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Biomedical subjects

Y K Liu

Publications and source records attributed to Y K Liu.

At least 73 records · Page 4Linked to original sources
PubMed1982

Periodic neutropenia and monocytopenia.

A patient with periodic neutropenia exhibited simultaneous monocytopenia, and epinephrine infusion revealed no monocytes in the marginating pool during neutropenia. Lymphocytes, eosinophils, and platelets also fluctuated periodically, but serial bone marrow studies and epinephrine infusion data indicate these fluctuations could have represented epiphenomena rather than a more global form of periodic hematopoiesis. Bone marrow descriptions of most cases of periodic neutropenia have indicated a "maturation arrest" at the promyelocyte or myelocyte stage prior to development of neutropenia; peripheral blood monocytes are usually normal or fluctuate out of phase with neutrophils. In this present case, "maturation arrest" occurred at the myeloblast stage, and neutrophils and monocytes cycled together. Morphologically normal eosinophilopoiesis with a mean eosinophil to erythroid ratio in the marrow of 0.27 +/- 0.10 (SD) persisted despite a sustained disappearance of promyelocytes.

Agranulocytosis↗
PubMed1980

Effects of alcohol on granulocytes and lymphocytes.

Transient granulocytopenia and lymphopenia may occur in acute alcoholics without splenomegaly, cirrhosis, infection, and megaloblastic anemia due to folate deficiency. The bone marrow in granulocytopenic patients is frequently hypocellular with few mature granulocytes, and the functional marrow granulocyte reserve is reduced. These findings suggest a depressed granulopoietic activity in these patients. The mechanism by which alcohol suppresses granulopoiesis remains unclear. Direct toxicity of alcohol on granulopoietic stem cells and increased individual susceptibility to the toxic effect of alcohol may be important factors. Alcohol also causes functional impairment of granulocytes (adherence, motility, and chemotaxis), macrophages (motility and phagocytosis), and lymphocytes (blastogenic transformation and development of delayed dermal hypersensitivity reaction), probably by perturbation of the cell membrane resulting in an increased intracellular cyclic AMP level.

Adult↗
PubMed1979

The proliferative states of circulating granulopoietic stem cells in man.

The fraction of granulocyte-macrophage colony-forming cells (CFC) in DNA synthetic phase in blood from 25 normal adults and those in blood and bone marrow from 8 haematologically normal subjects were evaluated by in vitro culture of cells with and without prior exposure to 3H-thymidine (12.5 muCi) for 1 h at 37 degrees C. The exposure of blood cells from normal adults to 3H-thymidine resulted in 26 +/- 10% reduction in colony formation and in 14 +/- 10% reduction in cluster formation. There was no difference in the magnitude of reduction in colony formation following exposure to 3H-thymidine by cells in blood and those in bone marrow in 6 of the 8 haematologically normal subjects. These findings indicated that about one fourth of the circulating CFC in normal adults are in proliferative state and that significant difference in proliferative states between CFC in blood and those in bone marrow probably does not exist in the majority of haematologically normal subjects.

Adult↗
PubMed1979

Renal tubular transport of methotrexate in the rhesus monkey and dog.

The mechanism and localization of renal transport of methotrexate (MTX) were studied in the rhesus monkey and the dog. It was found that in both animals MTX was bound with plasma protein in a range of 50 to 68% varying with the MTX plasma concentration. Paper chromatographic analysis showed that a negligible amount of MTX was metabolized. The excretion of MTX in rhesus monkey was mainly by tubular secretion which was blocked by probenecid, but in the dog a bidirectional transport mechanism for MTX was indicated. Tubular secretion was localized in the proximal tubules, and a tubular reabsorptive process was in the distal section. Simultaneous administration of folic acid blocked the tubular reabsorption of MTX, resulting in an increase of renal excretion. Maximum tubular excretory capacity determination showed that a maximum tubular excretory capacity value of approximately 5 mumol/100 ml of glomerular filtrate was observed in the rhesus monkey at a plasma concentration of 0.07 mM and a value of 2 mumol/100 ml of glomerular filtrate for the dog. Studies with renal cortical slice technique also indicated that the monkey kidney can accumulate greater amounts of MTX than can the dog kidney.

Animals↗
PubMed1979

Serum inhibitor activity of granulocyte-macrophage colony formation in patients with cancer.

The serum inhibitor activities of granulocyte-macrophage colony formation were evaluated by the in vitro culture technique in 60 patients with cancer and control subjects including 24 normal adults and 27 patients with a variety of nonneoplastic disorders. The inhibitor activity in cancer patients (mean, 59%) was significantly higher (p less than 0.001) than was that in normal adults (mean, 31%) and patients with nonneoplastic diseases (mean 36%). There was no difference in the inhibitor activity between the latter two groups of subjects. There was no correlation between the serum inhibitor activity in cancer patients and the histological type or primary site of tumor, the estimated duration of extent of disease, and serum albumin levels. Preliminary observations indicated that the inhibitor activity may be associated with serum lipoproteins. There was no significant difference in serum colony-stimulating activity among cancer patients, normal subjects, and patients with nonneoplastic diseases.

