5 DISRUPTION OF THE HIGH MOBILITY GROUP AT-HOOK 2 (HMGA2) GENE IN SWINE REDUCES POSTNATAL GROWTH

The high mobility group AT-hook 2 (HMGA2) protein has been shown to be a crucial gene for cell growth, proliferation, and apoptosis; HMGA2 is also a strong biological candidate for growth, because mutations in this gene alter body size in mice and humans. Compared with wild-type controls, adult mice lacking HMGA2 are 60% smaller, and adult heterozygous mutants are 20% smaller. In humans, HMGA2 has been associated with adult and childhood height without any other deleterious effect. Additionally, a microdeletion in the HMGA2 gene in a human patient resulted in short stature, with no dysmorphologies and normal puberty. In order to determine the effect of HMGA2 on fetal and adult growth in pigs, a transgenic pig line deficient in HMGA2 expression was generated by gene targeting in fetal fibroblasts (FF). Using a targeting vector carrying a reporter gene, and homology arms specific to HMGA2, heterozygous mutant cell lines were generated. The cell lines were then used to generate 6 heterozygous females by somatic cell nuclear transfer (SCNT). Bodyweights and lengths from snout to base of tail were measured every 2 weeks for a year for mutant (n = 6) and wild-type farm gilts (n = 6). Data were analysed by one-way ANOVA. As in mice, disruption of one allele of the HMGA2 gene resulted in 25% reduction in weight (P < 0.0001) and 14% reduction in length (P < 0.0001). Early in postnatal growth (2 months), weights of mutants were not different than wild-type. However, mutants were 20 to 35% lighter (P < 0.05) during mid stages (6 months) and 25 to 30% (P < 0.0001) in late stages (3 months). The same insertional mutation generated 8 heterozygous male clones by SCNT. In addition, 7 nontransgenic males from the same FF line were generated as SCNT controls. Bodyweights and lengths were measured every 2 weeks for 30 weeks for HMGA2 heterozygous mutants (n = 8), control SCNT (n = 7) and wild-type farm boars (n = 5). The weight curve of boars showed similar pattern as for mutant gilts. At 30-week postnatal stage, mutants were 17% (P < 0.05) and 16% (P < 0.05) lighter in weight compared with littermate and wild-type animals, respectively. We are presently developing homozygous HMGA2 mutant lines. Currently, 3 of 6 heterozygous gilts have been bred with heterozygous boars, with 1 confirmed pregnancy. The expectation is that the homozygous animals will, like mice, be 60% smaller than the wild-type animals. The approach described here will result not only in a valuable large-animal model of dwarfism, but also in a tool to reduce the size of existing transgenic and nontransgenic swine lines. This, in turn, will increase the receptivity of valuable transgenic lines by the biomedical community. Funding for this work was provided by NIH grant R21-OD010553 to JP.

Elliptic flow in Au+Au collisions at square root(S)NN = 130 GeV

Elliptic flow from nuclear collisions is a hadronic observable sensitive to the early stages of system evolution. We report first results on elliptic flow of charged particles at midrapidity in Au+Au collisions at square root(S)NN = 130 GeV using the STAR Time Projection Chamber at the Relativistic Heavy Ion Collider. The elliptic flow signal, v2, averaged over transverse momentum, reaches values of about 6% for relatively peripheral collisions and decreases for the more central collisions. This can be interpreted as the observation of a higher degree of thermalization than at lower collision energies. Pseudorapidity and transverse momentum dependence of elliptic flow are also presented.

IL-13-mediated worm expulsion is B7 independent and IFN-gamma sensitive

B7 costimulation is a required component of many type 2 immune responses, including allergy and protective immunity to many nematode parasites. This response includes elevations in Th2 cytokines and associated effector functions including elevations in serum IgG1 and IgE and parasite expulsion. In studies of mice infected with Trichuris muris, blocking B7 ligand interactions inhibited protective immunity, suppressed IL-4 production, and enhanced IFN-gamma production, but unexpectedly did not inhibit production of the Th2 cytokine, IL-13. Blocking both IFN-gamma and B7 restored protective immunity, which was IL-13 dependent, but did not restore IL-4 or associated IgE responses. Although IL-13 was required for worm expulsion in mice in which both IFN-gamma and B7 were blocked, IL-4 could mediate expulsion in the absence of both IL-13 and IFN-gamma. These studies demonstrate that 1) B7 costimulation is required to induce IL-4, but not IL-13 responses; 2) IL-13 is elevated in association with the IFN-gamma response that occurs following inhibition of B7 interactions, but can only mediate IL-4-independent protection when IFN-gamma is also inhibited; and 3) increased IL-13 production, in the absence of increased IL-4 production, is not associated with an IgE response, even in the absence of IFN-gamma.

