PubMed Health⌕ Search

Biomedical subjects

W Calvo

Publications and source records attributed to W Calvo.

At least 55 records · Page 3Linked to original sources
PubMed1979

Collection, storage and transfusion of blood stem cells for the treatment of hemopoietic failure.

Migration of hemopoietic stem cells via the blood to sites of stem cell need is a principle that becomes established during the embryonic development of hemopoiesis and can be observed in the adult whenever bone marrow transplantations are being performed. The regular presence of stem cells in the peripheral blood lends itself to the study of their collection, storage, and use for transfusion purposes in cases of bone marrow failure. Both in dog and in man, granulocyte-macrophage progenitor cells (CFU-C) can be collected by leukapheresis from the blood in large quantities, particularly if the yield is increased by the administration of mobilizing agents such as dextran sulfate, and appear to be an indicator for the presence of stem cells. For collection and storage, a closed plastic bag system has been developed that allows the safe handling of the cells. The loss of CFU-C from freezing and thawing with DMSO as a cryoprotective agent is only 10%-20%. If frozen and thawed mononuclear leukocytes are transfused into 1200 rad whole-body X-irradiated autologous or allogeneic recipient dogs, a hemopoietic take is observed when 0.2 X 10(5) CFU-C are present among the mononuclear leukocytes (MNC). Graft-versus-host disease can be avoided in the allogeneic situation when a purified CFU-C rich cell fraction is being transfused. In man collection and storage of MNC including CFU-C is feasible and may eventually become a therapeutic tool.

Animals↗
PubMed1979

Albumin density gradient purification of canine hemopoietic blood stem cells (HBSC): long-term allogeneic engraftment without GVH-reaction.

Long-term repopulation of the blood-forming organs of dogs, conditioned by wholebody X-irradiation (1200 R midplane dose), was achieved by transfusion of cryopreserved allogeneic blood mononuclear cells (MNC) without causing graft-versus-host-reaction (GVH-R). Donor and recipient dogs were DL-A identical, MLC-negative, no siblings, non-related. The blood stem cells (CFUc) were procured by a 3- to 4-hour continuous-flow leukapheresis. To increase the CFUc concentration in the peripheral blood, dextran sulfate (DS) was administered intravenously beforehand. About 1 x 10(10) MNC, among them about 1 x 10(7) CFUc, were collected and further segregated using a discontinuous albumin density gradient. Less dense cells were to be found in the upper part of the gradient (fraction 2). These cells included most of the CFUc, enriched by a factor of between 275 and 1730 compared to their concentration in the peripheral blood beforehand. After cryopreservation, these cells, when transfused into lethally irradiated dogs, completely repopulated the marrow and lymph nodes, caused no GVH-R and allowed long-term survival. These dogs received no immunosuppressive therapy, either before or after transfusion. More dense MNC were to be found in fraction 3; their transfusion caused a severe GVH-R, followed quickly by death. Fraction 4 was rich in lymphocytes and poor in CFUc. The transfusion of these cells produced a selective plasma-cell hyperplasia of the lymph nodes but failed to repopulate permanently the marrow. The reappearance of the different cell lineages in the marrow and in the peripheral blood after conditioning and transfusion of these cells produced a selective plasma-cell hyperplasia of the lymph nodes but failed to repopulate permanently the marrow. The reappearance of the different cell lineages in the marrow and in the peripheral blood after conditioning and transfusion of the segregated MNC is described in detail.

Animals↗
PubMed1979

Morphologic alterations in canine marrow of long-term survivors after 1200 R whole-body x-irradiation and autologous blood leukocyte engraftment.

The marrow matrix of total-body x-irradiated dogs (1200 R midline dose) was able to support effective hemopoiesis for several hundred days if the animals were transfused with their own mononuclear leukocytes collected from the blood prior to irradiation and preserved at ultralow temperatures. However, a lesion developed in the marrow, consisting of a fibrosis originating in conjunction with or from the endosteum. The fibrotic tissue substantially reduced the available marrow space in dogs with advanced lesions. The number of autologous, cryopreserved mononuclear leukocytes transfused ranged from 0.32 X 10(9) to 1.63 X 10(9)/kg body weight. The observation period extended to a maximum of 898 days after irradiation.

