PubMed Health⌕ Search

Biomedical subjects

S A Rutherford

Publications and source records attributed to S A Rutherford.

10 recordsLinked to original sources

Vestibular schwannoma management: What is the 'best' option?

There is an abundance of medical literature describing the management options for vestibular schwannomas. However, the lack of high quality clinical trials means that, for any individual patient, the decision is often based on the clinician's personal biases. The management options that are available are conservative treatment, surgery, single-dose stereotactic radiosurgery and fractionated radiotherapy. In this review, we set out what the aims of managing a vestibular schwannoma should be and compare how these different treatment modalities perform. The particular objectives of tumour control, cranial nerve preservation, prevention of malignancy, quality of life and cost-effectiveness are discussed. It remains difficult to differentiate between these methods when more than one is suitable; the literature confirms that they are all safe and effective, but the decision must be the patient's, based on their individual priorities. This review should equip the clinician to provide an informed overview of the options.

Cost-Benefit Analysis↗

Generic waiting lists for routine spinal surgery.

National Health Service Hospitals are under pressure to reduce waiting lists within the constraints of a limited infrastructure. We implemented two systems to reduce waiting times for elective non-complex spinal surgery. The first of these was the introduction of managed generic waiting lists for both initial outpatient appointments and subsequent surgery. Thereafter, the MRI booking system was integrated with outpatient review appointments. Times from referral to first outpatient appointment and from scan to outpatient review and time on waiting list for surgery were analysed before and after implementation of these changes. Despite constant unit capacity there was a global decrease in waiting times. Before introduction of the generic waiting list, 37% of listed patients waited for more than 9 months; this figure fell to zero. Time from scan to outpatient review was 185 days before integration, 30 days after. Changes of this sort demand a quorum of consultants who will accept each others' recommendations. The generic waiting list will have impact only when there are large disparities in waiting times for different consultants. Targets are met at the expense of continuity of care.

Continuity of Patient Care↗

Remote hypertensive intracerebral haematoma following clipping of an intracranial aneurysm.

We report a case of a 58-year-old woman who presented with an aneurysmal subarachnoid haemorrhage. Immediately following clipping of this aneurysm, she had a spontaneous hypertensive bleed in the contralateral hemisphere. Although very unusual, hypertensive episodes following aneurysmal subarachnoid haemorrhage must carry a risk of such an intracranial event.

Cerebral Arteries↗

The Mycobacterium avium-intracellulare complex dnaB locus and protein intein splicing.

Intein is a protein sequence mebedded in-frame within a precursor protein and is posttranslationally excised by a self-catalytic protein splicing process. Protein splicing is believed to follow a pathway requiring Cys, Ser, or Thr residues at the intein N-terminus and substitutions other than Cys, Ser, or Thr residues prevent splicing. We show that the dnaB locus in some strains of M. avium-intracellulare complex (MAC) contains intein and that the intein N-terminal amino acid is Ala [Ala-type]. We demonstrate that the M. avium DnaB precursor protein undergoes posttranslational proteolytic processing producing proteins corresponding to the sizes of the DnaB and intein. Further, by Western analysis we detect a protein corresponding to the size of the spliced DnaB protein in MAC cell extracts. Together, these results indicate that the Ala-type MAC DnaB inteins can splice and provide another example that points to an interesting alternative splicing mechanism (Southworth, M. W., Benner, J., and Perler, F. B., EMBO J. 19, 5019-5026, 2000).

Bacterial Proteins↗

Ran alters nuclear pore complex conformation.

Transport across the nuclear membranes occurs through the nuclear pore complex (NPC), and is mediated by soluble transport factors including Ran, a small GTPase that is generally GDP-bound during import and GTP-bound for export. The dynamic nature of the NPC structure suggests a possible active role for it in driving translocation. Here we show that RanGTP but not RanGDP causes alterations of NPC structure when injected into the cytoplasm of Xenopus oocytes, including compaction of the NPC and extension of the cytoplasmic filaments. RanGTP caused accumulation of nucleoplasmin-gold along the length of extended cytoplasmic filaments, whereas RanGDP caused accumulation around the cytoplasmic rim of the NPC. This suggests a possible role for Ran in altering the conformation of the cytoplasmic filaments during transport.

Amino Acid Substitution↗

Three-dimensional visualization of the route of protein import: the role of nuclear pore complex substructures.

The three-dimensional localization of nucleoplasmin and wheat germ agglutinin (WGA) at the nuclear envelope of Xenopus oocytes is demonstrated by microinjecting protein coated gold colloids and examining their distribution using both stereo transmission electron microscopy and field emission in-lens scanning electron microscopy. Localization of many WGA gold particles and nucleoplasmin gold particles at the same nuclear pore complex (NPC) following coinjection is demonstrated. Binding of the WGA gold in the central region of the NPCs appears to form a barrier, preventing the import of nucleoplasmin gold, and includes central localization along radial "tracks" which correspond to the internal filaments connecting the cytoplasmic ring and the central region of the NPC. We suggest that these filaments may in some way be involved in opening and closing of the central channel of the NPC for transport. Transport of nucleoplasmin through the central region of the NPCs appears to be in "single file" regardless of the size of the colloidal gold, and distribution into the nucleoplasm appears to be through the basket rings with no association of the nucleoplasmin gold with the basket filaments being observed.

Animals↗

Accessing nuclear structure for field emission, in lens, scanning electron microscopy (FEISEM).

Scanning electron microscopy (SEM) has had a shorter time course in biology than conventional transmission electron microscopy (TEM) but has nevertheless produced a wealth of images that have significantly complemented our perception of biological structure and function from TEM information. By its nature, SEM is a surface imaging technology, and its impact at the subcellular level has been restricted by the considerably reduced resolution in conventional SEM in comparison to TEM. This restriction has been removed by the recent advent of high-brightness sources used in lensfield emission instruments (FEISEM) which have produced resolution of around 1 nanometre, which is not usually a limiting figure for biological material. This communication reviews our findings in the use of FEISEM in the imaging of nuclear surfaces, then associated structures, such as nuclear pore complexes, and the relationships of these structures with cytoplasmic and nucleoplasmic elements. High resolution SEM allows the structurally orientated cell biologist to visualise, directly and in three dimensions, subcellular structure and its modulation with a view to understanding, its functional significance. Clearly, intracellular surfaces require separation from surrounding structural elements in vivo to allow surface imaging, and we review a combination of biochemical and mechanical isolation methods for nuclear surfaces.

Animals↗