Nitrosopumilus maritimus genome reveals unique mechanisms for nitrification and autotrophy in globally distributed marine crenarchaea.

Ammonia-oxidizing archaea are ubiquitous in marine and terrestrial environments and now thought to be significant contributors to carbon and nitrogen cycling. The isolation of Candidatus "Nitrosopumilus maritimus" strain SCM1 provided the opportunity for linking its chemolithotrophic physiology with a genomic inventory of the globally distributed archaea. Here we report the 1,645,259-bp closed genome of strain SCM1, revealing highly copper-dependent systems for ammonia oxidation and electron transport that are distinctly different from known ammonia-oxidizing bacteria. Consistent with in situ isotopic studies of marine archaea, the genome sequence indicates N. maritimus grows autotrophically using a variant of the 3-hydroxypropionate/4-hydroxybutryrate pathway for carbon assimilation, while maintaining limited capacity for assimilation of organic carbon. This unique instance of archaeal biosynthesis of the osmoprotectant ectoine and an unprecedented enrichment of multicopper oxidases, thioredoxin-like proteins, and transcriptional regulators points to an organism responsive to environmental cues and adapted to handling reactive copper and nitrogen species that likely derive from its distinctive biochemistry. The conservation of N. maritimus gene content and organization within marine metagenomes indicates that the unique physiology of these specialized oligophiles may play a significant role in the biogeochemical cycles of carbon and nitrogen.

Crown group Oxyphotobacteria postdate the rise of oxygen.

The rise of oxygen ca. 2.3 billion years ago (Ga) is the most distinct environmental transition in Earth history. This event was enabled by the evolution of oxygenic photosynthesis in the ancestors of Cyanobacteria. However, long-standing questions concern the evolutionary timing of this metabolism, with conflicting answers spanning more than one billion years. Recently, knowledge of the Cyanobacteria phylum has expanded with the discovery of non-photosynthetic members, including a closely related sister group termed Melainabacteria, with the known oxygenic phototrophs restricted to a clade recently designated Oxyphotobacteria. By integrating genomic data from the Melainabacteria, cross-calibrated Bayesian relaxed molecular clock analyses show that crown group Oxyphotobacteria evolved ca. 2.0 billion years ago (Ga), well after the rise of atmospheric dioxygen. We further estimate the divergence between Oxyphotobacteria and Melainabacteria ca. 2.5-2.6 Ga, which-if oxygenic photosynthesis is an evolutionary synapomorphy of the Oxyphotobacteria-marks an upper limit for the origin of oxygenic photosynthesis. Together, these results are consistent with the hypothesis that oxygenic photosynthesis evolved relatively close in time to the rise of oxygen.

Mitral valve replacement through the aortic root.

This report discusses the case histories of two patients who had had previous cardiac operations and required extensive reoperations including mitral valve replacement. In both patients the replacement of the mitral valve was performed through the aortic root. This rare approach to the mitral valve, conducted with remarkable facility in these patients, encourages more liberal use of transaortic mitral valve operations in selected patients.

Prevention of distal limb ischemia during cardiopulmonary support via femoral cannulation.

The indications for prolonged cardiopulmonary support or extracorporeal membrane oxygenation are expanding. A potential serious complication of these techniques is distal limb ischemia. Techniques have been developed to provide the distal limb with blood flow. Unfortunately, specialized skills and materials are required. We describe a simple method of providing distal limb perfusion using ordinary pressure tubing and a standard cordis catheter. This technique is capable of reproducing normal superficial femoral artery blood flow.

Teleplot: a computing system for objective analysis of fetal heart rate recordings.

In human pregnancies, fetal heart rate recordings are useful both in predicting and in preventing imminent fetal death. Although an objective numerical measurement of such recordings is preferable to visual analysis, few obstetric centres have the computer expertise to implement this. Here we describe the principles of a technique whereby the fetal heart rate versus time trace may be transferred into computer memory for further processing in a numerical and objective fashion. The methodology is valid howsoever the fetal heart rate is detected.

Calciphylaxis, a poorly understood clinical syndrome: three case reports and a review of the literature.

