A novel genetic screen identifies checkpoint-defective alleles of Schizosaccharomyces pombe chk1

The protein kinase Chk1 is required in the fission yeast Schizosaccharomyces pombe for delaying cell cycle progression in response to DNA damage. Chk1 becomes phosphorylated when DNA is damaged by a variety of agents, including the anti-tumor drug camptothecin. To further characterize the behavior of Chk1 in response to DNA damage, we used PCR-based mutagenesis of the chk1 gene coupled with in vivo gap repair to generate mutant alleles. Of 44 chk1 mutants recovered, six encode full-length proteins that confer a DNA damage-sensitive phenotype. All of the alleles render cells checkpoint-defective, but confer subtle differences in sensitivity to camptothecin or UV light. Mutant alleles were sequenced and served to identify regions of the protein that are critical for checkpoint function.

Multi-organ protection during open heart surgery

PURPOSE AND METHODS

Open-heart surgery with the use of cardiopulmonary bypass (CPB) is associated with an inflammatory cascade which contributes to the development of postoperative complications including multiple organ failure. To provide an update on the subject, we briefly review the recent English-language literature.

RESULTS

During CPB, various factors have been recognized to induce a complex inflammatory response. Based on an enhanced understanding of the underlying mechanisms, therapeutic strategies have been developed to reduce this inflammatory reaction and its subsequent damaging effects. Off-pump coronary artery bypass grafting may result in less inflammatory injury as compared with the conventional maneuver, which can in turn, diminish the incidence of cardiac, renal, or neurological dysfunction. It is also clear that improving the biocompatibility of CPB materials can lead to a better patient recovery. Inasmuch as the pathophysiology involved appears to be multifactorial, it is unlikely that a single intervention could achieve the desired goal. Both pharmacologic strategies, such as steroid pretreatment, and modification of mechanical devices, such as the use of heparin-coated CPB circuits, could have important clinical implications. The balance pro- and anti-inflammatory responses may be crucial in limiting the extent of inflammatory injury.

CONCLUSIONS

To date, the concept of organ protection should no longer be limited to the individual organ. Instead, investigations must be extended to focus on a systemic level.

Can CT scanning be used to select patients with unilateral primary spontaneous pneumothorax for bilateral surgery?

STUDY OBJECTIVES

Despite advances in the surgical treatment of spontaneous pneumothorax, the timing of surgical intervention continues to be a subject of controversy. We test the hypothesis that CT scanning can help to predict the probability of the occurrence of primary spontaneous pneumothorax (PSP) by detecting lung bullae.

DESIGN

Prospective, longitudinal cohort study.

PATIENTS AND METHODS

Between May 1994 to March 1995, 28 consecutive patients (23 men; age range, 18 to 47 years; mean, 29 years) with unilateral PSP who were to undergo video-assisted thoracic surgery (VATS) received preoperative CT of the thorax. CT scans were interpreted by one radiologist blinded to the clinical data for the presence of bullae in both lungs. All patients were followed-up in our outpatient clinic for an average of 59.0 months (range, 54 to 64 months).

RESULTS

Eighty-eight percent of the blebs or bullae identified intraoperatively were demonstrated on preoperative CT scans. CT scans also showed the presence of lung blebs or bullae in the contralateral lung in 15 patients (53.6%). During the follow-up period, 4 of these 15 patients (26.7%) with contralateral blebs developed PSP in the untreated lung; none of the patients who did not have contralateral blebs (n = 13) developed PSP (p = 0.04 [chi(2) analysis]).

CONCLUSIONS

The detection of lung bullae by CT scanning in the contralateral lung following unilateral PSP is associated with a higher rate of subsequent occurrence of pneumothorax in that lung. Thus, CT scanning can be used to predict the risk of occurrence of this condition, allowing preemptive surgical intervention in selected patients.

Management of massive hemoptysis: a single institution experience

BACKGROUND

Massive hemoptysis is a life threatening condition. Several therapeutic strategies have been applied in the clinical setting, with variable results. We reviewed our recent experience on this subject.

