Trauma mannequin assessment of management skills of surgical residents after advanced trauma life support training

BACKGROUND

We tested the effectiveness of Advanced Trauma Life Support (ATLS) training among surgical residents using a specially designed mannequin.

MATERIALS AND METHODS

Thirty-two Postgraduate Year I surgical residents were randomly assigned to two groups of 16 each. By use of a trauma mannequin, the 32 residents' performances were scored using four trauma scenarios before 16 residents (ATLS group) completed a standard ATLS course. Performances were also scored after the ATLS course on another four trauma scenarios. The scores were standardized to a maximum of 20 for each scenario. Organized Approach scores with a range of 1 to 5, Priority scores ranging from 1 to 7, and global ratings of Honors, Pass, Borderline, or Fail were assigned for each clinical scenario.

RESULTS

The pre-ATLS assessment scores were similar for both groups ranging between 9.4 +/- 3.5 and 11.4 +/- 2.9 for the ATLS group and between 10.2 +/- 3.8 and 11.4 +/- 3.9 for the non-ATLS group. The ATLS group scores ranged from 16.0 +/- 1.3 to 17.4 +/- 3.1 after the course and the non-ATLS group scores ranged from 11.4 +/- 4.2 to 12.9 +/- 4.0 (P < 0.05). Pre-ATLS Organized Approach scores were 2.9 +/- 1.0 and 2.7 +/- 1.1 (NS) for the ATLS and non-ATLS groups, respectively, with post-ATLS scores being significantly higher in the ATLS group (4.9 +/- 1.2 compared with 2.8 +/- 1.2 for the non-ATLS group, P < 0. 05). Initial Priority scores were also similar for both groups (3.2 +/- 1.4 for the ATLS group and 3.3 +/- 2.0 for the non-ATLS group). Post-ATLS Priority scores were significantly higher (6.4 +/- 1.4) in the ATLS group compared with 4.2 +/- 1.9 for the non-ATLS group (P < 0.05). The pre-ATLS global ratings were similar for both groups and post-ATLS there were 10 Honors ratings in the ATLS group and none for the control group.

CONCLUSIONS

Using a trauma mannequin, for assessment, surgical residents completing the ATLS course demonstrated superior resuscitation skills compared with a non-ATLS group.

Forskolin-induced apical membrane insertion of virally expressed, epitope-tagged CFTR in polarized MDCK cells

Channel gating of the cystic fibrosis transmembrane conductance regulator (CFTR) is activated in response to cAMP stimulation. In addition, CFTR activation may also involve rapid insertion of a subapical pool of CFTR into the plasma membrane (PM). However, this issue has been controversial, in part because of the difficulty in distinguishing cell surface vs. intracellular CFTR. Recently, a fully functional, epitope-tagged form of CFTR (M2-901/CFTR) that can be detected immunologically in nonpermeabilized cells was characterized (Howard M, Duvall MD, Devor DC, Dong J-Y, Henze K, and Frizzell RA. Am J Physiol Cell Physiol 269: C1565-C1576, 1995; and Schultz BD, Takahashi A, Liu C, Frizzell RA, and Howard M. Am J Physiol Cell Physiol 273: C2080-C2089, 1997). We have developed replication-defective recombinant adenoviruses that express M2-901/CFTR and used them to probe cell surface CFTR in forskolin (FSK)-stimulated polarized Madin-Darby canine kidney (MDCK) cells. Virally expressed M2-901/CFTR was functional and was readily detected on the apical surface of FSK-stimulated polarized MDCK cells. Interestingly, at low multiplicity of infection, we observed FSK-stimulated insertion of M2901/CFTR into the apical PM, whereas at higher M2-901/CFTR expression levels, no increase in surface expression was detected using indirect immunofluorescence. Immunoelectron microscopy of unstimulated and FSK-stimulated cells confirmed the M2-901/CFTR redistribution to the PM upon FSK stimulation and demonstrates that the apically inserted M2-901/CFTR originates from a population of subapical vesicles. Our observations may reconcile previous conflicting reports regarding the effect of cAMP stimulation on CFTR trafficking.

