[Effect of anisodamine in prevention and treatment of visceral complications in serious burns]

From January 1992 to December 1994, anisodamine was used in 156 cases of serious burns. The results showed that there was a significant lowering of incidence of visceral complications in the treatment group than in the control group. Also the cure rate of visceral complications was significantly elevated in the treatment group than control group. The result indicated that anisodamine had both prevention and treatment effects on visceral complications in serious burns.

[A study on the pathogenetic role of the viral structural proteins of hemorrhagic fever with renal syndrome]

In order to clarify the pathogenesis of hemorrhagic fever with renal syndrome (HFRS), we detected HFRS virus structural proteins expressed in perepheral blood mononuclear cells (PBMC) by using immunohistochemical technique. Meanwhile we also determined plasma endothelin (ET), substance P (SP) and some sensitive markers of renal function with radioimmunoassay. The result showed that in HFRS patients, from the day of admission up to the thirteenth day of illness, the antigens of HFRS virus membrane protein (MP) and nucleocapsid (NP) could simultaneously be found in PBMC, though their expressive degree gradually decreased when the condition of the patients became better. Based on the external appearance and nucleus pattern of PBMC we recognized the MP and NP positive cells were mainly monocytes among which only a few presented faint IgM and C3 stain. On admission there was difference in expressive intensity between MP and NP. The MP expressive intensity was in parallel with plasma ET/SP ratio, the general condition and the severity of renal damage. These data suggest that HFRS virus can invade PBMC, replicate in them, and express their structural proteins. MP may be related with the pathogenesis of HFRS virus and the increase of plasma ET/SP ratio may be an important factor aggravating kidney injury.

Long-term results of operation for paravalvular abscess

BACKGROUND

Operation for infective endocarditis with paravalvular abscess is reportedly associated with high mortality and morbidity rates. In an attempt to improve surgical outcome, an approach of radical resection of the abscess and inflamed tissues and reconstruction of the heart with either fresh or glutaraldehyde-fixed bovine pericardium was adopted by two surgeons at our institution.

METHODS

From 1979 to 1995, 70 consecutive patients with active infective endocarditis and paravalvular abscess underwent operation. Their mean age was 49 years (range, 16 to 75 years), and 50 patients (71%) were men. Thirty-four patients had native and 36 had prosthetic valve endocarditis (8 had had composite replacement of the aortic valve and ascending aorta). Most patients (78%) were in New York Heart Association functional class IV. The principal indication for operation was cardiogenic or septic shock in 11 patients, or one or more of the following: persistent sepsis despite adequate antibiotic therapy in 36, congestive heart failure in 31, and recurrent emboli in 16. Staphylococci were responsible for the infection in 37 patients (53%). The abscess was in the mitral annulus in 11 patients, in the aortic root in 44, and in the aortic root and at least one other annulus in 15. After wide resection of the abscess, we reconstructed the heart and annuli with autologous or bovine pericardium. Mechanical heart valves were implanted in 36 patients, bioprostheses in 30, and aortic homografts in 2; valve repair was possible in 2. Sixteen patients required composite replacement of the ascending aorta and aortic valve.

RESULTS

There were 9 operative deaths (13%). Infections caused by staphylococci and infections in multiple annuli were associated with increased operative mortality rates. Only 1 patient had persistent infection and required reoperation. The mean follow-up was 56 +/- 40 months. There were 12 late deaths, mostly cardiac. The actuarial survival including operative deaths was 64% +/- 8% at 8 years. In 8 patients, recurrent infective endocarditis developed 10 to 102 months after operation. The freedom from recurrent endocarditis was 76% +/- 10% at 8 years.

CONCLUSIONS

This experience indicates that radical resection of the abscess and reconstruction of the heart with pericardium yield an excellent chance of eradicating the infection in patients with infective endocarditis and paravalvular abscess. The type of valve implanted may not be as important as radical resection of the abscess. These patients appear to have a greater than average risk of recurrent endocarditis.

