Evolution of a minimal cell.

Possessing only essential genes, a minimal cell can reveal mechanisms and processes that are critical for the persistence and stability of life1,2. Here we report on how an engineered minimal cell3,4 contends with the forces of evolution compared with the Mycoplasma mycoides non-minimal cell from which it was synthetically derived. Mutation rates were the highest among all reported bacteria, but were not affected by genome minimization. Genome streamlining was costly, leading to a decrease in fitness of greater than 50%, but this deficit was regained during 2,000 generations of evolution. Despite selection acting on distinct genetic targets, increases in the maximum growth rate of the synthetic cells were comparable. Moreover, when performance was assessed by relative fitness, the minimal cell evolved 39% faster than the non-minimal cell. The only apparent constraint involved the evolution of cell size. The size of the non-minimal cell increased by 80%, whereas the minimal cell remained the same. This pattern reflected epistatic effects of mutations in ftsZ, which encodes a tubulin-homologue protein that regulates cell division and morphology5,6. Our findings demonstrate that natural selection can rapidly increase the fitness of one of the simplest autonomously growing organisms. Understanding how species with small genomes overcome evolutionary challenges provides critical insights into the persistence of host-associated endosymbionts, the stability of streamlined chassis for biotechnology and the targeted refinement of synthetically engineered cells2,7-9.

Protein families, natural history and biotechnological aspects of spider silk.

Spiders are exceptionally diverse and abundant organisms in terrestrial ecosystems and their evolutionary success is certainly related to their capacity to produce different types of silks during their life cycle, making a specialized use on each of them. Presenting particularly tandemly arranged amino acid repeats, silk proteins (spidroins) have mechanical properties superior to most synthetic or natural high-performance fibers, which makes them very promising for biotechnology industry, with putative applications in the production of new biomaterials. During the evolution of spider species, complex behaviors of web production and usage have been coupled with anatomical specialization of spinning glands. Spiders retaining ancestral characters, such as the ones belonging to the Mygalomorph group, present simpler sorts of webs used mainly to build burrows and egg sacs, and their silks are produced by globular undifferentiated spinning glands. In contrast, Araneomorphae spiders have a complex spinning apparatus, presenting up to seven morphologically distinct glands, capable to produce a more complex set of silk polymers with different degrees of rigidness and elasticity associated with distinct behaviors. Aiming to provide a discussion involving a number of spider silks' biological aspects, in this review we present descriptions of members from each family of spidroin identified from five spider species of the Brazilian biodiversity, and an evolutionary study of them in correlation with the anatomical specialization of glands and spider's spinning behaviors. Due to the biotechnological importance of spider silks for the production of new biomaterials, we also discuss about the new possible technical and biomedical applications of spider silks and the current status of it.

Phase Angle Reflects Loss of Functionality in Older Women.

OBJECTIVE: This study verified if the phase angle (PA) formed by the resistance (R) and reactance (Xc) obtained from bioimpedance (BIA) might be a useful tool to identify functionality. DESIGN AND PARTICIPANTS: It was conducted a cross-sectional study with 152 women ≥ 65 years old from the community. MEASUREMENTS: weight, height, body mass index (BMI), calf circumference (CC), hand grip strength (HGS), gait speed (GS), fat free mass (FFM), body fat (BF), PA with R and Xc from the BIA were measured. Spearman's and Pearson's correlations and the odds ratio (OR) were performed using the IBM SPSS software version 22.0. RESULTS: Sixty-four percent (n=98) women are with PA below the reference. Negative moderate significant correlation was found between PA and age (r =- 0.440*; p<0.001). Moderate significant correlation was observed between PA and GS (r = 0.484**; p<0.001). Weak significant correlation was found between PA and HGS (r = 0.177*; p = 0.029). Odds ratio (OR) demonstrated that individuals with PA above the mean value have 4.77 times more chances of having increased GS (confidence interval 2.40-9.48; 95%). Women aged below the mean value have 4.02 times more chances of having higher PA (confidence interval 2.02-7.99; 95%). Younger aged women showed 4.02 times more chances of having higher PA (confidence interval 2.02-7.99; 95%). CONCLUSIONS: Phase angle can be associated with functional tests, such as gait speed and hand grip strength, in older women.

Spidroins from the Brazilian spider Nephilengys cruentata (Araneae: Nephilidae).

Spiders produce up to six different kinds of silk, each one for a specific biological function. Spider silks are also known for their unique mechanical properties. The possibility of producing new materials with similar properties motivated research on these silk proteins (spidroins). Using expression sequence tags, we identified four spidroins produced by major ampullate, minor ampullate, flagelliform and tubuliform silk glands from the Brazilian spider Nephilengys cruentata (Araneae: Nephilidae). The new protein sequences showed substantial similarity to other spidroins previously described, with high content of alanine and glycine due to the presence of the highly repetitive motifs (polyAla, (GA)n, (GGX)n, (GPGGX)n). Similarities among sequences were also observed between the different spidroins with the exception of tubuliform spidroin, which presents a unique complex amino acid sequence with high amounts of serine and low amounts of glycine.