The left atrial appendage: our most lethal human attachment! Surgical implications

OBJECTIVES

To prevent death from atrial fibrillation, a cardiac disease which kills by producing emboli. Atrial fibrillation causes about 25% of strokes and increases stroke rate by five times. Over 90% of these embolic strokes are from clots originating in the left atrial appendage. This study addresses the surgical feasibility of removing the appendage to prevent future deaths in two subcategories of patients. (1) Prophylactic removal during open-heart surgery to study its safety. Theoretically, as these patients age and some develop atrial fibrillation, protection from embolic strokes would already be present. (2) Therapeutic removal in chronic atrial fibrillation patients by means of a thorascopic approach. Its technical feasibility is demonstrated. Its actual stroke prevention potential awaits large studies.

METHODS

Appendectomy has been evaluated three ways. (1) Experimentally, thorascopic appendage removal was performed on 20 goats with endoscopic approach. Late studies showed a cleanly healed atrial closure after stapling, and no puckering of tissue as seen with the purse-string approach. (2) Safety of human appendectomy was demonstrated in 437 patients (1995-1997). Routine appendectomy was performed during open-heart surgery. Forty-three appendages were stapled, 391 sutured off. (3) Thorascopic appendectomy in seven patients with chronic atrial fibrillation has been successfully accomplished as an isolated surgical procedure. Stapling or suture closure provides a much cleaner, non-puckered suture line than a purse string.

RESULTS

In prophylactic removal, no acute bleeding occurred. No late problems have been identified. Endoscopic removal of the appendage has been successful in seven atrial fibrillation patients.

CONCLUSIONS

The left atrial appendage is a lethal source of emboli in atrial fibrillation patients. As patients age and often develop atrial fibrillation, prophylactic appendage removal whenever the chest is open is suggested as a method to prevent future strokes. In chronic atrial fibrillation patients, appendectomy can be done with a mini-thorascopic approach. Further studies are planned to demonstrate the effectiveness of appendectomy in preventing strokes in the chronic fibrillating patients.

Characterization of mucins from cultured normal human tracheobronchial epithelial cells

Early-passage normal human tracheobronchial epithelial (NHTBE) cells grown in air-liquid interface cultures in medium containing retinoids differentiate into a mucociliary epithelium over a 2- to 3-wk period and express increasing mRNA levels of the airway mucin genes MUC5AC and MUC5B as the cultures age; the levels of MUC2 mRNA were very low throughout the study. Using specific antibodies to MUC5AC and MUC5B mucins, we noted a gradual increase in these two mucins in the intracellular and apically secreted pools as a function of time. A low level of MUC2 mucin was detected, which did not change with time. The intracellular and apically secreted mucins isolated from day 14 and day 21 cultures by density gradient centrifugation were similar in density to those previously isolated from human respiratory mucus secretions. The sedimentation rate of the apically secreted mucins indicated that they were highly oligomerized, polydisperse macromolecules similar to those previously documented from in vivo secretions. In contrast, the cell-associated mucins from the cultured NHTBE cells were much smaller, possibly only monomers and dimers. Anion-exchange chromatography detected no differences in charge density between the reduced and carboxymethylated cell-associated and secreted forms of the MUC5AC and MUC5B mucins. The MUC5AC mucin was of similar charge density to its in vivo counterpart; however, MUC5B was more homogeneous than that found in vivo. Finally, evidence is presented for an intracellular NH(2)-terminal cleavage of the MUC5B mucins. These studies indicate that the mucins produced by cultured NHTBE cells are similar to those found in human airways, suggesting that this cell culture model is suited for studies of respiratory mucin biosynthesis, processing, and assembly.

