Autotransplantation of the lung: experimental studies on the cape baboon

Autotransplantation of the left lung was performed on 15 adult baboons with an 8-day survival rate of 80% and a long-term survival rate of 60%. On 5 of the survivors a subsequent contralateral pneumonectomy was performed without mortality. Most deaths occurred early in the series due to technical problems. A surgical technique has been standardized and with further experience in this field the mortality associated with autotransplantation of the lung in baboons should be less than 10%. Xenon-l33 ventilation-perfusion studies of the transplanted lung demonstrated a significant reduction in perfusion, and to a lesser extent of ventilation. Ventilation rapidly recovered towards normal but perfusion only approached normal values several months after transplantation. These physiological alterations may be due to the denervation attendant upon complete removal of tlu lung with reimplantation. The jilt! imbalance does not appear to be of major consequence when a contralateral pneumonectomy is performed. The autotransplanted lung appears to be a valuable model for studying the effects of lung transplantation alone, without the problems of rejection. These studies seem to be particularly valuable in the primate who closely resembles the human anatomically and physiologically. Further studies are currently in progress

Correction for Kipkorir et al., "De Novo Cobalamin Biosynthesis, Transport, and Assimilation and Cobalamin-Mediated Regulation of Methionine Biosynthesis in Mycobacterium smegmatis"

Volume 203, no. 7, e00620-20, 2021, https://doi.org/10.1128/JB.00620-20. Page 1: This article was published on 8 March 2021 with Stephanie S. Dawes missing from the byline. The byline was updated in the version posted on 21 January 2022. The following corrections were also made in that version. Page 1, footnote box: The following footnote was added. “§Present address: Stephanie S. Dawes, Laboratory of Structural Biology, School of Biological Sciences and Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland, New Zealand.” Page 14, Acknowledgments, line 3: “and Stephanie Dawes for providing the DmetE cobK::hyg mutant” was deleted. Page 14, Acknowledgments, lines 1 and 2 from bottom: “(to V.M. and D.F.W.)” was changed to “(to S.S.D., V.M., and D.F.W.).

Penetrating wounds of the heart and great vessels : experience with 24 cases including 3 with intracardiac defects

The original version is available at http://www.samj.org.za/Twenty four cases of penetrating cardiac injuries due to stab wounds, which were seen over a 3 yr period, are reviewed. Ten patients were treated by aspiration alone because tamponade was mild, or because they were seen more than 12 hr after injury. One patient with multiple stab wounds in the ventricles and left atrium died during emergency thoracotomy in the admission room. The mortality rate of 4.2% is considerably lower than rates reported in other series. Two cases of traumatic ventricular septal defects, one case of traumatic aortic incompetence and sinus of Valsalva fistulae with rupture into the right ventricle and right atrium, and one case of ascending aorta innominate vein fistula are discussed. A plan of management is outlined.Publishers' Versio

Supravalvular aortic stenosis in the adult : a case presentation with unique associated features

The original publication is available at http://www.samj.org.zaA 42-year-old symptomatic woman with possible adult Williams's syndrome (mental retardation, 'elfin facies' and supravalvular aortic steosis (SVAS)) is documented. This patient displayed many unique features in addition to the severe SVAS (peak systolic gradient 96 mmHg): there was an associated persistent left superior vena cava draining into the coronary sinus, mitral valve prolapse (Barlow's syndrome) and complete right bundle-branch block on ECG. Peripheral pulmonary artery stenosis was absent. M-mode echocardiography in the adult with SVAS is described for the first time in the literature, as is the use of the 60° cross-sectional scan. Both these non-invasive procedures proved of value in the diagnosis. The degree of subendocardial ischaemia, as determined by the 'endocardial viability ratio', was calculated and the possible mechanisms producing angina pectoris with 'coronary artery hypertension' in this condition are discussed. The literature on associated mitral valve abnormalities in SVAS is reviewed. A successful surgical result was obtained; the various forms of operation are outlined.Publishers' versio

Ventricular aneurysmectomy and infarctectomy

The original version is available at http://www.samj.org.za/Four patients underwent ventricular aneurysmectomy for congestive cardiac failure. In addition, 1 patient with an aneurysm and 3 patients with acute myocardial infarcts, ranging from 16 to 28 days postinfarction, underwent emergency surgery for recurrent malignant arrhythmias. The preoperative treatment, cardiac catheterization data and surgical findings are outlined. The overall survival rate is 75% for a mean followup period of 12.5 mth (range 8-22 mth). It is concluded that aneurysmectomy, for congestive cardiac failure, and infarctectomy, for life threatening ventricular arrhythmias, are gratifying and worthwhile procedures.Publishers' Versio

Rupture of sinus of Valsalva aneurysm into both right atrium and right ventricle : a case report

