Minor ampullate silks from Nephila and Argiope spiders: tensile properties and microstructural characterization.

The mechanical behavior and microstructure of minor ampullate gland silk (miS) of two orb-web spinning species, Argiope trifasciata and Nephila inaurata, were extensively characterized, enabling detailed comparison with other silks. The similarities and differences exhibited by miS when compared with the intensively studied major ampullate gland silk (MAS) and silkworm (Bombyx mori) silk offer a genuine opportunity for testing some of the hypotheses proposed to correlate microstructure and tensile properties in silk. In this work, we show that miSs of different species show similar properties, even when fibers spun by spiders that diverged over 100 million years are compared. The tensile properties of miS are comparable to those of MAS when tested in air, significantly in terms of work to fracture, but differ considerably when tested in water. In particular, miS does not show a supercontraction effect and an associated ground state. In this regard, the behavior of miS in water is similar to that of B. mori silk, and it is shown that the initial elastic modulus of both fibers can be explained using a common model. Intriguingly, the microstructural parameters measured in miS are comparable to those of MAS and considerably different from those found in B. mori. This fact suggests that some critical microstructural information is still missing in our description of silks, and our results suggest that the hydrophilicity of the lateral groups or the large scale organization of the sequences might be routes worth exploring.

Neocortical Sox9+ radial glia generate glutamatergic neurons for all layers, but lack discernible evidence of early laminar fate restriction.

Glutamatergic neurons in the cerebral cortex are derived from embryonic neural stem cells known as radial glial progenitors (RGPs). Early RGPs, present at the onset of cortical neurogenesis, are classically thought to produce columnar clones of glutamatergic neurons spanning the cortical layers. Recently, however, it has been reported that a subset of early RGPs may undergo early commitment to upper layer neuron fates, thus bypassing genesis of deep layer neurons. However, the latter mode of early RGP differentiation was not confirmed in some other studies, and remains controversial. To further investigate the clonal output from early RGPs, we employed genetic lineage tracing driven by Sox9, a transcription factor gene that is expressed in all early RGPs. We found that early RGPs produced columnar clones spanning all cortical layers, with no evidence of significant laminar fate restriction. These data support the classic progressive restriction model of cortical neurogenesis, and suggest that early RGPs do not undergo early commitment to only upper or lower layer fates.

Prolonged survival of an HIV-infected patient with multidrug-resistant Mycobacterium bovis infection treated with surgical resection.

We describe a case of multidrug-resistant tuberculosis due to Mycobacterium bovis in a human immunodeficiency virus-infected woman with good immunologic status. The patient presented with a hard mass measuring 10 cm in diameter on the lower left ribs and a lung nodule measuring 3 cm in diameter in the left superior lobe. No adequate pharmacological treatment was available. Both lesions were surgically resected. The patient has remained asymptomatic (without fever, cough, lymphadenopathy, or cutaneous masses) for 20 months, after discharge from the hospital.

Postnatal shifts of interneuron position in the neocortex of normal and reeler mice: evidence for inward radial migration.

During development, interneurons migrate to precise positions in the cortex by tangential and radial migration. The objectives of this study were to characterize the net radial migrations of interneurons during the first postnatal week, and to investigate the role of reelin signaling in regulating those migrations. To observe radial migrations, we compared the laminar positions of interneurons (immunoreactive for GABA or Dlx) in mouse neocortex on postnatal days (P) 0.5 and P7.5. In addition, we used bromodeoxyuridine birthdating to reveal the migrations of different interneuron cohorts. To study the effects of reelin deficiency, experiments were performed in reeler mutant mice. In normal P0.5 cortex, interneurons were most abundant in the marginal zone and layer 5. By P7.5, interneurons were least abundant in the marginal zone, and were distributed more evenly in the cortical plate. This change was attributed mainly to inward migration of middle- to late-born interneurons (produced on embryonic days (E) 13.5 to E16.5) from the marginal zone to layers 2-5. During the same interval, late-born projection neurons (non-immunoreactive for GABA or Dlx) migrated mainly outward, from the intermediate zone to upper cortical layers. In reeler cortex, middle- and late-born interneurons migrated from the superplate on P0.5, to the deep cortical plate on P7.5. Late-born projection neurons in reeler migrated in the opposite direction, from the intermediate zone to the deep cortical plate. We conclude that many middle- and late-born interneurons migrate radially inward, from the marginal zone (or superplate) to the cortical plate, during the first postnatal week in normal and reeler mice. We propose that within the cortical plate, interneuron laminar positions may be determined in part by interactions with projection neurons born on the same day in neurogenesis.

