Clinical use of blood,blood components and blood products.

The goal of modern transfusion therapy is to provide appropriate replacement therapy with blood components as opposed to whole blood for patients with specific hematologic deficiencies. A prerequisite of component therapy is, therefore, correct identification of the deficiency. Appropriate use of components avoids many of the hazards associated with the use of whole blood, and at the same time makes maximal use of this valuable resource. Blood components separated from whole blood soon after collection and appropriately stored can, in combination, provide all the factors present in fresh whole blood. Red cell concentrates prepared from multiple packs have a hematocrit of approximately 70%. They may be stored for up to 3 weeks at 4 degrees C and are recommended for most situations requiring red cell transfusions. Platelet concentrates, which can be stored for up to 72 hours at 22 degrees C, may be used for thrombocytopenic patients. Fresh frozen plasma, stored plasma, cryoprecipitated factor VIII, factor VIII concentrate and factor IX complex concentrate are available for the proper treatment of patients with hemorrhagic disorders due to coagulation factor deficiencies. Similarly, albumin and immune serum globulin are available for their oncotic and antibody properties respectively. Thus, the availability and appropriate use of the various blood products allows not only optimal transfusion therapy for each patient, but also fuller utilization of national blood resources.     

Canine blood groups. 2. Description of a new allele in the Tr blood group system

A previously unrecognized canine red cell antigen, tentatively named O, was found after absorption analysis of an alloimmune antiserum and absorption of several immune or naturally occurring cross-reacting heteroantibodies from man, cattle and swine. The serological results and genetic analysis of a limited number of complete dog families indicated that the new factor probably belongs to the Tr blood group system. No individual possessed both factors Tr and O, and a large proportion of animals was negative for both factors. The serological pattern for the new Tr system obtained was consistent with similar systems observed in sheep (A-O), pig (R-O) and man (Bombay) in which the gene for one factor was dominant over and masked the gene for the second factor in the system. The negative phenotype was accounted for by the actions of an epistatic gene.     

The human blood platelet: its derivation from the red blood cell. A morphologic study.

The blood platelet arises from the interior of the red blood cell when blood is either damaged or disturbed. The platelet body may be seen to form from an amorphous granular mass to a definite granular platelet body when blood is prevented from coagulating by the use of a retardant solution.     

The blood circulation inside the spleen. I. The arterial blood vessels general distribution in the rat spleen

As an attempt to investigate the different pathways followed by the blood into the spleen and to analyse their functional significance, a technique was used mainly based on the intraarterial perfusion of a Prussian blue "solution" added of some chemical mediators and vasoactive substances. Such technique provides results which may be analysed taking into account the effect of the anaesthetic used, that may influence the findings. From the anaesthetic used, the sulfuric ether and the barbital sodium produce vasoconstriction of the white pulp blood vessels, whereas the chlorpromazine-promethazine doesn't have this effect, and so the Prussian blue appears inside these vessels. The vasodilator drugs, such as succinonitrile and papaverine hydrochloride, show a general vasodilator effect on the splenic arterial system. Teh arterial vessels of the white and the red pulp, including those placed at the subcapsular areas, become enlarged; into the white pulp, either the central or the peripheral blood vessel plexus of the lymphatic follicle becomes evident. The latter readily constitutes the perifollicular and the pericolumnar plexus. The blood vessels of this plexus become permeable to the Prussian blue "solution" by the heparin sodium effect, and so the dye particles enter the marginal zone and the splenic sinuses. In addition, from the white pulp arteries arise 2 types of anastomotic arterioles which appear enlarged after succinonitrile treatment: The short anastomotic arterioles that crosses the marginal zone entering the red pulp near the white pulp; the long anastomotic arterioles which enter the red pulp and after a long course end up into or around a collector sinus. The addition of histamine dihydrochloride to the perfusion solutions shows a slight vasodilator effect mainly on the subcapsular penicillar arterioles, including the helicine arterioles. The adrenergic stimulation of the splenic blood vessels induces a generalized arterial constriction, except of the anastomotic arterioles, that becomes open; in such way, the blood pathway follows the course of the anastomotic arterioles and the collector arterioles also become constricted. The adrenergic vasoconstrictor effect is inhibited by the phenoxy-benzamine hydrochloride. The addition of acetylcholine chloride, in the dosage, used, induces a generalized arterial vessel constriction, mainly of the perifollicular plexus. This effect is inhibited by atropine sulfate which, on the other hand, produces evident enlargement of the perifollicular and pericolumnar arterial plexus.     

High blood pressure: hunting the genes.

High blood pressure is a disease of unknown cause. Family history of the disease indicates higher risk, but it is not known which genes are involved or how they interact with environmental influences to produce the disorder. Molecular biology offers an approach to problems that have not so far been solved by classical physiology or biochemistry. By analysing polymorphic variation in chromosome markers such as minisatellite sequences, or by restriction fragment polymorphism analysis of candidate genes, attempts are being made to link genetic variations with hypertension. In genetically hypertensive rats, hypertension is associated with a polymorphism of the renin gene and with other loci on chromosomes 10 and 18. The role of these loci in human hypertension remains to be determined. Other genes such as sodium-lithium countertransport may be involved. Environmental factors such as stress or salt intake could influence the rate or timing of expression of certain genes and thus result in hypertension.     

Origins of blood acetate in the rat.

1. Fluorimetric techniques were used to characterize the environment of tryptophan residues in thermolysin and apo-thermolysin. The apo-thermolysin was obtained by dissolving the enzyme in the presence of 10mm-EDTA, which removed the functional Zn(2+) ion and the four Ca(2+) ions/molecule from the enzyme. 2. At 25 degrees C in aqueous solution the fluorescence-emission spectrum of the native holoenzyme, on excitation at 290nm, was essentially characteristic of tryptophan, with an emission maximum at 333nm. The emission maximum of the apoenzyme is red-shifted to 338nm and the relative intensity of fluorescence is decreased by 10%, both effects indicating some unfolding of the protein molecule, with the indole groups being transferred to a more hydrophilic environment. 3. Fluorescence quenching studies using KI, N'-methylnicotinamide hydrochloride and acrylamide indicated a more open structure in the apoenzyme, with the tryptophan residues located in a negatively charged environment. 4. The thermal properties of the apoenzyme, as monitored by fluorescence-emission measurements, are dramatically changed with respect to the native holoenzyme. In fact, whereas the native enzyme is heat-stable up to about 80 degrees C, for the apoenzyme a thermal transition is observed near 48 degrees C. The apoenzyme is also unstable to the action of unfolding agents such as urea and guanidinium chloride, much as for other globular proteins from mesophilic organisms. 5. The functional Zn(2+) ion does not contribute noticeably to the stability of thermolysin. 6. It is concluded that a major role in the structural stability of thermolysin is played by the Ca(2+) ions, which have a bridging function within this disulphide-free protein molecule.