[Selection strategy of pedicled axial flaps for repairing high-voltage electric burn wounds in foot and ankle]

Objective: To explore the selection strategy of pedicled axial flaps for repairing high-voltage electric burn wounds in foot and ankle. Methods: The retrospective observational research method was used. From January 2017 to December 2022, 16 patients with skin and soft tissue defects in foot and ankle after high-voltage electric burns were treated in General Hospital of Eastern Theater Command, including 11 cases of unilateral defect and 5 cases of bilateral defect. All patients were male, aged from 25 to 75 years. After thorough debridement, the area of the defect to be repaired with the flap was 5.0 cm×4.0 cm to 12.0 cm×8.0 cm. Before operation, the color Doppler ultrasound, computed tomography angiography, or digital subtraction angiography was used to fully evaluate the degree of vascular injury in the affected limb and to identify the distribution and traffic anastomosis of vascular network. Pedicled axial flaps with reliable blood supply were used to repair the wounds as soon as possible, and the area of flaps ranged from 3.0 cm×2.0 cm to 13.0 cm×8.0 cm. The wound in the donor area of flaps was repaired with split-thickness skin graft from head or medium-thickness skin graft from thigh. The flap repair of wounds in various areas of the ankle and foot was recorded. The postoperative survivals of the flaps and skin grafts were observed after surgery. The postoperative appearance of flaps and walking function of patients were followed up. At the last follow-up, the foot and ankle function was evaluated and rated using the American Association of Foot and Ankle Surgeons Ankle Posterior Foot Scoring System. Results: Two wounds in toe area were repaired with reverse dorsal pedis flaps, 3 wounds in medial ankle area and 2 wounds in heel area were repaired with medial plantar flaps, 2 wounds in anterior plantar area combined with toe area were repaired with reverse medial plantar flaps, 2 wounds in anterior plantar area combined with toe area and 5 wounds in anterior plantar area were repaired with reverse medial pedis flaps, 1 wound in toe area was combined with proper plantar digital artery flap, 1 dorsal pedis wound and 1 lateral malleolus wound were repaired with lateral supramalleolar perforator flaps, and 1 lateral malleolus wound and 1 dorsal pedis wound were repaired with sural neurovascular flap. One flap had venous reflux disorder after surgery and survived after treatment, while the other flaps and skin grafts survived completely after surgery. During the follow-up of 6 to 24 months after operation, the appearance of the flaps was good, and the walking function of patients was normal. At the last follow-up, the functional score of foot and ankle was 76 to 95, which was evaluated as excellent in 11 cases and good in 5 cases. Conclusions: According to the condition of high-voltage electric burn in foot and ankle, early and thorough debridement, preoperative imaging examination to evaluate blood vessels of the affected limb, and selection of pedicled axial flap with reliable blood supply are good methods for wound repair and related functional reconstruction of high-voltage electric burn in foot and ankle.

[Effects of three methods for correction of low-degree against-the-rule corneal astigmatism during cataract surgery]