Early myeloid cells are high producers of nitric oxide upon CD40 plus IFN-gamma stimulation through a mechanism dependent on endogenous TNF-alpha and IL-1alpha

Bone marrow contains nonadherent low-density wheat germ agglutinin-positive (Fr3-WGA(+)) cells that release large amounts of NO and show natural suppressor activity if stimulated with activated T cells. We have assessed the involvement of CD40-derived signals in NO production and their cytokine requirements. Production of NO by Fr3-WGA(+) cells in co-culture with activated T cells is inhibited by a competing CD40 soluble fusion protein. Fr3-WGA(+) cells express the inducible NO synthase (iNOS) and release NO following CD40 plus IFN-gamma activation. Production of NO through CD40 is strictly dependent on endogenous TNF-alpha and / or IL-1alpha, since it is inhibited by neutralizing these cytokines or blocking the TNF receptor (p55). Both cytokines are transcribed when Fr3-WGA(+) cells are stimulated by CD40 signaling plus IFN-gamma, although TNF-alpha remains below detection limits in stimulated Fr3-WGA(+) cell cultures. Phenotypic studies combined with data on intracellular iNOS expression and cell sorting indicate that NO-producing cells are CD40, CD31 (ER-MP12), CD11b (Mac-1)low, ER-MP20 (Ly-6C) and Gr-1 (Ly-6G) positive, consistent with myeloid progenitors. The results point to early myeloid cells as an important cell source of NO once triggered by activated T cells through CD40 and IFN-gamma-derived signals, in a mechanism involving the production of TNF-alpha and / or IL-1alpha.

Cyclin D2 is essential for BCR-mediated proliferation and CD5 B cell development

Progression into G(1) in B lymphocytes is regulated by cyclins D2 and D3, components of the cell cycle machinery currently believed to have overlapping and potentially redundant roles in cell cycle control. To study the specific role of cyclin D2 in B lymphocyte proliferation, we examined B cells from cyclin D2(-/-) mice and demonstrate a specific requirement for cyclin D2 in BCR- but not CD40- or lipopolysaccharide-induced proliferation. Furthermore, conventional B cell development proceeds normally in the mutant mice; however, the CD5 B cell compartment is dramatically reduced, suggesting that cyclin D2 is important in CD5 B cell development as well as antigen-dependent B cell clonal expansion.

Physical characterization of the MUC5AC mucin: a highly oligomeric glycoprotein whether isolated from cell culture or in vivo from respiratory mucous secretions

We have isolated the high-M(r) mucins from growth medium of the early stage of an HT-29 cell culture by gel chromatography and isopycnic density gradient centrifugation. The mucins (buoyant density 1.34-1.44 g/ml) were reactive with an anti-peptide antiserum (MAN-5ACI) raised against a sequence from within the MUC5AC mucin. Similar antisera raised against the MUC2 and MUC5B mucins were not reactive. The MUC5AC reduced-mucin subunits exhibited a homogeneous charge distribution on anion-exchange chromatography, but appeared as two bands, one major and one more minor, after agarose gel electrophoresis. The unreduced mucins had an average M(r) in excess of 40 MDa and were visualized in the electron microscope as large, fine filamentous threads (many microns in length) that after reduction were greatly reduced in size (number average length 570 nm). Agarose gel electrophoresis of unreduced MUC5AC mucins identified a major band just entering the gel with evidence of a 'ladder' of faster-migrating minor bands. Partial reduction of the mucins increased the proportion of the faster bands and at least 16 could be discriminated. M(r) measurements showed that these bands differed by single monomer units. The mucins behaved as very stiff extended structures in solution and this characteristic might explain the poor separation of different-sized oligomers in sedimentation-rate experiments. The cell-culture mucin preparation had similar characteristics of charge and buoyant density to MUC5AC mucins from respiratory secretions in vivo. In addition the MUC5AC mucin from respiratory tract secretions exhibited similar behaviour, reduced and unreduced on agarose gel electrophoresis, indicating that the mucin has a similar molecular phenotype in vivo and in vitro.

African American grandmothers' perceptions of caregiver concerns associated with rearing adolescent grandchildren

In 1996, grandparents were the sole providers of care for 269,000 grandchildren. Research findings indicate that grandmothers are usually the primary caretakers of grandchildren. Previous issues associated with raising grandchildren vary, but usually relate to the grandparents' health, financial concerns, or lack of social support. This qualitative descriptive study was designed to describe African American grandmothers' perceptions about the burdens of raising adolescent grandchildren. Using this approach, the researchers were able to study the richness and diversity of the grandmothers' perceptions. Data were collected from 35 grandmothers through a focus group (n = 7) and during a 4-day intervention research study (n = 28) entitled "Grandmother-Grandchild Health Promotion Program." Numerous concerns were voiced by both groups, but those stated most frequently were associated with the well-being of grandchildren (grandchildren's sexual behavior, potential drug use, and potential risk of encountering violence) and relational conflicts with adult children. Unexpected findings were the absence of stated concerns associated with the grandmothers' financial situation or health. Recommendations for intervention, clinical practice, and research are discussed.