Identification and analysis of the human and murine putative chromatin structure regulator SUPT6H and Supt6h

We have isolated and sequenced SUPT6H and Supt6h, the human and murine homologues of the Saccharomyces cerevisiae and Caenorhabditis elegans genes SPT6 (P using 1603 aa = 6.7 e-95) and emb-5 (P using 1603 aa = 7.0 e-288), respectively. The human and murine SPT6 homologues are virtually identical, as they share >98% identity and >99% similarity at the protein level. The derived amino acid sequences of these two genes predict a 1603-aa protein (human) and a 1726-bp protein (mouse), respectively. There were several known features, including a highly acidic 5'-region, a degenerate SH2 domain, and a leucine zipper. These features are consistent with a nuclear protein that regulates transcription, whose extreme conservation underscores the likely importance of this gene in mammalian development. Expression of human and murine SPT6 homologues was analyzed by Northern blotting, which revealed a 7. 0-kb transcript that was expressed constitutively. The SPT6 homologue was mapped to chromosome 17q11.2 in human by somatic cell hybrid analysis and in situ hybridization. These data indicate that SUPT6H and Supt6h are functionally analogous to SPT6 and emb-5 and may therefore regulate transcription through establishment or maintenance of chromatin structure.

[The secondary ossification center of fetus]

Most textbooks on human anatomy and human embryology state that the appearance of the secondary ossification center (SOC) of the fetus is considered to be after or around birth. In our study, while collecting the data on growth indexes from 346 fetuses in normal pregnancy with conceptional ages from 12 to 38 complete weeks, we investigated using B-ultrasonography the appearance of the secondary ossification center and compared them in part with the anatomically observed data collected from fetal specimens. The results of B-ultrasonic observation show that SOC can be seen at the distal end of femur after 29 complete weeks. From them on, the percentage of the appearance of SOC increases weekly, and it is almost 100% in 34 complete weeks.

[The nonfunctional adrenal tumors: report of 30 cases]

79 cases of adrenal tumors were treated in our hospital from 1985 to Aprit. 1994. 30 of them had nonfunctional adrenal tumors. Data have shown that nonfunction adrenal tumor is not unusual. The detection rate of the disease will increase with the development and popularization of medical imageology which consists of B-ultrasonography and CT scanning etc. In this article, the diagnosis and treatment of this disease were discussed in detail with a review of the literature.

In vitro models of biocompatibility: a review

The objectives of this paper were to define in vitro biocompatibility of materials, to discuss some of the issues concerning why conclusions from tissue culture are sometimes different from in vivo biocompatibility, to give highlights of the sequence of the development of these in vitro assays from the early 1950s to their present state of development, and to discuss possible future trends for in vitro testing. In vitro biocompatibility tests were developed to simulate and predict biological reactions to materials when placed into or on tissues in the body. Traditional assays have measured cytotoxicity by means of either an end-stage event, (i.e., permeability of cytoplasmic membranes of dead and dying cells, or some metabolic parameter such as cell division or an enzymatic reaction). In vitro assays for initiation of inflammatory and immune reactions to materials have also begun to appear in the literature. More recently, the concept of dentin barrier tests has been introduced for dental restorative materials. Four models which measure both permeability and biological effects of materials are compared and discussed. Future efforts may be directed toward development of materials which will allow or promote function and differentiation of tissues associated with materials. New analytical procedures and understanding of optimal characteristics of materials should improve our ability to develop more biocompatible materials. Both molecular biology techniques, and altered design of material surfaces may make the materials either more or less reactive to the biological milieu. These trends suggest a greater future role of the biological sciences in the development of biomaterials.

