Dynamic proteome allocation regulates the profile of interaction of auxotrophic bacterial consortia

Microbial ecosystems are composed of multiple species in constant metabolic exchange. A pervasive interaction in microbial communities is metabolic cross-feeding and occurs when the metabolic burden of producing costly metabolites is distributed between community members, in some cases for the benefit of all interacting partners. In particular, amino acid auxotrophies generate obligate metabolic inter-dependencies in mixed populations and have been shown to produce a dynamic profile of interaction that depends upon nutrient availability. However, identifying the key components that determine the pair-wise interaction profile remains a challenging problem, partly because metabolic exchange has consequences on multiple levels, from allocating proteomic resources at a cellular level to modulating the structure, function and stability of microbial communities. To evaluate how ppGpp-mediated resource allocation drives the population-level profile of interaction, here we postulate a multi-scale mathematical model that incorporates dynamics of proteome partition into a population dynamics model. We compare our computational results with experimental data obtained from co-cultures of auxotrophic Escherichia coli K12 strains under a range of amino acid concentrations and population structures. We conclude by arguing that the stringent response promotes cooperation by inhibiting the growth of fast-growing strains and promoting the synthesis of metabolites essential for other community members.

Sclerosis in bisphosphonate-related osteonecrosis of the jaws and its correlation with the clinical stages: study of 43 cases

We analysed the degree of sclerosis in the different stages of bisphosphonate-related osteonecrosis of the jaws (BRONJ) and studied the relation between the grade of sclerosis, the clinical symptoms, and the depth of lucency. We compared 43 patients with mandibular BRONJ with a control group of 40 cases with no bony lesions. The presence of sclerotic bone, cortical irregularities, radiolucency, fragmentation or sequestration, periostitis, and narrowing of the mandibular canal were studied from computed tomographic (CT) scans using the program ImageJ 1.47v (National Institute of Health, Bethesda, USA) to measure the radiolucency, width of the cortices, and degree of sclerosis. Patients with BRONJ had more severe sclerosis than controls (p<0.01). There was also a significant difference among the different stages of BRONJ, with the highest values found in stage III (p=0.02). The degree of sclerosis differed according to sex, type of bisphosphonate, and the clinical characteristics such as pain, or suppuration, but not significantly so (p>0.05). We conclude that the degree of sclerosis increases with the clinical stage of BRONJ, and is correlated with the depth of lucency.

Engineering the Escherichia coli fermentative metabolism

Fermentative metabolism constitutes a fundamental cellular capacity for industrial biocatalysis. Escherichia coli is an important microorganism in the field of metabolic engineering for its well-known molecular characteristics and its rapid growth. It can adapt to different growth conditions and is able to grow in the presence or absence of oxygen. Through the use of metabolic pathway engineering and bioprocessing techniques, it is possible to explore the fundamental cellular properties and to exploit its capacity to be applied as industrial biocatalysts to produce a wide array of chemicals. The objective of this chapter is to review the metabolic engineering efforts carried out with E. coli by manipulating the central carbon metabolism and fermentative pathways to obtain strains that produce metabolites with high titers, such as ethanol, alanine, lactate and succinate.

Abdominal mass: "fetus in fetu"

A female newborn presented a mass in the left upper abdominal quadrant. It was removed by surgery and contained two independent fetuses. Dissection and radiological study of the fetuses showed an axial skeleton and long bones. It corresponds to the generally recognized diagnostic criteria of fetus in fetu.

Partial splenic embolization in hypersplenism

Four patients with portal hypertension, oesophageal varices and severe hypersplenism were treated by partial splenic embolization. All showed improvement of blood and platelet counts early in the postoperative period. Three months after embolization IgA and C3 levels increased significantly. All patients had a decrease in the incidence of variceal bleeding and this procedure provides an acceptable alternative to splenectomy.

[Intestinal malrotation in children]

Intestinal malrotation has received, so far, little attention in the Spanish medical literature. This is probably due to the fact that is variable forms of clinical presentation may be overlooked during infancy and childhood and be present or not later in adult life. This is a report on 33 patients between 1 week and 8 years old operated upon, from 1965 to 1985, at the Clinica Infantil "La Paz", Madrid, with pre or postoperative diagnoses of intestinal malrotation (patients with Bochdalek's hernia, omphalocele and gastrosschisis are excluded). Midgut volvulus has been the most frequent preoperative complication and has occurred in 50% of patients. Intestinal obstruction was the most frequent clinical presentation, specially in patients under one week of age. There was a 30% figure of associated malformations, mostly of the duodenojejunal area (atresia, diaphragm, anular pancreas). All 5 deceased patients had other associated malformations. Long term survival was 85%.

[Pathogenic factors and therapeutic criteria in 82 newborn infants with necrotizing enterocolitis]

Sixty newborn infants with necrotizing enterocolitis (NEC) were retrospectively studied in 1979. The incidence was 0,49/1.000 living newborns: 81% were under 2,500 g and 30% under 1.500 g. We found a very low incidence of the so-called pathogenic factors. Feeding started in this group on the 24 h of life, with adapted formulas; 28% underwent surgery with a postoperative mortality of 62% and an overall mortality of 28%. Ten out of the 17 deceased were under 1.500 g. From 1979 with a similar medical treatment we introduced a prospective study consisting of a protocol of 10 different parameters including clinical, radiological and analytical values, the aim being a more objective way of indicating when to operate the patient. Special meticulous care of the nutrition of the low-weight babies was taken; 22 patients were treated til 1982, only 4,5% were under 1.500 g. The initial feeding time in all high risk babies under 1.250 g being 7 days with gastric gavage and elementary diets. All the infants with more than 60% values in the protocol underwent surgery (38%). The postoperative mortality was 37% with an overall mortality of 19%. A look back to our series suggests a clear usefulness of the protocol and the suspicion that the delay on feeding with intragastric continuous perfusion in low weight babies reduces NEC.

[Leydig cell tumor with pseudoprecocious puberty (author's transl)]

Authors present a case of a Leydig cell testicular tumor in a boy aged three years with a six-month follow-up. This type of tumor which is usually hormone-producing has in children a virilizing effect giving signs of pseudoprecocious puberty. Hormonal tests before and after surgery are described as well as the histological study. The various possibilities of differential diagnosis, treatment and prognosis in the presence of a unilateral testis enlargement in a boy are commented.