MATERIAL AND METHODS

In a 5-year period, fifty-four patients (41 males, mean age 57.9 years) were treated for massive hemoptysis in our unit. The underlying pathology included bronchiectasis (n=31), active tuberculosis (n=9), pneumoconiosis (n=3), lung cancer (n=2) and pulmonary angiodysplasia (n=1). These patients often present with continuous bleeding with large volume of hemoptysis, or with recurrent episodes of bleeding. Bronchoscopic assessment and interventions were performed upon admission in all patients. Surgery was considered if the patient had acceptable pulmonary reserve and a bleeding source was clearly identified. If the patient was not considered fit for surgery, bronchial artery embolization was attempted.

RESULTS

Hemoptysis ceased with conservative management in 7 patients (13%) only. Twenty seven (50%) patients received surgical resection. The procedures included lobectomy (n=21), bilobectomy (n=4) and pneumonectomy (n=2). The in-hospital mortality after surgery was 15%. Postoperative morbidity occurred in 8 patients, including prolonged ventilatory support, bronchopleural fistulae, empyema and myocardial infarction. Twenty-one patients not suitable for surgery were treated with bronchial artery embolisation, which was successful in 17 patients without any complications.

CONCLUSION

The clinical outcome for massive hemoptysis reflects the generalized nature of a destructive disease process involving both lungs and a limited respiratory reserve. Surgery is associated with high risk of morbidity and mortality, and should be performed only in selected patients. Meanwhile, aggressive conservative therapy including bronchial artery embolization should be pursued.

Coordinating cell fate and morphogenesis in Drosophila renal tubules

Using the renal tubules of Drosophila as an example, we explore how cell specification leads to the morphogenetic movements that underlie the generation of tissue architecture. Taking two stages of development, we show first that the tubule cells are allocated by signalling between the endodermal and ectodermal compartments of the posterior gut. Activation of the Wnt pathway patterns the ectodermal anlage, resulting in the expression of tubule genes in a subset of cells and their eversion from the hindgut to form the tubule primordia. We argue that early gene expression directs these morphogenetic movements but not the complete programme of tubule differentiation. In the second example we show that the allocation of the mitogenic tip cell lineage in each tubule is required not only for the normal pattern of cell division but also for the stereotyped three-dimensional arrangement of the mature tubules. Analysis of mutants in which the tip cell lineage is misspecified reveals that both daughters of the tip cell progenitor are required for the tubules to navigate through the body cavity, so that the distal tips locate in their characteristic positions. We show that the regulator of Rac, Myoblast city is essential for this second morphogenetic process.

VATS lobectomy reduces cytokine responses compared with conventional surgery

BACKGROUND

Video-assisted thoracic surgery (VATS) lobectomy for early lung cancer has been shown to be technically feasible. Comparative studies on laparoscopic versus open procedures indicate that laparoscopy may reduce inflammatory reactions as reflected by the lesser release of cytokines. We investigated the cytokine responses following VATS and conventional lobectomy for clinical stage I lung cancer.

METHODS

Thirty-six patients with clinical stage I nonsmall cell lung cancer were studied. 18 patients underwent VATS lobectomy and the other 18 by conventional thoracotomy. There were no differences between the two groups with respect to age, gender, pulmonary function, smoking history, comorbidity, tumor size, and pathology. Plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, IL-6, IL-8, and an antiinflammatory cytokine IL-10 were measured before surgery, at the end of the procedure, and 4, 8, 24, and 48 hours thereafter in all patients.

RESULTS

There was no mortality or major complication in either group. Analgesic requirement was significantly less in the VATS group. Although the release of TNF-alpha and IL-1beta were minimal after surgery in both groups, the levels of IL-6, IL-8, and IL-10 were elevated. IL-6 and IL-8 levels were significantly lower in the VATS group at the end of surgery than in the open group. In addition, reduced release of IL-10 was also observed in the VATS group shortly after surgery.