Correction of pulmonary atresia with ventricular septal defect in the absence of the pulmonary trunk and the central pulmonary arteries (so-called truncus type IV).

A child with pulmonary atresia and ventricular septal defect and no extraparenchymal pulmonary arteries had all the bronchopulmonary arterial segments connected to naturally occurring systemic-pulmonary collaterals. A three-staged surgical correction was performed. At the first and second stages, the arteries of each hilus were interconnected with synthetic arteries. At the third stage, the ventricular septal defect was closed, and continuity between the right ventricle and the bilateral pulmonary circulation was established with a valved conduit giving rise to a side arm. Postoperative evolution was good, with acceptable postrepair per right ventricular--left ventricular pressure ratio.

Variable-column bubble oxygenator. A new system for bubble oxygenation.

A new bubble oxygenator has been developed. Its main advantage is that the dimensions of the oxygenating chamber can be varied. Thus, the capacity for oxygenation may be adapted to different patients. It was used in 2,700 open-heart operations performed at the Institut do Coracão, Faculdade de Medicina, Universidade de São Paulo, between January, 1971, and December, 1973. A group of 50 patients were subjected to more detailed studies. We found that the average hemolysis was 38.67 mg. per cent with a mean perfusion duration of 69 minutes, 38 seconds. Fibrinogen and platelet concentrations decreased by 14 and 25 per cent, respectively. The pH, PcO2, PO2, and base excess before and after cardiopulmonary bypass ranged within normal levels, and oxygenation (PO2) was always satisfactory.

Homologous dura mater cardiac valves. Structural aspects of eight implanted valves.

We studied eight homologous dura mater valves removed 1 to 35 months after implantation. Five dura mater valves were placed in the mitral position and three in the aortic position. Two of the valves were obtained after deaths not related to the valve itself and six after reoperations due to immediate or late incompetence. In 2 cases the dura mater valves were entirely normal, both macroscopically and microscopically. In 2 other cases the leaflets were caught by stitches related to the struts, a technical error that caused laceration of the leaflets. Not withstanding this fact, the dura mater was normal on histologic examination. In 3 cases, and probably in 1 other, one or two leaflets were detached partially from the suture line, probably because of a technical error in the manufacture of the valve. These studies demonstrated satisfactory evolution of the homologous dura mater valves until 35 months after implantation. No signs of rejection or degeneration of the dura mater were observed in the present series.

Inferior epigastric artery as a free graft for myocardial revascularization.

The inferior epigastric artery was used as a free graft for direct myocardial revascularization in 22 patients from October 1987 to July 1988. The artery was used either alone or along with internal mammary artery or saphenous vein grafts. The inferior epigastric artery was dissected through an infraumbilical incision without entrance into the peritoneal cavity. The results depend on the technique used for the aortoepigastric anastomosis. When a segment of saphenous vein or a patch of bovine pericardium was sutured to a large aortic orifice with the inferior epigastric artery previously anastomosed to these patches, the patency rate of the free grafts in the early postoperative period was 100%. Histologic examination showed identical structure of the inferior epigastric artery and the internal mammary artery. Application of the inferior epigastric artery is an attempt to increase the use of arterial grafts for myocardial revascularization.

Surgical treatment of ruptured aneurysms of the innominate artery.

The cases of 3 patients with an aneurysm of the innominate artery treated surgically are reported. The clinical manifestations were different, and the surgical procedures employed also varied. In 1 patient, the neck of the aneurysm was isolated and clamped near the aortic arch. It was closed, and a graft was interposed between the ascending aorta and the right carotid and subclavian arteries. In the second, the aneurysm was resected under cardiopulmonary bypass, deep hypothermia, and total circulatory arrest. The neck was closed with a large Teflon patch, and a tube graft was interposed between the ascending aorta and the right carotid artery. In the third, a graft was interposed between both carotid arteries; conventional cardiopulmonary bypass was instituted, and the aorta was clamped between the innominate and the left carotid arteries. The neck of the aneurysm was closed, and a graft was interposed between the ascending aorta and the right carotid and subclavian arteries. All patients had an excellent postoperative course. Our comments regarding the clinical and surgical aspects of this condition are based on the present experience and reports in the literature.

Management of aortic insufficiency in chronic aortic dissection.