Psychopathology, adversity, and service utilization of young refugees

OBJECTIVE

To investigate the psychopathology, social impairment, adversities, and service utilization of refugee families and their children seeking help at a child and adolescent psychiatry clinic in London.

METHOD

A retrospective case-control study of 30 refugee children and families individually matched with nonrefugee immigrant families and white British families. Case note review was carried out to obtain data on diagnosis, social adjustment, past adversity, exposure to violence, current socioeconomic circumstances, and use of the child and adolescent psychiatric service.

RESULTS

Refugee children tended to have disorders with a psychosocial etiology rather than neurobiological disorders. Refugees had similar levels of social impairment compared with the other groups. Refugees were much more isolated and disadvantaged and had different referral pathways but were not more likely to drop out of treatment prematurely.

CONCLUSIONS

Refugee children and families had been exposed to high levels of adversity. The ability of community agencies to refer families who could use treatment has significant resource implications.

[Myocardial revascularization of the anterior descending artery with the classical technic of mammary anastomosis]

INTRODUCTION AND OBJECTIVES

To establish the results obtained with the classical technique of mammary anastomosis of the anterior descending artery.

MATERIALS AND METHODS

Between January 1982 and July 1997, 154 patients received an anastomosis of the left internal mammary artery to the left anterior descending coronary artery with use of the classical technique (sternotomy and extracorporeal circulation).

RESULTS

There was no operative mortality in our group, nor paraoperational myocardial infarction, nor cephalic vascular accidents. One (0.6%) patient had sternal wound infection, and another (0.6%) required another reoperation for postoperational bleeding. All (100%) were followed-up from 3-183 months (average 64. 4 months). Actuarial global survival at 5, 10 and 15 years was 95.6%+/-2.1; 92.1%+/-4 and 85.5+/- 7.5 respectively, and the actuarial probability of being free from cardiac death was 99%+/-0.9; 99% and 99%. The actuarial probability of being free from myocardial infarction was 99%+/-0.9; 99%+/-0.9 and 99%; and from angina was 95%+/-2.2; 86.9%+/-4.9 and 74.5%+/-12.2 at 5, 10 and 15 years.Finally, the actuarial probability of being free from reoperation was 99%+/-0.9; 99%; 99% and from angioplasty 96.9%+/-1.7; 91.4%+/-4.1; 91.4%+/-4.1 at 5, 10 and 15 years, respectively. The average hospital charges in the last 10% of the patients was U$ 6.200.

CONCLUSIONS

Revascularization of the left anterior descending with the left internal mammary artery and the classical technique (sternotomy and extracorporeal circulation) is a safe, minimal risk, effective, long lasting and cost efficient procedure with excellent results at 10 and 15 years.

Effect of preventive home visits by a nurse on the outcomes of frail elderly people in the community: a randomized controlled trial

BACKGROUND

Timely recognition and prevention of health problems among elderly people have been shown to improve their health. In this randomized controlled trial the authors examined the impact of preventive home visits by a nurse compared with usual care on the outcomes of frail elderly people living in the community.

METHODS

A screening questionnaire identified eligible participants (those aged 70 years or more at risk of sudden deterioration in health). Those randomly assigned to the visiting nurse group were assessed and followed up in their homes for 14 months. The primary outcome measure was the combined rate of deaths and admissions to an institution, and the secondary outcome measure the rate of health services utilization, during the 14 months; these rates were determined through a medical chart audit by a research nurse who was blind to group allocation.