Activity of cefotaxime and amikacin against 14,272 gram-negative bacteria from clinical samples in the period 1980 to 1985.

The sensitivity to cefotaxime and amikacin of 14,272 Gram-negative bacilli (Enterobacteriaceae and non-fermenting Gram-negative bacilli) isolated from clinical samples was studied during the period 1980 to 1985. The minimum inhibitory concentration (MIC) was determined by means of diffusion in agar. Strains were considered resistant to cefotaxime and amikacin if the MIC values were greater than 16 mg/L and greater than 8 mg/L, respectively. The MIC90 reached the critical value for cefotaxime in the case of Citrobacter spp., Escherichia coli, Klebsiella spp., Proteus mirabilis, Salmonella spp. and Shigella spp., and for amikacin in the case of Citrobacter spp., Enterobacter spp., E. coli, Klebsiella spp., P. mirabilis, Proteus vulgaris, Salmonella spp. and Serratia spp. Only Shigella spp. were sensitive to cefotaxime but not to amikacin, and only strains of Enterobacter spp. and Serratia spp. were sensitive to amikacin but not to cefotaxime.

Rhodococcus equi: first case in a heart transplant recipient.

Rhodococcus equi is a gram-positive diphtheroid that occasionally affects immunocompromised patients, usually causing a chronic respiratory infection with cavitating pulmonary opacities on chest radiograph that resemble mycobacterial or fungal disease. Etiologic diagnosis presents a number of pitfalls, because Rhodococcus equi isolates mimic many of the characteristics of other microorganisms more familiar to the laboratory staff. The treatment of choice for this disease has not yet been established, and its mortality rate is greater than 50% in individuals with human immunodeficiency virus and 20% to 25% among the remaining patients. We describe here the first case of Rhodococcus equi infection in a heart transplant recipient. Clinical presentation was typical, and treatment with a sensitivity-based combination of antibiotics resulted in resolution of both the clinical and radiologic picture.

Antibiotic susceptibility of bacterial strains isolated from patients with community-acquired urinary tract infections.

Isolates from urine samples obtained during 1999 were identified and their susceptibility to antimicrobial agents studied along with any production of extended-spectrum beta-lactamases (ESBL) by Escherichia coli and Klebsiella pneumoniae. A total of 13774 samples were analysed using an automatic system for the detection of bacterial ATP (Coral, USA). Of these samples, 49% were reported to be positive and uncontaminated; bacteria most frequently isolated were E. coli (47%), Proteus mirabilis (7%), Enterococcus faecalis (6%) and K. pneumoniae (5%). The susceptibility studies showed 37% E. coli strains resistant to amoxycillin+clavulanate 33% to cotrimoxazole and 22% to ciprofloxacin. Seven strains of E. coli produced ESBL. Thirteen per cent of strains were resistant to cefuroxime but only (1%) to fosfomycin. Resistance to nitrofurantoin in K. pneumoniae was 38%. P. mirabilis showed 52% resistance to cotrimoxazole and 13% Staphylococcus aureus, were methicillin-resistant. E. faecalis did not show any special resistance to normal medication. Fosfomycin continued to show high activity against Gram-negative bacilli. However, enterococci, some species of staphylococci and yeasts were difficult to treat empirically. ESBL were detected in the isolates of E. coli and there were some methicillin-resistant strains of S. aureus.

[Infections in lung transplantation]. / Infecciones en el trasplante pulmonar.

