The plastocyanin binding domain of photosystem I

The molecular recognition between plastocyanin and photosystem I was studied. Photosystem I and plastocyanin can be cross-linked to an active electron transfer complex. Immunoblots and mass spectrometric analysis of proteolytic peptides indicate that the two negative patches conserved in plant plastocyanins are cross-linked with lysine residues of a domain near the N-terminus of the PsaF subunit of photosystem I. Conversion of these negative to uncharged patches of plastocyanin by site-directed mutation D42N/E43Q/D44N/E45Q and E59Q/E60Q/D61N respectively, reveals the first patch to be essential for the electrostatic interaction in the electron transfer complex with photosystem I and the second one to lower the redox potential. The domain in PsaF, not found in cyanobacteria, is predicted to fold into two amphipathic alpha-helices. The interacting N-terminal helix lines up six lysines on one side which may guide a fast one-dimensional diffusion of plastocyanin and provide the electrostatic attraction at the attachment site, in addition to the hydrophobic interaction in the area where the electron is transferred to P700 in the reaction center of photosystem I. This two-step interaction is likely to increase the electron transfer rate by more than two orders of magnitude in plants as compared with cyanobacteria. Our data resolve the controversy about the function of PsaF.

[Sudden infant death syndrome--sudden and unexpected pediatric death]

Sudden infant death syndrome [SIDS] is the most common cause of death between the ages of one month and one year, affecting one to three infants of 1000 life births. SIDS is defined as a sudden death of an infant under one year of age, which remains unexplained even after performance of a complete postmortem examination, examination of the death scene and review of the case history. SIDS is unexpected, so parents have not had the opportunity to prepare for the death. Because SIDS remains unexplained, SIDS parents blame themselves for the death. For most families of SIDS victims, the best resource for help and support is a SIDS parent support group. Finally, risk factors and possible preventive measures are discussed.

[Adult respiratory distress syndrome (ARDS) after poisoning by local anesthetics]

Two children who received an overdose of nupercaine (cinchocainium chloratum) showed severe neurological and cardiovascular disturbances and developed adult respiratory distress syndrome (ARDS). Following initial cardiovascular resuscitation they underwent invasive neurointensive care and required controlled ventilation for a period of 6-15 days, initially with high positive end expiratory pressure (PEEP) for treatment of the ARDS. However, both survived and made a complete recovery.

Surgical treatment for cholelithiasis

In a retrospective study, the results of 1,631 consecutive operations for cholelithiasis were analyzed. With an overall mortality rate of 0.18 percent and a reoperation rate of 1.3 percent, conventional cholecystectomy proved to be a safe method. Mortality proved to be age dependent, with a zero mortality rate for patients less than 60 years of age. Choledochotomy had a 13-fold greater mortality rate than simple cholecystectomy (0.92 versus 0.07 percent). For acute cholecystitis, we observed an unusual zero mortality rate, whereas the mortality rate in chronic cholecystitis was 0.2 percent. All three patients who died had an accompanying cirrhosis of the liver. Morbidity, defined as reoperation during the same period of hospitalization, was mainly the result of retained stones after choledochotomy; endoscopic papillotomy was the treatment of choice. Cholecystectomy remains the "gold standard" in the treatment of cholelithiasis.