Hideya Mitsui

Induction of antibacterial activity in larvae of the blowfly Lucilia sericata by an infected environment

Maggot debridement therapy (MDT) is a method for the treatment of intractable, infected and necrotic wounds. In MDT, sterile larvae of Lucilia sericata Meigen (Diptera: Calliphoridae) are applied to infected wounds, where they exert antibacterial effects. Once the larvae are placed in the wound, they are no longer germ‐free. This study analysed the influence of infected environments on larval antibacterial activities. Sterile larvae were mixed in a test tube containing a bacterial suspension of Staphylococcus aureus or Pseudomonas aeruginosa, transferred to liver puree agar, and incubated at 25 °C for set periods. To collect the larval extracts, the incubated larvae were transferred to a test tube containing phosphate buffered saline (PBS), cut into multiple pieces with scissors, and centrifuged. The supernatant was used to test antibacterial activities. The results showed that infected larvae had better antibacterial capacities than sterile larvae. Antibacterial activities were induced by pretreatment with a single bacterial species, S. aureus or P. aeruginosa, within 24 h and 12 h, respectively, and disappeared after 36 h. The activities were effective against S. aureus, but not against P. aeruginosa. This natural infection model is very similar to the clinical wound context in MDT and will be a powerful tool with which to study the antibacterial activities of L. sericata larvae in MDT.

Intravascular ultrasound complements the diagnostic capability of carbon dioxide digital subtraction angiography for patients with allergies to iodinated contrast medium.

Carbon dioxide digital subtraction angiography (CO2 DSA) is a useful and safe alternative for patients with renal dysfunction or allergies to iodinated contrast medium. However, CO2 DSA image quality is worse than that of angiography with iodinated contrast medium, primarily because of movement during imaging and stent struts. In angioplasty of arteries of the lower extremities, CO2 DSA cannot be used to sufficiently evaluate target lesions and determine the most efficient intervention. However, in the current case report, we describe a patient with severe allergies to iodinated contrast medium (Stevens–Johnson syndrome), because of which we were unable to use any iodinated contrast medium when conducting angioplasty. Therefore, we used intravascular ultrasound (IVUS), which facilitated the complete observation of the target lesion after stent implantation without requiring iodinated contrast medium. In this case, IVUS was used to complement the diagnostic capabilities of CO2 DSA.

Atrionatriuretic Peptide Improves Left Ventricular Function After Myocardial Global Ischemia–Reperfusion in Hypoxic Hearts

Atrionatriuretic peptide (ANP) is reported to be useful for attenuating myocardial ischemia-reperfusion injury and improving left ventricular function after reperfusion. However, ANP may be either ineffectual or harmful in cases where the myocardium has been chronically hypoxic since birth. This can be a result of the concomitant high levels of cyclic guanosine monophosphate (cGMP) produced within the myocardium. This study aimed to verify the validity of using ANP to improve left ventricular function after myocardial ischemia-reperfusion injury. For this purpose, a cyanotic congenital disease model that was developed using isolated rat hearts was used. Hearts were obtained from Sprague-Dawley rats that were housed from birth until 6 weeks of age either in a hypoxic environment with 13-14% FiO(2) (hypoxic group) or in ambient air (normoxic group). These hearts were subjected to 30min of normothermic global ischemia followed by 30min of reperfusion using the Langendorff technique. Left ventricular functional recovery in hearts administered ANP (0.1µM) into the reperfusion solution was compared with those hearts that were not administered ANP in both hypoxic (without ANP: n=6, with ANP: n=6, with ANP and HS-142-1[an antagonist of ANP]: n=6) and normoxic hearts (without ANP: n =6, with ANP: n=6). In the hypoxic hearts, ANP administration improved the percent recovery of the left ventricular developed pressure (76.3±9.2% without ANP vs. 86.9±6.7% with ANP), maximum first derivative of the left ventricular pressure (82.4±1.1% without ANP vs. 95.8±6.5% with ANP), and heart rate (85.6±4.7% without ANP vs. 96.1±5.2% with ANP) after reperfusion. The improvement and recovery of these cardiac functions were closely related to significantly increased levels of postischemic cGMP release after ANP administration. The effect of ANP was blocked by HS-142-1. The improvements observed in the hypoxic group were similar to those found in the normoxic group. ANP administration during reperfusion improved left ventricular function after myocardial acute global ischemia-reperfusion equally in both the chronically hypoxic and age-matched normoxic groups.

A simple, heat-sterilizable artificial diet excluding animal-derived ingredients for adult blowfly, Lucilia sericata.

Artificial diets have been developed for Lucilia sericata (Meigen) blowfly larvae; however, diets for adults have not yet been developed. An adult diet that excludes animal tissues and animal‐derived ingredients and promotes not only ovarian development, but also oviposition, would aid in basic research and maggot debridement therapy. We have successfully developed artificial diets that exclude animal tissues and animal‐derived ingredients for L. sericata adults. The outcomes of the diets were comparable with those of a beef liver diet in terms of oviposition, adult survival and number of offspring.

Short‐term cold storage of blowfly Lucilia sericata embryos

The developmental rate under low temperatures and cold tolerance were investigated in embryos of the blowfly Lucilia sericata. The larvae of this species are now widely used in maggot debridement therapy. Embryonic development was dependent on temperature, with a lower developmental threshold of 9.0 °C. The duration of the egg stage at a rearing temperature of 25 °C was 14 h, and a low temperature of 12.5 °C successfully prolonged this period to 66 h. Embryonic stages differed markedly in their cold tolerance; young embryos were less tolerant to cold than old ones. Late embryonic stages are suitable for cold storage at 5 °C and the storage for 72 h did not decrease the hatching rate by more than 50%. In the mass‐rearing process required for maggot debridement therapy, either of these two simple protocols would be beneficial.