[Treatment of oral leukoplakia with retinamide]

Inhibition of buccal pouch carcinogenesis induced by dimethyl-benzanthracene in hamsters with retinamide was studied. Group A received oral retinamide at a dosage of 20mg/kg, every day for eight weeks. Group B was treated by retinamide orally at the same dosage, plus topical treatment by retinamide. Group C was treated by retinamide topically for eight weeks. Experiments exhibited that under the action of retinamide the incidence of tumor was lowered significantly. All the Group A, B and C had a good response. Clinically 80 patients were randomly arranged into two groups. One group received placebo and served as controls and the other group was treated by retinamide. Results indicate that retinamide is effective against leukoplakia and the response rate is as high as 84.0%. By contrast, only 16.7% of patients receiving placebo showed some improvement.

Properties of human prolactin (PRL) and H27A-PRL, a mutant that does not bind Zn++

The ability of protein hormones to self-associate is likely to play an important role in concentrating hormones into secretory granules; therefore, the aggregation properties of human PRL and H27A mutant were investigated. Human PRL bound (65)Zn++; the Scatchard analysis was convex up, and limited by the solubility of PRL, but at least 0.7 mole Zn++ bound per mole of PRL. Binding of (65)Zn++ to H27A-PRL was greatly reduced. The biological activity in an Nb2 cell assay and the circular dichroism spectrum of wild type and H27A-PRL were similar, indicating the H27A mutant folded correctly, and the binding of Zn++ to the high affinity site is not essential for biological activity. Dynamic light scattering measurements indicated 10 and 20 mu M Zn++ caused some aggregation of both wild type and H27A-PRL. Sedimentation equilibrium analysis indicated that PRL is primarily a monomer in the absence of Zn++ and that there is increasing self-association in the presence of 5 and 10 mu M Zn++. The mutant H27A exhibited a greater tendency to aggregate without changing detectably the mode of association. Although human PRL binds Zn++ as human GH does, it differs in that the ability to bind Zn++ and to self-associate were decoupled in PRL. Human PRL must have two types of interactions with Zn++; one is binding to a site involving histidine 27, and the other is weaker interactions that induce self-association of PRL.

Spk1/Rad53 is regulated by Mec1-dependent protein phosphorylation in DNA replication and damage checkpoint pathways

SPK1/RAD53/MEC2/SAD1 of Saccharomyces cerevisiae encodes an essential protein kinase that is required for activation of replication-sensitive and DNA damage-sensitive checkpoint arrest. We have investigated the regulation of phosphorylation and kinase activity of Spk1p during the cell cycle and by conditions that activate checkpoint pathways. Phosphorylation of Spk1p is induced by treatment of cells with agents that damage DNA or interfere with DNA synthesis. Although only S- and G2-phase cdc mutants arrest with hyperphosphorylated Spk1p, damage-induced phosphorylation of Spk1p can occur in G1 and M as well. Hydroxyurea (HU) induces phosphorylation of kinase-defective forms of Spk1p, demonstrating that this regulated phosphorylation of Spk1p occurs in trans. HU-induced phosphorylation is associated with increased catalytic activity of Spk1p. Furthermore, overexpression of wild-type SPK1, but not checkpoint-defective alleles, delays progression through the G1/S boundary. Damage-dependent phosphorylation of Spk1p requires both MEC1 and MEC3, whereas MEC1 but not MEC3, is required for replication block-induced phosphorylation. These data support the model that Spk1p is an essential intermediate component in a signal transduction pathway coupling damage and checkpoint functions to cell cycle arrest. This regulation is mediated through a protein kinase cascade that potentially includes Mec1p and Tel1p as the upstream kinases.