The original publication is available at http://www.samj.org.zaA young man had a congenital sinus of Valsalva aneurysm originating from the right coronary sinus, complicated by fistulas draining into both right atrium and right ventricle, as well as congenitally abnormal aortic valve with mild aortic insufficiency. His dramatic clinical presentation, with the sudden appearance of severe biventricular cardiac failure unresponsive to intensive medical therapy, was an important clue to making the correct pre-operative diagnosis. The use of non-invasive techniques, such as phonocardiography and M-mode and two-dimensional echocardiography, is highlighted. Full cardiac catheterization was employed to define the cardiac pathophysiology. This was one of the few cases documented in which a catheter could be passed from the aorta into the right ventricle via the fistula connecting these two chambers. The fistulas were closed and the aortic valve replaced. Postoperative investigations confirmed the success of corrective surgery. As far as we are aware this is the first documented case of successful repair of a congenital sinus of Valsalva aneurysm rupturing into both the right atrium and right ventricle, accompanied by aortic insufficiency.Publishers' versio

Rupture of sinus of Valsalva aneurysm into both right atrium and right ventricle

A young man had a congenital sinus of Valsalva aneurysm originating from the right coronary sinus, complicated by fistulas draining into both right atrium and right ventricle, as well as a congenitally abnormal aortic valve with mild aortic insufficiency. His dramatic clinical presentation, with the sudden appearance of severe biventricular cardiac failure unresponsive to intensive medical therapy, was an important clue to making the correct pre-operative diagnosis. The use of non-invasive techniques, such as phonocardiography and M-mode and twodimensional echocardiography, is highlighted. Full cardiac catheterization was employed to define the cardiac pathophysiology. This was one of the few cases documented in which a catheter could be passed from the aorta into the right ventricle via the fistula connecting these two chambers. The fistulas were closed and the aortic valve replaced. Postoperative investigations confirmed the success of corrective surgery. As far as we are aware this is the first documented case of successful repair of a congenital sinus of Valsalva aneurysm rupturing into both the right atrium and right ventricle, accompanied by aortic insufficiency

De Novo Cobalamin Biosynthesis, Transport, and Assimilation and Cobalamin-Mediated Regulation of Methionine Biosynthesis in Mycobacterium smegmatis.

Cobalamin is an essential cofactor in all domains of life, yet its biosynthesis is restricted to some bacteria and archaea. Mycobacterium smegmatis, an environmental saprophyte frequently used as surrogate for the obligate human pathogen M. tuberculosis, carries approximately 30 genes predicted to be involved in de novo cobalamin biosynthesis. M. smegmatis also encodes multiple cobalamin-dependent enzymes, including MetH, a methionine synthase that catalyzes the final reaction in methionine biosynthesis. In addition to metH, M. smegmatis possesses a cobalamin-independent methionine synthase, metE, suggesting that enzyme use-MetH versus MetE-is regulated by cobalamin availability. Consistent with this notion, we previously described a cobalamin-sensing riboswitch controlling metE expression in M. tuberculosis Here, we apply a targeted mass spectrometry-based approach to confirm de novo cobalamin biosynthesis in M. smegmatis during aerobic growth in vitro We also demonstrate that M. smegmatis can transport and assimilate exogenous cyanocobalamin (CNCbl; also known as vitamin B12) and its precursor, dicyanocobinamide ([CN]2Cbi). However, the uptake of CNCbl and (CN)2Cbi in this organism is restricted and seems dependent on the conditional essentiality of the cobalamin-dependent methionine synthase. Using gene and protein expression analyses combined with single-cell growth kinetics and live-cell time-lapse microscopy, we show that transcription and translation of metE are strongly attenuated by endogenous cobalamin. These results support the inference that metH essentiality in M. smegmatis results from riboswitch-mediated repression of MetE expression. Moreover, differences observed in cobalamin-dependent metabolism between M. smegmatis and M. tuberculosis provide some insight into the selective pressures which might have shaped mycobacterial metabolism for pathogenicity.IMPORTANCE Alterations in cobalamin-dependent metabolism have marked the evolution of Mycobacterium tuberculosis into a human pathogen. However, the role(s) of cobalamin in mycobacterial physiology remains poorly understood. Using the nonpathogenic saprophyte M. smegmatis, we investigated the production of cobalamin, transport and assimilation of cobalamin precursors, and the role of cobalamin in regulating methionine biosynthesis. We confirm constitutive de novo cobalamin biosynthesis in M. smegmatis, in contrast with M. tuberculosis, which appears to lack de novo cobalamin biosynthetic capacity. We also show that uptake of cyanocobalamin (vitamin B12) and its precursors is restricted in M. smegmatis, apparently depending on the cofactor requirements of the cobalamin-dependent methionine synthase. These observations establish M. smegmatis as an informative foil to elucidate key metabolic adaptations enabling mycobacterial pathogenicity