Animals↗
PubMed1977

Cryopreservation of blood mononuclear leukocytes and stem cells suspended in a large fluid volume. A preclinical model for a blood stem cell bank.

It was the purpose of this study to establish and evaluate a freezing-and-thawing method for preservation of hemopoietic stem cells from the peripheral blood. Blood leukocytes collected by means of an IBM Blood-Cell-Separator were frozen in plastic bags using 10% DMSO and controlled cooling rates. Thawing was performed rapidly, and DMSO was diluted and removed prior to the in-vitro and in-vivo assays. The mean recovery of mononuclear cells collected from 82 leukaphereses was 86%. To assess the recovery of cryopreserved hemopoietic stem cells, the soft agar culture method adapted for the dog was used. There was no significant difference in the CFUc recovery per 1 X 10(6) mononuclear cells or in per leukapheresis after different cryopreservation times (1--6 and 7--27 months). To evaluate the hemopoietic repopulation capability of cryopreserved blood stem cells, leukapheresis-derived leukocytes were transfused into 1200 R whole body x-irradiated dogs. The hemopoietic repopulation pattern at day 10 after transfusion of comparable numbers of fresh or frozen leukocytes was not significantly different, as measured in bone marrow smears and sections and by granulocyte concentration in the peripheral blood.

Animals↗
PubMed1977

In-vitro and in-vivo properties of canine blood mononuclear leukocytes separated by discontinuous albumin density gradient centrifugation.

Dogs were given 1 200 R whole body x-irradiation and transfused with frozen and thawed mononuclear leukocytes from a DLA identical, MLC negative donor dog. These leukocytes had been obtained from the peripheral blood by means of leukapheresis, using the IBM experimental cell separator after injection of 15 mg/kg body weight of dextran sulphate to increase the yield of CFUc upon collection. The segregation of leukocytes by means of the discontinuous albumin gradient centrifugation method resulted in a fraction 2 that contained a very high proportion of CFUc, and in other fractions 3 and 4 with a high proportion of lymphocytes with few CFUc. The dog receiving fraction-2 cells showed a rapid bone marrow recovery (permanent) and displayed no signs of gvh-reaction. The dogs receiving cells of fraction 3 or 4 died of gvh-reaction within 25 days. The dog receiving fraction 4 cells showed little hemopoietic recovery, but a marked lymph node hyperplasia of plasma cells.

Animals↗
PubMed1976

Involvement of the central nervous system in rats with acute leukemia L 5222.

Young adult BD-IX rats made leukemic by intravenous infusion of 2 times 10(7) nucleated blood cells from leukemic donors (L 5222), showed lesions in the central nervous system 6 days after transfer when their leukocyte count was between 250,000 and 350,000 cells/mul. The brain was affected in only half of the animals, whereas all showed an infiltration of the meanings. Furthermore, all animals had extensive lesions in the spinal cord. The lesions consisted of nodules of leukemic cells and hemorrhages which were predominant in the lower half of the spinal cord and more abundant in the white than in the gray matter. Paraplegic appeared in some animals shortly before death. Since there is a consistent involvement of the meninges and spinal cord, the L 5222 leukemia seems to be a useful model for the study of leukemic infiltration of the central nervous system and the reaction to chemotherapy.

Acute Disease↗
PubMed1976

Regeneration of blood-forming organs after autologous leukocyte transfusion in lethally irradiated dogs. II. Distribution and cellularity of the marrow in irradiated and transfused animals.

Dogs were given transfusions of cryopreserved autologous mononuclear blood leukocytes after 1200 roentgens (R) (midline dose) whole-body x-irradiation. Bone marrow repopulation was studied by means of histomorphological methods at days 9 and 10 after transfusion of an average of 3 X 10(9), 7 X 10(9), 13 X 10(9), and 31 X 10(9) cells. The return of marrow cellularity to normal values was related to the number of cells transfused. With low cell doses (3 X 10(9) and 7 X 10(9)), the marrow regeneration at 10 days was focal. There were groups of cells (colonies) showing either erythropoiesis, myelopoiesis, or megakaryocytopoiesis in the osteal niches of the trabecular bones. Frequently such niches were seen showing complete cellular recovery next to niches with complete aplasia. With higher cell doses, all niches showed hemopoietic regeneration, and the cellularity approached normal values. No hemopoietic regeneration was observed in those skeletal parts that do not show hemopoiesis, even under normal circumstances.

