Gene therapy: a novel method for the treatment of myocardial ischemia and reperfusion injury--mini-review

Myocardial ischemia and reperfusion injury (MI/R) represents important sequelae of clinical events. Historically, a number of approaches including, surgical intervention, pharmacological therapy and physical exercise regimes have been prescribed for the treatment of patients with cardiovascular disease. Recently, however, attention has focused upon more novel approaches using gene-based therapies to treat cardiovascular and MI/R. This mini-review will examine the role that heat shock proteins (HSP), in particular the HSP70 family, and the antiapoptotic protein Bcl-2 play in myocardial protection. Also examined in this review are several techniques including adenovirus and Japan-Liposomal method for delivering genes into the myocardium.

Type II myosin regulatory light chain relieves auto-inhibition of myosin-heavy-chain function

The F-actin based motor protein myosin II has a key role in cytokinesis. Here we show that the Schizosaccharomyces pombe regulatory light chain (RLC) protein Rlc1p binds to Myo2p in manner that is dependent on the IQ sequence motif (the RLC-binding site), and that Rlc1p is a component of the actomyosin ring. Rlc1p is important for cytokinesis at all growth temperatures and is essential for this process at lower temperatures. Interestingly, all deleterious phenotypes associated with the loss of Rlc1p function are suppressed by deletion of the RLC binding site on Myo2p. We conclude that the sole essential function of RLCs in fission yeast is to relieve the auto-inhibition of myosin II function, which is mediated by the RLC-binding site, on the myosin heavy chain (MHC).

A human and a mouse anti-idiotypic antibody specific for human T14(+) anti-DNA antibodies reconstructed by phage display

Little is known about human anti-idiotypic antibodies. Phage display methodology was used to reconstruct these antibodies from lupus patients, which recognize a subset (T14(+)) of anti-DNA antibodies. Antigen-specific B cells were isolated from the blood using a peptide based on a complementarity determining region (V(H)CDR3) of the prototypic T14(+) antibody. cDNA fragments of the V(H) and V(L) genes prepared from the cells were expressed as phage displayed single chain Fv (scFv) fragments using the pCANTAB-5E phagemid vector. From a reactive clone obtained, the Ig genes used were identified to be V(H)3, D5-D3, J(H)4b, V(kappa)I and J(kappa)2. The heavy chain was highly mutated, especially in CDR3, which bears mutations mostly of the replacement type; this region is also unusual in being extremely long due to a D-D fusion. In contrast, a mouse hybridoma antibody, made to the same T14(+) peptide and transformed as a scFv fragment, uses a short V(H)CDR3 comprising five amino acids, three of which are tyrosines. Tyrosines may be important for antigen binding because two of these also exist in the human V(H)CDR3. The light chains of both antibodies may also contribute to the specificity of the protein, because their V(L) segments, including the CDRs, are highly homologous to each other.

Administration of sevoflurane and isoflurane prior to prolonged global ischemia improves heart function in isolated rat heart

BACKGROUND

The Langendorff model was used to determine whether pretreatment with sevoflurane, isoflurane, or ischemic preconditioning (IP) could protect the myocardium of rats against global ischemia.

METHODS

After 15-min perfusion, each isolated heart was assigned to (1) CONTROL GROUP: no pretreatment, (2) Sevoflurane group: 20-min exposure of 1.7% sevoflurane prior to ischemia, (3) Isoflurane group: exposure of 1.4% isoflurane prior to ischemia, or (4) IP group: two 5-min ischemic periods separated by 5-min perfusion. Following pretreatment, each heart was exposed to 20-min global normothermic ischemia followed by 60-min reperfusion. Heart rate (HR), left ventricular end-diastolic pressure (LVEDP), left ventricular developed pressure (LVDP), HR x LVDP, left ventricular contractility (+dLVP/dt), and coronary flow were recorded continuously. Myocardial damage was assessed by hematoxylin and eosin (H&E) staining.

