Molecular dissection of a cosmid from a gene-rich region in 17q21 and characterization of a candidate gene for alpha-N-acetylglucosaminidase with two cDNA isoforms

A cosmid mapped to human Chromosome (Chr) 17q21, c140c10, was found to contain a CpG island. We completed the sequence analysis of c140c10 because of two considerations: the cosmid contained an STS from the 17-beta-hydroxysteroid dehydrogenase gene (17-HSD), which was believed to be a neighbor of the breast cancer susceptibility gene, BRCA1; CpG islands are usually associated downstream and/or upstream of human genes. Computer-based exon trapping of the cosmid sequence revealed putative additional exons. With two of those exons used as a probe to screen human placental cDNA libraries, two cDNA isoforms for a novel gene, designated as ufHSD, were isolated. The amino acid sequence of the open reading frames of the cDNA showed no significant homology to any protein in the data base. However, it is possible that our cDNAs are from the gene for alpha-acetylglucosaminidase, which has recently been localized to the same region. Northern analyses show that the major isoform is expressed in all tissues tested, with the highest expression in blood leukocytes and lowest in brain. Finally, our study has shown that the 46.7-kb cosmid c140c10 encompasses loci for five genes and pseudo-genes: PsiPTP4A, ufHSD, 17-HSDI, 17-HSDII, and 22A1.

Replacement of chordae tendineae with Gore-Tex sutures: a ten-year experience

BACKGROUND AND AIMS OF THE STUDY

Expanded polytetrafluoroethylene sutures have been used for the replacement of chordae tendineae of the mitral valve since 1985 at The Toronto Hospital. This study examines the long term results of mitral valve repair with chordal replacement with this material.

MATERIALS AND METHODS

From July 1985 to December 1993, 134 consecutive patients with mitral regurgitation due to degenerative disease of the mitral valve underwent mitral valve repair with replacement of elongated or ruptured chordae tendineae with one to six (mean of 2.8) Gore-Tex sutures. The patients' mean age was 61 years, range 22-86. In addition to mitral valve repair, 14 patients underwent aortic valve surgery, three underwent replacement of the ascending aorta, six underwent tricuspid valve repair, nine underwent the maze procedure for atrial fibrillation, and 13 underwent coronary artery bypass. The patients were followed for between 20 and 116 months, mean 51 months. No patient has been lost to follow up.

RESULTS

There were one operative and eight late deaths. The actuarial survival at eight years was 88% +/- 6%. Four patients required reoperation, one for persistent hemolysis and three for recurrent mitral regurgitation. The Gore-Tex chordae were not responsible for the reoperation in any patient. The freedom from reoperation at eight years was 96% +/- 2%.

CONCLUSIONS

Expanded polytetrafluoroethylene sutures are excellent for chordal replacement during mitral valve repair and do not fail during the first decade following surgery. This material has allowed us to increase the probability of successful mitral valve repair in patients with degenerative disease of the mitral valve and prolapse of both leaflets.

[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.

The Hancock II bioprosthesis at ten years

The Hancock II bioprosthesis was used for heart valve replacement in 843 patients from 1982 to 1993. Aortic valve replacement (AVR) was performed in 536 patients, mitral valve replacement (MVR) in 250, and aortic and mitral valve replacement (DVR) in 57. The mean age was 64 +/- 12 years. Before operation, 80% of the patients were in New York Heart Association functional class III or IV; approximately one-third of the patients had coronary artery disease, and 60 patients had ascending aorta aneurysm. There were 47 operative deaths (AVR, 4%; MVR, 7%; DVR, 10%) and 147 late deaths. Follow-up was complete in 98.6% of the patients and extended from 3 to 140 months (mean, 59 months). At the last follow-up, 84% of the patients were in New York Heart Association class I or II. The actuarial survival at 10 years was 63% +/- 4% for AVR, 55% +/- 5% for MVR, and 53% +/- 9% for DVR. At the end of 10 years, the freedom from thromboembolic complications was 80% +/- 4% for AVR, 88% +/- 3% for MVR, and 86% +/- 5% for DVR; the freedom from endocarditis was 95% +/- 2% for AVR, 96% +/- 1% for MVR, and 87% +/- 5% for DVR; the freedom from primary tissue failure was 92% +/- 3% for AVR, 81% +/- 6% for MVR, and 65% +/- 16% for DVR; and the freedom from reoperation was 89% +/- 2% for AVR, 81% +/- 6% for MVR, and 61% +/- 15% for DVR. The durability of this bioprosthetic valve was affected by the patient's age and by the position where it was implanted. The clinical results of the Hancock II bioprosthesis at 10 years are comparable to those of other current porcine and pericardial valves.