Objective: To compare the clinical effects of and visual quality after correction of low-degree against-the-rule (ATR) corneal astigmatism by implantation of an astigmatism-corrected intraocular lens (IOL), femtosecond laser release and manual release in cataract surgery. Methods: It was a prospective cohort study. A total of 120 patients (120 eyes) with cataract combined with low-degree ATR corneal astigmatism diagnosed in Chongqing Aier Mega Eye Hospital from December 2017 to October 2020 were included and divided into 3 groups, each with 40 patients, according to their own selections of astigmatism correction methods during cataract surgery. In the astigmatism-corrected IOL group, phacoemulsification for cataract extraction combined with toric IOL implantation was performed. In the femtosecond laser release group, astigmatic keratotomy using a femtosecond laser was combined. In the manual release group, a limbal relaxing incision was made. Uncorrected distance visual acuity (UDVA) and corneal astigmatism were measured before surgery. At 3 months and 1 year after surgery, UDVA and best-corrected distance visual acuity were examined, as well as whole eye residual astigmatism by ARK-1, corneal astigmatism by the IOLMaster 500, whole eye high order aberration (HOA) and modulation transfer function (MTF) by the iTrace visual function analyzer. Analysis of variance was used for the comparison of data in a normal distribution. Repeated measures were used for the comparison within groups. The rank sum test was used for the comparison of data that were not normally distributed. Results: Of the 120 patients, 100 patients (100 eyes), including 44 males and 56 females, with an age of (66.48±6.20) years, completed the follow-up. Among the three groups, the differences were not statistically significant in terms of gender distribution, age, preoperative corneal astigmatism, UDVA and spherical equivalent of the IOL (all P>0.05). At 3 months and 1 year after surgery, the UDVA was significantly better than that before surgery in each group (Z=5.18, 5.04, 4.98, 4.99, 4.90, 4.89; all P<0.001). At the two time points, the differences in the whole eye residual astigmatism among the three groups were statistically significant (H=30.69, 31.23; both P<0.001). At 3 months, the whole eye residual astigmatism in the astigmatism-corrected IOL group was lower than that in the other two groups. At 1 year, the residual astigmatism in the astigmatism-corrected IOL group [0.25(0.00, 0.50) D] was also lower compared to that in the femtosecond laser release group [0.50(0.50, 0.75) D] and the manual release group [0.75(0.50, 0.75) D] (Z=-3.71, -5.18, -3.94, -5.15; all P<0.001). The differences in the HOA at 3 months and 1 year among the three groups were statistically significant (H=36.30, 34.38; both P<0.001). The HOA in the astigmatism-corrected IOL group was significantly higher than that in the other two groups at the two time points (Z=5.01, 4.73, 5.31, 5.27; all P<0.001). At 3 months and 1 year, the differences in the MTF value among the three groups were also statistically significant (H=30.02, 29.92; both P<0.001), and the MTF value in the femtosecond laser release group was significantly higher than that in the other two groups (Z=4.61, 4.67, 4.66, 4.69; all P<0.001). Conclusions: All the three astigmatism correction methods used at the time of cataract surgery can effectively correct low-degree ATR corneal astigmatism. The residual astigmatism in the whole eye after astigmatism-corrected IOL implantation is small and stable, while the HOA after release using the femtosecond laser is low with good visual quality.

[Analysis of occupational health input-output of a iron mine in Hebei province]

Objective: To explore the relationship between input and output of occupational health funds, and to provide basis for relevant departments to make decisions. Methods: In September 2018, a state-owned iron ore in Hebei Province (mining history of more than 10 years, which can represent the general type of iron ore) was selected as the research object. Through the investigation and collection of enterprise general situation, occupational health input, loss and output related indicators, the iron mine occupational health expenditure input-output table and model were established, and the digital relationship between the investment and output was solved by MATLAB software. Results: The labor consumption in the departments of underground mining, open pit mining, crushing and rock discharging, transportation, tailings and mineral processing (taking labor wages as reference) were 756.46, 1.281.78, 987.61, 1 570.71, 50.956 and 18.9116 million yuan/year respectively. The output value of each sector is 11 207.19, 18 989.95, 15 176.40, 25 294.00, 7.704.94 and 280.1797 million yuan/year respectively. The ratio of health input to total output was 0.004 5, and the ratio of occupational health input to output was 1/0.046. Conclusion: The input-output table model of occupational health in iron mine can reflect the relationship between input and output of occupational health funds. The input situation of the coal mine is poor, and the input does not bring obvious occupational health benefits.