RESULTS

No significant differences (P > 0.05) in hemodynamic variables were recorded among the four groups before the experiment. After ischemia during reperfusion, sevoflurane, isoflurane and IP pretreated hearts recovered left ventricular function significantly better than control hearts. After 60-min reperfusion, +dLVP/dt recovered to 6.84 +/- 1.06%, 23.3 +/- 4.80%, 42.3 +/- 3.16%, and 59.6 +/- 5.75% of baseline values respectively for control, sevoflurane, isoflurane and IP groups. HR x LVDP recovered to 8.9 +/- 1.7%, 27.9 +/- 6.42%, 38.7 +/- 2.78%, and 59.6 +/- 3.98% respectively. H&E staining supported the hemodynamic data in that hearts pretreated with sevoflurane, isoflurane and IP showed significantly less ischemic damage when compared to control hearts.

CONCLUSIONS

Our study shows pretreatment with sevoflurane or isoflurane provided moderate protection to the isolated heart against prolonged periods of global ischemia.

Pemphigus with pemphigoid-like presentation, associated with squamous cell carcinoma of the tongue

A 53-year-old woman presented with an inoperable squamous cell carcinoma of the tongue associated with tense large bullae consistent with bullous pemphigoid, preceded by a prodrome of urticarial plaques. The histological findings showed a regenerating subepidermal blister with eosinophils and no acantholysis. Direct immunofluorescence study, however, showed positive staining for IgG and C3 throughout the epidermis consistent with pemphigus. The blistering eruption had no mucosal involvement and responded to low dose corticosteroids. Our patient may represent another presentation of a 'paraneoplastic pemphigus spectrum'.

Fission yeast Rng3p: an UCS-domain protein that mediates myosin II assembly during cytokinesis

Cell division in many eukaryotes, including the fission yeast Schizosaccharomyces pombe, utilizes a contractile actomyosin ring. In S. pombe, the actomyosin ring is assembled at the medial cortex upon entry into mitosis and constricts at the end of anaphase to guide the centripetal deposition of the septum. Despite identification of several structural components essential for actomyosin ring assembly, the interdependencies between these gene-products in the process of ring assembly are unknown. This study investigates the role of Rng3p, a member of the UCS-domain containing protein family (Unc-45p, Cro1p, She4p), in actomyosin ring assembly. Null mutants in rng3 resemble deletion mutants in the type II myosin heavy chain (myo2) and rng3(ts) mutants show strong negative interactions with the myo2-E1 mutant, suggesting that Rng3p is involved in modulating aspects of type II myosin function. Interestingly, a green fluorescent protein (GFP) tagged Rng3p fusion is detected at the division site in the myo2-E1 mutant, but not in other myo2-alleles, wild-type cells or in 18 other cytokinesis mutants. Assembly and maintenance of Rng3p at the division site in the myo2-E1 mutant requires F-actin. Rng3p is also required for the proper assembly of Myo2p and F-actin into a functional actomyosin ring but is not necessary for their accumulation at the division site. We conclude that Rng3p is a novel component of the F-actin cytoskeleton essential for a late step in actomyosin ring assembly and that it might monitor some aspect of type II myosin assembly during actomyosin ring construction.

Eukaryotic initiation factor 4B from wheat and Arabidopsis thaliana is a member of a multigene family

Clones of eukaryotic initiation factor (eIF) 4B from wheat and Arabidopsis thaliana were obtained from cDNA and genomic libraries. The exon/intron organization of the genes from wheat and A. thaliana is very similar. The deduced amino acid sequences for the wheat and Arabidopsis eIF4B proteins showed overall similarity to each other, but very little similarity to eIF4B from other eukaryotes. The recombinant form of eIF4B supports polypeptide synthesis in an in vitro translation system and reacts with antibodies to native wheat eIF4B. In contrast to mammalian eIF4B and eIF4A, the combination of wheat eIF4B and eIF4A does not stimulate RNA-dependent ATP hydrolysis activity; however, wheat eIF4B does stimulate eIF4F and eIF4A RNA-dependent ATP hydrolysis activity. Interestingly, eIF4B does not stimulate eIF(iso)4F and eIF4A hydrolysis activity. Gel filtration experiments indicate wheat eIF4B, like its mammalian counterpart, self-associates to form a homodimer.

