Sulphide Resistance in the Cyanobacterium Microcystis aeruginosa: a Comparative Study of Morphology and Photosynthetic Performance Between the Sulphide-Resistant Mutant and the Wild-Type Strain.

The cyanobacterium Microcystis aeruginosa is a mesophilic freshwater organism, which cannot tolerate sulphide. However, it was possible to isolate a sulphide-resistant (S(r)) mutant strain that was able to survive in a normally lethal medium sulphide. In order to evaluate the cost of the mutation conferring sulphide resistance in the S(r) strain of M. aeruginosa, the morphology and the photosynthetic performance were compared to that found in the wild-type, sulphide-sensitive (S(s)) strain. An increase in size and a disrupted morphology was observed in S(r) cells in comparison to the S(s) counterpart. Phycoerythrin and phycocyanin levels were higher in the S(r) than in the S(s) cells, whereas a higher carotenoid content, per unit volume, was found in the S(s) strain. The irradiance-saturated photosynthetic oxygen-production rate (GPR max) and the photosynthetic efficiency (measured both by oxygen production and fluorescence, α(GPR) and α(ETR)) were lower in the S(r) strain than in the wild-type. These results appear to be the result of package effect. On the other hand, the S(r) strain showed higher quantum yield of non-photochemical quenching, especially those regulated mechanisms (estimated throughout qN and Y(NPQ)) and a significantly lower slope in the maximum quantum yield of light-adapted samples (Fv'/Fm') compared to the S(s) strain. These findings point to a change in the regulation of the quenching of the transition states (qT) in the S(r) strain which may be generated by a change in the distribution of thylakoidal membranes, which somehow could protect metalloenzymes of the electron transport chain from the lethal effect of sulphide.

Disentangling mechanisms involved in the adaptation of photosynthetic microorganisms to the extreme sulphureous water from Los Baños de Vilo (S Spain).

Los Baños de Vilo (S Spain) is a natural spa characterized by extreme sulphureous waters; however, populations of chlorophyceans inhabit in the spa. The adaptation mechanisms allowing resistance by photosynthetic microorganisms to the extreme sulphureous waters were studied by using a modified Luria-Delbrück fluctuation analysis. For this purpose, the adaptation of the chlorophycean Dictyosphaerium chlorelloides and the cyanobacterium Microcystis aeruginosa (both isolated from non-sulphureous water) were analysed in order to distinguish between physiological adaptation (acclimation) and genetic adaptation by the selection of rare spontaneous mutations. Acclimation to the extreme water was achieved by D. chlorelloides; however, M. aeruginosa cells proliferated as a consequence of selection of favoured mutants (i.e. genetic adaptation). The resistant cells of M. aeruginosa appeared with a frequency of 7.1 × 10(-7) per cell per generation, and the frequency of the resistant allele, under non-selective conditions, was estimated to be 1.1 × 10(-6) per cells as a consequence of the balance mutation-selection. It could be hypothesized that the populations of eukaryotic algae living in the Los Baños de Vilo could be the descendants of chlorophyceans that arrived fortuitously at the spa in the past. On the other hand, cyanobacteria could quickly adapt by the selection of favoured mutants. The single mutation that allows resistance to sulphureous water from Baños de Vilo in M. aeruginosa represents a phenotypic burden impairing growth rate and photosynthetic performance. The resistant-variant cells of M. aeruginosa showed a lower acclimated growth rate and a decreased maximum quantum yield and photosynthetic efficiency, in comparison to the wild-type cells.

Experiencia en el tratamiento del abscesos perinefrítico en el Servicio de Urología y Nefrología del Hospital General de México y revisión de la literatura / Experience in the treatment of perinephritic abscesses at the Urology and Nephrology Wards of the Hospital General de México and a review of the literature

Se comunica el acervo de la experiencia obtenida durante ocho años en el tratamiento del absceso perirrenal en el servicio de urología y nefrología de este hospital, concluyendo que el tratamiento más adecuado es el drenaje percutáneo con punción lumbar bajo anestesia local, ya que este método proporciona un control adecuado de la infección, una mejor recuperación de la función renal y un índice bajo de morbimortalidad

Experiencia en el tratamiento del absceso perinefrítico en el servicio de urología y nefrología del Hospital General de México y revisión de la literatura / Experience in the perinephritic abscess treates in the urology and neprhrology service of Hospital General de Mexico and literature review

El absceso perinefrítico es una afección poco frecuente caracterizada por la acumulación de pus en el espacio comprendido entre la cápsula renal y la fascia de Gerota, cuyo curso clínico es insidioso y sus síntomas muy variados, los que hace que su diagnóstico y tratamiento sean retardados. elevándose de esta manera en forma importante su morbimortalidad. Se comunica el acervo de la experiencia obstenida durante ocho años en el tratamiento del absceso perirrenal en el servicio de urología y nefrología del Hospital General de México, SS. Se concluye que el tratamiento más adecuado es el drenaje percutáneo con punción lumbar bajo anestesia local, ya que este método proporciona un control adecuado de la infección, una mejor recuperación de la función renal y un índice bajo de morbimortalidad.

Divertículo vesical gigante: informe de tres casos y revisión de la bibliografía / Gigant urinary bladder diverticulum: report of tree cases and review of the bibliography

Se comunica el caso de tres pacientes condivertículo vesical gigante atendidos en el servicio de urología y nefrología del Hospital General de México SS, todos ellos del sexo masculino, con historia de padecimiento de obstrucción urinaria baja, dos con estenosis de uretra bulbar y uno con crecimiento prostático trilobular importante. Se practicaron estudios radiológicos y endoscópicos que hicieron el hallazgo de esta afección como complicación de la enfermedad con la que ingresaron. Se describe su tratamiento específico del divertículo de cada uno de los casos, su evolución y seguimiento.

Fístulas vesicovaginales: experiencia personal con la técnica transabdominal, transperitoneal (O'Conor): 23 casos / Vesical-vaginal fistulas: experience with transabdominal and transperitoneal technique (O'Conor): 23 cases

Se comunican los casos de 23 pacientes con diagnóstico de fístula vesicovaginal, corroborado endoscópica y radiológicamente. En todos los casos el tratamiento fue quirúrgico con técnica transabdominal y transperitoneal. se concluye que la cirugía ginecoobstétrica sigue siendo la causa más frecuente de las fístulas.