RESULTS

The questionnaire was mailed to 415 elderly people, of whom 369 (88.9%) responded. Of these, 198 (53.7%) were eligible, and 142 consented to participate and were randomly assigned to either the visiting nurse group (73) or the usual care group (69). The combined rate of deaths and admissions to an institution was 10.0% in the visiting nurse group and 5.8% in the usual care group (p = 0.52). The rate of health services utilization did not differ significantly between the 2 groups. Influenza and pneumonia vaccination rates were significantly higher in the visiting nurse group (90.1% and 81.9%) than in the usual care group (53.0% and 0%) (p < 0.001).

INTERPRETATION

The trial failed to show any effect of a visiting nurse other than vastly improved vaccination coverage.

A new visual indicator of chlamydial cervicitis?

OBJECTIVES

To determine the usefulness of endocervical discharge opacity as a risk indicator for chlamydial infection in relation to two acknowledged visual indicators--yellow endocervical discharge and easily induced mucosal bleeding of the cervix.

METHODS

Women from two family planning clinics, a therapeutic abortion clinic, and a university student health clinic (n = 1418 total) consented to a pelvic examination and chlamydia testing, and completed a questionnaire on socio-demographics, sexual behaviour, medical history, and symptoms. A case of chlamydia was defined as positive by culture or blocked enzyme immunoassay in an endocervical swab.

RESULTS

The prevalence of chlamydial infection in the clinics was 6.3%. All three of the visual indicators--yellow endocervical discharge, easily induced bleeding, and opaque cervical discharge--were statistically significantly and independently associated with chlamydial infection (odds ratios 2.8, 2.3, and 2.9 respectively), independent of clinic type. Adjustment for the other visual indicators made little difference to the odds ratios.

CONCLUSION

Opacity of endocervical discharge was at least as important as the other two commonly acknowledged indicators of chlamydial cervicitis--yellow endocervical discharge and easily induced mucosal bleeding of the cervix.

Universal PCR amplification of mouse immunoglobulin gene variable regions: the design of degenerate primers and an assessment of the effect of DNA polymerase 3' to 5' exonuclease activity

Degenerate primers were designed for PCR amplification of unknown mouse immunoglobulin (Ig) light (L) and heavy (H) chain variable (V) genes. Each subgroup of mouse Ig gene sequences [Kabat, E.A., Wu, T. T., Perry, H.H., Gottesman, K.S., Foeller, C., 1991. Sequences of Proteins of Immunological Interest, 5th edn. US Department of Health and Human Services, Public Health Service, NIH.] was analyzed, and highly degenerate primers in the framework one (FR1) region were designed. A single highly degenerate FR1 primer sufficed for the amplification of light chains; for heavy chains, a series of FR1 primers was used. At the same time, we assessed the effect of 3' to 5' exonuclease activity of DNA polymerase on the utilization of these degenerate primers. Using Taq polymerase, which lacks 3' to 5' exonuclease activity, we successfully amplified the Ig VL and VH genes expressed in more than a hundred monoclonal hybridoma cell lines reactive against a phosphonamidate hapten. Sequence analysis of the cloned VL and VH genes, 52 of each, showed that they are derived from multiple germline families (10 of the 17 VL families and 9 of the 14 VH families) as recently defined [Martinez, C., Lefranc, M., 1998. The mouse (Mus musculus) immunoglobulin kappa variable (IGKV) genes and joining (IGKJ) segments. Exp. Clin. Immunogenet. 15, 184.]. The universality of our primers was also demonstrated by successful amplification of other mouse hybridoma cell lines that are specific to different antigens.

Surface critical behavior in systems with nonequilibrium phase transitions

We study the surface critical behavior of branching-annihilating random walks with an even number of offspring (BARW) and directed percolation (DP) using a variety of theoretical techniques. Above the upper critical dimensions d(c), with d(c)=4 (DP) and d(c)=2 (BARW), we use mean field-theory to analyze the surface phase diagrams using the standard classification into ordinary, special, surface, and extraordinary transitions. For the case of BARW, at or below the upper critical dimension d</=d(c), we use field theoretic methods to study the effects of fluctuations. As in the bulk, the field-theory suffers from technical difficulties associated with the presence of a second critical dimension. However, we are still able to analyze the phase diagrams for BARW in d=1 and 2, which turn out to be very different from their mean field analog. Furthermore, for the case of BARW only (and not for DP), we find two independent surface beta(1) exponents in d=1, arising from two distinct definitions of the order parameter. Using an exact duality transformation on a lattice BARW model in d=1, we uncover a relationship between these two surface beta(1) exponents at the ordinary and special transitions. Many of our predictions are supported using Monte Carlo simulations of two different models belonging to the BARW universality class.