Reproductive biology and conservation genetics of Goodyera procera (Orchidaceae)

Goodyera procera is an endangered terrestrial orchid in Hong Kong. Information on its reproductive biology and pattern of genetic variation is needed to develop efficient conservation strategies. Pollination experiments showed that the species is self-compatible, but dependent on pollinators for fruit set. Bagged plants produced no fruits. Artificial pollinations resulted in 92% fruit set through selfing, 94% with geitonogamous pollination, and 95% following xenogamous pollination. Fruit set in the open-pollinated control was 75% at the same sites. Allozyme electrophoresis and random amplified polymorphic DNA (RAPD) were used to evaluate genetic variation and structure of 15 populations of Goodyera procera. Despite its outbreeding system, allozyme data revealed low variation both at the population (P = 21.78%, A = 1.22, and H = 0.073) and species (P = 33%, A = 1.33, and H = 0.15) levels, in comparison with other animal-pollinated outbreeding plant species. However, RAPD variation was relatively high (P = 55.13% and H = 0.18 at the population level, and P = 97.03% and H = 0.29 at the species level). G(ST) estimates indicated high levels of genetic differentiation among populations (G(ST) = 0.52 and I = 0.909 ± 0.049 based on allozyme data, and G(ST) = 0.39 and I = 0.859 ± 0.038 based on RAPD data), much above the average for outcrossing species, suggesting that gene flow was limited in this species. Based on these data, suitable strategies were developed for the genetic conservation and management of the species.

Integrins at the neuromuscular junction are important for motoneuron survival

During development motoneurons depend on target contact for their survival. Following injury to the sciatic nerve in neonatal rats, a large proportion of motoneurons die. However, the same injury inflicted at 5 days of age results in no loss of motoneurons. This critical period of postnatal development coincides with the time during which there is a significant increase in the release of transmitter from the nerve terminals at the neuromuscular junction. We have proposed that the role of the target muscle cell during this period is to induce this up-regulation of transmitter release from motor nerve terminals. It has been shown that stretch-induced increase in transmitter release from frog motor nerve terminals is accomplished via an integrin-dependent mechanism. In this study we examined the role of integrins at the rat neuromuscular junction in motoneuron survival. We found that blocking integrin binding at the developing neuromuscular junction delayed the increase in choline acetyltransferase activity that normally takes place during the early postnatal period, and resulted in motoneuron death. Furthermore, the maturation of those motoneurons that survived was delayed so they remained susceptible to subsequent nerve injury. These results support the possibility that integrins, by their involvement in modulating transmitter release, can influence motoneuron survival.

Anesthesia and postoperative shivering: its etiology, treatment and prevention

Postoperative shivering following anesthesia varies between 5 and 65%. The etiology of postoperative shivering is unclear. Pharmacologic agents are still the most popular mode of treatment for postanesthetic shivering, such as meperidine, clonidine and physostigmine. Nonpharmacologic approaches such as maintaining ambient temperature and warming air blankets and intravenous infusions remain as effective preventive measures for postoperative shivering. This review will address its etiology, treatment and prevention.

Clinical manifestations and outcomes in 17 cases of Stevens-Johnson syndrome and toxic epidermal necrolysis

The clinical features and outcomes of 17 patients with Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) were retrospectively reviewed. There were 11 males and six females with an average age of 61.5 years. Ten patients with SJS (seven males, three females) and seven patients with TEN (four males, three females) were identified. Antibiotics, mainly beta-lactams, were the most common cause of SJS/TEN in this series. The mean skin loss in TEN was 45.7% total body surface area in contrast to the lesser skin loss (< 10%) observed in three patients with SJS. Complications included septicaemia, pneumonia and multi-organ failure, mainly in the TEN group. Two patients died from TEN-related complications and one patient with SJS died from unrelated causes. Ocular involvement and skin pigmentary changes represented the most significant long-term sequelae.