Interleukin-5 receptor alpha subunit gene regulation in human eosinophil development: identification of a unique cis-element that acts lie an enhancer in regulating activity of the IL-5R alpha promoter

Further functional and biochemical characterization of the nuclear factor(s) which interacts with the EOS1 enhancer-like element in the IL-5R alpha promoter is currently in progress. Since different transcription factors recognize and interact with DNA in distinct fashions and with distinct structural motifs, we have modeled potential binding of the EOS1 factor to its cis-element based upon its methylation interference pattern (Fig. 2), using a cylindrical DNA helical projection (Fig. 6). Over a length of two helical turns, all nuclear protein contacts indicated by methylation interference map to one side of the DNA helix, suggesting that EOS1 binds in the major groove, across the minor groove, and on only one side of the helix. Further review of the model also reveals a potential diad symmetry for the binding site, suggestive of binding by a homodimer and consistent with the formation of the two DNA-protein complexes in our electrophoretic mobility shift experiments that could represent interactions with monomer versus dimer. Comparison of the EOS1 binding motif to similar models for the binding of other transcription factor families for which structural crystallographic and/or binding data is available suggests a similarity of the EOS1 complex to that of the bacterial helix-turn-helix phage lambda and 434 repressor-operator complexes, and the Cys4 zinc finger glucocorticoid response element (GRE) DNA-binding motifs, all of which show similar diad symmetry and binding in the major groove on one side of the DNA. The possibility that EOS1 functions as a GRE is being investigated, especially since there is a consensus AP-1 site at bp -440 to -432 of the IL-5R alpha promoter, immediately adjacent to the EOS1 binding site (see Fig. 5 in reference [36]) and AP-1/GRE interactions have been identified for composite response elements in the regulation of a number of different genes. The identification or cloning of EOS1, a potentially novel and eosinophil lineage-active transcription factor, should enhance our understanding of the processes involved in eosinophil development in particular and myeloid lineage commitment and differentiation in general.

Organization and analysis of the complete rat calmodulin-dependent protein kinase IV gene

A 42-kilobase pair region of rat DNA containing the Ca2+/calmodulin-dependent protein kinase IV (CaM kinase IV) gene has been cloned and characterized. The gene consists of 12 exons and 11 introns and is predicted to encode both beta and alpha forms of CaM kinase IV as well as the testis-specific calmodulin-binding protein calspermin. The promoter utilized to generate the alpha-kinase isoform is located in intron 1, whereas the promoter utilized to produce the calspermin transcript is contained in intron 10. The calspermin promoter region which extends from -200 to +321 relative to the calspermin transcription initiation site that contains two cyclic AMP response elements (CRE) at -70 and -50 and has been shown previously to be inactive in NIH3T3 cells (Sun, Z., Sassone-Corsi, P., and Means, A. R. (1995) Mol. Cell. Biol. 15, 561-571) was ligated to the lacZ reporter gene and used to generate transgenic mice. The promoter was expressed exclusively in postmeiotic testis where beta-galactosidase was found predominantly in elongating spermatids. The cell and developmental specificity of transgene expression was very similar to the pattern shown by the endogenous gene. Although the transgene promoter was silent in somatic tissues, beta-galactosidase expression could be restored in primary cultures of skin fibroblasts by introduction of vectors encoding CREM tau and CaM kinase IV.

[Scavenging effects of daphnetin and its Cu, Zn complexes on superoxide radical]

The scavenging effects of daphnetin (D) and its Cu, Zn complexes on superoxide radical (O2-.) generated through the photooxidation of riboflavin were studied with human red blood cells (RBC) and RBC membrane as experimental material. The Cu ( II ) complex showed the highest activity. SOD, D and its Cu ( II ), Zn ( II ) complexes were found to have inhibitory effect on the production of lipid peroxide in the membrane, SOD being the best among them.