CONCLUSIONS

VATS lobectomy is associated with reduced postoperative release of both proinflammatory and antiinflammatory cytokines compared with the open approach. The clinical significance of these findings remains to be fully elucidated.

'Needlescopic' video-assisted thoracic surgery for palmar hyperhidrosis

OBJECTIVE

The video-assisted thoracic surgery (VATS) approach for thoracodorsal sympathectomy has been well accepted. We report the use of ultra-fine thoracoscopic equipment for this procedure, based on the experience from two centers in Asia.

MATERIALS AND METHODS

Thirty-eight patients with palmar hyperhidrosis underwent bilateral VATS thoracodorsal sympathectomy using 2-mm instruments exclusively. General anesthesia with selective one lung ventilation was used. Carbon dioxide insufflation was used when lung collapse was found to be inadequate. In 11 patients, the sympathetic chain was excised (T2-T3 for palmar hyperhidrosis alone, extending to T4 for axillary hyperhidrosis), and in 27 patients, the chain was cauterized. The choice of procedure reflects the surgeon's preference. No chest drains were left after the procedure and no stitching of the wound was necessary.

RESULTS

There was no mortality or major complications. A small pneumothorax was found in the postoperative chest X-ray in three patients. They all resolved without further intervention. Twenty-seven patients were discharged on the same day of admission, and 11 patients were discharged on postoperative day one. After an average follow-up of 16 months (range 5-28), there has been no recurrence of symptoms. Compensatory truncal hyperhidrosis was encountered in two patients, but the symptoms were not severe enough to interfere with lifestyle, and this required no further treatment.

CONCLUSION

Thoracodorsal sympathectomy using 2-mm instruments is technically feasible and is associated with an excellent clinical outcome. Limitations of the equipment, however, exist (narrow field of vision, lower resolution and difficulty in maintaining fine control), and we are currently restricting its use to relatively simple procedures.

[Study on the IR and UV dual-spectrum radiation]

The article gives a method to produce dual spectrum radiation in IR and UV. Relying on theoretical analysis, the relative data are computed, some atomic materials are selected and added to a double-base propellants. When the UV pyrotechnics is ignited together with traditional IR pyrotechnics, the spectrum of IR and UV is emitted at the same time. The final measuring curves show that all results are satisfying.

[Study on the quality standard of changan oral solution]

OBJECTIVE

To study the quality standard of Changan oral solution.

METHOD

Thin layer chromatography was used for identification pig's bile plaster. TLC scanning was used for the determination of hyodeoxycholic acid.

RESULTS

The TLC identification was highly specific and the spots was clear and concentrated. Linear regression for hyodeoxycholic acid was over the range of 3.50-12.25 micrograms. The average recovery of hyodeoxycholic acid was 100.5%, RSD was 3.2%.

CONCLUSION

This standard was capable to effectively control the quality of Changan oral solution.

Multiple signalling pathways establish cell fate and cell number in Drosophila malpighian tubules

A unique cell, the tip mother cell, arises in the primordium of each Drosophila Malpighian tubule by lateral inhibition within a cluster of achaete-expressing cells. This cell maintains achaete expression and divides to produce daughters of equivalent potential, of which only one, the tip cell, adopts the primary fate and continues to express achaete, while in the other, the sibling cell, achaete expression is lost (M. Hoch et al., 1994, Development 120, 3439-3450). In this paper we chart the mechanisms by which achaete expression is differentially maintained in the tip cell lineage to stabilise cell fate. First, wingless is required to maintain the expression of achaete in the tubule primordium so that wingless mutants lack tip cells. Conversely, increasing wingless expression results in the persistence of achaete expression in the cell cluster. Second, Notch signalling is restricted by the asymmetric segregation of Numb, as the tip mother cell divides, so that achaete expression is maintained only in the tip cell. In embryos mutant for Notch tip cells segregate at the expense of sibling cells, whereas in numb neither daughter cell adopts the tip cell fate resulting in tubules with two sibling cells. Conversely, when numb is overexpressed two tip cells segregate and tubules have no sibling cells. Analysis of cell proliferation in the developing tubules of embryos lacking Wingless after the critical period for tip cell allocation reveals an additional requirement for wingless for the promotion of cell division. In contrast, alteration in the expression of numb has no effect on the final tubule cell number.

