Population heterogeneity in and .

Bacteria use population heterogeneity, the presence of more than one phenotypic variant in a clonal population, to endure diverse environmental challenges - a 'bet-hedging' strategy. Phenotypic variants have been described in many bacteria, but the phenomenon is not well-understood in mycobacteria, including the environmental factors that influence heterogeneity. Here, we describe three reproducible morphological variants in - smooth, rough, and an intermediate morphotype that predominated under typical laboratory conditions.

Protein kinase B controls Mycobacterium tuberculosis growth via phosphorylation of the transcriptional regulator Lsr2 at threonine 112.

Mycobacterium tuberculosis (Mtb) is able to persist in the body through months of multi-drug therapy. Mycobacteria possess a wide range of regulatory proteins, including the protein kinase B (PknB) which controls peptidoglycan biosynthesis during growth. Here, we observed that depletion of PknB resulted in specific transcriptional changes that are likely caused by reduced phosphorylation of the H-NS-like regulator Lsr2 at threonine 112.

Antibiotic Bactericidal Activity Is Countered by Maintaining pH Homeostasis in Mycobacterium smegmatis.

Antibiotics target specific biosynthetic processes essential for bacterial growth. It is intriguing that several commonalities connect the bactericidal activity of seemingly disparate antibiotics, such as the numerous conditions that confer broad-spectrum antibiotic tolerance. Whether antibiotics kill in a manner unique to their specific targets or by a universal mechanism is a critical and contested subject.

A Burkholderia pseudomallei colony variant necessary for gastric colonization.

Unlabelled: Diverse colony morphologies are a hallmark of Burkholderia pseudomallei recovered from infected patients. We observed that stresses that inhibit aerobic respiration shifted populations of B. pseudomallei from the canonical white colony morphotype toward two distinct, reversible, yet relatively stable yellow colony variants (YA and YB).

Mycobacterium tuberculosis Lsr2 is a global transcriptional regulator required for adaptation to changing oxygen levels and virulence.

Unlabelled: To survive a dynamic host environment, Mycobacterium tuberculosis must endure a series of challenges, from reactive oxygen and nitrogen stress to drastic shifts in oxygen availability. The mycobacterial Lsr2 protein has been implicated in reactive oxygen defense via direct protection of DNA. To examine the role of Lsr2 in pathogenesis and physiology of M.

The oxidation-sensing regulator (MosR) is a new redox-dependent transcription factor in Mycobacterium tuberculosis.

Mycobacterium tuberculosis thrives in oxidative environments such as the macrophage. To survive, the bacterium must sense and adapt to the oxidative conditions. Several antioxidant defenses including a thick cell wall, millimolar concentrations of small molecule thiols, and protective enzymes are known to help the bacterium withstand the oxidative stress.

The response of mycobacterium tuberculosis to reactive oxygen and nitrogen species.

The bacteriostatic and bactericidal effects and the transcriptional response of Mycobacterium tuberculosis to representative oxidative and nitrosative stresses were investigated by growth and survival studies and whole genome expression analysis. The M. tuberculosis reaction to a range of hydrogen peroxide (H(2)O(2)) concentrations fell into three distinct categories: (1) low level exposure resulted in induction of a few highly sensitive H(2)O(2)-responsive genes, (2) intermediate exposure resulted in massive transcriptional changes without an effect on growth or survival, and (3) high exposure resulted in a muted transcriptional response and eventual death.

The Mycobacterium tuberculosis DosR regulon assists in metabolic homeostasis and enables rapid recovery from nonrespiring dormancy.

Mycobacterium tuberculosis survives in latently infected individuals, likely in a nonreplicating or dormancy-like state. The M. tuberculosis DosR regulon is a genetic program induced by conditions that inhibit aerobic respiration and prevent bacillus replication.

The DosR regulon of M. tuberculosis and antibacterial tolerance.

Adaptation of Mycobacterium tuberculosis to an anaerobic dormant state that is tolerant to several antibacterials is mediated largely by a set of highly expressed genes controlled by DosR. A DosR mutant was constructed to investigate whether the DosR regulon is involved in antibacterial tolerance. We demonstrate that induction of the regulon is not required for drug tolerance either in vivo during a mouse infection or in vitro during anaerobic dormancy.

Unique roles of DosT and DosS in DosR regulon induction and Mycobacterium tuberculosis dormancy.

In Mycobacterium tuberculosis, the sensor kinases DosT and DosS activate the transcriptional regulator DosR, resulting in the induction of the DosR regulon, which is important for anaerobic survival and perhaps latent infection. The individual and collective roles of these sensors have been postulated biochemically, but their roles in vivo have remained unclear. This work demonstrates distinct and additive roles for each sensor during anaerobic dormancy.

[Mobile multiple left chamber thrombi causing multiple embolism in the limbs requiring surgery].

The authors report on the case of a 35-year-old man with multiple risk factors, who was sent to cardiac examination in order to find the cause of microembolisms on his fingers of his hands and on his right leg. According to the history and the ECG the patient had suffered an anterior myocardial infarction at home two months before the embolisms which had not been detected at that time. Performing 2D echocardiography, wall motion abnormality indicating anterior myocardial infarction and several thrombi were found as the source of embolisms.

[Prinzmetal angina pectoris causing diagnostic and therapeutic problems].

A 53 year old patient was hospitalized because of retrosternal oppression which was unrelated to effort and recurred in the early morning hours. An esophageal diverticulum and a hiatal hernia were found. The patient had complaints in spite of medical therapy and an operation was performed because of his oesophageal disorders.

Ruptured aneurysms of the sinus of Valsalva.

From 1969 to 1989, 15 patients with an aneurysm of the sinus of Valsalva underwent operative correction. This represents 0.23% of 6515 cardiac operations with cardiopulmonary bypass during that time.

Surgical treatment of left ventricular thrombi: two-dimensional echocardiographic diagnosis.

Two cases of successful surgical removal of left ventricular thrombi are presented. Two-dimensional echocardiography revealed in the first case multiple masses of thrombi in the dilated ventricle consistent with congestive cardiomyopathy and emergency surgery was performed for cerebral embolism. In the second case the thrombus was pedunculated and calcified, a probable sequel of a 17-year old myocardial infarction.

The importance of endothelial cells in the course of vascular surgical interventions.

Aorto-coronary bypass made by implanting the patient's own saphenous vein may exhibit a tendency to early and late occlusion. This phenomenon is influenced by a number of factors including intraoperative damages of the graft. To determine preferable techniques for preserving vein integrity, various human graft preparation techniques were compared.

Guidewire snap causing left main coronary occlusion during coronary angioplasty.

The case of a 34-year-old female patient is presented. During attempted left anterior descending coronary angioplasty, the exchange guidewire (0.018 inch, 300 cm) snapped and the distal 20 cm of the wire caused immediate thrombotic occlusion of both the left anterior descending and circumflex arteries.