Cell shape, cytoskeletal mechanics, and cell cycle control in angiogenesis

Capillary endothelial cells can be switched between growth and differentiation by altering cell-extracellular matrix interactions and thereby, modulating cell shape. Studies were carried out to determine when cell shape exerts its growth-regulatory influence during cell cycle progression and to explore the role of cytoskeletal structure and mechanics in this control mechanism. When G0-synchronized cells were cultured in basic fibroblast growth factor (FGF)-containing defined medium on dishes coated with increasing densities of fibronectin or a synthetic integrin ligand (RGD-containing peptide), cell spreading, nuclear extension, and DNA synthesis all increased in parallel. To determine the minimum time cells must be adherent and spread on extracellular matrix (ECM) to gain entry into S phase, cells were removed with trypsin or induced to retract using cytochalasin D at different times after plating. Both approaches revealed that cells must remain extended for approximately 12-15 h and hence, most of G1, in order to enter S phase. After this restriction point was passed, normally 'anchorage-dependent' endothelial cells turned on DNA synthesis even when round and in suspension. The importance of actin-containing microfilaments in shape-dependent growth control was confirmed by culturing cells in the presence of cytochalasin D (25-1000 ng ml-1): dose-dependent inhibition of cell spreading, nuclear extension, and DNA synthesis resulted. In contrast, induction of microtubule disassembly using nocodazole had little effect on cell or nuclear spreading and only partially inhibited DNA synthesis. Interestingly, combination of nocodazole with a suboptimal dose of cytochalasin D (100 ng ml-1) resulted in potent inhibition of both spreading and growth, suggesting that microtubules are redundant structural elements which can provide critical load-bearing functions when microfilaments are partially compromised. Similar synergism between nocodazole and cytochalasin D was observed when cytoskeletal stiffness was measured directly in living cells using magnetic twisting cytometry. These results emphasize the importance of matrix-dependent changes in cell and nuclear shape as well as higher order structural interactions between different cytoskeletal filament systems for control of capillary cell growth during angiogenesis.

Reconstruction of the mitral anulus. A ten-year experience

Reconstruction of the mitral anulus was done in 93 patients because of extensive calcification in 24, infective endocarditis with annular abscess in 27, damaged anulus as a result of previous valve replacement in 36, and rupture of the posterior wall of the left ventricle after mitral valve replacement in 6. The reconstruction was done with fresh autologous pericardium in 30 patients, glutaraldehyde-fixed bovine pericardium in 56, and Dacron graft in 7. An appropriately tailored patch was sutured to the endocardium of the left ventricle or to fibrous skeleton of the heart, or to both. Sixty patients had had previous operation; most patients were in New York Heart Association functional class IV and 15 were in shock. The mitral valve was repaired in 10 patients and replaced in 83. Other procedures were aortic valve replacement in 40, tricuspid valve repair in 25, coronary artery bypass in 12, and replacement of the ascending aorta in 2. Eight patients died in the perioperative period. Postoperative complications were common. Patients were followed up from 12 to 96 months, with a mean of 30 months. There have been 18 late deaths, mostly cardiac. The actuarial survival at 5 years was 68% +/- 6%. A total of 8 patients have required reoperation: 4 because of endocarditis, 2 because of bioprosthetic valve failure, and 2 because of patch dehiscence. The freedom from reoperation was 80% +/- 8% at 5 years. The freedom from patch dehiscence was 95% +/- 4% at 5 years. Reconstruction of the mitral anulus has been an extremely useful operative technique for patients with complex mitral valve disease.

Biological activity and immunological reactivity of human prolactin mutants

We examined the biological activity and immunological reactivity of four mutants of human PRL. Two were mutants that changed the ability of human PRL to inhibit rat PRL storage when transfected into a rat pituitary cell line:mutations S34A and N31T. Two mutations were in regions of PRL that are highly conserved. One, des(3-11)-PRL, removed the N-terminal cystine loop that most PRLs, except those from certain fish, have, and no GHs have. The other, S90A, mutated a serine that is present in all PRLs but those from some fish and in all GHs. The immunological properties of des(3-11)-PRL were reduced 10-fold compared to those of wildtype human PRL in a RIA using NIH antihuman PRL-3, AFP C11580; the others were similar to those of wild-type PRL. The biological activity of des(3-11)-PRL was the most affected; activity was reduced about 8-fold compared to that of wild-type PRL in the Nb2 cell assay. The activities of the others were similar to that of the wild type. Serine 90 may be partially buried by loops connecting the alpha-helixes. The mutation of serine 90 did not affect the stability of the molecule in vitro, determined by comparing the red shift in tryptophan fluorescence that occurs with increasing concentrations of urea in S90A and wild-type PRL. The activity of S34A and N31T mutations indicates there is no correlation between biological activity and ability to affect storage. The N-terminal cystine loop may be conserved because it is needed for biological activity, but the conservation of serine 90 in GH and PRL must be determined by other properties, such as spacial requirements.