In vitro reaction of macrophages to metal ions from dental biomaterials

OBJECTIVES

This study was conducted to 1) measure the sensitivity of human and mouse macrophages to metal ions which are released from dental biomaterials, 2) compare these sensitivities with those of other cell types in the oral cavity, and 3) determine if metal ions alter the metabolism and synthetic processes of these cells at lower concentrations than are required to lyse the cells. This information will help define the biological risks associated with the release of metal ions into the oral cavity.

METHODS

Macrophages were exposed to a range of concentrations of Ag1+, Au3+, Cu2+, Hg2+, Ni2+, Pd2+, Pt4+, and Zn2+ for 24 h in cell culture. The concentrations which caused a 50% decrease in succinic dehydrogenase (SDH) activity, protein production, and lactate dehydrogenase (LDH) release were measured and compared with these values for fibroblasts and osteoblasts.

RESULTS

Most metal ions caused alteration in SDH activity and protein production at lower concentrations than were required to induce LDH release. There were exceptions to this trend, and the differences were not always statistically significant. Furthermore, although the macrophages sometimes had statistically different sensitivities to metal ions than fibroblasts or osteoblasts, these differences were less than one order of magnitude. Macrophage response to the metal ions was highly dependent on the metal ion and the species of macrophage.

SIGNIFICANCE

Macrophages react adversely to metal ions at similar concentrations as other cell types found in the oral cavity. Furthermore, the concentrations which affect cell metabolism and protein production are generally lower than those which lyse the cells. Thus, non-lethal concentrations of metal ions may alter the secretion of protein inflammatory mediators such as cytokines which direct the inflammatory response in tissues.

Follow up of patients after valvular surgery: mail vs. telephone

A study was undertaken to compare the results of patient follow up done by mail and by telephone. Using valve follow up questionnaires recently received by mail, 100 patients were randomly selected from this group for further follow up by telephone. Interviews were conducted while blinded to the mail response. Patients were questioned as to their functional status (NYHA), improvement as a result of surgery (IMP), incidence of reoperation (REOP) or bacterial endocarditis (SBE) and thromboembolic complications (TE). They were also asked whether they would prefer future follow up by mail or telephone. Analysis using the kappa coefficient and McNemar's test revealed a difference (p < 0.001) in NYHA when comparing mail and telephone responses but no difference in either IMP or TE. There was no incidence of REOP or SBE. Sixty-six percent of patients had no preference in type of future follow up and of the remaining 33%, two-thirds preferred to be contacted by phone. It appears that NYHA is significantly overestimated by the patient whereas the two methods of follow up are comparable when assessing IMP and TE. It should be noted, however, that patients seem to have difficulty in identifying the occurrence of TE and in differentiating between stroke and TIA.

The Role of Pea Chloroplast [alpha]-Glucosidase in Transitory Starch Degradation

Pea chloroplastic [alpha]-glucosidase (EC 3.2.1.20) involved in transitory starch degradation was purified to apparent homogeneity by ion exchange, reactive dye, hydroxylapatite, hydrophobic interaction, and gel filtration column chromatography. The native molecular mass and the subunit molecular mass were about 49.1 and 24.4 kD, respectively, suggesting that the enzyme is a homodimer. The enzyme had a Km of 7.18 mM for maltose. The enzyme's maximal activity at pH 7.0 and stability at pH 6.5 are compatible with the diurnal oscillations of the chloroplastic stromal pH and transitory starch accumulation. This pH modulation of the [alpha]-glucosidase's activity and stability is the only mechanism known to regulate starch degradative enzymes in leaves. Although the enzyme was specific for the [alpha]-D-glucose in the nonreducing end as the glycon, the aglycon moieties could be composed of a variety of groups. However, the hydrolysis rate was greatly influenced by the aglycon residues. Also, the enzyme could hydrolyze glucans in which carbon 1 of the glycon was linked to different carbon positions of the penultimate glucose residue. The ability of the [alpha]-glucosidase to hydrolyze [alpha]-1,2- and [alpha]-1,3-glucosidic bonds may be vital if these bonds exist in starch granules because they would be barriers to other starch degradative enzymes. This purified pea chloroplastic [alpha]-glucosidase was demonstrated to initiate attacks on native transitory chloroplastic starch granules.