Laparoscopic Colon Resections: A Five-Year Retrospective Review

In recent years, laparoscopic surgery has become a matter of growing interest. It has been shown that laparoscopic colectomy is well tolerated and safe for benign disease. However, there is some uncertainty about using this method for malignant disease when curative resection is the aim. These uncertainties mainly consist of spread of cancer to port site, long-term survival, and adequacy of resection. The majority of laparoscopic colectomies are technically assisted procedures in which anastomosis is performed outside the abdomen. However, some surgeons are now performing this surgery totally laparoscopically with the anastomosis performed inside the abdomen. Laparoscopic colectomy is currently practiced with great frequency by general surgeons. Its performance requires a steep learning curve and a large number of cases to obtain proficiency. The indications for laparoscopic colectomy are different from one institution to another. In some institutions all patients with colorectal disease are candidates for laparoscopic colectomy and in others it may be limited to benign disease only. The purpose of this review is to analyze all laparoscopic colectomies performed at our medical center since 1992. We conducted a retrospective chart review of both hospital and clinic charts of patients who underwent colectomies at our hospital. A total of 338 patient charts were reviewed. In a comparison of both laparoscopic (n = 285) and converted (n = 53) methods, the age and operative time were about the same. Age average and operating room time average were similar for both groups. With laparoscopy, there was a 3-day drop in length of hospital stay as well as a 1-day-earlier regaining of bowel function. Hospital cost dropped $5000 average for the laparoscopic colectomy. The conversion rate at our center was 15 per cent. Complication rates were lower in the laparoscopic group. Recurrence of cancer at the port site (0.7%) was no higher than in the converted group (incisional recurrence, 1.8%). We conclude that laparoscopic colectomy does show an improvement in return of bowel function, hospital cost, and shorter hospital stay. Long-term follow-up will be necessary to determine the effectiveness of laparoscopic colon resection for colorectal cancer.

Laparoscopic colon resections: a five-year retrospective review

In recent years, laparoscopic surgery has become a matter of growing interest. It has been shown that laparoscopic colectomy is well tolerated and safe for benign disease. However, there is some uncertainty about using this method for malignant disease when curative resection is the aim. These uncertainties mainly consist of spread of cancer to port site, long-term survival, and adequacy of resection. The majority of laparoscopic colectomies are technically assisted procedures in which anastomosis is performed outside the abdomen. However, some surgeons are now performing this surgery totally laparoscopically with the anastomosis performed inside the abdomen. Laparoscopic colectomy is currently practiced with great frequency by general surgeons. Its performance requires a steep learning curve and a large number of cases to obtain proficiency. The indications for laparoscopic colectomy are different from one institution to another. In some institutions all patients with colorectal disease are candidates for laparoscopic colectomy and in others it may be limited to benign disease only. The purpose of this review is to analyze all laparoscopic colectomies performed at our medical center since 1992. We conducted a retrospective chart review of both hospital and clinic charts of patients who underwent colectomies at our hospital. A total of 338 patient charts were reviewed. In a comparison of both laparoscopic (n = 285) and converted (n = 53) methods, the age and operative time were about the same. Age average and operating room time average were similar for both groups. With laparoscopy, there was a 3-day drop in length of hospital stay as well as a 1-day-earlier regaining of bowel function. Hospital cost dropped 5000 dollars average for the laparoscopic colectomy. The conversion rate at our center was 15 per cent. Complication rates were lower in the laparoscopic group. Recurrence of cancer at the port site (0.7%) was no higher than in the converted group (incisional recurrence, 1.8%). We conclude that laparoscopic colectomy does show an improvement in return of bowel function, hospital cost, and shorter hospital stay. Long-term follow-up will be necessary to determine the effectiveness of laparoscopic colon resection for colorectal cancer.

Stat6 signaling promotes protective immunity against Trichinella spiralis through a mast cell- and T cell-dependent mechanism

Studies in mice infected with the gastrointestinal nematode parasite Nippostrongylus brasiliensis demonstrated that IL-4/IL-13 activation of Stat6 suppresses development of intestinal mastocytosis and does not contribute to IL-4/IL-13 production, but is still essential for parasite expulsion. Because expulsion of another gastrointestinal nematode, Trichinella spiralis, unlike N. brasiliensis expulsion, is mast cell dependent, these observations suggested that T. spiralis expulsion would be Stat6 independent. Instead, we find that Stat6 activation by IL-4/IL-13 is required in T. spiralis-infected mice for the mast cell responses that induce worm expulsion and for the cytokine responses that induce intestinal mastocytosis. Furthermore, although IL-4 induces N. brasiliensis expulsion in the absence of B cells, T cells, and mast cells, mast cells and T cells are required for IL-4 induction of T. spiralis expulsion. Thus, Stat6 signaling is required for host protection against N. brasiliensis and T. spiralis but contributes to expulsion of these two worms by different mechanisms. The induction of multiple effector mechanisms by Stat6 signaling provides a way for a cytokine response induced by most gastrointestinal nematode parasites to protect against most of these parasites, even though different effector mechanisms are required for protection against different nematodes.