[Chorionic villus cell culture and karyotype analysis in 1 983 cases of spontaneous miscarriage]

Objective: To investigate the relationship between spontaneous miscarriage and embryonic chromosome abnormalities, and to evaluate the clinical application of karyotype analysis by chorionic villus cell culture. Methods: The chorionic villus karyotype of 1 983 cases of miscarriage from January 2010 to July 2016 in Guangzhou Women and Children's Mecical Center were analyzed retrospectively. The miscarried chorionic villi were obtained by curettage under sterilized condition. The chromosome specimens were prepared after chorionic villus cell culture. Karyotype analysis was performed by G-banding technique. Results: In the 1 983 samples, successful karyotype analysis was performed in 1 770 cases, with the successful rate of 89.98%. Chromosomal abnormalities were found in 1 038 cases (58.64%, 1 038/1 770). Chromosomal structural abnormalities were found in 37 cases. The numeral abnormalities were more common than structural abnormalities, and most of the numeral abnormalities were aneupoidies. In turn, they were trisomy 16, 45,X, trisomy 22, trisomy 2, trisomy 21, trisomy 15. The most common structural abnormality was balanced translocation, including Robersonian translocation. Female embryoes accounted for 61.02% (1 080/1 770) miscarriages and for 57.4%(596/1 770) of chromosomal abnormalities, while male embroyes acoounted for 61.02% (1 080/1 770) , 57.4% (596/1 770) respectively. The proportion of female embryoes was higher than male embryoes. The median age of the patients was 30 years old (16-46 years old) . As the maternal age increased, the proportion chromosomal abnormalities increased. The incidence of chromosomal abnormalities in the advanced age group (≥35 years) was 68.38% (240/351) , which was significantly higher than that in the younger group (56.24%, 798/1 419; χ(2)=17.10, P<0.01). Conclusions: Embryonic chromosomal abnormalities are the most common cause of early spontaneous miscarriage. The abnormalities centralize in some karyotypes. There is certain relationship between maternal age and the incidence of miscarriage, as well as the embryonic gender. Chorionic villus cell culture and karyotype analysis are helpful in finding the cause of miscarriage and counsel the patients.

Innovations of surgical techniques for the management of inferior vena cava tumor thrombus of renal cell carcinoma

Surgery for renal cell carcinoma with inferior vena cava thrombus is challenging. Cardiopulmonary bypass and deep hypothermic circulatory arrest significantly decreased the morbidity and mortality but associated with considerable postoperative complications. Debates still exist in one- or two-stage operations on which of the cardiac and urologic parts should be performed first. Modified maneuvers with main pulmonary artery clamping, vena cystoscope, transesophageal echocardiographic incorporation, and inferior vena cava interruptions are good for reduced perioperative morbidities. Surgical innovations have greatly facilitated the resection of renal cell carcinoma and inferior vena cava involvement. The advantages have been remarkable in less trauma, more cosmetic advantages, shorter hospital stay, and quicker recovery over the conventional open surgery with or without the use of bypass techniques. Such procedures have brought about improved long-term survivals. However, novel minimally invasive techniques such as robotic-assisted and hybrid approaches remain to gain further popularity in larger patient population. This article aims at a collection of the innovations of the surgical techniques in relation to the management of inferior vena cava tumor thrombus.

Mitral valve myxoma: a large-scale collective review

PURPOSE

Despite the review articles repeatedly published with respect to mitral valve myxomas, hardly could we find one based upon complete literature retrieval. We took an effort on complete literature retrieval and made a comprehensive review of the mitral valve myxomas.

METHODS

An instant thorough literature retrieval of the heart myxoma was made by using the MEDLINE and EMBASE databases, as well as secondary references cited in the articles obtained from the MEDLINE search. In addition, we searched the Google and HighWire Press.

RESULTS

The patients with mitral valve myxoma were young. Their major symptoms were cerebrovascular, cardiovascular, or constitutional. The tumors had small sizes, predilection of mitral leaflet location, solitary and pedicled nature, and good response to surgical resection.

CONCLUSION

These clinical characteristics of mitral valve myxoma may help the differential diagnosis between mitral valve myxoma and other valvular lesions, and help making a decision of a surgical treatment.

