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Biomedical subjects

N Price

Publications and source records attributed to N Price.

52 records · Page 3Linked to original sources
PubMed1994

The guanine nucleotide-exchange factor, eIF-2B.

Eukaryotic initiation factor eIF-2B catalyses the exchange of guanine nucleotides on another translation initiation factor, eIF-2, which itself mediates the binding of the initiator Met-tRNA to the 40S ribosomal subunit during translation initiation. eIF-2B promotes the release of GDP from inactive [eIF-2.GDP] complexes, thus allowing formation of the active [eIF-2.GTP] species which subsequently binds the Met-tRNA. This guanine nucleotide-exchange step, and thus eIF-2B activity, are known to be an important control point for translation initiation. The activity of eIF-2B can be modulated in several ways. The best characterised of these involves the phosphorylation of the alpha-subunit of eIF-2 by specific protein kinases regulated by particular ligands. Phosphorylation of eIF-2 alpha leads to inhibition of eIF-2B. This mechanism is involved in the control of translation under a variety of conditions, including amino acid deprivation in yeast (Saccharomyces cerevisiae) where it causes translational upregulation of the transcription factor GCN4, and in virus-infected animal cells, where it involves a protein kinase activated by double-stranded RNA. There is now also growing evidence for direct regulation of eIF-2B. This appears likely to involve the phosphorylation of its largest subunit. Under certain circumstances eIF-2B may also be regulated by allosteric mechanisms. eIF-2B is a heteropentamer (subunits termed alpha, beta, gamma, delta and epsilon) and is thus more complex than most other guanine nucleotide-exchange factors. The genes encoding all five subunits have been cloned in yeast (exploiting the GCN4 regulatory system): all but the alpha appear to be essential for eIF-2B activity. However, this subunit may confer sensitivity to eIF-2 alpha phosphorylation. cDNAs encoding the alpha, beta, delta and epsilon subunits have been cloned from mammalian sources. There is substantial homology between the yeast and mammalian sequences. Attention is now directed towards understanding the roles of individual subunits in the function and regulation of eIF-2B.

Allosteric Regulation↗
PubMed1990

Laparoscopic laser cholecystectomy and choledocholithiasis.

The management of common bile duct stones during laparoscopic laser cholecystectomy (LLC) is uncertain. Open common bile duct exploration is the least desirable option since it defeats the purpose of LLC. Endoscopic retrograde cholangiopancreatography (ERCP) with papillotomy has become the procedure of choice since it has a high rate of success and results in minimal morbidity. Intraoperative techniques using balloon catheters and the flexible choledochoscope via the cystic duct may obviate the need for ERCP in selected cases.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1990

The inwardly pointing knee. An unrecognized problem of external rotational malalignment.

Twelve patients with inwardly pointing knees had chronic knee pain and disability suggestive of patellofemoral subluxation. None had responded well to conservative measures or surgical correction at the level of the soft tissues. Their pattern of limb alignment was studied roentgenographically and was found to differ significantly from the control group of 49 healthy young adults. The deformities primarily related to the tibia were external tibial torsion, excess varus angulation of the tibial plateau, and varus knees. Angulation of the femoral condyles was normal and femoral anteversion did not appear to contribute significantly to the deformity. Surgery in seven cases (nine knees) was by derotation valgus Maquet osteotomy of the tibia and lateral release realignment of the patellae. Outcome assessments after a three-year follow-up period (five knees) were excellent. Early results on the remaining cases were satisfactory.

Adolescent↗
PubMed1989

Effects of temazepam premedication on cognitive recovery following alfentanil-propofol anaesthesia.

The effects of temazepam 20 mg and placebo were compared for premedication in patients anaesthetized with propofol and alfentanil and undergoing day surgery. Temazepam 20 mg significantly reduced preoperative anxiety and increased recovery time. A series of computerized cognitive tasks revealed significant deficits in attention and memory following anaesthesia, which were increased in range and magnitude by temazepam, which were apparent 30 min after surgery and had largely, but not completely, recovered at 4 h. This study has demonstrated that computerized cognitive testing can identify a wider profile of impairments produced by temazepam than has been found in previous work using non-computerized techniques.

Adolescent↗
PubMed1985

Responses of the pig isolated renal artery to transmural electrical stimulation and drugs.