[Protective effect of total flavonoids of radix Astragali on mammalian cell damage caused by hydroxyl radical]

The protective effect of total flavonoids of Radix Astragali (TFA) on V79 cell damage caused by H2O2-Fe2+ system has been studied. The results show that total flavonoids of Radix Astragali inhibit lipid peroxides and increase SOD activity. It has also been found that TFA has different protective effect against various damages of V79 cells caused by hydroxyl radical.

[The human fetal development time table of the major limb bones-ultrasonic bone age]

B-ultrasonic technique was used to examine 297 Chinese fetuses in normal pregnancy woman of completed week age from 12 to 38 weeks. The lengths of the major limb bones were measured and statistical analysis showed that the positive linear correlation between the development of fetuses' limb bones and the completed fetal age is significant.

Aberrant cell cycle inhibition pattern in human colon carcinoma cell lines after exposure to 5-fluorouracil

In this report, we describe the use of two human colon carcinoma cell lines, HCT-8 and HT-29, as potential models to study DNA- and RNA-directed cytotoxicity due to 5-fluorouracil (FUra) exposure by flow microfluorimetric analysis of DNA cell content. The sensitivity of the HT-29 line (EC50 = 0.9 microM) to FUra was somewhat greater than that of the HCT-8 line (EC50 = 4 microM), but each presented a dramatically different DNA histogram after exposure to FUra. In HCT-8, an unexpected and nearly complete disappearance of cells in S-phase occurred, whereas in HT-29 the expected accumulation of cells at the G1-S border was observed. The absence of HCT-8 cells in S-phase also occurred as a result of two RNA polymerase inhibitors: actinomycin D and dichloro-D-ribofuranosylbenzimidazole. However, an accumulation of cells in S-phase was observed in the presence of 5-fluorodeoxyuridine. These results suggest that in the HCT-8 cell line, FUra predominantly causes an RNA-related toxicity. By comparison, the rate of formation of 5-fluorodeoxyuridine monophosphate, the increased dUMP pool size, and low thymidylate synthase activity in the HT-29 line are consistent with its greater susceptibility to DNA-directed toxicity. Further evidence was seen in the prevention of FUra cytotoxicity by thymidine in HT-29, but not in HCT-8 cells. Similarly, Leucovorin synergized the action of FUra in HT-29 but not in HCT-8. Enzymatic correlates supporting these observations are seen in the greater activity of uridine kinase than thymidine kinase (20:1) in HCT-8 cells compared with that in HT-29 cells (4:1).

Identification and characterization of a functional promoter region in the human eosinophil IL-5 receptor alpha subunit gene

The molecular basis for the commitment of multipotential myeloid progenitors to the eosinophil lineage, and the transcriptional mechanisms by which eosinophil-specific genes are subsequently expressed and regulated during eosinophil development are currently unknown. Interleukin-5 (IL-5) is a T cell and mast cell-derived cytokine with actions restricted to the eosinophil and closely related basophil lineages in humans. The high affinity receptor for IL-5 (IL-5R) is composed of an alpha subunit (IL-5R alpha) expressed by the eosinophil lineage, that associates with a beta c subunit shared with the receptors for IL-3 and granulocyte-macrophage colony stimulating factor (GM-CSF). As a prerequisite to studies of the transcriptional regulation of the IL-5R alpha subunit gene, we used three different methods, including primer extension, RNase protection, and 5'-RACE to precisely map the transcriptional start site to a position 15 base pairs (bp) upstream of the 5' end of the published sequence of IL-5R alpha exon 1. To initially identify the IL-5R alpha promoter, 3.5 kilobases (kb) and 561 bp of the 5' sequence flanking the transcriptional start site were subcloned into the promoterless pXP2-luciferase vector. Transient transfection of these constructs into an eosinophil-committed HL-60 subline, clone HL-60-C15, induced the expression of approximately 240-fold greater luciferase activity than the promoterless vector, identifying a strong functionally active promoter region within the 561 bp of sequence proximal to the transcriptional start site and with activity equivalent to pXP2 constructs containing the entire 3.5 kb of upstream sequence. To more precisely localize the cis-acting regulatory elements in this region important for promoter activity, a series of 5' deletion mutants of the 561-bp region were generated in the pXP2-luciferase vector. Deletion of the region between bp -432 and -398 reduced promoter activity by more than 80% in the HL-60-C15 cell line. Further analyses of the activity of the IL-5R alpha promoter constructs in various other eosinophil, myeloid, and non-myeloid cell lines indicated that the promoter was relatively myeloid and eosinophil lineage-specific in its expression. Consensus sequences for known transcription factor binding sites were not present in the 34-bp region of the promoter required for maximal activity, suggesting unique myeloid- and possibly eosinophil-specific regulatory elements.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of renal denervation on elevation of blood pressure in cold-exposed rats