Echocardiographic Delineation of Type a Aortic Dissection

Introduction

In addition to proving the visualisation data, studies on the intimal flaps of aortic dissection based on echocardiography have been very limited.

Methods

Twenty-seven patients undergoing an operation of type A aortic dissection with preoperative transthoracic and/or intraoperative transesophageal echocardiography archived in the Horizon Cardiology Web of the hospital available for review and measurement were selected into this retrospective study. By way of quantitative and qualitative approaches, flap movement, dissection extent and aortic obstruction were sufficiently evaluated.

Results

An intimal flap was visualised in 22 (81.5%) patients and linear artifact was viewed in 1 (3.7%), and in the remaining 4 (14.8%), neither an intimal flap nor a linear artifact was visible. Dissection extents were 2.78±1.53 cm and 2.03±1.19 cm in the horizontal and vertical direction, respectively. Sub- or semi-circumferential dissection was noted in 14 (51.8%) patients. No total circumferential dissection was found in this patient population with type A aortic dissection. The obstruction of the aortic valve orifice or aortic cavity developed in 11 (40.7%) patients. Flow disturbance and thrombus in the false lumen were visualised in 24 (88.9%) and 4 (14.8%) patients, respectively. The breadth of flap movement in short-axis plane was much larger in the Aortic Obstruction Group than that of the Non-Obstruction Group (1.55±1.14 cm vs. 0.75±0.526 cm, p <0.05).

Conclusions

Preoperative transthoracic or transesophageal echocardiographic evaluations offer a convenient and precise diagnostic tool for aortic dissection. The dissection extent may directly correlate and substantially reflect the clinical symptoms of the patients with type A aortic dissection in response to the haemodynamic impairment. Preoperative echocardiographic delineation would assure adequate means and extent of the impending operation.

Preparation and lithium storage performances of mesoporous Fe₃O₄@C microcapsules

Fe(3)O(4)@C microcapsules were prepared using carbon-coated α-FeOOH nanorods as precursors, which were synthesized via two-step hydrothermal reactions. During the subsequent sintering procedure, α-FeOOH was reduced to Fe(3)O(4) by carbon, accompanied by the formation of mesopores. In Fe(3)O(4)@C microcapsules, mesoporous Fe(3)O(4) nanorods are coated with amorphorous carbon layers. The Fe(3)O(4)/C composites with such special structures demonstrate high specific capacity and good cyclic stability as anode materials in Li test cells.

A delivery circuit for normothermic reperfusion model

In order to facilitate the introduction and assessment of Injectio Radix Ginseng Compositae in normothermic reperfusion model, a simplified delivery circuit is described herein. The circuit added mainly a venous reservoir collecting Injectio Radix Ginseng Compositae with cardiopulmonary bypass. Injectio Radix Ginseng Compositae was pumped into the ascending aorta of the animal after mixing with cardioplegia in the venous reservoir. The circuit was acceptable in terms of price by most inland medical laboratories. Perfusion as well as biochemical results monitored were satisfactory. Significant difference was noted between the average damage rates of the reperfused myocardial mitochondria in groups by ultrastructural analysis (70.12 +/- 2.56% vs. 25.33 +/- 17.62%, p = 0.023). No complications associated with perfusion technique occurred in either group. The circuit could offer a constant arterial perfusion, and was proved to be simple, safe and effective in cohort.

