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Biomedical subjects

G Vaughan

Publications and source records attributed to G Vaughan.

At least 19 recordsLinked to original sources
PubMed2006

SAOZ measurements of NO2 at Aberystwyth.

We present in this paper fifteen years' measurements, from March 1991 to September 2005, of stratospheric NO2 vertical columns measured by a SAOZ zenith-sky visible spectrometer. The instrument spent most of its time at Aberystwyth, Wales, with occasional excursions to other locations. The data have been analysed with the WinDOAS analysis program with low-temperature high-resolution NO2 cross-sections and fitting a slit function to each spectrum. Because of a change in detector in May 1998 there is some uncertainty about the relative changes before and after this date, which are partially constrained by the results of an intercomparison exercise. However, the effect of the Mt Pinatubo aerosol cloud is very evident in the data from 1991-94, with a decrease of 10% in NO2 in the summer of 1992 (the SAOZ was located in Lerwick, Scotland during the winter of 1991-92 and observed very low NO2 values but these cannot be directly compared to the Aberystwyth data). To focus more on interannual and long-term variations in NO2, a seasonal variation comprising an annual and semi-annual component was fitted to the morning and evening twilight separately from 1995 to the present. This fit yielded average NO2 columns of 4.08 x 10(15) cm(-2) and 2.68 x 10(15) cm(-2) for the evening and morning twilight, respectively, with a corresponding annual amplitude of +/-2.08 x 10(15) cm(-2) and +/-1.50 x 10(15) cm(-2). Departures from the fitted curve show a trend of 6% per decade, consistent with that reported elsewhere, for the period 1998-2003, but in the past two years a distinct interannual variation of amplitude of approximately 8% has emerged.

Air Pollutants↗
PubMed2003

Long-term effect of a watch and wait policy versus immediate systemic treatment for asymptomatic advanced-stage non-Hodgkin lymphoma: a randomised controlled trial.

BACKGROUND: Neither chemotherapy with a single-alkylating agent nor aggressive combination chemotherapy cures advanced stage low-grade non-Hodgkin lymphomas, even when combined with radiotherapy. Our aim was to compare administration of immediate chlorambucil treatment with a policy of delaying chlorambucil until clinical progression necessitated its use, in asymptomatic patients with advanced-stage, low-grade non-Hodgkin lymphoma. METHODS: 309 patients with asymptomatic, advanced-stage, low-grade non-Hodgkin lymphomas were recruited from 44 UK centres between Feb 1, 1981, and July 31, 1990. 158 patients were randomised to receive immediate systemic therapy with oral chlorambucil 10 mg per day continuously. The remaining 151 were randomised to an initial policy of observation, with systemic therapy delayed until disease progression. In both groups, local radiotherapy to symptomatic nodes was allowed. FINDINGS: Median length of follow-up was 16 years. Overall survival or cause-specific survival did not differ between the two groups (median overall survival for oral chlorambucil 5.9 [range 0-17.8] years and for observation 6.7 [0.5-18.9] years, p=0.84; median cause-specific survival 9 [0-17.8] years and 9.1 [0.67-18.9] years, respectively p=0.44). In a multivariate analysis, age younger than 60 years, erythrocyte sedimentation rate (ESR) 20 mm/h or less, and stage III disease, conferred significant advantages in both overall survival (p<0.0001, 0.03, and 0.03, respectively) and cause-specific survival (p=0.002, 0.008, and 0.001, respectively). In the observation group, at 10 years' follow-up, 19 patients were alive and had not received chemotherapy. The actuarial chance of not needing chemotherapy (non-lymphoma deaths censored) at 10 years was 19% (40% if older than 70 years). INTERPRETATION: An initial policy of watchful waiting in patients with asymptomatic, advanced stage low-grade non-Hodgkin lymphoma is appropriate, especially in patients older than age 70 years.

Age Factors↗
PubMed2000

Recognition-directed supramolecular assemblies of metal complexes of terpyridine derived ligands with self-complementary hydrogen bonding sites.