Microcirculatory response to halothane and isoflurane anesthesia

Microcirculatory hemodynamics are often used to monitor tissue and organ survival. This study investigated the effect of halothane and isoflurane anesthesia on peripheral microcirculation using the cremaster muscle during intravital microscopy. Twenty-three Sprague-Dawley rats were studied in four groups. Two groups served as controls and did not undergo flap isolation but did receive halothane (N = 6) or isoflurane (N = 5). After induction with a single dose of intraperitoneal pentobarbital (40 mg per kilogram), rats were ventilated with either 2 minimum alveolar concentration (MAC) halothane or 2 MAC isoflurane. Esophageal temperature, electrocardiography, central venous pressure, mean arterial pressure, and blood gases were measured over 4 hours. In groups receiving surgery with either halothane (N = 6) or isoflurane (N = 6), the cremaster muscle was isolated on the neurovascular pedicle. Microcirculatory responses to both halothane and isoflurane anesthesia were evaluated by measuring red blood cell (RBC) velocity, vascular diameters in arterioles (A1, A2-1, A2-2, and A3) and the main venule (V1), functional capillary perfusion, and leukocytic endothelial interactions in postcapillary venules (rolling, adherent, and transmigrating leukocytes). Hemodynamic variables were compared among all four groups, and microcirculatory variables were compared between the two surgical groups. During isoflurane anesthesia in animals with flaps, significantly higher (p < 0.05) RBC velocities were recorded in arterioles A1 (24.4%), A2-2 (28.2%), and A3 (17.4%). Capillary perfusion was significantly higher in animals with flaps and halothane anesthesia (17.8%; p < 0.05). The number of rolling leukocytes (39.4%) was significantly higher during isoflurane anesthesia in animals with flaps (p < 0.05). Better flow hemodynamics in the peripheral microcirculation were seen during halothane anesthesia, and were confirmed by greater functional capillary perfusion and fewer activated leukocytes. In the isoflurane group, RBC velocity alone cannot serve as an indicator of microcirculatory function.

Acquired perforating dermatosis in diabetes mellitus: an unusual case

A case of elastosis perforans serpiginosa in a patient who presented with insulin-dependent diabetes mellitus secondary to pancreatic insufficiency in a background of common variable immunodeficiency and endocrinopathy, as evidenced by pernicious anaemia and growth hormone deficiency, is described. In acquired perforating dermatosis occurring in patients with diabetes or renal failure, there is a spectrum of changes that may show an overlap of histological features of the four classic perforating diseases. The biopsy changes of the patient described in the present study most closely resembled those of elastosis perforans serpiginosa.

2-year clinical performance of a resin-modified glass ionomer sealant

PURPOSE

To compare the 2-year clinical performance of an experimental resin-modified glass ionomer cement sealant (K-512 = Fuji III LC) with that of a light-cured resin-based sealant (Delton Opaque) in young adults:

MATERIALS AND METHODS

14 subjects with 47 K-512 and 41 Delton sealants were recalled at 2 years for clinical examination, photographs after enamel etching, impressions and radiographs.

RESULTS

K-512 showed 0% complete retention, 62% partial retention, and 38% nil retention. The corresponding percentages for Delton were 32%, 58% and 10%, respectively. There was one instance of fissure caries for K-512 and three for Delton. Sealants deemed to need retreatments because of retention failures were 62% for K-512 and 34% for Delton. The K-512 sealants continued to darken over the study, many becoming slightly darker than the sealed teeth.

