Signal transduction and the regulation of actin conformation during myeloid maturation: studies in HL60 cells

Maturation of human myeloid cells is associated with quantitative and qualitative changes in protein kinase C (PKC) and increases in N-formyl- L-methionyl-L-leucyl-L-phenylalanine (FMLP) receptors, actin, and actin regulatory proteins. We have studied the actin responses and cell shape changes caused by FMLP and its second messenger pathways in HL60 cells undergoing neutrophilic maturation. In uninduced cells, the PKC activators 12-O-tetradecanoyl phorbol-13-acetate (TPA), bryostatin, and 1-oleyl-2-acetylglycerol (OAG) resulted in 15% to 30% decreases in F- actin, whereas FMLP had no effect. Ionomycin had no effect on actin but did cause a 10-fold increase in intracellular calcium. Cells grown for 24 hours in 1% dimethyl sulfoxide (DMSO) acquired the ability to polymerize actin in response to FMLP and ionomycin. TPA continued to cause a decrease in F-actin at 24 hours, but caused an increase in F- actin at 48 to 72 hours of maturation. The PKC inhibitor 1-5- isoquinolinesulfonyl 2-methylpiperazine (H7) partially blocked the F- actin increase caused by TPA in induced cells, but had no effect on the decrease in F-actin caused by TPA in uninduced cells or the increase in F-actin seen in FMLP-treated neutrophils. F-actin rich pseudopods developed following TPA or FMLP stimulation of induced HL60 cells; in uninduced cells neither agent caused pseudopod formation but TPA caused a dramatic loss of surface ruffles. The ability of FMLP and ionomycin to elicit a neutrophil-like actin response in HL60 cells within 24 hours after DMSO treatment shows that the actin regulatory mechanism is mature by that time. The inability of ionomycin to increase F-actin in uninduced cells supports the view that calcium increases alone are insufficient for actin polymerization. The longer maturation time required for HL60 cells to develop an actin polymerization response to TPA compared with FMLP, coupled with the inability of H7 to block the FMLP-mediated F-actin increase in neutrophils, suggests that the F- actin increase caused by FMLP is not mediated solely by PKC. Lastly, the TPA-induced F-actin decrease and shape changes in uninduced HL60 cells, and the longer time required for a "mature" response to TPA, may reflect immaturity in the PKC isoenzyme pattern rather than immaturity of the actin regulatory mechanism.     

A second BamHI DNA polymorphism and haplotype association in the factor IX gene

A second BamHI DNA polymorphism has been identified in the factor IX gene in an American black population at an allelic frequency of 0.13. This site has been localized within 500 basepairs (bp) 5' to the XmnI intron 3 polymorphic site and increases the heterozygosity of black females at the factor IX gene locus. In addition, haplotype analysis of factor IX genes at five polymorphic loci indicates that although there is conservation of sequences between the races, factor IX genes show more heterogeneity in an American black population and thus more heterozygosity is observed in black females compared with whites. This increased heterogeneity is due to DNA polymorphisms unique to black populations and to linkage equilibrium between the most 5' and 3' polymorphic sites in factor IX genes in blacks.     

DIFFUSE IDIOPATHIC SKELETAL HYPEROSTOSIS (DISH) OF THE SPINE: A CAUSE OF BACK PAIN? A CONTROLLED STUDY

This is the first controlled study of the frequency of backpain in a European caucasian population with diffuse idiopathicskeletal hyperostosis (DISH). Elderly patients admitted to hospital for reasons other thanback pain were assessed for the presence of spinal DISH usingthe routine lateral chest radiograph films. A total of 106 probands(82 males, 24 females) with a mean age of 70 years fulfilledthe criteria for DISH as defined previously. One hundred andseventyeight patients (117 males, 61 females) not meeting thesecriteria were used as controls. The prevalence of back painwas assessed by a blinded interviewer using a structured questionnaire.Our primary hymthesis was that spinal DISH positive probandshad not had back pain more often than controls. The controlledstudy showed no statistically significant difference in painfrequency between spinal DISH positive probands and controlsat any spinal level. We conclude that back pain does not occur more often in radiographicallydefined DISH positive probands than in controls. The radiologicalfinding of spinal DISH, as far as it does not lead to stenosisof the spinal canal or dysphagia, thus seems to be a findingwithout clinical relevance. KEY WORDS: Spine, Radiographs, Pain, Osteoarthritis, Forestier's disease, Ankylosing vertebral hyperostosis     

Incidence, clinical significance and prognosis of ventricular fibrillation in the early phase of myocardial infarction

Of 1265 patients admitted to the CCU with the diagnosis of acuteMI, 96 (7.6%) developed ventricular fibrillation within 72 hoursfollowing admission. Of these 96, 35 (36.5%) had secondary VFassociated with left ventricular failure; they had a high in-hospitalmortality of 57.1%. The remaining 61 (63.5%) had primary VF,i.e. VF occurring in the absence of significant LV failure.Fourteen of these (23%) died in hospital: 9 due to PVF (3 duringthe first episode, 6 during a recurrence). This mortality figurewas significantly higher (P<0.001) than the mortality of10% seen among patients who did not experience VF. Primary VFshowed a recurrence rate of 20%. Compared with the 1061 patientswho left the hospital without primary VF, the 61 subjects withthis rhythm disorder were older, had larger infarcts and morefrequent complications, such as pericarditis, conduction abnormalities,frequent ventricular premature contractions and signs of rightventricular failure. These findings, in contrast with a widelyheld view, suggest that primary VFmay carry a guarded prognosis.     

Infection of human T-cell leukemia virus type I and development of human T-cell leukemia lymphoma in patients with hematologic neoplasms: a possible linkage to blood transfusion

Among 354 adult patients with either hematological malignancy or aplastic anemia, eight were positive for anti-HTLV-I antibodies; six of eight had received multiple transfusions. There was an approximately 3.5-fold increase (P less than .001) of HTLV-I seropositivity in the patients with hematologic disease (8 of 354, 2.23%) compared to the healthy adults older than 20 years (34 of 5252, .65%). Two hematological patients, one with Hodgkin's disease and one with acute promyelocytic leukemia, were found to be positive for HTLV-I, and developed and died of adult T-cell leukemia/lymphoma (ATL) subsequently. Both were long-term survivors of the primary disease and had received multiple transfusions. The latent period from blood transfusion to onset of ATL was 6 months and 11 years, respectively. Immunocompromised patients, who were seropositive for HTLV-I, may be at increased risk for ATL compared to healthy carriers of HTLV-I, and the latent period may be shorter.     

Studies of circulating hemopoietic progenitor cells in human fetal blood

High levels of committed erythroid and granulocytic/monocytic progenitor cells have been demonstrated in fresh blood obtained at fetoscopy. The fetal progenitor cells were more sensitive to appropriate stimuli (erythropoietin and colony-stimulating factor) than adult progenitor cells grown under the same conditions, and this was shown to be due to intrinsic differences in the progenitor cells at the different developmental stages.