Expression of HAND gene products may be sufficient for the differentiation of avian neural crest-derived cells into catecholaminergic neurons in culture

Members of the basic helix-loop-helix family of DNA binding proteins have important roles in the development of subpopulations of neural crest-derived neurons. We have cloned the chicken homologues of dHAND (HAND2) and eHAND (HAND1), basic helix-loop-helix DNA binding proteins whose neuronal expression is restricted to sympathetic and enteric neural crest-derived ganglia. Transcripts encoding dHAND and eHAND are expressed in sympathetic ganglia beginning at Hamburger and Hamilton stage 17-18. Antisense blockade of transcripts encoding HAND genes in neural crest-derived cells in vitro results in a significant reduction in neurogenesis. Differentiation of catecholaminergic neurons is also reduced by 52% if the expression of transcripts encoding dHAND and eHAND is reduced using antisense oligonucleotide blockade. The effect on neurogenesis and phenotypic expression of neural crest-derived neurons is specific; blockade of HAND gene expression has no apparent influence on the differentiation in vitro of neural tube-derived neurons. Use of a replication-competent avian retrovirus to constitutively express HAND genes in neural crest-derived cells in vitro, under nonpermissive growth conditions in medium supplemented with 2% chick embryo extract (CEE), induced precocious catecholaminergic differentiation. Constitutive expression of HAND gene products resulted in a significant increase in catecholaminergic differentiation of cells grown in medium supplemented with 10% CEE, a permissive growth condition for catecholaminergic development. These results suggest that the expression by neural crest cells of dHAND and eHAND may be both sufficient and necessary for catecholaminergic phenotypic expression.

[Long-term results of reconstructive surgery for mitral insufficiency]

BACKGROUND

Surgical repair is the procedure of choice for mitral insufficiency since it preserves better left ventricular structure and function.

AIM

To assess the long term clinical and echocardiographic results of mitral valve reconstructive surgery.

MATERIAL AND METHODS

A review of clinical and echocardiographic data of 68 patients (34 male, age range 17 to 82 years), subjected to surgical mitral valve repair between December 1991 and March 1998. Preoperative functional capacity of these patients was 2.96 +/- 0.7. Surgical repair was assessed using transesophagic echocardiography in all subjects.

RESULTS

The etiology of mitral insufficiency was degenerative in 43 patients, rheumatic in 10, infectious in 6, ischemic in 5 and miscellaneous in 4. The most frequent pathological findings were dilatation of the mitral ring in 42% of patients, chordae tendinae rupture in 32% and enlargement in 24%. A mitral anuloplasty was done in 90% of patients, a cuadrilateral resection of posterior leaflet in 52% and chordae tendinae transference in 12%. An additional surgical procedure was done in 34% of subjects. Three patients died during hospitalization (4.4%). During the follow up of 36.5 +/- 22.3 months, five patients died and one required a mitral valve replacement. The actuarial survival probability was 95.3 +/- 2.6% at one year and 83.5 +/- 6.5% at five years. The reoperation free survival was 100% at one year and 97.4 +/- 2.5% at five years. At the end of follow up the functional capacity improved to 1.25 +/- 0.4. Echocardiography showed absence of mitral insufficiency in 48.4% of patients, minimal, mild and moderate insufficiency in 35.5, 14.5 and 1.6% of patients respectively.

CONCLUSIONS

Surgical valve reconstruction in mitral insufficiency has satisfactory long term results and should be the procedure of choice for eligible patients.

The hippocampus and delayed recall: bigger is not necessarily better?

Healthy young female participants were tested on a measure of delayed verbal recall and then received volumetric Magnetic Resonance Imaging (MRI) scans. The analysis of the MRI scans focused on the volume of the hippocampus. Left hippocampal volume was negatively associated with the level of delayed verbal recall performance. This relationship was confirmed in further testing. This finding is consistent with a previous report of a similar relationship in healthy elderly individuals, but not in patients with Alzheimer's disease, in whom the opposite relationship was observed. An explanation of these findings in terms of impaired neural pruning of the hippocampus is advanced, whereby insufficient pruning of the hippocampus during childhood and adolescence (following adequate growth) may lead to reduced mnemonic efficiency.

