunting, and hepatic failure in the dog

The cerebrospinal fluid (CSF) composition was studied in 54 premature infants. The pregnancy was normal and the delivery normal and non traumatic in all of them, and the 5 minutes Apgar score ranged from 6 to 9. No abnormalities were found on physical examination including neurological examination. Blood cell countings and blood gasometry were normal. CSF composition was studied as to: total cell count and total protein, glucose, bilirrubin and hemoglobin concentrations. Data found permit to stablish as physiologic the following values: leucocytes, until 16 per cumm; erithrocytes, until 1,280 per cumm; total protein content until 300 mgm/100 ml; bilirrubin until 80 micrometer/1; hemoglobin until 8 micrometer/1; glucose, two thirds of the concentration found in the blood. Protein, bilirrubin and hemoglobin are significantly increased as compared to values found for the CSF of 79 fullterm normal newborn babies evaluated previously. Hemoglobin was not detected in the CSF of any full term newborn baby. The differences found are probably due to a less efficient blood-CSF barrier in premature infants as compared to full-term newborn babies.