The synthesis and X-ray structures of three metal complexes with terpyridine-derived ligands that contain amino-pyrimidine and amino-pyrazine moieties are presented. They have been designed in view of directing their self-assembly into specific supramolecular arrays through molecular recognition interactions. The solid-state structures indeed reveal extensive hydrogen-bonded networks. The Co complex 4a with PF6- counterions builds a two-dimensional infinite interwoven grid through strong double hydrogen bonds (d(N-H-N) =2.918-3.018 A) between the amino groups and the N atoms of the rings, with all H-bonding sites saturated. Changing the anions to BF4- in 4b leads to a similar infinite but partially broken grid with a quarter of the H-bonding sites unsaturated (d(N-H-N)=2.984-3.206 A). In the case of the Zn complex 12 with triflate anions, half of the hydrogen bonds are formed. Only one of the two orthogonal ligands has hydrogen bonds (d(N-H-N) = 3.082, 3.096 A) to the neighbouring complexes and thus builds linear, supramolecular, polymeric chains. These structural differences are mainly attributed to crystal-packing effects caused by the different anions. The data presented here may also be regarded as a prototype for the generation of organised arrays through sequential self-assembly processes.

Journal Article↗
PubMed2000

A randomized British National Lymphoma Investigation trial of CHOP vs. a weekly multi-agent regimen (PACEBOM) in patients with histologically aggressive non-Hodgkin's lymphoma.

BACKGROUND: Between 1987 and 1991, the British National Lymphoma Investigation randomized 459 patients with non-Hodgkin's lymphoma with a large-cell component to either CHOP or the PACEBOM regimen. PATIENTS AND METHODS: Four hundred fifty-nine eligible patients were included in this trial, four hundred one with diffuse large-cell lymphoma and fifty-eight with diffuse mixed-cell lymphoma according to the Working Formulation. Two hundred twenty-six patients were randomized to receive CHOP and two hundred thirty-three to receive PACEBOM. The two arms of the trial were well balanced for all potential prognostic factors. RESULTS: The complete remission rate with PACEBOM was 64% and with CHOP 57% (NS). At eight years, the actuarial cause specific survival (CSS) in the PACEBOM arm is 59% compared to 49% in the CHOP arm (P = 0.09). Patients < 50 years of age fared significantly better in the PACEBOM arm both for CSS and overall survival (P = 0.002) and the CSS was also significantly improved in stage IV disease (P = 0.02). CONCLUSIONS: The mature data from this trial suggest that an etoposide-containing multi-agent weekly regimen can be superior to CHOP.

Adolescent↗
PubMed1998

Outcome of secondary myeloid malignancy in Hodgkin's disease: the BNLI experience.

In Hodgkin's disease where the majority of patients are long-term survivors secondary myeloid malignancies are a well-documented complication. The survival of those who develop secondary myelodysplasia/acute myeloid leukaemia (MDS/AML) is historically said to be extremely poor. This study from the BNLI database of over 4900 patients with Hodgkin's disease reports long-term follow-up of 30 patients with secondary MDS/AML. Five patients have survived at least 5 yr (1>12 yr) from the time of diagnosis of AML. These patients were significantly younger (p=0.03) than those who succumbed to this complication and each also had standard or favourable risk cytogenetics. The actuarial 5- and 10-yr survival rates are 17.4% (7.7-34.9%, 95% CI) and 8.7% (1.9-31.7%, 95% CI), respectively. There is therefore a subgroup of patients who will achieve long-term survival despite the development of secondary myeloid malignancy.

Adolescent↗
PubMed1996

Complications of 174 laparoscopic hysterectomies.

The case records of 174 patients who underwent laparoscopic hysterectomy between September, 1992 and April, 1995 were retrospectively reviewed. The mean age of the group was 45.4 (range 17.8-68.5) years, mean weight 70.2 (50-121) kg and mean parity 2.3 (0-4). Laparoscopic hysterectomy (i.e. uterine arteries secured laparoscopically) was performed in 98 patients, laparoscopically assisted vaginal hysterectomy in 70, and laparoscopic subtotal hysterectomy in 6. Bilateral or unilateral oophorectomy were performed in 40 cases. The mean operating time was 131 (45-285) minutes and mean hospitalization 2.6 (1-11) days. Endoscopic stapling devices were used in 135 cases, biopolar diathermy in 117, sutures and ties in 84, and the harmonic scalpel in 29. The overall complication rate was 16%. Seven cases (4%) required conversion to laparotomy. These included 2 inadvertent cystotomies (1 after 2 Caesarean sections), 3 cases of dense uterovesical adhesions following previous surgery and 2 instances of excessive uterine size (> 16 weeks). The mean follow-up period was 2.2 (1-18) months. One patient had a shortened vagina requiring dilatation and another had vault granulations requiring diathermy treatment. Overall 98.3% of patients were satisfied with their surgery.

