A simple way to assist placement of a bone graft into a soft tissue tunnel.

We describe a simple and cost effective technique for the insertion of calverial bone grafts for augmentation rhinoplasty.

Miniplate removal in trauma and orthognathic surgery--a retrospective study.

Records of patients undergoing the surgical removal of miniplates placed during the management of maxillofacial trauma (n=49) and orthognathic surgery (n=16) in a single unit, over a 2-year period have been analysed. Data concerning indications for plating, age and sex distribution, site of plating, time between insertion and removal, antibiotic prophylaxis, general medical factors and clinical indications for plate removal were evaluated for all patients. In addition, data for trauma patients included the site of fracture, and time delay between injury and plate insertion. Infection and/or wound dehiscence were the predominant causes for plate removal in both groups, in spite of the routine use of prophylactic antibiotics in a predominantly young, healthy cohort of patients.A removal rate of approximately 10% was found in the two groups of patients. This low rate would seem to imply that the routine removal of miniplates is not clinically indicated.

Skull reconstruction with a two-part interlocking custom-made titanium plate.

We have used a two-part interlocking titanium plate for cranioplasty in two patients with large skull defects in which reconstruction with a titanium plate was required and extensive contouring of the plate was necessary.

Bacterial expression and characterization of the mitochondrial outer membrane channel. Effects of n-terminal modifications.

Several forms of the voltage-dependent anion-selective channel (VDAC) have been expressed at high yield in Escherichia coli. Full-length constructs of the proteins of Neurospora crassa and Saccharomyces cerevisiae (ncVDAC and scVDAC) have been made with 20-residue-long, thrombin-cleavable, His6-containing N-terminal extensions. ncVDAC purified from bacteria or mitochondria displays a far-UV CD spectrum (in 1% lauryl dimethylamine oxide at pH 6-8) similar to that of bacterial porins, indicating extensive beta-sheet structure. Under the same conditions, the CD spectrum of bacterially expressed scVDAC indicates lower beta-sheet content, albeit higher than that of mitochondrial scVDAC under the same conditions. In phospholipid bilayers, the bacterially expressed proteins (with or without N-terminal extensions) form typical VDAC-like channels with stable, large conductance open states (4-4.5 nanosiemens in 1 M KCl) and voltage-dependent transitions to a predominant substate (about 2 nanosiemens). A variant of scVDAC missing the first eight residues and having no N-terminal extension also has been expressed in E. coli. The truncated protein has a CD spectrum similar to that of mitochondrial scVDAC, but its channel activity is abnormal, exhibiting an unstable open state and rapid transitions between multiple subconductance levels.

Primate testicular histone H1t genes are highly conserved and the human H1t gene is located on chromosome 6.

The testis-specific histone H1t gene is known to be transcribed only in pachytene primary spermatocytes during spermatogenesis. Previous studies of the rat histone H1t gene revealed a unique promoter sequence element between the H1/GC box and the H1/CCAAT box. Proteins in crude nuclear extracts of rat testis bind specifically to this sequence element and a temporal correlation exists between the appearance of these DNA binding proteins and the onset of transcription. These discoveries led to a search for histone H1t genes in other mammalian species. The human and monkey histone H1t genes were amplified from genomic DNA using the polymerase chain reaction (PCR). The amplified genes were cloned and the genomic derived inserts were sequenced using linear PCR. Both proximal promoters contained the highly conserved H1/AC box, H1/CCAAT box, and H1/TATA box found in nongerminal H1 genes. Both promoters also contained the H1/GC box and the H1t/CCTAGG sequence element between the H1/GC box and H1/CCAAT box previously seen only in the H1t promoter. Specific amplification of the human H1t gene using template DNA samples from a NIGMS human/rodent somatic cell hybrid mapping panel has shown that the human histone H1t gene is located on chromosome 6.

Tissue-specific binding of testis nuclear proteins to a sequence element within the promoter of the testis-specific histone H1t gene.

The rat histone H1t gene is transcribed only in testis germinal cells. This testis-specific chromosomal protein is first synthesized during spermatogenesis in pachytene spermatocytes and the entire complement of testis histones is replaced during the midspermatid stage of spermiogenesis by positively charged transition nuclear proteins TP1 and TP2. Mobility shift assays conducted using crude nuclear protein extracts from different tissues and an 18-bp DNA sequence element within the H1t promoter as a probe reveal binding only with nuclear proteins from testis. The binding is specifically competed with an excess of the same unlabeled DNA fragment but not with heterologous competitors. A larger oligonucleotide corresponding to the same sequence element plus 18 bp of the adjacent downstream H1/CCAAT element binds nuclear proteins from all tissues tested, but a unique low mobility band is formed only with testis extracts. Protein-DNA crosslinking experiments reveal that two major polypeptides with molecular weights of approximately 13 and 30 kDa bind to the 18-bp H1t promoter sequence element. This strong correlation between the tissue where the H1t gene is transcribed and the presence of testis-specific nuclear proteins that bind to a sequence element within the testis histone H1t promoter supports the possibility that these DNA-binding proteins may participate in formation of an active transcription initiation complex with the testis H1t promoter.

Temporal correlation between the appearance of testis-specific DNA-binding proteins and the onset of transcription of the testis-specific histone H1t gene.

The histone H1t gene is transcribed only in testis. Northern blot analyses reveal that transcription of the H1t gene occurs first in pachytene primary spermatocytes. Thus, there is a temporal correlation between onset of transcription of the gene and synthesis of histone H1t in primary spermatocytes during spermatogenesis. Previous studies revealed that replacement of most H1t and core histones occurs during the midspermatid stage of spermiogenesis by transition proteins TP1 and TP2. In this paper we extend our study of the specific binding of testis nuclear proteins to a unique sequence element within the H1t promoter. The relatively tight binding is competed with an excess of homologous DNA but not with a mutated element. Testis proteins from prepubertal animals do not bind to the 18-bp promoter element out proteins from enriched populations of primary spermatocytes do bind. Therefore, the temporal correlation between onset of transcription of the H1t gene and the time when the specific H1t promoter-binding proteins are detected in primary spermatocytes suggests that the DNA-binding proteins might be germinal cell-specific transcription factors that participate in formation of an active H1t transcription initiation complex. These studies present the first analysis of binding sites for testis nuclear proteins from primary spermatocytes within the promoter of a gene expressed only during this stage of spermatogenesis.