Nonequilibrium critical behavior in unidirectionally coupled stochastic processes

Phase transitions from an active into an absorbing, inactive state are generically described by the critical exponents of directed percolation (DP), with upper critical dimension d(c)=4. In the framework of single-species reaction-diffusion systems, this universality class is realized by the combined processes A-->A+A, A+A-->A, and A-->0. We study a hierarchy of such DP processes for particle species A,B,..., unidirectionally coupled via the reactions A-->B, ...(with rates mu(AB),...). When the DP critical points at all levels coincide, multicritical behavior emerges, with density exponents beta(i) which are markedly reduced at each hierarchy level i> or =2. This scenario can be understood on the basis of the mean-field rate equations, which yield beta(i)=1/2(i-1) at the multicritical point. Using field-theoretic renormalization-group techniques in d=4-epsilon dimensions, we identify a new crossover exponent phi, and compute phi=1+O(epsilon(2)) in the multicritical regime (for small mu(AB)) of the second hierarchy level. In the active phase, we calculate the fluctuation correction to the density exponent on the second hierarchy level, beta(2)=1/2-epsilon/8+O(epsilon(2)). Outside the multicritical region, we discuss the crossover to ordinary DP behavior, with the density exponent beta(1)=1-epsilon/6+O(epsilon(2)). Monte Carlo simulations are then employed to confirm the crossover scenario, and to determine the values for the new scaling exponents in dimensions d< or =3, including the critical initial slip exponent. Our theory is connected to specific classes of growth processes and to certain cellular automata, and the above ideas are also applied to unidirectionally coupled pair annihilation processes. We also discuss some technical as well as conceptual problems of the loop expansion, and suggest some possible interpretations of these difficulties.

A conformationally-constrained MHC class II I-Ag7-derived peptide protects NOD mice from the development of diabetes

Allele-specific peptide vaccination against disease-associated MHC class II molecules is a promising new strategy for modulating self-antigen presentation to autoreactive T cells in autoimmune diseases. To evaluate the potential of this approach for treatment of insulin-dependent diabetes mellitus (IDDM), we have designed a cyclic peptide vaccine, DiavaX, from the third hypervariable region of the beta-chain of the NOD mouse MHC class II I-Ag7. NOD mice were treated at 5 and 9 weeks of age with 100 microg DiavaX emulsified in alum, a control peptide in alum, or alum alone. At the end of the study, 87% of alum treated mice had developed diabetes, compared with only 28% of DiavaX-treated mice. None of the control peptides, including a linear I-Ag7, a scrambled cyclic I-Ag7, or an analogous cyclic I-Aspeptide, reduced the incidence of diabetes, demonstrating that the protective effect of DiavaX is conformationally dependent and both allele- and sequence-specific. DiavaX treatment did not cause any general immune suppression, but did induce peptide-specific antibodies and memory T cells. DiavaX-induced protection from diabetes was associated with the maintenance of a non-destructive islet-associated autoimmune response. These data indicate that a conformationally constrained peptide from the disease-associated MHC represents a potential vaccine candidate for the prevention of clinical IDDM.

Physical characterization of a low-charge glycoform of the MUC5B mucin comprising the gel-phase of an asthmatic respiratory mucous plug