Adolescent↗
PubMed1991

Promotion of neuronal survival in vitro by thermal proteins and poly(dicarboxylic)amino acids.

Evaluating molecules for their ability to promote survival and growth of neurons, we tested thermal proteins on cultures of dissociated fetal rat forebrain neurons. (Thermal proteins are polyamino acids formed when mixtures of amino acids with minimal proportions of glutamic or aspartic acid are heated.) Thermal proteins, added to low-density cultures in serum-free medium, stimulated neurite outgrowth and induced the formation of neuronal networks which survived for 6-10 days. Neurons in control cultures failed to grow and degenerated completely within 2-4 days. Effective concentrations (EC50) of thermal proteins ranged from 3 to 100 micrograms/ml. They were equally effective when present in the medium during the culture time or after precoating of the culture dishes. A single preparation which contained only aspartic and glutamic acid was effective, and similar survival promoting actions were then found for polyglutamic acid and mixed polyamino acids containing glutamic or aspartic acid. Thermal proteins and polyglutamic acid acted in a specific manner since, under the same experimental conditions, many control peptides, proteins and growth hormones failed to promote survival of neurons. Furthermore, their effects were antagonized by heparin, but not heparan sulfate nor chondroitin sulfate. These findings suggest that sequences of successive dicarboxylic amino acid residues are able to promote survival and neurite elongation of cultured neurons and that such sequences are responsible for the survival promoting action of thermal proteins. They invite the speculation that sequences of successive dicarboxylic amino acids, while occur in many proteins and show a high degree of evolutionary conservation, may have functional role in molecular recognition processes during neuronal development.

Amino Acid Sequence↗
PubMed1987

Pharmacological activities in thermal proteins: relationships in molecular evolution.

The model of protobiological events that has been presented in these pages has increasing relevance to pharmacological research. The thermal proteins that function as key substances in the proteinoid theory have recently been found to prolong the survival of rat forebrain neurons in culture and to stimulate the growth of neurites. A search for such activity in thermal proteins added to cultures of modern neurons was suggested by the fact that some of the microspheres assembled from proteinoids rich in hydrophobic amino acids themselves generate fibrous outgrowths.

Amino Acids↗
PubMed1987

Thermal proteinoids as excitability-inducing materials.

The deposition of thermal copolyamino acids on planar lipid membranes causes oscillations and action potentials upon electrical stimulation. Results are reported for compositionally simple thermal copoly(asp,glu) and for a more heterotonic polyamino acid. The data conform to the interference that electrical activity of cellular membranes is due to the polypeptide components, not to the lipid components. Because of the ease and controllability of producing polypeptides by thermal copolymerization of amino acids, new possibilities in investigation of structure-excitability relationships are provided.

Amino Acids↗
PubMed1986

A pathological classification of nasal fractures.

The management of nasal fractures has been found by several authors to be inadequate. The reason for this is obscure but may be poor understanding of the pathology of nasal fractures. There is no adequate comprehensive classification of nasal fractures. Various weights were dropped on cadavers' noses and the resultant fractured nasal pyramid was dissected out. The fracture lines are described and particular reference is directed to the involvement of the septum in grossly deviated noses. Confirmation of septal involvement is obtained using a CAT scanner. It has been found that correction of this septal involvement at the time of manipulation significantly improves the end-results (Murray and Maran, 1984).

Humans↗
PubMed1980

Health administration: two and two making five.

Gerard Vaughan expects to save pounds 30m by streamlining NHS administration, but where did that figure come from--thin air perhaps? Nick Davidson has been doing some calculations and reckons that to save anything like that amount, many heads must roll. But at what point does a reduction in administrative costs become a reduction in efficiency?

Administrative Personnel↗