The objective of this experiment was to determine whether bilateral renal denervation (RD) prevents the elevation of blood pressure and cardiac hypertrophy characteristically induced by chronic exposure to cold. Four groups (nine male rats each) were used. The kidneys of two groups were bilaterally denervated, while the remaining two groups were sham operated. Systolic blood pressures of the four groups, measured indirectly from the tail, did not differ significantly during the control period and following RD. At this time, 1 RD and 1 sham-operated group was exposed to cold (5 degrees C, 41 degrees F). The remaining RD and sham-operated groups were kept at 25 degrees C. Blood pressure of the cold-exposed, sham-operated group increased significantly during the 1st week of cold exposure (125 +/- 2 mmHg; 1 mmHg = 133.3 Pa), and rose to 139 +/- 4 mmHg by the 5th week, whereas the blood pressure of the RD group exposed to cold remained at the control level (116 +/- 2 mmHg). Both RD and sham-operated cold-exposed groups developed cardiac hypertrophy with significantly increased resting heart rates compared with controls kept at 25 degrees C. Plasma renin activities and renal norepinephrine content of kidneys of both RD groups at 7 weeks after RD were significantly less than those of sham-operated controls, confirming that renal nerves had been severed. Thus, RD prevented the elevation of blood pressure induced by chronic exposure to cold but had no significant effect on cardiac hypertrophy.

Calspermin gene transcription is regulated by two cyclic AMP response elements contained in an alternative promoter in the calmodulin kinase IV gene

The transcript for the high-affinity Ca2+/calmodulin-binding protein calspermin is generated from the gene encoding Ca2+/calmodulin-dependent protein kinase IV only in postmeiotic germ cells during spermatogenesis. We demonstrate that this testis-specific calspermin transcript can be produced in heterologous cells by utilization of a promoter located in an intron of the calmodulin (CaM) kinase IV gene. Critical motifs within this promoter are two cyclic AMP response element (CRE)-like sequences located about -70 and -50 bp upstream of the transcriptional initiation site. Both CRE motifs are footprinted by the authentic testis-specific transcriptional activator CREM tau or by CREM tau present in adult testis nuclear extract. Whereas a 2.1-kb DNA fragment containing the calspermin promoter is inactive when transfected into NIH 3T3 cells, activity can be restored by cotransfection of CREM tau and protein kinase A or CaM kinase IV but not CaM kinase II alpha. Restoration of activity is greatly reduced by mutation of the two CRE motifs. Since CRE-like motifs have been identified in many genes uniquely expressed in postmeiotic germ cells, which contain abundant CREM tau protein, we suggest that CREM tau may function as one transcription factor responsible for the expression of postmeiotic germ cell-specific genes.

Effect of chronic treatment with prazosin and L-arginine on the elevation of blood pressure during cold exposure

