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Biomedical subjects

C N Penfold

Publications and source records attributed to C N Penfold.

At least 19 recordsLinked to original sources
PubMed2005

Total mandibular reconstruction for massive osteolysis of the mandible (Gorham-Stout syndrome).

Massive osteolysis (Gorham-Stout syndrome) is a rare condition of unknown aetiology that is thought to result from a localised endothelial proliferation of lymphatic vessels resulting in destruction and absorption of bone. The diagnosis of Gorham-Stout syndrome can be made only after first excluding osteolysis from infection, inflammation, endocrine disease, and cancer. The syndrome is rarely seen in the facial skeleton and has a variable prognosis. Many treatments have been advocated but only surgery and radiotherapy have had some success. We present a case of massive osteolysis of the entire mandible, which was reconstructed with a free vascularised fibular graft and bilateral prosthetic replacements of the temporomandibular (TMJ) joints. Four years later the fibular graft had been absorbed requiring further reconstruction with another fibula graft.

Bone Transplantation↗
PubMed2002

Insertion of percutaneous endoscopic gastrostomy tubes by a maxillofacial surgical team in patients with oropharyngeal cancer.

This study assessed the clinical outcome after insertion of a percutaneous endoscopic gastrostomy tube (PEGT) by a maxillofacial team in a series of 54 patients. The indication for PEG feeding was any patient with oropharyngeal cancer who was unlikely to return to oral feeding within 14 days. Fifty-two patients (96%) had tubes successfully inserted at the time of examination under anaesthesia (n = 19) or definitive operation (n = 33). Feeding was established at a median of 2 days (range 1-6). Median duration of tube feeding was 18 weeks (range 4-70). There were no deaths or major complications and 10 minor complications. No tube was lost or required premature removal. We conclude that insertion of a PEG tube is a procedure that can be done safely by maxillofacial surgeons.

Aged↗
PubMed2002

Chronic eosinophilic pneumonia associated with T-cell lymphoma.

A case of a woman presenting with a parotid swelling is described. She had chronic eosinophilic pneumonia (CEP) for approximately 2 years prior to presentation. After further investigation she had biopsy of her parotid, which proved to be T-cell lymphoma. This is a rare association, the diagnosis and the management of this condition is discussed.

Chronic Disease↗
PubMed2000

The structure of TolB, an essential component of the tol-dependent translocation system, and its protein-protein interaction with the translocation domain of colicin E9.

BACKGROUND: E colicin proteins have three functional domains, each of which is implicated in one of the stages of killing Escherichia coli cells: receptor binding, translocation and cytotoxicity. The central (R) domain is responsible for receptor-binding activity whereas the N-terminal (T) domain mediates translocation, the process by which the C-terminal cytotoxic domain is transported from the receptor to the site of its cytotoxicity. The translocation of enzymatic E colicins like colicin E9 is dependent upon TolB but the details of the process are not known. RESULTS: We have demonstrated a protein-protein interaction between the T domain of colicin E9 and TolB, an essential component of the tol-dependent translocation system in E. coli, using the yeast two-hybrid system. The crystal structure of TolB, a procaryotic tryptophan-aspartate (WD) repeat protein, reveals an N-terminal alpha + beta domain based on a five-stranded mixed beta sheet and a C-terminal six-bladed beta-propeller domain. CONCLUSIONS: The results suggest that the TolB-box residues of the T domain of colicin E9 interact with the beta-propeller domain of TolB. The protein-protein interactions of other beta-propeller-containing proteins, the yeast yPrp4 protein and G proteins, are mediated by the loops or outer sheets of the propeller blades. The determination of the three-dimensional structure of the T domain-TolB complex and the isolation of mutations in TolB that abolish the interaction with the T domain will reveal fine details of the protein-protein interaction of TolB and the T domain of E colicins.

Amino Acid Sequence↗
PubMed2000

A 76-residue polypeptide of colicin E9 confers receptor specificity and inhibits the growth of vitamin B12-dependent Escherichia coli 113/3 cells.

The mechanism by which E colicins recognize and then bind to BtuB receptors in the outer membrane of Escherichia coli cells is a poorly understood first step in the process that results in cell killing. Using N- and C-terminal deletions of the N-terminal 448 residues of colicin E9, we demonstrated that the smallest polypeptide encoded by one of these constructs that retained receptor-binding activity consisted of residues 343-418. The results of the in vivo receptor-binding assay were supported by an alternative competition assay that we developed using a fusion protein consisting of residues 1-497 of colicin E9 fused to the green fluorescent protein as a fluorescent probe of binding to BtuB in E. coli cells. Using this improved assay, we demonstrated competitive inhibition of the binding of the fluorescent fusion protein by the minimal receptor-binding domain of colicin E9 and by vitamin B12. Mutations located in the minimum R domain that abolished or reduced the biological activity of colicin E9 similarly affected the competitive binding of the mutant colicin protein to BtuB. The sequence of the 76-residue R domain in colicin E9 is identical to that found in colicin E3, an RNase type E colicin. Comparative sequence analysis of colicin E3 and cloacin DF13, which is also an RNase-type colicin but uses the IutA receptor to bind to E. coli cells, revealed significant sequence homology throughout the two proteins, with the exception of a region of 92 residues that included the minimum R domain. We constructed two chimeras between cloacin DF13 and colicin E9 in which (i) the DNase domain of colicin E9 was fused onto the T+R domains of cloacin DF13; and (ii) the R domain and DNase domain of colicin E9 were fused onto the T domain of cloacin DF13. The killing activities of these two chimeric colicins against indicator strains expressing BtuB or IutA receptors support the conclusion that the 76 residues of colicin E9 confer receptor specificity. The minimum receptor-binding domain polypeptide inhibited the growth of the vitamin B12-dependent E. coli 113/3 mutant cells, demonstrating that vitamin B12 and colicin E9 binding is mutually exclusive.