Is sex a factor in determining operative risk for aortocoronary bypass graft surgery?

BACKGROUND

This study examines trends and sex differences in characteristics of patients referred for bypass graft surgery to identify factors associated with operative morbidity and mortality.

METHODS AND RESULTS

Data were collected prospectively on consecutive patients (1132 men and 355 women). Over time, the proportion of patients > 65 years old, with diabetes, or requiring urgent surgery, increased. Predictors of mortality were age > 75 years, urgent surgery, and poor left ventricular (LV) grade. Women were older (62 +/- 9 versus 59 +/- 9 years, P < .001) and had more varicose veins (18% versus 7%, P < .001), diabetes (27% versus 18%, P < .001), hypertension (48% versus 41%, P < .05), peripheral vascular disease (16% versus 12%, P < .05), and more severe angina (P < .001). There were no sex differences in prior myocardial infarction (59% versus 62%) or need for urgent surgery (17% versus 18%). Women had a higher ejection fraction (51% +/- 12% versus 47% +/- 14%, P < .001) and fewer diseased vessels (2.4 +/- 0.7 versus 2.6 +/- 0.6, P < .001) and received fewer grafts (2.9 +/- 0.9 versus 3.3 +/- 0.8, P < .001). Women had smaller body size but were no more likely to have small target vessels (< 1.5 mm). There was no sex difference in operative mortality (1.4% versus 1.1%), perioperative myocardial infarction (4.8% versus 3.5%), need for intra-aortic balloon pump (10% versus 8%), stroke (1.7% versus 1.4%), reexploration for bleeding (1.7% versus 1.7%), or leg infection (2.0% versus 1.4%). Women had fewer sternal wound infections (0.6% versus 2.2%, P < .05).

CONCLUSIONS

Predictors of mortality include advanced age, decreased LV function, and need for urgent surgery. With time, despite increasing age, associated diabetes, and increased urgent surgery, operative mortality has decreased. Women were older and had more diabetes and hypertension but less extensive disease and better LV function. Bypass graft surgery was associated with equally low mortality in women and men (1.4% versus 1.1%). Concern over increased operative mortality in women should not bias referral patterns for angiography and coronary bypass graft surgery.

Results of revascularization in patients with severe left ventricular dysfunction

BACKGROUND

In patients with coronary artery disease and poor ventricular function (ejection fraction, < 20%), bypass grafting remains a surgical challenge. This study evaluates experience with isolated revascularization in such patients.

METHODS AND RESULTS

In 79 consecutive patients (69 men, 10 women; average age, 59 +/- 9 years), preoperative ejection fraction was 18 +/- 5%. Indications for surgery were congestive heart failure (CHF) in 5 of 79 patients (6%), CHF and angina in 19 (24%), angina in 41 (52%), ventricular arrhythmias (VAs) in 8 (10%), and critical anatomy in 6 (8%). Some patients had prior VAs (23 of 79; 29%) or mitral regurgitation (18; 23%) and required emergent surgery (25; 32%). At surgery, temperature mapping ensured adequate distribution of antegrade cold cardioplegia, with 3.6 +/- 0.7 grafts per patient, including left internal mammary artery graft in 60 of 79 (76%) and endarterectomy in 14 (18%). Hospital mortality was 3.8%. Perioperative support included intra-aortic balloon pump in 18 of 79 (23%) and drugs for VAs in 28 (35%). Morbidity included myocardial infarction in 2 of 79 (2.5%) and stroke in 2 (2.5%). During follow-up, there were 19 late deaths. Actuarial survival was 94%, 82%, and 68% at 1, 2, and 5 years, respectively, and was similar in patients with severe angina, CHF, mitral regurgitation, or VAs. Freedom from sudden death was 100%, 98%, and 91% at 1, 2, and 5 years, respectively. Among survivors, angina improved in 84% and heart failure improved in 26%.