The voltage-gating process of the voltage-dependent anion channel is sensitive to ion flow

The voltage-dependent anion channel (VDAC) is a voltage-gated channel from the mitochondrial outer membrane. It has two gating processes: one at positive potentials and the other at negative potentials. The energetics of VDAC gating are quite different when measured in the presence or absence of an ion gradient. A positive potential on the high-salt side results in channel closure at lower transmembrane potentials. The midpoint potential (V0) shifted from 25 to 5.7 mV, with an activity gradient for KCl of 0.6 versus 0.06. The opposite occurred for negative potentials on the high-salt side (V0 shifted from -25 to -29 mV). Thus the salt gradient favored closure for one gating process and opening for the other. These results could be explained if part of the electrochemical potential of the gradients present were transferred to the gating mechanism. If the kinetic energy of the ion flow were coupled to the gating process, the effects of the gradient would depend on the mass and velocities of these ions. This was tested by using a series of different salts (KCl, NaCl, LiCl, KBr, K acetate, Na butyrate, and RbBr) under an identical activity gradient. The kinetic energy correlated very well with the measured shifts in free energy of the channel gating. This was true for both polarities. Thus the gating of VDAC is influenced by ion flow. These results are consistent in sign and direction with the voltage gating process in VDAC, which is believed to involve the movement of a positively charged portion of the wall of the channel out of the membrane.

The N-end rule pathway controls the import of peptides through degradation of a transcriptional repressor

Ubiquitin-dependent proteolytic systems underlie many processes, including the cell cycle, cell differentiation and responses to stress. One such system is the N-end rule pathway, which targets proteins bearing destabilizing N-terminal residues. Here we report that Ubr1p, the main recognition component of this pathway, regulates peptide import in the yeast Saccharomyces cerevisiae through degradation of Cup9p, a 35 kDa homeodomain protein. Cup9p was identified using a screen for mutants that bypass the previously observed requirement for Ubr1p in peptide import. We show that Cup9p is a short-lived protein (t1/2 approximately 5 min) whose degradation requires Ubr1p. Cup9p acts as a repressor of PTR2, a gene encoding the transmembrane peptide transporter. In contrast to engineered N-end rule substrates, which are recognized by Ubr1p through their destabilizing N-terminal residues, Cup9p is targeted by Ubr1p through an internal degradation signal. The Ubr1p-Cup9p-Ptr2p circuit is the first example of a physiological process controlled by the N-end rule pathway. An earlier study identified Cup9p as a protein required for an aspect of resistance to copper toxicity in S.cerevisiae. Thus, one physiological substrate of the N-end rule pathway functions as both a repressor of peptide import and a regulator of copper homeostasis.

Comparison of CoMFA models for Salmonella typhimurium TA98, TA100, TA98 + S9 and TA100 + S9 mutagenicity of nitroaromatics

Comparative Molecular Field Analysis (CoMFA) was applied to a comprehensive data set of heterogeneous nitroaromatics tested in Salmonella typhimurium TA98 and TA100 with and without S9 microsomal activation. The four CoMFA models developed agree with postulated mechanisms of mutagenicity, and explain over 70% of the corresponding mutagenic variance The standard deviation coefficient contours common in the four models included high electronic density regions equivalent to C4-C5 in the pyrene ring, and an electron deficient site equivalent to C6. These areas are associated with high mutagenicity. Electron deficient areas may be related with the nitroreductive bioactivation of nitroaromatics. Electron rich sites may be involved with oxidative mechanisms analogous to the bioactivation pathway of polycyclic aromatic hydrocarbons. The contribution of steric factors to mutagenicity follows the order TA98 + S9 > TA98 > TA100 + S9 > TA100. The models indicated that increasing bulk perpendicular to the aromatic plane would decrease mutagenicity, but increasing the aromatic ring system along a region corresponding to C6-C7 in 1-nitropyrene would increase mutagenicity.

FAS-induced apoptosis is mediated via a ceramide-initiated RAS signaling pathway

Fas receptor-induced apoptosis plays critical roles in immune homeostasis. However, most of the signal transduction events distal to Fas ligation have not been elucidated. Here, we show that Ras is activated following ligation of Fas on lymphoid lines. The activation of Ras is a critical component of this apoptotic pathway, since inhibition of Ras by neutralizing antibody or a dominant-negative Ras mutant interfered with Fas-induced apoptosis. Furthermore, ligation of Fas also resulted in stimulation of the sphingomyelin signalling pathway to produce ceramides, which, in turn, are capable of inducing both Ras activation and apoptosis. This suggests that ceramides acts as second messengers in Fas signaling via Ras. Thus, ligation of the Fas molecule on lymphocyte lines induces activation of Ras via the action of ceramide, and this activation is necessary, but not sufficient, for subsequent apoptosis.