Tolerance of the developing cyanotic heart to ischemia-reperfusion injury in the rat

ObjectiveWhether chronic hypoxia attenuates myocardial ischemia-reperfusion injury remains controversial because conflicting data have been reported probably due to the existence of many factors influencing the functional recovery of hearts. These factors include the differences of species, the time at which hypoxia begins, the degree of hypoxia, and so on. Regarding chronic hypoxia from birth, so far the only available data are based on findings in rabbit hearts. The purpose of this study was to describe the effect of chronic hypoxia from birth on myocardial reperfusion injury in the rat heart.MethodsNormoxic hearts were obtained from rats housed in ambient air for 6 weeks (normoxic group); hypoxic hearts were obtained from rats housed in a hypoxic chamber (13%–14% oxygen) from birth for 6 weeks (hypoxic group). Isolated, crystalloid perfused working hearts were subjected to 30 min of global normothermic ischemia followed by 15 min of reperfusion; functional recovery was then measured in the two groups. The excretion of cyclic guanosine monophosphate (cGMP) in the coronary drainage was measured at the end of the preischemia and reperfusion periods.ResultsThe percent recovery of the left ventricular developed pressure and the first derivative of left ventricular pressure were significantly better in the hypoxic group than in the normoxic group. cGMP excretion in the coronary drainage was significantly increased during both the preischemia and reperfusion periods.ConclusionChronic hypoxia from birth increased myocardial tolerance to ischemia-reperfusion injury with increased cGMP synthesis in the isolated heart model in rats.

Effects of Atrial Natriuretic Peptide After Prolonged Hypothermic Storage of the Isolated Rat Heart

Primary graft failure (PGF) caused by ischemia-reperfusion injury (IRI) is the strongest determinant of perioperative mortality after heart transplantation. Atrial natriuretic peptide (ANP) has been found to reduce the IRI of cardiomyocytes and may be beneficial in alleviating PGF after heart transplantation, although there is a lack of evidence to support this issue. The purpose of this study was to investigate the cardioprotective effects of ANP after prolonged hypothermic storage. For this purpose, an isolated working-heart rat model was used. After the preparation, the hearts were arrested with and stored in an extracellular-based cardioplegic solution at 3-4°C for 6 h and followed by 25 min of reperfusion. The hearts were divided into four groups (n = 7 in each group) according to the timing of ANP administration: Group 1 (in perfusate before storage), Group 2 (in cardioplegia), Group 3 (in reperfusate), and control (no administration of ANP). Left ventricular functional recovery and the incidence of ventricular fibrillation (VF) were compared. ANP administration at the time of reperfusion improved the percent recovery of left ventricular developed pressure (control, 45.5 ± 10.2; Group 1, 47.4 ± 8.8; Group 2, 45.3 ± 12 vs. Group 3, 76.3 ± 7; P < 0.05) and maximum first derivative of the left ventricular pressure (control, 47.9 ± 8.7; Group 1, 46.7 ± 8.8; Group 2, 49.6 ± 10.8 vs. Group 3, 76.6 ± 7.5; P < 0.05). The incidence of VF after reperfusion did not differ significantly among these four groups (71.4, 85.7, 57.1, and 85.7% in Groups 1, 2, 3, and control, respectively). This result suggests that the administration of ANP at the time of reperfusion may have the potential to decrease the incidence of PGF after heart transplantation.

Surgical Repair of Axillary Graft Stump Syndrome: Report of Two Cases

Late upper extremity embolic complications of occluded axillofemoral bypass graft (AxFG) or occluded axillo- axillary bypass graft (AxAG) are not frequently noted. A patient presented with acute right upper extremity thromboembolism 2 years after an AxFG occlusion. Computed tomography (CT) findings revealed kinking and occlusion of the axillary artery at the anastomosis. Another patient presented with acute left upper extremity thromboembolism 2 years and 6 years after an AxAG occlusion. CT indicated a thrombus progressing from the occluded graft to the axillary artery. Surgical repair of the axillary artery was performed in both patients without any complications.

Patient with a massive idiopathic thrombosis in the inferior vena cava.

A 50 year-old man with no significant medical history was admitted for dyspnea and left femoral swelling. Contrast-enhanced computed tomography revealed pulmonary thromboembolism (PTE) and a thrombus in the inferior vena cava (IVC). The thrombus extended from the proximal IVC to the left popliteal vein. Therefore, we decided that an IVC filter insertion was difficult to indicate. Urgent IVC and peripheral vein thrombectomy was performed under cardiopulmonary bypass. On postoperative day 1, venous ultrasonography showed residual deep vein thrombosis in the left external iliac-femoral vein and the popliteal vein. The IVC filter insertion was performed to prevent the recurrence of PTE.

History of Coronary Angiography

Diagnostic cardiac catheterization is recommended whenever it is clinically important to define the presence of cardiac disease that cannot be evaluated adequately by noninvasive techniques. Because the risk of a major complication from cardiac catheterization is less than 1% with mortality of less than 0.08%, many doctors can perform the catheterization safely now. We discuss the history of coronary angiography.