Chronic exposure to cold (5 degrees C) is well known to increase both tyrosine hydroxylase (TH) activity in brown adipose tissue and systemic blood pressure. The effect of chronic dietary administration of the alpha-adrenergic antagonist, prazosin, and the amino acid, L-arginine, on both the elevation of blood pressure during exposure to cold and on TH activity and expression of TH mRNA in the adrenal glands of rats was studied. As observed previously, chronic exposure to cold increased systolic blood pressure significantly and induced cardiac hypertrophy. Chronic dietary treatment with prazosin (8 mg/kg food) and arginine (20 g/kg food) returned blood pressure to control levels, did not affect body weight significantly, but failed to prevent cardiac hypertrophy. Both prazosin and L-arginine reduced the drinking response to administration of angiotensin II. Treatment with arginine and prazosin was accompanied by a significant increase in the urinary outputs of dopamine and L-DOPA. The 3 cold-treated groups (control, L-arginine and prazosin) had increases in plasma T3 and decreases in plasma T4 and plasma renin activity. Plasma concentrations of epinephrine and norepinephrine were increased significantly in the L-arginine-treated group. TH mRNA and TH activity in the adrenal glands were increased in the 3 cold-treated groups and these measures were correlated directly and significantly with plasma norepinephrine and epinephrine concentrations. Although both prazosin and arginine prevented the cold-induced elevation of blood pressure, they did not prevent the increase in TH mRNA, TH activity or epinephrine in plasma. The protective effect of arginine and prazosin in cold-induced hypertension may be related both to their reduction in plasma renin activity and to a reduced responsiveness to angiotensin II, as well as to their abilities to increase the secretion of dopamine.

Aortic valve replacement with a stentless porcine aortic valve. A six-year experience

A stentless porcine aortic valve was used for aortic valve replacement in 123 patients from 1987 to 1993. The mean age of 86 men and 37 women was 61 +/- 12 years. Most patients had aortic stenosis; one-third had coronary artery disease and six had mitral valve disease. The stentless valve was secured in the subcoronary position by the same technique used for a freehand aortic valve homograft. The size of valve was based largely on the diameter of the sinotubular junction of the aortic root. The mean valve size was 26.5 mm (range 19 to 29 mm) and 87% were 25 mm or larger. Two operative deaths occurred, one the result of myocardial infarction and the other the result of infective endocarditis. Patients have been followed up from 3 to 77 months, mean 22 months. Three late deaths, none related to the valve, have occurred. The actuarial survival at 6 years was 91% +/- 4%. Four transient cerebral ischemic events have occurred, but two patients had extracranial cerebrovascular disease. One patient had endocarditis late in the postoperative period and required reoperation. All patients had Doppler echocardiographic studies before discharge from the hospital, 3 to 6 months later and annually. Only 15 patients have aortic insufficiency, trivial in 6 and mild in 9. The peak and mean systolic gradients decreased significantly during the first 3 to 6 months after implantation (p < 0.001), and the effective valve areas increased significantly during this time interval (p < 0.001). This improvement in valve hemodynamics is believed to be due to remodeling of the aortic root and regression of left ventricular hypertrophy. The results of aortic valve replacement with this stentless bioprosthesis have been excellent and justify its continued use in older patients.

Late hemodynamic effects of the preserved papillary muscles during mitral valve replacement

BACKGROUND

The late hemodynamic effects of preserving the papillary muscles during mitral valve replacement have not been evaluated.

METHODS AND RESULTS

Sixteen patients who had chronic mitral regurgitation due to myxomatous degeneration were randomized to preservation (Pres group, n = 8) or no preservation (No Pres group, n = 8) of the chordae tendineae and papillary muscles during mitral valve replacement. Rest and exercise nuclear ventriculograms were performed early (3 months) and late (5 years) after surgery. Early after surgery, the No Pres group had lower ejection fractions and stroke work indexes (P < .05 by repeated-measures [rm] ANOVA) than the Pres group did at similar end-diastolic volume indexes. The No Pres group had similar cardiac indexes after exercise because heart rate increased (P < .005 by rm ANOVA). Late after surgery, ejection fraction was greater at similar end-diastolic volume indexes (P < .005 by rm ANCOVA), and preload recruitable stroke work indexes (P < .001 by rm ANCOVA) were better in the Pres group.

CONCLUSIONS

Preserving chordal attachments enhanced the late hemodynamic recovery after mitral valve replacement for mitral regurgitation.

Are patients receiving amiodarone at increased risk for cardiac operations?