Neuroleptic malignant syndrome: a dangerous complication of neuroleptic therapy

Neuroleptic malignant syndrome is a potentially fatal syndrome that can occur in patients taking neuroleptics or other psychotropic drugs. It is characterized by muscle rigidity, hyperthermia, altered mentation, autonomic dysfunction, increased CPK and leukocytosis. A primary factor in NMS may be a decrease in functioning of dopaminergic neurons. Treatment usually consists of discontinuation of the neuroleptic drug, drug therapy with bromocriptine and dantrolene and supportive measures. The key to successful medical and nursing management is aggressive supportive care with a focus on preventing complications. With the frequency of administration of neuroleptic drugs, neuroscience nurses should be aware of this potentially lethal complication of neuroleptic therapy.

Probing the activation of the replicative origin of broad host-range plasmid R1162 with Tus, the E.coli anti-helicase protein

The E.coli Tus protein is an anti-helicase involved in the termination of chromosome replication. The binding site for this protein, ter, was cloned into derivatives of the broad host-range plasmid R1162. The ter site caused the orientation-specific termination of plasmid replication fork movement in cell extracts containing Tus. Plasmids were constructed so that two sites for initiation of R1162 replication flanked the iteron-containing domain of the origin. In these plasmids, the site next to the AT-rich region within the iteron-containing domain was more active. In addition, when ter was placed between the more active site and the iterons, initiation of replication from this site was specifically inhibited. The data support a model for entry of the essential, plasmid-encoded helicase at one side of the direct repeats, and for its movement primarily in one direction away from these repeats to activate the initiation sites for DNA replication.

Pacer-induced tachycardia associated with an atrial synchronous ventricular inhibited (ASVIP) pulse generator

A 68-year-old white male underwent permanent pacemaker implantation with an atrial synchronous ventricular inhibited pulse generator (Medtronic model 2409) because of syncope and abnormal H-V interval of 70 ms. Paroxysmal bouts of pacemaker associated tachycardia were subsequently recorded on several occasions, initiated and terminated by spontaneous ventricular premature beats. The mechanism for the occurrence of the tachyarrhythmia is discussed in detail and the functional characteristics of the pulse generator are described. Replacement of the unit with a different pacer device prevented further occurrence of the arrhythmia.

Mitral valve replacement in medically unresponsive congestive heart failure due to papillary muscle dysfunction

Forty patients with a mean age of 65 years (range 44-76 years) were operated on; 30 of 40 patients (75%) had prior myocardial infarction. All had severe therapy-resistant congestive heart failure, 75% (30 of 40 patients) were symptomatic at rest, and 25% (10 of 40 patients) were symptomatic on minimal exertion. Cardiac index ranged from 1.24-2.84 L/min/m2 (mean 1.99). Left ventricular end-diastolic pressure ranged from 3-36 mm Hg (mean 18). All patients had significant mitral insufficiency and contractility was reduced markedly to moderately in 63% (25 of 40 patients). Significant coronary artery disease (obstruction greater than or equal to 75%) was present in all patients. All had mitral valve replacement, 30 had bypass surgery, and 7 left ventricular aneurysmectomy. Five died during surgery or before discharge (early mortality 12.5%). After a mean follow-up period of 16 months, another eight patients died, two with causes not related to the cardiovascular system (total mortality 32.5%). Of 20 patients with a cardiac index greater than or equal to 1.5 L/min/m2 and an ejection fraction greater than or equal to 0.40, 17 survived surgery and improved postoperatively. Mitral valve replacement for this group of patients is recommended.

Significance of abnormal echoes in left ventricular outflow tract

We have observed abnormal echoes in the left ventricular outflow tract in 4 patients: 3 of the subjects had bacterial endocarditis and the fourth patient had myxomatous degeneration of the aortic valve (floppy aortic valve). A single diastolic echo with fine high frequency fluttering was seen in the patient with the floppy aortic valve, whereas the patients with endocarditis had associated infection of the mitral valve and an aneurysm of the anterior mitral leaflet, which was represented by dense systolic echoes on the proximal part of the mitral valve...

Echocardiography of the "floppy" aortic valve. Report of a case

The echocardiographic features of a patient with severe aortic regurgitation due to a "floppy" aortic valve are presented. The salient abnormality observed was marked fluttering of the aortic valve cusps in diastole. Fluttering of the anterior leaflet of the mitral valve and left ventricular enlargement were noted. The diagnosis of a "floppy" aortic valve was substantiated at surgery.