Animals↗
PubMed1976

The repopulation of lymph nodes of dogs after 1200 R whole-body x-irradiation and intravenous administration of mononuclear blood leukocytes.

Fresh and cryopreserved autologous or allogeneic mononuclear blood cells (MBCs) intravenously injected in 1200 R total-body x-irradiated dogs repopulated lymph nodes within 10 days after tranfusion. Several parameters of the lymphopoietic regeneration were correlated with the number of cells transfused and with the number of colony-forming units contained in the cell suspension when they were cultured in agar (CFUc). Values within the normal or close to normal range were reached in the mesenteric nodes of most of the animals transfused with 10 X 10(9) MBC or more. These values were obtained when 5 X 10(5) CFUc or more were transfused. Axillary nodes showed lower values than mesenteric nodes. They were mostly under the normal range but well over those of the irradiated controls. Frozen and thawed MBCs seem to be as effective as fresh cells for lymphopoietic restoration. The mesenteric nodes of dogs transfused with allogeneic MBCs showed higher cellularity and larger cortical-paracortical areas than those of dogs tranfused with approximately the same number of autologous cells. The repopulation of lymph nodes parallels that of the marrow.

Animals↗
PubMed1975

[Platelet dysfunction as a result of inhibition of ADP release (aspirin-like defect) in two identical twins(author's transl)].

An abnormal release of platelet adenosine diphosphate (ADP), as seen after intake of acetylsalicylic acid, was demonstrated to be the cause of a clotting disorder in two identical female twins. The signs of bleeding occurred at the age of 26 and consisted of an increased frequency of haematomas, hypermenorrhoea not explained on gynaecological grounds, and prolonged bleeding after minor injuries. Increased bleeding time, abnormal aggregation after stimulation with collagen and absence of the second aggregation phase after addition of ADP were the abnormal findings of this clearly hereditary form of platelet dysfunction. The platelets were slightly larger than normal ones and there were changes in ultrastructure.

Adenosine Diphosphate↗
PubMed1975

[Collection of hematopoietic stem cells from canine peripheral blood and their ability to regenerate hematopoiesis].

A procedure is presented for the collection of a large number of hemopoietic stem cells from the peripheral blood of dogs by means of a single leukapheresis using the NCI-IBM Blood Cell Separator. In the course of a leukapheresis of about 285 min duration a mean of 23 x 10-9 leukocytes is collected from the blood. The hemopoietic stem cells among such separated leukocytes initiate repopulation of bone marrow within 10 days after whole body X-irradiation with 1200 R. The cell numbers in a defined histological section of femoral bone marrow are evaluated 9 to 10 days after irradiation and subsequent autologous transfusion of 6.72 x 10-9 separated mononuclear leukocytes. The results indicate that the bone marrow cell numbers of transfused dogs are significantly greater than in dogs given only 1200 R and reach a level of approximately 49% of the normal value. Possible ways of increasing the yield of hemopoietic stem cells from the peripheral blood will be considered.

Animals↗
PubMed1975

Regeneration of blood-forming organs after autologous leukocyte transfusion in lethally irradiated dogs. I. Distribution and cellularity of the bone marrow in normal dogs.

Marrow cellularity in adult beagles (1-2 yr old) is highest in centrally located bones, with values between 8000 and 12,000 nucleated cells per sq mm. It decreases gradually towards the peripheral parts of the body, reaching values below 1000 per sq mm in bones distal to the elbow and knee. The first tail segment always contains some active marrow. The fifth segment has only stromal elements. In spongy bones fat cells appear to be distributed at random among the blood-forming elements. In the middle part of the femur the fatty marrow predominates in the center of the cylinder, while the subendosteal area is very cellular. The proximal and distal ends of the femur are more cellular than the middle. The small standard deviation of the cellularity in the spongy bones of the trunk and in the proximal and middle part of the humerus makes these sites areas of choice for quantitative studies of marrow regeneration. The large variations in cellularity of the marrow in the radius and tibia of young adult dogs make these sites unsuitable for such studies. The distribution of active and fatty marrow in dogs is similar to that of humans. The differential count of active marrow is quite constant between different dogs and in the various sites of each animal.

Animals↗