Cytochemistry and ultrastructure of canine myocardium undergoing global ischemia and reperfusion injury

In order to highlight severity of myocardial injury during the course of global ischemia and reperfusion, cytochemistry of glycogen and succinate dehydrogenase (SDH) as well as hematoxylin and eosin staining (H & E) and electron microscopy were observed in canine myocardium. Seven mongrel dogs were selected for reperfusion injury after global ischemia in this study. Myocardial biopsies were taken from the anterior wall of the left ventricle (a) after cardiopulmonary bypass (the first biopsy); (b) at the end of the aortic crossclamp (the second biopsy); and (c) 30 minutes after crossclamp removal (the third biopsy). All biopsies were cytochemically assessed, and the latter two, for electron microscopic studies. The averages of myocardial necrotic rate and surface to volume ratio of myocardial mitochondria were calculated under electron microscopy and in electron microscopic slices, respectively. Myofibrillae were of normal morphology in the first biopsy; in wave-shape and partly vacuolated, with large and deformed nuclei in the second one; and in wave-shape and severely vacuolated in the third one, in H & E. Glycogen granules were variously stained in moderate, weak and intensive positive reactions in the three biopsies respectively in glycogen staining. SDH was stained in intensive, weak, and moderate positive reactions in three, respectively. By electron microscopy, Z bands twisted severely, and local dissolution of cristae and matrix occurred in a minority of the mitochondria in the second biopsy; and majority of the Z bands in necrotic region had disappeared, the myofibrillae were obscure and patchily dissolved. Clustered and deformed mitochondria could be found in the third biopsy. Significant difference could be noted between the averages of the second and third biopsies (14.88 +/- 3.09% vs. 60.25 +/- 8.55%, p < 0.001). The surface to volume ratio of the ischemic mitochondria was much bigger than that of the reperfused (3.95 +/- 1.09 micron-1 vs. 2.77 +/- 0.93 micron-1, p = 0.041). Myocardial injury was more severe in reperfusion than in ischemia myocardium. There were correlations between histobiochemical and ultrastructural alterations in damaged canine myocardium.

In vitro flow visualization on the right ventricular outflow reconstruction utilizing extracardiac conduits: set-up of duplicator system and its clinical significance

The right ventricular outflow tract (RVOT) reconstruction with cryopreserved valved homograft conduits was one of the most important methods in the surgical management of congenital heart defects. However, the hemodynamics for long-term conduit failure remain uncertain, and in vitro studies have not been conducted. Based on the surgical patterns of RVOT reconstruction in clinical practice, the compliant silicon elastomers were cast, and the simplified duplicator system was set up. When the system connected with an eight-channel recorder, and driven by a specified software, flow patterns were able to be visualized, and data to be collected. The simplified right heart system was stable and duplicated well as to the characteristics according with laws of similitude in geometry and physiology, although the conduit model is not in accordance with the clinical extracardiac conduit in angulation, length, diameter, curvature and anastomsis fashion. The right heart duplicator system was a prerequisite condition for the successful research of flow fields of the right heart conduits.

Benefits and pitfalls of warm blood cardioplegia in heart valve replacement: systemic protective effects

The purpose of this paper was to assess the role of continuous warm blood cardioplegia in heart valve replacement in comparison with standard intermittent cold crystalloid cardioplegia. Twenty patients undergoing open heart valve replacement were divided arbitrarily into two groups in this study; Group I was given intermittent perfusion of cold crystalloid (St. Thomas Hospital solution) with hypothermic cardiopulmonary bypass (CPB) (10 patients) and Group II was given continuous administration of warm blood cardioplegia with normothermic CPB (10 patients). The groups were similar with respect to sex, age, body surface area and preoperative ventricular function. Bypass conditions as well as perioperative complications were evaluated in the respective groups. Peak values of the serum enzyme levels within 120 hours of postoperation including alanine transaminase, aspartate aminotransferase, lactate dehydrogenase (LDH) and its isoenzymes LDH1 + LDH2, phosphokinase (CK) and its isoenzyme CK-MB, superoxide dismutase, and malondialdehyde in the two groups were also assessed. Biopsies from the right atrium were obtained immediately before aortic cross clamp removal (ischemic period), and 30 minutes after cross clamp removal (reperfusion period). Myocardial structures were observed and scored. No significant intergroup differences were found in the bypass conditions except for the perfusion flow, systemic temperature and central venous pressure. There were no significant differences in the intergroup perioperative complications, either. Serum enzymes except CK which reached peak values in Group I appeared prior to or consistent with Group II. There were no significant intergroup differences in peak levels of the serum enzymes except CK (307.44 +/- 38.56 U/L vs. 466.29 +/- 52.03 U/L, p = 0.039 for CK). From the pathological assessment, the structural alterations were the most severe during the reperfusion period in group I. Myocardial damage showed more severely in reperfusion than in ischemia in both. Warm blood cardioplegic technique, raising potential hazards, is still a practical method for myocardial protection in open heart surgery, but might be less effective in protecting the tissues beyond myocardium.