Systemic calcification syndromes are a recognized complication occurring in some patients with end-stage renal disease (ESRD) and secondary hyperparathyroidism. These patients develop severe livedo reticularis and subcutaneous tissue lesions progressing to frank necrosis and ultimately large areas of eschar. Clinically this syndrome is known as calciphylaxis; these lesions are usually resistant to aggressive debridement, systemic antibiotics, and revascularization procedures. We report three patients with somewhat different clinical presentations but all sharing a common link of exquisitely painful leg ulcers initially being treated as ischemic lesions or venous stasis-type ulcerations. These three patients were diagnosed with calciphylaxis on the basis of clinical, biochemical, and histopathological criteria. Two patients underwent parathyroidectomy late in the progression of their disease, with some resolution of their ulcerative lesions.

Treatment of varicose veins: proximal saphenofemoral ligation comparing adjunctive varicose phlebectomy with sclerotherapy at a military medical center.

There is no consensus as to the single best approach to the treatment of varicose veins. There has been a trend toward less invasive procedures to reduce the number of incisions and provide more selective ablation of varicosities. Ultimately, therapeutic decisions have depended on surgeon preference and the patient population. The active duty military population presents a unique challenge in the treatment of varicose veins. This mobile and active population requires a treatment method that provides maximum relief with the lowest possible morbidity and rapid recovery. The authors previously reported their experience with 104 patients who underwent saphenofemoral ligation combined with perforator point ligation and staged sclerotherapy. This group was compared to 103 patients who underwent saphenofemoral ligation, point perforator ligation, and stab avulsion phlebectomy as a single procedure. Follow-up for the sclerotherapy group included patient satisfaction surveys and documentation of recurrent varicosities. All ambulatory phlebectomy patients responded positively with respect to symptomatic and cosmetic results. Overall satisfaction was favorable and there was no significant difference in patient satisfaction between the ambulatory phlebectomy and sclerotherapy groups. Twelve per cent of the sclerotherapy patients developed true recurrences or new varicosities compared to 11% in the ambulatory phlebectomy group. The most common complication was superficial thrombophlebitis (20% ambulatory phlebectomy, 16% sclerotherapy) which was mild in all cases. All but three patients in the ambulatory phlebectomy group returned to work within 7 days and 75% returned to full duty within 72 hours. Completion of therapy was accomplished in a much shorter period for the ambulatory phlebectomy group. Overall patient satisfaction was achieved for both ambulatory phlebectomy and sclerotherapy patients. Completion of therapy was achieved in a shorter period with fewer clinic visits in the ambulatory phlebectomy group and this has become our procedure of choice for active duty military patients.

Internal iliac artery aneurysm following aortic reconstruction.

Fewer than 100 internal iliac artery aneurysms have been reported in the English literature. Of these the incidence of true aneurysms occurring after aortic reconstruction is exceedingly low. A 73-year old man presented with 7 cm asymptomatic left internal iliac artery aneurysm 12 years after repair of an abdominal aortic aneurysm with a bifurcation graft. We report our experience with this patient along with a review of the literature and recommendations for aneurysm surveillance.

Vascular thoracic outlet syndrome: successful outcomes with multimodal therapy.

PURPOSE: Vascular thoracic outlet syndrome (TOS) can present with signs of arterial impingement or, more commonly, as venous obstruction. In an effort to decrease morbidity associated with vascular thoracic outlet syndrome, we have used an aggressive multimodal treatment approach. METHODS: Since November 1992, we have evaluated 29 patients with vascular thoracic outlet syndrome. Nine of ten patients with arterial thoracic outlet syndrome had first rib resections. Eighteen of 19 patients with venous occlusion underwent anticoagulation, thrombolysis, and first rib resection. Eight patients required additional endovascular therapy for persistent stenoses, either venous angioplasty alone (2) or angioplasty plus stent placement (6). RESULTS: Follow up extends to 75months with a mean of 24months. Patients with stents have been followed for a mean of 38months. Twenty-five of 28 patients managed with multimodal therapy were essentially asymptomatic at last follow up. CONCLUSION: Thrombolysis, anticoagulation, surgical decompression, and endovascular procedures act synergistically to improve results of therapy in patients with vascular thoracic outlet syndrome.

Left iliac vein occlusion: its clinical spectrum.

The cases reported here demonstrate the variability of the clinical manifestations of left common iliac venous occlusive disease. In each instance, therapy must be adjusted to meet the symptomatic needs of the individual patient. The experience reported here should reinforce the fact that occlusions even 25 months or longer in duration may be reopened. Continuing patency can be enhanced by stent placement.