Amiodarone therapy has been implicated as a risk factor for cardiothoracic surgical procedures. In patients undergoing map-guided surgical procedures for the treatment of ventricular tachycardia, we compared the perioperative course of those receiving long-term amiodarone therapy (n = 36) versus that in those not receiving the drug (n = 31). The two groups were similar with respect to age, sex, presenting symptoms, functional class, extent of coronary artery disease, presence of a ventricular aneurysm, technique of ventricular tachycardia ablation, cross-clamp or pump time, the number of vessels grafted, the operative fluid balance, and a need for intraaortic balloon pump or inotropic agent support. In 5 patients receiving amiodarone, epinephrine was required to maintain a normal systemic vascular resistance and adequate arterial pressure. Postoperatively, 6 patients (17%) on amiodarone therapy suffered acute respiratory failure. In spite of aggressive therapy, 3 of these patients died. Only 1 patient not receiving amiodarone died of a stroke. We conclude that amiodarone therapy in patients undergoing open heart operations is associated with an increased risk of severe pulmonary complications (p = 0.03 by Fisher's exact test). Amiodarone therapy should be withheld in patients with ventricular tachycardia until they have been assessed as candidates for possible surgical intervention.

[Construction of human glioma cDNA library]

Total RNA from a human glioma was extracted by acid guanidinium-thiocyanate-chloroform one step method, and poly(A+)RNA was separated by affinity chromatography on oligo (dT) cellulose. The cDNA was synthesized by using poly (A+) RNA as template, the length of cDNA being 0.2-5 kb. The glioma cDNA inserts could be cloned into lambda gt11 vector, the resulting recombinant DNA was packaged in vitro. The cDNA library of 1.12 x 10(5) pfu/ml was obtained, and the cloning efficiency was 4.8 x 10(3)/ng cDNA. This library might contribute an important basis to study of the structure and function of human glioma genes.

Molecular structure and enzymatic function of lycopene cyclase from the cyanobacterium Synechococcus sp strain PCC7942

A gene encoding the enzyme lycopene cyclase in the cyanobacterium Synechococcus sp strain PCC7942 was mapped by genetic complementation, cloned, and sequenced. This gene, which we have named crtL, was expressed in strains of Escherichia coli that were genetically engineered to accumulate the carotenoid precursors lycopene, neurosporene, and zeta-carotene. The crtL gene product converts the acyclic hydrocarbon lycopene into the bicyclic beta-carotene, an essential component of the photosynthetic apparatus in oxygen-evolving organisms and a source of vitamin A in human and animal nutrition. The enzyme also converts neurosporene to the monocyclic beta-zeacarotene but does not cyclize zeta-carotene, indicating that desaturation of the 7-8 or 7'-8' carbon-carbon bond is required for cyclization. The bleaching herbicide 2-(4-methylphenoxy)triethylamine hydrochloride (MPTA) effectively inhibits both cyclization reactions. A mutation that confers resistance to MPTA in Synechococcus sp PCC7942 was identified as a point mutation in the promoter region of crtL. The deduced amino acid sequence of lycopene cyclase specifies a polypeptide of 411 amino acids with a molecular weight of 46,125 and a pI of 6.0. An amino acid sequence motif indicative of FAD utilization is located at the N terminus of the polypeptide. DNA gel blot hybridization analysis indicated a single copy of crtL in Synechococcus sp PCC7942. Other than the FAD binding motif, the predicted amino acid sequence of the cyanobacterial lycopene cyclase bears little resemblance to the two known lycopene cyclase enzymes from nonphotosynthetic bacteria. Preliminary results from DNA gel blot hybridization experiments suggest that, like two earlier genes in the pathway, the Synechococcus gene encoding lycopene cyclase is homologous to plant and algal genes encoding this enzyme.

Functional characterization of the promoter for the gene encoding human eosinophil peroxidase