From January 1980 to December 1988, 44 patients with chronic aortic dissection and aortic insufficiency underwent operation. This group of patients was analyzed to evaluate the outcome of those in whom the aortic valve was preserved compared with those having valve replacement. The overall preoperative characteristics of the two groups were similar except for the incidence of Marfan's syndrome. Valve replacement was the elected procedure in patients with valve degeneration or annuloaortic ectasia. In patients with leaflet prolapse with or without an enlarged annulus, a plastic procedure was used. In 48% of the patients, it was possible to preserve the valve. There were five hospital deaths (11%): three were due to low-output syndrome, one was due to bleeding, and one was due to neurological complications. There were two late deaths (5%). Follow-up of the 37 surviving patients ranged from 2 to 108 months (mean follow-up, 18 months). Seventy-eight percent of the survivors were in functional class I and the others were in class II. Two patients in whom the aortic valve was preserved had mild aortic insufficiency. Three patients with bioprostheses underwent reoperation because of prosthetic valve dysfunction. One patient who had aortoplasty and an aortic valve plastic procedure was seen with redissection and aortic insufficiency after 60 months and was reoperated on using the Bentall technique. The actuarial survival curves showed that patients who underwent valvoplasty had higher, but not significantly higher, survival rates than the valve replacement patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Four years experience with dura mater cardiac valves.

The clinical use of homologous dura mater cardiac valves was begun in January 1971. Between January 1971 and May 1975, 751 patients received 849 dura mater valves: 428 mitral, 365 aortic, 52 tricuspid and 4 pulmonary. The hospital mortality observed in this series was 13.6% and late mortality was 2.5%. The main causes of death were low-output syndrome in the immediate post-operative period or cardiac failure in the late post-operative period, due to myocardial impairment. Paravalvular leaks and errors in the manufacture of the valve were the main causes of regurgitation both in the immediate and late post-operative period. The incidence of thromboembolism, bacterial and fungal endocarditis was: 0.79%, 0.39%, 0.53% respectively. The results obtained with dura mater valve in a period of four years are satisfactory from the clinical and hemodynamic points of view.

Long-term results of mammary artery implants.

Eighty out of eighty-six patients (93%) with mammary artery implants were followed postoperatively for an average of three and a half years. The immediate mortality rate was 7% (6 cases), and the late mortality was 6% (5 cases). All had angina preoperatively. Twenty-four had a history of myocardial infarction and thirty-one were on limited physical activity, because of the pain. After surgery, thirty-three (45%) became asymptomatic. The angina improved significantly in thirty-five (47%) and remained unchanged in six (8%). Improvement in ventricular repolarization on ECG was observed in 69% of the patients. Postoperative cineangiography was performed in twenty-three patients; thirteen with single and ten with double implants. Out of the total of thirty-three implants, four (12%) were obstructed and twenty-seven patent (82%); twenty were in two cases of double implant, only one implant could be satisfactorily studied effectively functioning (61%). No obstructions were seen in the single implants. Non functioning implants were found in five (38%) of the thirteen single implants and in two of the twenty double ones (10%). The highest incidence of obstruction or non-functioning implants occurred in the group that did not show improvement (43%). This rate fell to 40% in the group that had some improvement and to 29% in those that were completely asymptomatic. Twelve of the eighteen patent mammary implants (67%) on the anterior wall of the left ventricle and eight of nine (89%) on the lateroinferior wall, established collateral circulation to the coronaries. Indication for surgery was considered satisfactory for nineteen out of the twenty-three patients and poor in four. There were two cases of obstruction of the implant (7%) in the group where surgery was correctly indicated and three of the twenty-three (11%) patent implants were non-functioning. Clinical improvement of the angina occurred in 84% in the first group and 50% in the other. In conclusion, this technique of indirect revascularization of the myocardium is valid for patients with severe diffuse lesions of the coronaries with a collateral network and preserved myocardial contractility.

Vascular anastomosis by argon laser beam.

Twenty-four mongrel dogs, weighing 13 to 24 kg, were used to study the effectiveness of anastomosis by Argon Laser beam. After anesthesia, intubation and controlled ventilation, they were submitted to three types of vascular anastomoses: saphenous vein intercarotid artery bypass; left mammary artery/left anterior descending coronary artery bypass; and veno-venous anastomosis. In all groups, 0.8 to 1.5 watts of Argon Laser power were applied for a total time of 90 to 300 seconds. The lower power was for veno-venous anastomoses and the greater was applied for arterial anastomoses. The mean values of resistance of the laser anastomosis to pressure-induced repture were 730 mm Hg in the immediate postoperative study, but increased to 2,500 mm Hg 30 days after surgery. No signs of occlusion were demonstrated at the anastomotic sites by the angiographic and anatomopathological studies performed.

The De Vega annuloplasty as surgical treatment for tricuspid incompetence.

