Binding of Cryptococcus neoformans to heterologously expressed human complement receptors.

Previously, we demonstrated that monoclonal antibodies (MAb) directed against any of the three defined complement receptors (CR) for the third component of complement (CR1, CR3, and CR4) profoundly inhibited the binding of serum-opsonized Cryptococcus neoformans to monocyte-derived macrophages. These studies suggested either that a synergistic interaction between multiple CR was required for optimal binding of C. neoformans or that the MAb were exerting nonspecific effects (such as receptor coassociation). In the present studies, we took a novel approach to dissecting out the contributions of individual receptors to binding of a microbial pathogen. Chinese hamster ovary (CHO) cells stably transfected with human CR1, CR3, or CR4 were challenged with serum-opsonized C. neoformans. We found that CHO cells transfected with any of the three receptors bound C. neoformans, with the avidity of binding to CR3 being the greatest followed in decreasing order by CR1 and CR4. Following binding of C. neoformans to transfected CHO cells, most organisms remained surface attached only, although for each receptor a significant percentage (18.5 to 27.3%) of C. neoformans was internalized. Both C. neoformans and sheep erythrocytes that were selectively opsonized with the fragments of the third component of complement, C3b and iC3b, were bound preferentially by CHO cells transfected with CR1 and CR3, respectively. These data establish CR1, CR3, and CR4 as receptors independently capable of binding C. neoformans opsonized with fragments of C3. Moreover, our study demonstrates the usefulness of transfected cell lines as a powerful tool for identifying the contribution of individual receptors to the binding of a microbial pathogen.     

Identification of two mutations in a compound heterozygous child with dihydrolipoamide dehydrogenase deficiency

An infant girl with elevated blood lactate, pyruvate, and plasma branched-chain amino acids was diagnosed with dihydrolipoamide dehydrogenase (E3; dihydrolipoamide: NAD+ oxidoreductase, EC 1.8.1.4) deficiency. Activities of the pyruvate dehydrogenase complex and E3 from patient were 26 and 2% of controls in blood lymphocytes, and 11 and 14% in cultured skin fibroblasts, respectively. Western blot analysis demonstrated that the amount of E3 protein in fibroblasts from the patient and her father was about half of controls, while Northern blot analysis showed normal amounts of E3 RNA. DNA sequencing of cloned full-length E3 cDNAs from the patient revealed two mutations in separate alleles. One is a single base insertion of an extra adenine in the last codon of the leader peptide sequence (TAC-->TAAC) leading to a nonsense mutation which results in the premature termination of the precursor E3 polypeptide (Y35X). The other is a missense mutation due to substitution of guanine for adenine, causing an Arg-->Gly substitution at amino acid 460 of the mature protein (R460G) which triggers the loss of E3 activity probably by structural change in the E3 dimer. DNA sequencing of E3 cDNAs from the parents demonstrated that the nonsense mutation was inherited from the father and the missense mutation was inherited from the mother.      

Biological resurfacing of the knee: a review of surgical management

Lesions of the articular surfaces of the knee have been managed by various techniques over the last 50 years. Surgical management has involved: excising the damaged area, refashioning the underlying bone to produce a fibrous response, and introducing allograft, autograft and synthetic materials to encourage a repair matrix. The techniques and their pitfalls are reviewed and discussed, and suggestions made as to the direction of future studies for the repair of osteochondral lesions in the painful knee.     

Impact of a daily 10-minute strength and flexibility program in a manufacturing plant

In summary, employees' flexibility and mood showed modest improvements following the implementation of a plant-wide, 10-minute, daily flexibility and strength program. The initial six-week pilot study, administered prior to the plant-wide program implementation, successfully assessed program feasibility, assessed the efficiency of program implementation, identified administrative and logistical concerns, and generated pilot data needed to secure managerial support. Despite the noted significant increases in grip strength in the pilot study, no increases were observed following the six months of plant-wide implementation. This may be related to the differences in low average pretest grip strength for the pilot study compared to the higher scores for the main study population. The pilot study subjects may have received a sufficient exercise stimulus to increase grip strength over the course of six weeks. In contrast, this may not have been the case for the main study subjects due to their higher initial mean grip strength. An increased number of exercises designed to directly impact grip strength may be needed to improve this parameter.