A generalized consideration of myocardial preservation with cold crystalloid versus warm blood cardioplegia in heart valve replacement

Continuous warm blood cardioplegia was widely used, as an effective means of myocardial preservation, in open heart surgery. The comparisons of myocardial protective effects between traditional cold crystalloid and warm blood cardioplegia, however, have been based mainly on hemodynamics, cardiac function and myocardial metabolism, other than clinical outcome. The present study was designed to examine myocardial protective effects by assessing clinical outcome, enzyme levels and myocardial cytochemistry. Twenty patients undergoing heart valve replacement were divided randomly into two groups: Group I was given intermittent perfusion of cold crystalloid (St. Thomas Hospital solution) with hypothermic cardiopulmonary bypass (CPB) and Group II was given continuous administration of warm blood cardioplegia with normothermic CPB. The groups were similar with respect to sex, age, body surface area and preoperative ventricular function. Blood samples were obtained from an indwelling radial arterial catheter or from the arterial end of the oxygenator. Biopsy specimens from the right atrium were obtained immediately before aortic declamping (ischemic period) and 30 minutes after crossclamp removal (reperfusion period). Serum enzymes, including alanine transaminase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and its isoenzymes and creatine phosphokinase (CK) and its isoenzyme, were determined. Myocardial cytochemistry were chiefly assessed by grey-scale image processing of adenosine triphosphatase (ATPase), succinate dehydrogenase (SDH) and cytochrome oxidase (CCO) examinations. Relations among the results were discussed. Reperfusion time was reduced and ventilation support time decreased in Group II (33.50 +/- 3.78 min vs. 25.00 +/- 4.46 min, p < 0.05; 38.98 +/- 16.55 h vs. 19.84 +/- 1.11 h, p < 0.05). Rates of atrial beating during aortic crossclamp and spontaneous recovery to normal sinus rhythm were much higher in Group II than in Group I (80% vs. 20%, p < 0.05; 70% vs. 10%, p < 0.05). Differences in hospital morbidity and mortality between groups were nonsignificant. Serum AST, ALT, LDH and LDH1 + LDH2 all showed no significant intergroup differences. There was a higher serum CK-MB level with a delayed peak in Group II. The cytochemistry activities of ATPase was not different between groups and periods and SDH was the highest during reperfusion period in Group I and of CCO significantly much promoted in Group II in both periods. Continuous warm blood cardioplegia resulted in higher spontaneous recovery to sinus rhythm, shorter reperfusion and ventilation support time. Damage to the myocardium, skeletal muscle and liver always occur in warm blood cardioplegic patients. However, warm blood cardioplegia is still a practical method for myocardial preservation in open heart surgery.

In vitro pulsatile flow visualization on extracardiac conduits for the right ventricular outflow tract reconstruction: qualitative considerations