Lung transplantation has become the therapeutic hope of terminal respiratory patients. Infections are among the main causes of morbidity and mortality in these patients. We therefore analyze infections suffered after lung transplants performed at Clínica Puerta de Hierro over a two-year period. The cases of 14 transplanted patients, 6 bilateral and 8 unilateral, were analyzed. Pre-transplant data available for all included analysis of serum antibodies to several viruses, as well as bacterial and fungal cultures, and Ziehl's sputum test. All received prophylactic antibiotic, antifungal and antiviral treatment according to protocol. The bronchial aspirate of the donor, and recipient specimens of bronchial aspirate, bronchoalveolar lavage and biopsies obtained by bronchoscopy after transplantation were cultured. Bronchoscopies were performed according to protocol, based on clinical picture. Other cultures were obtained as needed. We recorded 27 respiratory infections, among which 4 were pneumonia transmitted by the donor, 3 were tuberculosis, 3 were Aspergillus infections, 5 were cytomegalovirus pneumonitis and one, P. carinii pneumonia. Lung infections have a strong impact on outcome of lung transplant patients. Knowledge of the chronological development of infections made appropriate prophylaxis and early detection possible, such that survival during the first two years after transplantation was approximately 70% in our hospital.

[Comparative study of different serological tests for the diagnosis of brucellosis (author's transl)]. / Estudio comparativo de diversas pruebas en el diagnóstico serológico de la brucelosis.

The diagnosis of brucellosis is frequently a difficult one, and it is founded basically on the results of blood cultures and serological tests. Wright's classical agglutination test is commonly utilized in the serological diagnosis of brucellosis and its value is well established in the acute forms of the disease; for the diagnosis of subacute or chronic forms, however, a Coombs test must be performed to show incomplete antibodies. The agglutination carried out with serum treated with 2-mercaptoethanol allows the determination of the type of immunoglobulins present. Indirect immunofluorescence has been infrequently utilized in the diagnosis of brucellosis. The first three tests have been compared with indirect immunofluorescence using sera from 100 patients presenting with fever of unknown origin. All tests were negative in 40 sera, and of the 60 remaining sera only 32 were positive to all four tests. The highest titers were found with the Coombs test, while immunofluorescence yielded titers which were never above 1/320. Significant correlation coefficients were obtained between the tests. The best correlation was obtained between immunofluorescence and 2-mercaptoethanol, followed by immunofluorescence and Coombs, and by immunofluorescence and agglutination. Only immunofluorescence titers above 1/80 corresponded to the same of superior titers in the remaining tests; thus immunofluorescence titers below 1/80 can not be considered as diagnostic of the disease. The authors believe that immunofluorescence to 1/80 can be utilized as a quick routine test for the diagnosis of brucellosis, its disadvantages being a high cost and the requirement for an immunofluorescence microscope which may not be available in many laboratories.

[Late vascular complication after fracture of tibia and fibula]. / Complicación vascular tardía tras fractura de tibia y peroné.

Authors present a case report of an aneurysm from Posterior Tibial artery secondary to a traffic accident with trauma on tibia and perone. First symptoms appeared four months after accident.

[A case of multiple arteriovenous fistulae in a postphlebitic syndrome of longterm evolution]. / Un caso de múltiples fístulas arteriovenosas en síndrome postflebítico de larga evolución.

Authors report a case of a 77-years-old man who, after an accident of traffic on 1968, presented a left ileo-femoral deep venous thrombosis. Consequently, the patient suffered and important postphlebitic syndrome, with several varicose packs which were treated by surgical procedure in other centre. During several years, patient presented severe trophic diseases. Seventeen years after the beginning of his pathology, and during an angiologic examination, multiple arteriovenous fistulas at the left ileofemoral area have been shown. An skeletalization was impossible because of the severe ulcerations of the leg; so a left iliac arterial ligature and a Dacron Banding in primitive iliac artery, reducing a 50% the diameter, were made. The postoperative result was excellent, with an spectacular reduction of the fistulous communications and a complete remission of the cutaneous ulcerations.

[Thoracic sympathectomy in the surgical treatment of Raynaud's phenomenon]. / Simpatectomia torácica en el tratamiento quirúrgico del fenómeno de Raynaud.