CONCLUSIONS

These data support bypass graft surgery in patients with severe LV dysfunction. With careful cardioplegic techniques, hospital mortality was low (3.8%). Long-term survival is encouraging, with good relief of symptoms in most patients. Perioperative VAs are frequent but respond to medical treatment, with only 23% of patients discharged on antiarrhythmic drugs. Five-year freedom from sudden death is 91%, with only 3 late sudden deaths in this series.

Postinfarction ventricular septal rupture: repair by endocardial patch with infarct exclusion

A novel operative technique for postinfarction ventricular septal defect has been used in 44 consecutive patients. The operation consists of excluding rather than excising the infarcted septum and ventricular walls. This is accomplished by performance of a left ventriculotomy through the infarcted muscle and securing a glutaraldehyde-fixed bovine pericardium patch to the endocardium of the left ventricle all around the infarcted myocardium. The ventriculotomy is simply closed over the pericardial patch. There were 21 men and 23 women whose mean age was 69 +/- 7 years. Twenty-nine patients were in cardiogenic shock at the time of operation. All patients had Doppler echocardiography and coronary angiography before operation. All but two patients were operated on during the acute phase of the myocardial infarction. There were six operative deaths. Postoperative complications included renal failure in 10 patients and respiratory failure in 18. Severe right ventricular dysfunction was the only independent predictor of operative mortality. Patients have been followed up for a mean of 40 +/- 34 months. There have been six late deaths and three of these were because of cardiac problems. The actuarial survival at 6 years was 66% +/- 7%. Only one patient had a small residual ventricular septal defect. Late postoperative assessment of ventricular function by echocardiography revealed that most patients had normal or mild impairment of right ventricular function and mild or moderate impairment of left ventricular function. Repair of acute postinfarction ventricular septal defect by endocardial patch with infarct exclusion of the left ventricule probably avoids additional damage to the right ventricle, remodels the acutely infarcted left ventricle, and enhances survival.

PU.1 (Spi-1) and C/EBP alpha regulate expression of the granulocyte-macrophage colony-stimulating factor receptor alpha gene