Valved homograft conduits play an important role in the right ventricular outflow tract (RVOT) reconstruction for the surgical treatment of complex congenital heart disease. An excellent immediate rather than long-term outcome could be obtained. The hemodynamics for late failure, however, remained unclear. In vitro pulsatile flow visualization was not conducted before. A simplified right heart duplicator system was set up and driven under physiologic conditions. Polystyrene of 0.18 mm in diameter was applied as the tracing particle. Flow characteristics of models of normal pulmonary circulation as well as pulmonary artery atresia with the RVOT reconstructed utilizing valved and non-valved extracardiac conduits were observed. Flow patterns in the normal pulmonary circulatory model were mainly of axial flow associated with small scope of flow disturbances. A single vortex in the right ventricle was noted in diastole. In the pulmonary artery atresia model, a couple of vortexes were found in the right ventricle, a secondary flow in the main pulmonary artery, and a stronger secondary flow than in the normal pulmonary circulatory model in the two branches in both systole and diastole. A secondary flow was found in the proximal, an axial flow was observed in the distal portion of the extracardiac conduit with normal bioprosthetic valves and a secondary flow was observed in the entire conduit with stenotic bioprosthetic valves. The secondary flow intensity became stronger with the development of the stenosis. Severe insufficiency occurred in the bileaflet ceramic tilting-disc prosthesis during the entire cardiac circle, i.e., the prosthesis was in a maximum open position. Severe reverse flow could be found in the extracardiac conduit in the deceleration phase. Concavity of the crank shaft was found by examination to be filled with tracing particles and the prosthesis became stuck. Model of RVOT reconstruction with non-valved conduit yielded reverse flow inside the extracardiac conduit as well. Secondary flow may occur in normal or diseased extracardiac conduit for RVOT reconstruction. If micro-thrombus of over 0.18 mm in diameter attached in the concave of the crank shaft of a bileaflet tilting-disc prosthesis under a condition of resistance as occurred in the present study, the prosthesis may become stuck. Model of RVOT reconstruction with non-valved extracardiac conduit yielded reverse flow inside the conduit, of which the flow pattern was of greater energy consumption. Thus, a non-valved conduit should be avoided in clinical practice as far as possible.

A hybrid sequence approach to the paracelsus challenge

Inspired by the Paracelsus Challenge of Rose and Creamer (Proteins 19: 1-3, 1994), we have designed a protein sequence that is 50% identical to an all-helical protein but is intended to fold into a largely beta-sheet structure. Rather than attempt a de novo design, our strategy was to construct a hybrid sequence based on a helical "parent" protein (434 Cro) and a "target" protein with the desired fold (the B1 domain of protein G). The hybrid sequence (Crotein-G) is 50% identical to 434 Cro but is also 62% identical to the B1 domain of protein G. We also created a variant of Crotein-G (ZCrotein-G) that contains a potential His3Cys1 zinc binding site. At low protein concentrations and in the presence of 20% 2,2,2-trifluoroethanol (TFE) (v/v), the circular dichroism spectra of the designed proteins are distinct from that of 434 Cro and similar to that of the B1 domain of protein G. However, the proteins fail to denature in a cooperative manner. Furthermore, aggregation occurs at moderate protein concentrations or in the absence of TFE. Addition of zinc to ZCrotein-G does not promote structure formation. In summary, 434 Cro has been altered to something that may resemble the B1 domain of protein G, but the protein does not adopt a native structure.

Association of secundum atrial septal defect and mitral lesion in childhood: a case report

The association of secundum atrial septal defect (ASD) and congenital or acquired mitral lesions is rare. Only one case of secundum ASD and mitral lesion, in a three-year-old girl, has been encountered over a three-year period in this hospital. Diagnosis was not difficult with echocardiography, and was confirmed by operation. Surgical procedures including repair of ASD and annuloplasty of the mitral valve were performed under cardiopulmonary bypass. The mitral valve lesion was found during the operation to be of a congenital origin. Mitral lesions should not be neglected, and repair should be attempted even in a pediatric patient. Otherwise, anatomical and functional disorders of the mitral valve may develop at the early postoperative stage.

Effects of myocardial preservation on enzyme levels in serum and myocardium: a clinical study comparing cold crystalloid versus warm blood cardioplegia

BACKGROUND

Enzyme activities have been recognized as one of the parameters in the assessment of the effects of various forms of myocardial preservation. However, comparisons between different methods of myocardial protection by the use of enzyme assay in clinical settings in uncommon.