[Spectral studies on the mechanism of rare earth poly (vinyl chloride) thermal stabilizers]

Rare earth Poly (Vinyl Chloride) (PVC) thermal stabilizers are one kind of effective and non-toxic stabilizers developed recently. By photoacoustic (PA) spectra and FT-IR analysis, their excellent performance in PVC stabilization progress can be studied conveniently. Good color remaining ability of rare earth stabilizers can be shown clearly by PA spectra and compared with others easily. From the IR spectrum and process data, the extra stabilization ability of rare earth stabilizers may be attributed to their conformation transforming effect.

Heparin-coated circuits reduce myocardial injury in heart or heart-lung transplantation: a prospective, randomized study

BACKGROUND

The effects of heparin-coated (HC) circuits have been primarily investigated in routine cardiac operations with limited duration of cardiopulmonary bypass (CPB) and ischemia. Their benefits have not been conclusively proven but could be more significant when CPB and ischemic times are longer, such as during heart transplantation (HTx) or heart-lung transplantation (HLTx).

METHODS

In a 22-month period, 29 patients undergoing HTx and HLTx were randomly divided into two groups using HC (Duraflo II, n = 14, 10 HTx and 4 HLTx) or uncoated but identical circuits (NHC group, n = 15, 10 HTx and 5 HLTx). All patients received full systemic heparinization (3 mg/kg) during CPB. Plasma endotoxin, interleukin (IL)-6, IL-8, IL-10, IL-12, and cardiac troponin-I were measured before heparin administration, immediately after aortic cross-clamping, 5, 30, 60, 90, 120 minutes, and 12 and 24 hours after aortic declamping. The intensive care unit (ICU) staff and the laboratory technologists were blinded as to the use of HC circuits.

RESULTS

No statistically significant differences between groups were found with respect to all baseline values, duration of CPB and aortic cross-clamping, graft ischemic time, doses of heparin, postoperative blood loss and transfusion, peak lactate and creatine kinase-MB isoenzyme values, duration of mechanical ventilation, or length of ICU stay. One patient in each group died during the hospital stay. Patients in the HC group needed more protamine sulfate after CPB. Although endotoxin levels were similar in the two groups, significantly lower IL-6, IL-8, and IL-10 levels were observed 1 hour after aortic declamping in the HC group. The release of cardiac troponin-I was also significantly reduced in the HC group 12 and 24 hours after reperfusion.

CONCLUSIONS

The use of HC circuit limits both pro- and anti-inflammatory responses to CPB. It may also reduce myocardial injury after prolonged duration of CPB and ischemia.

Cytokines in myocardial injury: impact on cardiac surgical approach

Myocardial ischemia-reperfusion injury associated with cardiac surgery is an acute inflammatory process in which activated leukocytes and endothelial cells play a critical role. Recent data indicate that the release of cytokines is crucial in inducing leukocytes and endothelial cells activation during cardiopulmonary bypass (CPB). Some inflammatory cytokines can be produced locally from the heart, particularly interleukin (IL)-8, which may further enhance leukocyte activation and accumulation in the injured myocardium. In fact, postoperative levels of cardiac troponin-I, a highly specific marker of myocardial injury, correlated strongly with IL-8 values in patients undergoing coronary artery bypass grafting (CABG). Off-pump CABG is associated with less IL-8 production compared with conventional procedure, which may in turn reduce the degree of myocardial injury. On the other hand, reduced release of IL-8 and cardiac troponin-I has also been discovered following the use of heparin-coated CPB circuits. In addition, the balance between pro- and anti-inflammatory mediators may be even more crucial in determining the extent of injury. Hence, avoiding the use of CPB or improving the biocompatibility of CPB may lead to better myocardial preservation. Research along these lines is expected to help in the development of ideal therapeutic strategies to minimize the inflammatory response and subsequent myocardial injury associated with cardiac surgery.