Pig isolated renal arteries contract in response to addition of noradrenaline, 5-hydroxytryptamine, histamine, angiotensin II, vasopressin and carbachol, whereas cholecystokinin, adenosine, and inosine produce relaxation. Transmural stimulation of the tissue causes contraction of circular muscle in the arterial wall which produces apparent elongation of the vessel. The effects of transmural stimulation are partially blocked by prazosin and potentiated by propranolol, indicating that noradrenaline acts through both alpha- and beta-adrenoceptors. Guanethidine (10(-5) M) reduces the size of responses to transmural stimulation in the presence of both prazosin (10(-6) M) and propranolol (10(-7) M). Both saralasin (10(-7) M), and desensitization of angiotensin II receptors by prolonged contact with the peptide, produced a reduction in response to transmural stimulation, indicating that angiotensin II may be involved in neurotransmission. This effect was blocked by tetrodotoxin. Transmural stimulation produces relaxation of renal arteries in the presence of maximal doses of saralasin, prazosin, and propranolol, suggesting that a third unidentified substance is also released from autonomic nerves.

Angiotensin II↗
PubMed1984

Woringer-Kolopp disease (pagetoid reticulosis). Four cases with histopathologic, ultrastructural, and immunohistologic observations.

Four patients had localized lesions of Woringer-Kolopp disease (pagetoid reticulosis). The clinical appearances and histopathologic features with light microscopy of the four cases were similar. However, electron microscopy in all four cases and enzyme histochemistry studies and immunophenotyping with monoclonal antibodies in three cases disclosed two subgroups of patients. The features of the predominant cells in the intraepidermal infiltrate of three cases were most consistent with those of helper T lymphocytes with cerebriform nuclei, as found in many cases of mycosis fungoides. In one case, however, the epidermis contained a predominant population of small, medium, and large lymphoid cells of cytotoxic/suppressor T-lymphocyte cell phenotype. It remains to be determined whether Woringer-Kolopp disease is a variant of mycosis fungoides (ie, within the spectrum of the cutaneous T-cell lymphomas), a benign reactive process, or a syndrome with various causes.

Adult↗
PubMed1982

Rate of endothelial cell loss in the early postoperative period after cataract surgery.

Central corneal endothelial cell density was estimated in 33 consecutive patients preoperatively and at monthly intervals for 6 months after cataract surgery. The patients were divided into 3 groups by a random procedure to have either intracapsular extraction or intracapsular extraction plus Federov 4-loop iris clip lens, or extracapsular extraction with Binkhorst 2-loop iridocapsular lens. In all groups the greatest cell loss had occurred by one month and thereafter no accelerated loss was apparent except in individual patients. The limitations of such a method of assessment are discussed.

Aged↗
PubMedDate not supplied

Theatre for health.

Explore the source record for details and available documents.

Australia↗
PubMedDate not supplied

Macula off retinal detachments. How long can they wait before it is too late?

PURPOSE: To determine the association between the duration of macula off detachment and the visual outcome following corrective surgery. METHODS: Retrospective review of the medical records of patients who underwent surgery for macula off detachment over a 5 year period (April 1994- March 1999). RESULTS: There were 104 patients in the study. Patients with macula off detachments wait a mean of 2.6 weeks (+/-0.3 SE mean) before presentation and 1.8 weeks (+/-0.2 SE of mean) thereafter before surgery. The mean duration of detachment prior to surgical repair was 4.2 weeks (+/-0.3 SE mean). 78% of patients achieved a postoperative improvement in visual acuity. 36.5% achieved functional visual success of 6/12 at 3 months, which increased to 51% at final discharge. There was no significant difference in visual outcomes for patient undergoing internal vs external procedures (p=0.188). The preoperative visual acuity was the most significant predictor of post operative visual acuity (p<0.0005). Less than 40% of macula off detachments of > or =6 weeks duration will achieve a vision of 6/12 or better compared with 68.2% of patients with macula off detachments of < or =1 week. CONCLUSIONS: The best mean postoperative vision (LogMAR 0.35) was seen in patients with detachment of <1 week duration. Patients <60 years are more likely to achieve visual improvement despite the duration of the detachment. Macula off detachments of >6 weeks duration have a significantly poor postoperative visual prognosis. Awareness of this visual prognosis can assist in planning the timing of surgery to ensure an acceptable result.

Adolescent↗