The molecular basis for commitment of progenitors to the eosinophil lineage and mechanisms by which eosinophil-specific genes are expressed and regulated during differentiation is unknown. Expression of eosinophil peroxidase (EPO) is restricted to the eosinophil lineage. To understand the mechanisms involved in transcriptional regulation of EPO gene expression, we clone the region of the EPO gene upstream of the transcriptional start site and analyzed the cis-acting elements required for EPO promoter activity in an eosinophil-inducible leukemic cell line, HL-60-C15. The 5'-flanking region of the EPO gene containing 1.5 kilobases of sequence upstream of the transcriptional start site was subcloned into the promoterless pXP2-luciferase vector. The EPO-pXP2 construct and 5' deletion mutants were electroporated into HL-60-C15 cells and luciferase reporter activity assessed. The -1.5-kilobase EPO-pXP2 promoter construct reproducibly expressed > 120-fold more luciferase activity than did promoterless pXP2, and a 12-fold (90%) decrease in promoter activity was obtained when sequences between -122 and -45 base pairs (bp) were deleted. The specificity of the EPO promoter for the eosinophil lineage was analyzed by transfecting the EPO-pXP2 constructs and deletion mutants into HL-60-C15 cells and the parental HL-60 line; EPO promoter activity was 8-10-fold less in the HL-60 parental line, suggesting lineage specific elements in the -122 to -45 bp region. To further characterize regulatory sequences important for promoter activity, we performed linker-scanning analysis on the -122 to -45 bp region and identified a number of positively and negatively acting elements in the promoter. DNase I footprinting was performed with HL-60-C15, HL-60, and HeLa nuclear extracts to identify nuclear proteins that may bind to the functional elements; these experiments identified three protected regions of the EPO promoter which correspond to the functional segments defined by linker-scanning analysis and which contain consensus, potential binding sites for Egr-1, H4TF-1, PuF, CTCF, UBP-1, and GaEII transcription factors. Further study of EPO promoter regulation should elucidate unique transcriptional features of eosinophil gene regulation in granulocyte development.

Trends in elastomeric impression materials

In the past three years more addition silicones have been supplied as hydrophilic materials and heavier viscosities have been provided in automatic mixing cartridges. Also, a polyether is now supplied in an automatic mixing system. There has been an increase in the number of products available as monophase or single viscosity systems. Both addition silicones and polyethers are available as bite registration materials.

Down syndrome phenotypes: the consequences of chromosomal imbalance

Down syndrome (DS) is a major cause of mental retardation and congenital heart disease. Besides a characteristic set of facial and physical features, DS is associated with congenital anomalies of the gastrointestinal tract, an increased risk of leukemia, immune system defects, and an Alzheimer-like dementia. Moreover, DS is a model for the study of human aneuploidy. Although usually caused by the presence of an extra chromosome 21, subsets of the phenotypic features of DS may be caused by the duplication of small regions of the chromosome. The physical map of chromosome 21 allows the molecular definition of the regions duplicated in these rare cases of partial trisomy. As a first step in identifying the genes responsible for individual DS features and their pathophysiology, a panel of cell lines derived from 16 such individuals has been established and the molecular break points have been determined using fluorescence in situ hybridization and Southern blot dosage analysis of 32 markers unique to human chromosome 21. Combining this information with detailed clinical evaluations of these patients, we have now constructed a "phenotypic map" that includes 25 features and assigns regions of 2-20 megabases as likely to contain the genes responsible. This study provides evidence for a significant contribution of genes outside the D21S55 region to the DS phenotypes, including the facies, microcephaly, short stature, hypotonia, abnormal dermatoglyphics, and mental retardation. This strongly suggests DS is a contiguous gene syndrome and augurs against a single DS chromosomal region responsible for most of the DS phenotypic features.

Effect of cell line on in vitro metal ion cytotoxicity

OBJECTIVES

The choice of cell line for in vitro biological tests which assess the cytotoxicity of dental materials remains controversial, yet this issue is important because these tests are widely used to rate the biocompatibility of new and existing materials, and many different cell lines are commonly used. The purpose of the current study was to quantify the responses of four cell lines (Balb/c 3T3, L929, ROS 17/2.8 and WI-38) to 14 metal ions which are released from dental materials, and relate these responses to the metabolic activity and population doubling times of these cells.

METHODS

Succinic dehydrogenase (SDH) activity was used to monitor metabolic activity and cytotoxic response.

RESULTS

The cell lines responded differently to most metal ions. In general, the Balb/c 3T3 line was the most sensitive, and the WI-38 line was the least sensitive. However, there were many exceptions depending on the metal ion. The passage number of the cells also affected the cytotoxic response. It was concluded that the cytotoxicity of materials which release metal ions will be significantly different depending on which cell line is selected and its passage number.

SIGNIFICANCE

Based on the findings that cell lines ranked the toxicities of the metal ions similarly, it seems reasonable to use these types of in vitro tests to rank the cytotoxicities of materials. However, if these types of tests are used to predict in vivo cytotoxicity, care should be taken to choose conditions and cells which are relevant.