We have previously noted that sequential extraction of an asthmatic mucous exudate with 6 M guanidinium chloride yielded a fraction of the mucins that were most resistant to solubilization and of high Mr [Sheehan, Richardson, Fung, Howard and Thornton (1995) Am. J. Respir. Cell Mol. Biol. 13, 748-756]. Here we show that this mucin fraction is dominated (at least 96% of the total) by the low-charge glycoform of the MUC5B gene product. Seen in the electron microscope the mucins appeared mainly as compact 'island' structures composed of linear threads often emanating from globular 'nodes' rather than the discrete linear threads more typical of mucins that we have previously described. The effect of reducing agents was as expected for other gel-forming mucins, i.e. reduced subunits or monomers of Mr 3x10(6)) were produced within 15 min of treatment. Kinetic experiments on the cleavage of the intact mucins with the proteinase trypsin indicated two clear regimes of fragmentation. An initial rapid cleavage generated mucins ranging from Mr=4x10(6) to 30x10(6) that in the electron microscope appeared as polydisperse threads (500-3000 nm in length), similar to normal and other respiratory mucins that we have previously characterized. A subsequent slower fragmentation over many hours yielded a major fragment of Mr 3x10(6) and length 200-600 nm, very similar in size and Mr to the subunits obtained by reduction. The results suggest that the MUC5B mucin is assembled, first into polydisperse linear threads, which are then linked together via a protein-mediated process. This might involve part of the mucin polypeptide or an as yet unidentified protein(s). The high proteinase susceptibility of the linkage suggests that it might be a point of control for mucin size and thus mucus rheology.

Salivary mucin MG1 is comprised almost entirely of different glycosylated forms of the MUC5B gene product

The MG1 population of mucins was isolated from human whole salivas by gel chromatography followed by isopycnic density gradient centrifugation. The reduced and alkylated MG1 mucins, separated by anion exchange chromatography, were of similar size (radius of gyration 55-64 nm) and molecular weight (2.5-2.9 x 10(6) Da). Two differently-charged populations of MG1 subunits were observed which showed different reactivity with monoclonal antibodies to glycan epitopes. Monosaccharide and amino acid compositional analyses indicated that the MG1 subunits had similar glycan structures on the same polypeptide. An antiserum recognizing the MUC5B mucin was reactive across the entire distribution, whereas antisera raised against the MUC2 and MUC5AC mucins showed no reactivity. Western blots of agarose gel electrophoresis of fractions across the anion exchange distribution indicated that the polypeptide underlying the mucins was the product of the MUC5B gene. Amino acid analysis and peptide mapping performed on the fragments produced by trypsin digestion of the two MG1 populations yielded data similar to that obtained for MUC5B mucin subunits prepared from respiratory mucus (Thornton et al., 1997) and confirmed that the MUC5B gene product was the predominant mucin polypeptide present. Isolation of the MG1 mucins from the secretions of the individual salivary glands (palatal, sublingual, and submandibular) indicate that the palatal gland is the source of the highly charged population of the MUC5B mucin.

[Minimally invasive coronary artery surgery]

BACKGROUND

There is a growing interest to perform a left internal mammary artery (LIMA) graft to the left anterior descending coronary artery (LAD) on a beating heart through a minimally invasive access to the chest cavity.

AIM

To report the experience with minimally invasive coronary artery surgery.

PATIENTS AND METHODS

Analysis of 11 patients aged 48 to 79 years old with single vessel disease that, between 1996 and 1997, had a LIMA graft to the LAD performed through a minimally invasive left anterior mediastinotomy, without cardiopulmonary bypass. A 6 to 10 cm left parasternal incision was done. The LIMA to the LAD anastomosis was done after pharmacological heart rate and blood pressure control and a period of ischemic pre conditioning. Graft patency was confirmed intraoperatively by standard Doppler techniques. Patients were followed for a mean of 11.6 months (7-15 months).

RESULTS

All patients were extubated in the operating room and transferred out of the intensive care unit on the next morning. Seven patients were discharged on the third postoperative day. Duplex scanning confirmed graft patency in all patients before discharge; in two patients, it was confirmed additionally by arteriography. There was no hospital mortality, no perioperative myocardial infarction and no bleeding problems. After follow up, ten patients were free of angina, in functional class I and pleased with the surgical and cosmetic results. One patient developed atypical angina on the seventh postoperative month and a selective arteriography confirmed stenosis of the anastomosis. A successful angioplasty of the original LAD lesion was carried out.

CONCLUSIONS

A minimally invasive left anterior mediastinotomy is a good surgical access to perform a successful LIMA to LAD graft without cardiopulmonary bypass, allowing a shorter hospital stay and earlier postoperative recovery. However, a larger experience and a longer follow up is required to define its role in the treatment of coronary artery disease.