Adult↗
PubMed1978

Myelopoietic abnormalities in patients with metastatic carcinoma.

Myelopoiesis was assessed in 41 untreated patients with widespread cancer without evidence of infection. None of these patients had neutropenia, although leukopenia due to decreased concentrations of blood lymphocytes was observed in two. Sixteen patients (39%) had neutrophilia and 12 patients (29%), 5 of them with neutrophilia, had decreased marrow granulocyte reserve. Neither the blood neutrophil counts nor the marrow granulocyte reserve correlated significantly with the marrow myeloid mitotic indices, myeloid to erythroid ratio or the number of marrow colony-forming cells. There was no difference in the duration of the disease, the extent of systemic metastasis and the degree of malnutrition between patients with or without myelopoietic abnormalities. Our findings suggest that decreased marrow granulocyte reserve and neutrophilia are common in untreated patients with disseminated carcinoma.

Adult↗
PubMed1978

Humoral regulation of thrombopoiesis in man.

Plasma was obtained before and after plateletpheresis-induced thrombocytopenia from two healthy male subjects during periods of ethanol ingestion and abstinence. Autologous reinfusion of these plasmas was performed at a later date when both subjects were hematologically normal. Eight thrombopoietically active plasmas produced an increased percent of immature megakaryocytes 24 hr after reinfusion and a peak rise in platelet count (averaging 148% of baseline values) at 5.8 days. Similar changes were not found with inactive plasmas, plasma collected at the end of a "sham" plateletpheresis, or plasma collected after 8 hr of ingestion of 296 gm of ethanol. A transient increase in TSA was found in plasmas collected at the end of plateletpheresis during abstinence, but this activity was not detected 12 hr later. The rapid disappearance of TSA, despite persistent thrombocytopenia, coincided with the appearance of an increased percent of immature magakaryocytes in the bone marrow. Elevated TSA was also noted at the end of plateletpheresis during ethanol ingestion but, in contrast to events during abstinence, remained elevated as long as ethanol ingestion continued.

Blood Cell Count↗
PubMed1978

Systems identification scheme for the estimation of the linear viscoelastic properties of the intervertebral disc.

In recent years, traumas due to pilot ejection, automobile accidents, etc., have generated much interest in the biomechanical modelling of the responses of the human spine to high rates of loading. The predicted responses of these models, however, are dependent on the assumed mechanical properties of the discs and vertebrae. The knowledge of these mechanical properties constitute an important aspect of any mathematical model of the spine, i.e., in both quasistatic and dynamic simulations.

Biomechanical Phenomena↗
PubMed1978

Mechanical response of the lumbar intervertebral joint under physiological (complex) loading.

Nineteen fresh, intact lumbar intervertebral joints (two vertebrae and the intervening joint) from twelve spines were loaded in a materials testing machine to determine their mechanical behavior. The loads applied were pure axial compression and complex loading conditions simulating physiological states. The measurements made included vertical load deflection, disc bulge, and strains in both the anterior and the lateral aspects of the vertebral body and in one lamina. The results showed that the posterior elements transmit considerable force during quasistatic complex loading, particularly in extension and frontal shear. When a healthy specimen is subjected to complex loading, "yielding or failure" occurs in the vertebral body and not in the annulus fibrosus of the disc.

Aged↗
PubMed1977

Induction of thrombocytopenia by thrombopheresis in man: patterns of recovery in normal subjects during ethanol ingestion and abstinence.

Using the technique of thrombophoresis (TP), platelet and megakaryocyte dynamics following acute thrombocytopenia were studied in two normal subjects during periods of ethanol ingestion and abstinence. Thrombocytopenia was induced over a period of 12 hr. A logarithmic decline in platelet count during TP and the serial morphologic changes in megakaryocytes during recovery from thrombocytopenia are described. Although these parameters were not affected by ethanol ingestion, platelet counts after TP did not return to normal until ethanol was discontinued. 51Cr-labeled platelet survival was normal in one subject studied, and no evidence of increased platelet sequestration was found. It is concluded that heavy ethanol ingestion induces, augments, or sustains thrombocytopenia by impairing megakaryocytopoiesis in man. The mechanism by which ethanol induces thrombocytopenia may be due, in part, to "ineffective thrombopoiesis," impairment of the differentiation of precursor cells into the megakaryocytic compartment, or a combination of these factors.

Adult↗