METHODS

Twenty patients who underwent open-heart valve replacement were divided equally into two groups: intermittent perfusion of cold crystalloid (St. Thomas Hospital solution) with hypothermic cardiopulmonary bypass (CPB) (Group I) and continuous administration of warm blood cardioplegia with normothermic CPB (Group II). The groups were similar with respect to sex, age, body surface area and preoperative ventricular function. Blood samples were obtained from an indwelling radial arterial catheter or from the arterial end of the oxygenator. Biopsy specimens from the right atrium were obtained immediately before aortic declamping (ischemic period), and 30 minutes after crossclamp removal (reperfusion period). The cumulative release of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and its isoenzymes; linear correlation between (iso)-enzymes of each group and multivariate regression between blood potassium and serum enzymes were determined. The enzyme levels of myocardial specimens including ALT, AST, LDH, creatine phosphokinase (CK), superoxide dismutase (SOD), and malondialdehyde (MDA) were recorded and compared both between the two groups and within each group.

RESULTS

No significant intergroup difference was found in the cumulative release of the serum (iso)-enzymes. Close relationships were found in all the correlation coefficients except for the CK-ALT couple in Group I. Neither were intergroup differences found in each parameter of the linear correlations between the (iso)-enzymes. A close correlation between blood potassium and serum enzymes was found in Group I rather than in Group II. Differences of enzyme levels of myocardial specimens between ischemic periods and reperfusion periods were also not statistically significant either within the group or between the groups.

CONCLUSIONS

Judging from the results of enzyme assay, similar myocardial preservation effects against ischemia-reperfusion injuries could be obtained by either of the techniques of myocardial preservation.

Metal search: a computer program that helps design tetrahedral metal-binding sites

We describe a computer program (Metal Search) that helps design tetrahedrally coordinated metal binding sites in proteins of known structure. The program takes as input the backbone coordinates of a protein and outputs lists of four residues that might form tetrahedral sites if wild-type amino acids were replaced by cysteine or histidine. The program also outputs the side chain dihedral angles of the amino acids and the coordinates of the predicted metal ion. The only function evaluated by Metal Search is the ability of side chains to meet simple geometric criteria for formation of a tetrahedral site, but these criteria are sufficient to produce a manageably small list that can then be evaluated by other means. The program has been used in the introduction of zinc binding sites in the designed four-helix bundle protein alpha 4 and in the B1 domain of streptococcal protein G, and in both cases the tetrahedral coordination of a bound metal ion has been confirmed (Klemba, M., Gardner, K. H., Marino, S., Clarke, N.D., and Regan, L., Nature: Structural Biology 2:368-373, 1995).

Myocardial protection of cold crystalloid and warm blood cardioplegia. A comparative study

Twenty patients undergoing open-heart valvular operations were divided randomly into two groups. Intermittent perfusion of cold crystalloid (St. Thomas Hospital solution) with hypothermic cardiopulmonary bypass (CPB) in the hypothermic group and continuous administration of warm blood cardioplegia with normothermic CPB in the normothermic group were used respectively. The results of warm blood cardioplegia were superior to those of cold crystalloid. 70% of patients treated with the warm technique had spontaneous return of normal sinus rhythm shortly after removal of the aortic cross-clamp, compared with only 10% of the hypothermic group (P < 0.05). The extracorporeal support time from releasing of aortic clamp to the weaning of CPB was significantly shorter in the normothermic group (33.50 +/- 3.78 min vs. 25.00 +/- 4.64 min, P < 0.05). The postoperative ventilation support time was also much shorter than that of the hypothermic group (19.84 +/- 1.11 h vs. 38.98 +/- 16.55 h, P < 0.05). More atrial beating occurred in the normothermic group (80% vs. 20%, P < 0.05) during aortic clamping, and it is showed that continuous warm blood cardioplegia might not efficiently prevent the atrium from damage.