[Intein-Mediated Protein trans-Splicing of the Recombinant Streptavidin on Magnetosomes]

When expressing streptavidin recombinant polypeptide on magnetosomes (called bacterial magnetic nanoparticles, or BMPs), the presence of endogenous bacterial biotin might be detrimental. In the study, the streptavidin monomer fragment (S1-116) was fused with the intein N-terminal (termed precursor S1-116-IN), and S1-116-IN was expressed in E. coli (BL21). Meanwhile, the SA117-160 fragment was fused with the C-terminal intein, and then this chimeric polypeptide was expressed on magnetosomes by fusion with magnetosome membrance protein MamF. In the in vitro protein splicing system, the purified engineered magnetosomes (BMP-SA117-160-IC) and the S1-116-IN precursor were mixed. Intein-mediated trans-splicing reaction was induced to produce the functional magnetic beads BMP-SA. Our results indicate that intein-mediated protein trans-splicing may lead to efficient synthesis of the recombinant streptavidin on the magnetosomes, showing its promising potential to produce other functional magnetic nanoparticles.

The incidence of thyroid abnormalities in adults irradiated for lymphoma

The aim of the study was to investigate the incidence of thyroid abnormalities in neck irradiated lymphoma patients. Of the 298 patients who had irradiation to the neck for lymphoma between 1966-1988, 174 were found to be alive and free of disease. These patients were invited to participate in the study. From the 174, 93 were able to participate (group 1). Two control groups were recruited; both were sex and aged matched. One group (group 2) consisted of lymphoma patients who were treated with chemotherapy (n=39) or irradiation to areas other than the neck (n=16). The other group (group 3) consisting of healthy volunteers (n=35) recruited from hospital staff and minor surgery attendees, had never had lymphoma or radiotherapy. All participants were required to complete a past medical history and thyroid symptom questionnaire, had blood taken for assays of thyroid stimulating hormone (TSH), thyroglobulin antibodies, thyroid peroxidase antibodies, sodium iodide symporter antibodies and TSH receptor antibodies and underwent ultrasound and clinical examination of the neck. A significant percentage of patients who had been irradiated in the neck had abnormalities on ultrasound, compared to groups 2 and 3 (77% vs 42% vs 24%). Abnormal TSH levels were found to be significantly more common in neck irradiated patients compared to the other groups (50% vs 9% vs 5%). There is a clear difference between neck irradiated patients and control groups. The importance of screening irradiated patients for thyroid abnormalities is re-emphasised.

Use of human menopausal gonadotropins in the treatment of endometrial defects associated with recurrent miscarriage: preliminary report

OBJECTIVE

To test the hypothesis that controlled ovarian stimulation by gonadotropins, which enhances estrogen priming, is of beneficial value in the treatment of endometrial defects associated with recurrent miscarriage.

DESIGN

A retrospective, observational, nonrandomized study.

SETTING

A regional recurrent miscarriage clinic in a teaching hospital.

PATIENT(S)

Twenty-one subjects with otherwise unexplained recurrent miscarriage who had retarded endometrial development in the mid-luteal phase. Endometrial biopsies were timed by the luteinizing hormone surge.

INTERVENTION(S)

Controlled ovarian stimulation using human menopausal gonadotropins and repeat endometrial biopsy in the treatment cycle in 13 subjects.

MAIN OUTCOME MEASURE(S)

Histological dating of endometrial biopsy in treatment cycles and miscarriage rate in treatment and nontreatment cycles.

RESULT(S)

Eleven (85%) of the 13 biopsies in the treatment cycle were found to be normal. The miscarriage rate in the treatment group, 2 of 13, was significantly lower than that in the nontreatment group (7/12) (chi2 5.0, P<.05).

CONCLUSION(S)

In this small series, preliminary experience suggests that controlled ovarian stimulation by human menopausal gonadotropins in the follicular phase is an effective treatment for luteal phase defect associated with recurrent pregnancy loss. There is now a case for a prospective, controlled study to confirm the value of such a treatment.

Two regulatory elements in the 5' region of the mouse mitochondrial malate dehydrogenase gene

We previously reported that the promoter region of the mouse mitochondrial malate dehydrogenase gene is located within the 160 base-pairs (bp) region upstream from the initiation codon, named P1, and that the -160/-131 bp region contains sequence(s) essential for the promoter activity of mitochondrial malate dehydrogenase gene. To define more precisely the regulatory mechanism of this gene, a 3' deletion analysis was performed using constructs with a constant 3' boundary at -130 bp. We obtained evidence of an additional positive regulatory element located between -393/-249 bp, named P2, the function of which can be separated from that of the P1. DNase I footprinting and gel-sift mobility experiments showed that nuclear protein binding to the P2 was not inhibited in the presence of the P1 sequences.

A novel Fmoc-based anchorage for the synthesis of protected peptides on solid phase

A novel bifunctional compound, 9-(hydroxymethyl)-2-fluoreneacetic acid, was synthesized, coupled to benzhydrylamine-resin, and evaluated for its application to the solid phase synthesis of protected peptide fragments. Anchor-bond cleavage was achieved with 15% piperidine/DMF. A protected heptapeptide, Boc-Val-Val-Ser(Bzl)-His(Tos)-Phe-Asn-Lys-(Z)-OH, corresponding to the sequence (1-7) of rat-transforming growth factor-alpha, was synthesized using this new support with an overall yield of 46%.

Regulatory regions of the mitochondrial and cytosolic isoenzyme genes participating in the malate-aspartate shuttle

The malate-aspartate shuttle, consisting of mitochondrial and cytosolic aspartate aminotransferase and mitochondrial and cytosolic malate dehydrogenase, is a major pathway for the transport of reducing equivalents from cytosol to mitochondria in mammals. To elucidate molecular mechanisms regulating metabolic coordination between the mitochondria and the cytosol, we analyzed the 5'-flanking regulatory regions of the complete set of mouse isoenzyme genes playing a pivotal role in the shuttle. Deletion analysis and an in vivo transfection assay, using NIH3T3 cells, revealed that all the promoter regions are located within the 300-base pair regions upstream from the initiation codon. Subsequently, DNase I footprinting analyses using NIH3T3 cell nuclear extracts led to identification of several protein binding sites within these promoter regions. A synthetic oligomer containing the consensus binding site sequence for CTF/NFI, a transcription factor for RNA polymerase II, competed for the binding of proteins to the promoter regions of cytosolic aspartate aminotransferase and mitochondrial and cytosolic malate dehydrogenase genes, but not for that of the mitochondrial aspartate amino-transferase gene. On the other hand, a synthetic oligomer containing the consensus binding site sequence for Sp1, which activates transcription from promoters containing properly positioned GC boxes, competed for protein(s) binding to the promoter region of the mitochondrial aspartate aminotransferase gene.