The topoisomerase I poison camptothecin generates a Chk1-dependent DNA damage checkpoint signal in fission yeast

The protein kinase Chk1 is essential for the DNA damage checkpoint. Cells lacking Chk1 are hypersensitive to DNA-damaging agents such as UV light and gamma-irradiation because they fail to arrest the cell cycle when DNA damage is generated. Phosphorylation of Chk1 occurs after DNA damage and is dependent on the integrity of the DNA damage checkpoint pathway. We have tested whether a topoisomerase I inhibitor, camptothecin (CPT), generates DNA damage in the fission yeast Schizosaccharomyces pombe that results in Chk1 phosphorylation. We demonstrate that Chk1 is phosphorylated in response to CPT treatment in a time- and dose-dependent manner and that phosphorylation is dependent on an intact DNA damage checkpoint pathway. Furthermore, we show that cells must be actively dividing in order for CPT to generate a Chk1-responsive DNA damage signal. This observation is consistent with a model whereby the cytotoxic event caused by CPT treatment is the production of a DNA double-strand break resulting from the collision of a DNA replication fork with a trapped CPT-topoisomerase I cleavable complex. Cells lacking Chk1 are hypersensitive to CPT treatment, suggesting that the DNA damage checkpoint pathway can be an important determinant for CPT sensitivity or resistance. Finally, as a well-characterized, soluble agent that specifically causes DNA damage, CPT will allow a biochemical analysis of the checkpoint pathway that responds to DNA damage.

Avoiding cardiopulmonary bypass in multivessel CABG reduces cytokine response and myocardial injury

BACKGROUND

Proinflammatory cytokines play a key role in the inflammatory cascade after cardiopulmonary bypass and may induce cardiac dysfunction. We compared the production of cytokines and the degree of postoperative myocardial injury in patients with multivessel coronary artery disease undergoing coronary artery bypass grafting through median sternotomy with or without cardiopulmonary bypass.

METHODS

Forty-four consecutive patients were studied. Patients were selected for off-pump coronary artery bypass grafting whenever complete revascularization was technically feasible. There were no differences between the two groups with respect to age, sex, symptoms, or functional class. Plasma levels of tumor necrosis factor-alpha, interleukin (IL)-6, IL-8, and IL-10 were measured before the operation, at the end of the procedure, and 2, 4, 8, 24, and 48 hours thereafter. Levels of the MB isoenzyme of creatine kinase and cardiac troponin-I were also measured after the operation.

RESULTS

The number of grafts was 2+/-0.7 in the off-pump group (n = 18) and 3+/-0.8 in the cardiopulmonary bypass group (n = 26). There were no deaths or major complications in either group. Levels of tumor necrosis factor-alpha were low in both groups. No significant intergroup differences were noted regarding serial IL-6 measurements. However, IL-8 and IL-10 levels after the operation were lower in the off-pump group (IL-8, 4+/-1 versus 38+/-12 pg/mL, p < 0.01; IL-10, 5+/-2 versus 191+/-33 pg/mL, p < 0.001). Whereas postoperative creatine kinase-MB values were similar in the two groups, cardiac troponin-I levels were significantly lower in the off-pump group (8 hours, p < 0.005; 24 hours, p < 0.02, respectively). Moreover, cardiac troponin-I values 24 hours after operation correlated strongly with IL-8 levels (r = 0.61, p < 0.005), indicating that the degree of myocardial injury may be related to IL-8 production.

CONCLUSIONS

Compared with conventional coronary artery bypass grafting, coronary revascularization without cardiopulmonary bypass is associated with reduced cytokine responses and less myocardial injury.