Authors present their results from a review of 38 thoracic sympathectomies practiced since 1977 to 1987, both included, on patients affected by a Raynaud syndrome resistant to medical treatment. Results show the evident clinical improvement of such patients after surgery. In all cases, surgical approach was a Crafoord thoracotomy.

[Popliteal artery entrapment syndrome in 3 young athletes]. / Síndrome de atrapamiento de arteria poplítea en tres jóvenes deportistas.

Three cases of entrapment of the popliteal arteries from three young patients are reported. In all cases, the symptomatology was erroneously attributed to several muscular injuries produced in practice of a sport: Basketball, Football and Roller Hockey, respectively. In all cases, symptoms were progressing for 6 months as a minimum. The roads followed by these patients until they were visited in a Vascular Surgery Department is described. Clinical picture, the results from the different examinations practiced and the applied treatments to each patients are described.

[Calf carotids in experimental vascular surgery]. / Carótidas de ternera en cirugía vascular experimental.

Use of calf [correction of sheep] carotids maintained on 98% glycerol is described as a material of substitution of aorta and femoral arteries in the dog, in experimental surgery. Taking, maintenance and application technics of such heterografts are described. Also, histology after 24 months following the surgical procedure was studied in 10 cases of dog aortic grafts and its results are presented.

Simple measurement of the apparent viscosity of a cell from only one picture: Application to cardiac stem cells.

Mechanical deformability of cells is a key property that influences their ability to migrate and their contribution to tissue development and regeneration. We analyze here the possibility of characterizing the overall deformability of cells by their apparent viscosity, using a simplified method to estimate that parameter. The proposed method simplifies the quantitative analysis of micropipette-aspiration experiments. We have studied by this procedure the overall apparent viscosity of cardiac stem cells, which are considered a promising tool to regenerate damaged cardiac tissue. Comparison with the apparent viscosity of low-viscosity cells such as immune-system cells suggests that treatments to reduce the viscosity of these cells could enhance their ability to repair damaged cardiac tissue.

Identification and dynamics of polyglycine II nanocrystals in Argiope trifasciata flagelliform silk.

Spider silks combine a significant number of desirable characteristics in one material, including large tensile strength and strain at breaking, biocompatibility, and the possibility of tailoring their properties. Major ampullate gland silk (MAS) is the most studied silk and their properties are explained by a double lattice of hydrogen bonds and elastomeric protein chains linked to polyalanine ß-nanocrystals. However, many basic details regarding the relationship between composition, microstructure and properties in silks are still lacking. Here we show that this relationship can be traced in flagelliform silk (Flag) spun by Argiope trifasciata spiders after identifying a phase consisting of polyglycine II nanocrystals. The presence of this phase is consistent with the dominant presence of the -GGX- and -GPG- motifs in its sequence. In contrast to the passive role assigned to polyalanine nanocrystals in MAS, polyglycine II nanocrystals can undergo growing/collapse processes that contribute to increase toughness and justify the ability of Flag to supercontract.

AGEP sistémico, un diagnóstico oculto en una falsa psoriasis paradójica por anti-TNF / Systemic AGEP, a hidden diagnosis in a false psoriasis paradoxical by anti-TNF

La pustulosis exantemática generalizada aguda (AGEP, en inglés) es una enfermedad poco frecuente, causada por drogas, caracterizada por aparición aguda de numerosas pústulas estériles en una base eritematosa, asociada en ocasiones a fiebre y leucocitosis, en algunos casos puede causar un compromiso de piel severo pero que resuelve rápidamente con la suspensión del fármaco sin tratamiento especial requerido. Puede confundirse con otras entidades como la psoriasis pustular e inusualmente produce compromiso sistémico. Presentamos un caso de AGEP secundario a terapia anti-TNF con compromiso sistémico.

The acute generalized exanthematous pustulosis (AGEP, in english)is a rare disease caused by drugs, characterized by acute onsetof numerous sterile pustules on an erythematous base, sometimesassociated with fever and leukocytosis, in some cases may causea severe skin involvement reaction but solved quickly with the drugsuspension without special treatment required. It can be confusedwith other entities such as pustular psoriasis and unusually producesystemic involvement. We present a case of secondary to anti-TNFtherapy AGEP systemic involvement.