Primary cutaneous B cell lymphoma: outcomes and treatment

This retrospective study documents six patients with primary cutaneous follicular centre cell lymphoma (FCCL) of the head and trunk. The back was the most common site of presentation of the primary. Despite a good response to initial therapy, cutaneous relapses were common and one patient developed lymph node metastases. Intralesional steroids may be effective in controlling localized skin relapses of this B cell lymphoma. All patients are currently alive with two surviving over 5 years.

Reproductive biology and population genetic structure of Kandelia candel (Rhizophoraceae), a viviparous mangrove species

The pollination biology, mating system, and population genetic structure of Kandelia candel were investigated. Field observations on its pollination and reproductive biology suggested that this species is pollinator dependent for fruit set, and bee activities can lead to substantial geitonogamous selfing. Quantitative analysis of the mating system parameters was performed using progeny arrays assayed for allozyme markers. Multilocus outcrossing rates (t(m)) were estimated to be 0.697 ± 0.091 and 0.797 ± 0.062 in two populations. In comparison to other plant species with mixed-mating system, the level of allozyme variation was very low in the 13 populations sampled along the coastlines of Hong Kong. At the species level, the proportion of polymorphic loci was 20%, number of alleles per locus was 1.2, and heterozygosity was 0.0362. The total gene diversity was primarily distributed within populations (H(S )= 0.0339), and the coefficient of genetic differentiation among populations was low (G(ST )= 0.064). This pattern of population genetic structure suggests that gene flow, primarily in the form of water-dispersed seedlings in viviparous mangrove species, is not as limited as previously thought. However, microgeographic pattern in allele frequency at the marker loci could still be detected between the western and eastern coastal populations.

Effects of dobutamine, norepinephrine and epinephrine on intramucosal pH and hemodynamics of dogs during endotoxic shock

This study assessed the effects of dobutamine (DOB), epinephrine (EPI) and norepinephrine (NE) on gastric tissue oxygenation indicated by gastric intramucosal pH (pHi) and hemodynamics in dogs subjected to endotoxic shock. Twenty-four dogs were assigned to four groups of 6 dogs each: endotoxin without catecholamine and endotoxin with DOB, or EPI or NE. Endotoxic shock was induced by intravenous injection of 3 mg/kg of E. coli over 1 min, with an additional 3 mg/kg over the next 2 hrs. Dogs were resuscitated with normal saline to maintain pulmonary capillary wedge pressure (PCWP) near baseline levels. Catecholamines were infused at 0.1, 0.4 and 1.6 micrograms/kg/min (EPI and NE) and 2.5, 5.0 and 10.0 micrograms/kg/min (DOB) for 30 min at each rate. After 2 hrs of endotoxemia, mean arterial pressure (MAP) and cardiac index (CI) and oxygenation delivery index (DO2I) for all dogs decreased by 46.5%, 43.9% and 15.1% respectively, while pHi decreased from 7.47 to 7.10. Endotoxemia increased blood lactate by 142%. Following fluid resuscitation, EPI (1.6 micrograms/kg/min) further increased lactate by 178% (1.22 to 3.4 mmol/L). No correlation was found between tonometry pHi and lactate (R2 = 0.003), pHi and pHa (R2 = 0.231), pHi and DO2I (R2 = 0.056) nor between intramucosal PCO2 and PaCO2 (R2 = 0.005). pHi did not reflect the improvements in cardiovascular hemodynamics observed following administration of catecholamines. NE improved MAP, CI and DO2I whereas DOB produced similar effects as NE but further reduced SVR. EPI produced similar effects as NE. DOB, NE and EPI further decreased pHi. EPI significantly (P < 0.05) increased blood lactate levels more than DOB and NE.

