The D2 protein contains an extended loop (the D-de loop) between helices D and de at the reducing side of photosystem II (PS II). Characterization of D2 mutants of the cyanobacterium Synechocystis sp. PCC 6803 has indicated that the length and amino acid composition of the D-de loop are not critical for basic PS II functions, although most of the residues in that region are conserved phylogenetically. Here we show using herbicide binding and electron-flow inhibition measurements that drastic modifications in the D-de loop of the D2 protein modify the interaction of some PS II-directed herbicides with their binding niche. The stability of (semi)-reduced QB in its binding pocket is altered in at least two of the mutants, as indicated by a shifted peak temperature of the thermoluminescence signal originating from charge recombination involving QB. These results suggest a close functional association between the D-de loop of the D2 protein and the QB/herbicide-binding environment, which is viewed as being coordinated mostly by residues of the D1 protein. This represents one of the first examples of modification of the QB/herbicide-binding domain by mutations in the D2 protein.

Amino Acid Sequence↗

PubMedDate not supplied

Arterialization of the coronary veins in diffuse coronary arteriosclerosis.

Since the coronary veins and capillaries are not involved with arteriosclerotic disease the authors performed experimental, and afterwards, clinical total and selective coronary vein arterialization. Acute myocardial ischaemia created for instance by ligation of the anterior descending branch, was treated by an internal mammary artery to regional coronary vein anastomosis. In 21 patients the selective arterialization of the "Vena cordis magna" or of "Vena cordis media", and total arterialization of the coronary sinus was performed. The clinical improvement and follow-up studies seem to be promising in the treatment of patients with advanced diffuse heavy coronary arteriosclerosis. In acute myocardial ischaemia with coronarographically localized coronary occlusion, the aim of regional vein arterialization is to minimize the area of infarction.

Adult↗

PubMedDate not supplied

Microglial nodule encephalitis: limited CNS infection despite disseminated systemic cryptococcosis.

A 28-year-old patient with AIDS was found at autopsy to have disseminated cryptococcal infection involving the lungs, spleen, lymph nodes, kidneys, gastrointestinal tract, thyroid, bone marrow, and liver. Despite widespread organ dissemination the patient did not have clinical or pathological evidence of meningitis. Microscopic examination of the brain showed cryptococci limited to the brainstem and basal ganglia; microglial nodules with multinucleate giant cells, a histological hallmark of HIV-1 encephalitis, were shown to contain Cryptococcus neoformans. This feature may suggest a form of synergism between HIV-1 and Cryptococcus neoformans. This case demonstrates an unusual form of cryptococcal neurotropism with limited CNS involvement.

AIDS-Related Opportunistic Infections↗