Amino Acid Sequence↗
PubMed1996

Characterisation of genes involved in biosynthesis of coronafacic acid, the polyketide component of the phytotoxin coronatine.

Coronafacic acid (CFA) is the polyketide component of coronatine (COR), a phytotoxin produced by the plant pathogen, Pseudomonas syringae. In the present study we have determined the nucleotide sequence of a 3.92-kb DNA fragment involved in CFA biosynthesis. Analysis of the sequence revealed four complete open reading frames (ORFs) designated cfa1 to cfa4 and one incomplete ORF (cfa5), all transcribed in the same direction. The predicted translation products of cfa1, cfa2 and cfa3 showed relatedness to acyl carrier proteins, fatty acid dehydrases and beta-ketoacylsynthases, respectively, which are required for polyketide synthesis. cfa1 was subcloned, its sequence was confirmed, and it was overexpressed in E. coli to yield a peptide with an apparent molecular mass of 6 kDa.

Amino Acid Sequence↗
PubMed1996

Isolation, characterisation and expression of the bacterioferritin gene of Rhodobacter capsulatus.

The nucleotide sequence of the Rhodobacter capsulatus bacterioferritin gene (bfr) was determined and found to encode a protein of 161 amino acids with a predicted molecular mass of 18,174 Da. The molecular mass of the purified protein was estimated to be 18,176. +/ 0.80 Da by electrospray mass spectrometry. The bfr was introduced into an expression vector, and bacterioferritin was produced to a high level in Escherichia coli. The amino acids which are involved in haem ligation, and those provide ligands in the binuclear metal centre in bacterioferritin from E. coli are conversed in the R. capsulatus protein. The sequences of bacterioferritins, ferritin-like proteins, and proteins similar to Dps of E. coli are compared, and membership of the bacterioferritin family re-evaluated.

Bacterial Proteins↗
PubMed1996

Combined radial forearm and pharyngeal flap for soft palate reconstruction.

The use of a free vascularised fascio-cutaneous radial forearm flap in combination with a cranially based pharyngeal flap for soft palate reconstruction has not been previously reported. We present the technique and illustrate its use in two cases of total and one case of subtotal soft palate reconstruction. The functional outcome is discussed with particular reference to nasal airway patency, speech and swallowing.

Bone Transplantation↗
PubMed1996

The role of angiogenesis in the spread of oral squamous cell carcinoma.

Microvessels were counted in 41 primary oral squamous cell carcinomas using JC70 antibody to PECAM (CD31). The counts were compared with clinical and pathological indicators of tumour behaviour including lymph node status, tumour stage, type of histological differentiation, size and velocity of tumour growth. Tumour microvessel counts correlated with lymph node metastasis (p < 0.001). This association was independent of tumour size, velocity and type of histological differentiation and when all the variables were analysed by multivariate analysis only vascular count showed a significant association with lymph node metastasis.

Carcinoma, Squamous Cell↗
PubMed1996

A review of 23 patients with tuberculosis of the head and neck.

OBJECTIVE: to review the clinical features and management of tuberculosis of the head and neck and to identify those features which may aid diagnosis. DESIGN: retrospective study. SETTING: teaching hospital, England, UK. SUBJECTS: Twenty-three patients with tuberculosis of the head and neck diagnosed by culture of specimens obtained by fine needle biopsy (n = 8) or by open biopsy of the lumps in the neck (n = 15) who presented between 1990 and 1993. MAIN OUTCOME MEASURES: methods of diagnosis and management. RESULTS: thirteen of the 23 patients (57%) presented with either a fluctuant mass or a discharging sinus in the neck. Nine (39%) had uncomplicated enlarged lymph nodes and 12 (55%) had systemic symptoms. The supraclavicular region was the most common site (n = 11) and 8 of these 11 had abnormalities in the chest radiograph. In 3 patients the disease was resistant to treatment with standard antituberculous treatment. CONCLUSIONS: atypical mycobacterial lymphadenitis is usually resistant to standard antituberculous treatment, so it is essential to obtain a microbiological diagnosis. Excision is usually the treatment of choice for such patients.

Adolescent↗
PubMed1993

Giant cell lesions complicating fibro-osseous conditions of the jaws.

Three patients who presented with giant cell lesions complicating ossifying fibroma, Paget's disease, and cherubism are reported. The giant cell lesions complicating ossifying fibroma and cherubism were diagnosed as giant cell granuloma (GCG), whereas the lesion complicating Paget's disease demonstrated more aggressive clinical and histologic features. The possible therapeutic and prognostic implications of these findings are discussed.

Adult↗
PubMed1993

Pain-free oral surgery.

Much routine dento-alveolar surgery can be performed comfortably under local anaesthesia. If this is not possible, and the patient's health permits, day-case general anaesthesia is a suitable alternative, thus reserving valuable inpatient facilities for patients who require more major surgical procedures or for medically compromised patients. Although anaesthetic techniques are becoming increasingly effective, improvement in postoperative pain relief has been less than satisfactory. The misconception that pain is an inevitable consequence of surgery and the difficulty in measuring pain have impeded progress in postoperative pain control. Despite these limitations, pain-free oral surgery is a real prospect for most patients, and the aim of this article is to highlight those factors which contribute to its achievement.

Analgesics↗