[The development of an intelligent vision testing instrument]

The paper introduces an intelligent vision testing instrument, which works on automatic method or manual method. The examinee inputs his or her judgement about the direction of the letter "E" with remote control. The system examines and judges the examinee's judgement, and then prints the testing report. The vision testing range is from logarithm vision 3.0 to 5.3. The distance between examinee and optometer can be measured automatically by the system with infrared and ultrasonic testing functions and a good accuracy.

Does steroid pretreatment increase endotoxin release during clinical cardiopulmonary bypass?

OBJECTIVE

The mechanism involved in the endotoxemia frequently recognized during cardiopulmonary bypass remains unclear. It has also been suggested that endotoxin levels were higher in steroid-pretreated patients undergoing cardiopulmonary bypass.

METHODS

Twenty patients undergoing cardiopulmonary bypass were randomly pretreated with steroids (methylprednisolone, 30 mg/kg) or placebo. Blood samples for endotoxin measurement were drawn simultaneously from the superior and inferior venae cavae before heparin administration, 5 and 50 minutes after the onset of bypass, 5 minutes after aortic declamping, at the end of bypass, and 1, 2, and 20 hours after the end of cardiopulmonary bypass.

RESULTS

The perioperative variables in the two groups were similar. Blood endotoxin levels were higher in the inferior vena cava than in the superior vena cava immediately after the onset of bypass. Endotoxin levels in inferior vena cava blood were significantly lower in steroid-pretreated patients than those in patients not receiving steroids.

CONCLUSIONS

Endotoxin is released during cardiopulmonary bypass from the region drained by the inferior vena cava. Steroid pretreatment may actually reduce endotoxin release during bypass.

A Chinese thoracic surgeon and his two decisions

Doctor Wu Ying-Kai is known to many in the thoracic surgical academia worldwide. This article focuses on the two decisions he made at the ages of 33 and 70 that profoundly influenced the development of thoracic and cardiovascular medicine in a country with one quarter of the world population. His successful career was gauged not so much by the position he achieved, but by the obstacles he had to overcome to achieve it.

Ministernotomy for aortic valve replacement in a patient with osteogenesis imperfecta

Open heart operations in patients with osteogenesis imperfecta are associated with increased morbidity and mortality resulting from tissue friability and bone brittleness. We used a ministernotomy approach for aortic valve replacement in a patient with osteogenesis imperfecta, with clear benefits and a satisfactory outcome.

Can cardioplegia management influence cytokine responses during clinical cardiopulmonary bypass?

BACKGROUND

Cytokines play an important role in the inflammatory response associated with cardiopulmonary bypass (CPB) and may contribute to postoperative complications. Although it has been shown that the production of tumor necrosis factor a (TNF-a) and interleukin (IL)-6 were higher following normothermic CPB than hypothermic CPB, whether different cardioplegic management could influence the release of cytokines remains unknown.

METHODS

We compared the blood concentrations of four cytokines (TNF-a, IL-6, IL-8, and IL-10) in two groups of patients undergoing complete revascularization with CPB in the same study period. Seventeen patients received cold crystalloid cardioplegia at a Belgian center (group-CC), while 21 patients received warm blood cardioplegia at a center in Hong Kong (group-WB). Blood samples were collected before and after surgery in each patient.

RESULTS

There were no differences between the 2 groups in terms of age, sex ratio, number of grafts, duration of CPB and aortic crossclamping. All patients survived their hospital stay. The levels of TNF-a, IL-6 and IL-8 after surgery were higher in group-CC than in group-WB. However, IL-10 levels were significantly lower at the end of surgery in group-CC than in group-WB.

CONCLUSIONS

Our data suggest that the use of warm blood cardioplegia, rather than cold crystalloid cardioplegia, may reduce the inflammatory response to CPB. This observation warrants future randomized investigation to determine its clinical relevance.