Long-term treatment of lupus nephritis with cyclosporin A

We evaluated the efficacy and safety of long-term treatment with cyclosporin A (CSA) in type IV lupus nephritis. Seventeen patients with biopsy-proven WHO type IV lupus nephritis were enrolled in a prospective, open study. Twelve of the 17 completed 48 months of treatment with CSA and prednisolone. Three patients required the addition of azathioprine, at 12, 38 and 47 months, respectively, for cutaneous disease flare with refractory rashes. One patient was lost to follow-up at 40 months. The mean +/- SD duration of treatment was 43.2 +/- 10.1 months (range 15.7-48 months). A significant reduction of proteinuria and a significant rise in serum albumin were noted 1 month after initiation of treatment. Improvement was maintained throughout the study except for three patients who relapsed with recurrence of nephrotic syndrome. There were no significant changes in serum creatinine level or creatinine clearances throughout the study. Repeat renal biopsy at 12 months following treatment with CSA showed histological improvement, with WHO type II changes in all 17 patients accompanying significant reduction in activity indices. Patients with baseline haemoglobin (Hgb) levels < 12 g/dl showed significant improvement. Serum C3 and C4 levels were not changed significantly. Corticosteroid-sparing effects were noted. Side-effects included hypertension, gum hypertrophy and mild hirsuitism, but were not serious. Combination therapy using CSA and prednisone is effective and safe for long-term treatment in lupus patients with WHO type IV nephritis.

Isolation and characterization of new fission yeast cytokinesis mutants

Schizosaccharomyces pombe is an excellent organism in which to study cytokinesis as it divides by medial fission using an F-actin contractile ring. To enhance our understanding of the cell division process, a large genetic screen was carried out in which 17 genetic loci essential for cytokinesis were identified, 5 of which are novel. Mutants identifying three genes, rng3(+), rng4(+), and rng5(+), were defective in organizing an actin contractile ring. Four mutants defective in septum deposition, septum initiation defective (sid)1, sid2, sid3, and sid4, were also identified and characterized. Genetic analyses revealed that the sid mutants display strong negative interactions with the previously described septation mutants cdc7-24, cdc11-123, and cdc14-118. The rng5(+), sid2(+), and sid3(+) genes were cloned and shown to encode Myo2p (a myosin heavy chain), a protein kinase related to budding yeast Dbf2p, and Spg1p, a GTP binding protein that is a member of the ras superfamily of GTPases, respectively. The ability of Spg1p to promote septum formation from any point in the cell cycle depends on the activity of Sid4p. In addition, we have characterized a phenotype that has not been described previously in cytokinesis mutants, namely the failure to reorganize actin patches to the medial region of the cell in preparation for septum formation.

Rng2p, a protein required for cytokinesis in fission yeast, is a component of the actomyosin ring and the spindle pole body

BACKGROUND

An actomyosin-based contractile ring plays a pivotal role in cytokinesis. Despite the identification of many components of the ring, the steps involved in its assembly are unknown. The fission yeast Schizosaccharomyces pombe is an attractive organism in which to study cytokinesis because its cell cycle has been well characterized; it divides by medial fission using an actomyosin ring; and a number of S. pombe mutants defective in actomyosin ring assembly have been isolated. Here, we have characterized one such mutant, rng2.

RESULTS

Temperature-sensitive rng2 mutants accumulated F-actin cables in the medial region of the cell but failed to organize the cables into a ring. In rng2-null mutants, only a spot-like structure containing F-actin was detected. The rng2+ gene encodes a protein related to human IQGAP1, a protein that binds actin and calmodulin and is a potential effector for the Rho family of GTPases. Rng2p localized to the actomyosin ring and to the spindle pole body (SPB) of interphase and mitotic cells. Localization of Rng2p to the actomyosin ring but not the SPB required F-actin. Rng2p interacted with calmodulin, a component of the SPB and the actomyosin ring. The rng2 gene showed genetic interactions with three other actomyosin ring assembly mutants, cdc4, cdc12, and rng5.

CONCLUSIONS

The S. pombe IQGAP-related protein Rng2p is a component of the actomyosin ring and the SPB and is required for actomyosin ring construction following assembly of F-actin at the division site.