Growth factor receptors play an important role in hematopoiesis. In order to further understand the mechanisms directing the expression of these key regulators of hematopoiesis, we initiated a study investigating the transcription factors activating the expression of the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor alpha gene. Here, we demonstrate that the human GM-CSF receptor alpha promoter directs reporter gene activity in a tissue-specific fashion in myelomonocytic cells, which correlates with its expression pattern as analyzed by reverse transcription PCR. The GM-CSF receptor alpha promoter contains an important functional site between positions -53 and -41 as identified by deletion analysis of reporter constructs. We show that the myeloid and B cell transcription factor PU.1 binds specifically to this site. Furthermore, we demonstrate that a CCAAT site located upstream of the PU.1 site between positions -70 and -54 is involved in positive-negative regulation of the GM-CSF receptor alpha promoter activity. C/EBP alpha is the major CCAAT/enhancer-binding protein (C/EBP) form binding to this site in nuclear extracts of U937 cells. Point mutations of either the PU.1 site or the C/EBP site that abolish the binding of the respective factors result in a significant decrease of GM-CSF receptor alpha promoter activity in myelomonocytic cells only. Furthermore, we demonstrate that in myeloid and B cell extracts, PU.1 forms a novel, specific, more slowly migrating complex (PU-SF) when binding the GM-CSF receptor alpha promoter PU.1 site. This is the first demonstration of a specific interaction with PU.1 on a myeloid PU.1 binding site. The novel complex is distinct from that described previously as binding to B cell enhancer sites and can be formed by addition of PU.1 to extracts from certain nonmyeloid cell types which do not express PU.1, including T cells and epithelial cells, but not from erythroid cells. Furthermore, we demonstrate that the PU-SF complex binds to PU.1 sites found on a number of myeloid promoters, and its formation requires an intact PU.1 site adjacent to a single-stranded region. Expression of PU.1 in nonmyeloid cells can activate the GM-CSF receptor alpha promoter. Deletion of the amino-terminal region of PU.1 results in a failure to form the PU-SF complex and in a concomitant loss of transactivation, suggesting that formation of the PU-SF complex is of functional importance for the activity of the GM-CSF receptor alpha promoter. Finally, we demonstrate that C/EBP alpha can also active the GM-CSF receptor alpha promoter in nonmyeloid cells. These results suggest that PU.1 and C/EBP alpha direct the cell-type-specific expression of GM-CSF receptor alpha, further establish the role of PU.1 as a key regulator of hematopoiesis, and point to C/EBP alpha as an additional important factor in this process.

Left ventricular function after mitral valve surgery

This study examined the effects of various operative procedures on the mitral valve of patients with mitral regurgitation due to degenerative disease of the mitral valve. A randomized clinical trial on the type of annuloplasty ring used at surgery revealed that early postoperative left ventricular systolic function was better in patients who had a flexible ring than in patients who had a rigid ring. Two years after surgery there were no differences between these groups and most patients were found to have fairly normal left ventricular function. The long term results of mitral valve repair in 184 patients revealed a 10-year actuarial survival of 86% +/- 6%. A randomized trial on the effect of preservation of chordae tendineae during mitral valve replacement revealed that the beneficial effect of this procedure on left ventricular function is a lasting one; five years after surgery patients who had mitral valve replacement with preservation of the chordae tendineae have better exercise capacity, and better left ventricular systolic function and performance. The long term results of mitral valve replacement in 154 patients revealed a 10-year actuarial survival of 69% +/- 5%. Logistic regression analysis indicated that age greater than 65 years and complete excision of the native mitral valve were predictors of late mortality. Of those patients, 70 had had chordal preservation during surgery and 84 did not. These two subgroups were remarkably similar preoperatively, but the 10-year actuarial survival was 80% +/- 6% for patients who had chordal preservation and 63% +/- 6% for those who did not. The mitral valve should be repaired whenever possible; if replacement is necessary it should be performed with preservation of the chordae tendineae.

An intron facilitates activation of the calspermin gene by the testis-specific transcription factor CREM tau

Calspermin is a high affinity Ca2+/calmodulin binding protein that is found only in postmeiotic male germ cells. Our previous studies have shown that the calspermin transcript is produced by utilization of a testis-specific promoter located within an intron of the calmodulin kinase IV gene. This promoter contains two cAMP response element-like motifs that bind the testis-specific transcription factor CREM tau. This interaction is required for transcriptional activation. Here we describe a novel regulatory element, the 111-base pair first intron of the calspermin gene, which is also required for enhancement of transcription by CREM tau via the cAMP response element motifs. Deletion or inversion of this intron results in loss of CREM tau-mediated stimulation of transcription. However, CREM tau stimulates calspermin promoter activity when the intron is moved upstream of the promoter but only when inserted in the proper orientation. Footprint, linker scanning, and deletion analyses were used to identify regulatory elements in the intron. We suggest that the intron functions as an orientation-dependent but position-independent regulatory element to activate the calspermin promoter by facilitating the stimulatory effect of CREM tau on transcription.