Seventy-six patients with tricuspid insufficiency associated with other valvular lesions underwent De Vega annuloplasty. There were mitral lesions in 74 patients, aortic valve lesions in eight and atrial septal defects (ASD) in four. The radiographic and electrocardiographic findings and hemodynamic data are reported for 66 patients. Replacement of one or two valves was performed in 56 patients, one or two valves commissurotomy in 21 and closure of the ASD in four. The immediate postoperative mortality was 19.7%. Forty-four patients were followed from six to 59 months. There were three late deaths and clinical conditions were improved in all the survivors except one who presented mitral restenosis. Discrete residual tricuspid incompetence occurred in 11 patients (25%). We conclude that the De Vega annuloplasty is the treatment of choice for functional tricuspid incompetence.

[Mammary-coronary anastomosis: a new technique of approach through the brachial route for angiographic study and angioplasty]. / Anastomose mamária-coronária: nova técnica de abordagem por via braquial para estudo angiográfico e angioplastia.

PURPOSE: A new technique of mammary artery catheterization, by a brachial artery approach, utilizing a pre-molded conventional Sones catheter is described. METHODS: In a series of 300 patients, 308 procedures were performed. Three hundred internal mammary-coronary anastomosis were studied. In eight cases angioplasty were performed, five in the anterior descending artery and three in the internal mammary artery itself, with recanalization of one of the three cases. The approach was through the brachial artery homolateral to the anastomosed mammary artery. After the conventional coronarographic and bypass studies were performed, the catheter was withdrawn and pre-molded, forming a closed loop of approximately 10 mm in its distal extremity. The loop was introduced through the arteriotomy reaching the origin of the vertebral artery. The internal mammary artery was then catheterized utilizing rotation and traction movements. In the percutaneous transluminal coronary angioplasty (PTCA) procedures, the Sones catheter was replaced by a Myler right coronary catheter with a 260 cm metallic wire. RESULTS: In the 308 procedures, the internal mammary artery was catheterized in 305 instances (99.03%). In the remaining three cases selective catheterization of the internal mammary artery was not possible. In these three cases there was extreme tortuosity of the subclavian artery. The only complication observed in this series was thrombosis of the brachial artery in two cases (90.65%). In the eight patients submitted to PTCA the existing lesions were successfully dilated. CONCLUSION: Catheterization of the internal mammary artery through a brachial approach utilizing a pre-molded Sones catheter was an efficient procedure, with low incidence of complications. This approach could be the elective technique in the services that habitually utilize the brachial artery approach. It could be also an alternative for those utilizing the Judkins technique, whenever the internal mammary artery catheterization is impossible due to the anatomic characteristics of the patient.

[Aneurysm of left ventricle associated with post-infarction interventricular communication]. / Aneurisma de ventrículo esquerdo associado à comunicação interventricular pós-infarto.

The authors report two cases of left ventricular aneurysm associated with post-infarction ventricular septal rupture. This rare association, usually aggravated by high mortality, received successful surgical treatment.

Inflammatory response in a rat model of gastroschisis is associated with an increase of NF-kappaB.

Babies with gastroschisis have high morbidity, which is associated with inflammatory bowel injury caused by exposure to amniotic fluid. The objective of this study was to identify components of the inflammatory response in the intestine and liver in an experimental model of gastroschisis in rats. The model was surgically created at 18.5 days of gestation. The fetuses were exposed through a hysterotomy and an incision at the right of the umbilicus was made, exposing the fetal bowel. Then, the fetus was placed back into the uterus until term. The bowel in this model had macro- and microscopic characteristics similar to those observed in gastroschisis. The study was conducted on three groups of 20 fetuses each: gastroschisis, control, and sham fetuses. Fetal body, intestine and liver weights and intestine length were measured. IL-1beta, IL-6, IL-10, TNF-alpha, IFN-gamma and NF-kappaB levels were assessed by ELISA. Data were analyzed statistically by ANOVA followed by the Tukey post-test. Gastroschisis fetuses had a decreased intestine length (means +/- SD, 125 +/- 25 vs 216 +/- 13.9; P < 0.005) and increased intestine weight (0.29 +/- 0.05 vs 0.24 +/- 0.04; P < 0.005). Intestine length correlated with liver weight only in gastroschisis fetuses (Pearson's correlation coefficient, r = 0.518, P = 0.019). There were no significant differences in the concentrations of IL-1beta, TNF-alpha or IFN-gamma in the intestine, whereas the concentration of NF-kappaB was increased in both the intestine and liver of fetuses with gastroschisis. These results show that the inflammatory response in the liver and intestine of the rat model of gastroschisis is accompanied by an increase in the amount of NF-kappaB in the intestine and liver.