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Biomedical subjects

D L Richardson

Publications and source records attributed to D L Richardson.

At least 19 recordsLinked to original sources
PubMed2006

Ultrasound guidance improves the adequacy of our preoperative thyroid cytology but not its accuracy.

AIMS: Our thyroid cytology audit results of 1990-1995 showed an unsatisfactory rate of 43.1% and prediction of neoplasia with a sensitivity of 86.8%. Increasingly, ultrasound scan (USS)-guided core sampling for cytology is proving a valuable tool instead of freehand fine needle aspiration (FNA) or following unsatisfactory freehand FNA. We present the results of freehand FNA and USS-guided core samples for cytology in two separate patient groups in our centre. METHODS: Patients who had a thyroid resection and preoperative thyroid cytology in our institution between 1996 and 2002 were included. The histological diagnoses were correlated with the preceding cytology results. RESULTS: A total of 450 FNAs were performed on 394 patients. Freehand FNAs were performed for 348 (77.3%) samples and USS-guided core for 102 (22.7%) samples; 121 (26.8%) were repeat aspirates performed on 45 patients. Using aspiration cytology (AC) grading, freehand FNA was cytologically inadequate (AC0 or AC1) in 34.8% cases whereas USS-guided core was inadequate in 17.6% cases (P = 0.001). Freehand FNA (AC3, AC4, AC5) predicted neoplasia with a sensitivity of 83.2%, specificity of 46.6%, accuracy of 63.0%, positive predictive value of 56.0% and negative predictive value of 77.1%. USS-guided core sample for cytology (AC3, AC4, AC5) predicted neoplasia with a sensitivity of 93.5%, specificity of 26.0%, accuracy of 51.9%, positive predictive value of 43.9% and negative predictive value of 86.7%. CONCLUSIONS: Although USS-guided core provides more satisfactory specimens than freehand FNA, in our centre it does not provide increased accuracy.

Biopsy, Fine-Needle↗
PubMed2006

Postpneumonectomy esophageal fistula: a combined radiological-endoscopic technique.

We report a case of a 70-year-old man who presented with a long-standing esophagocutaneous fistula following a pneumonectomy for aspergilloma. Major surgical procedures, including a pectoralis major flap reconstruction, a pedicled omental transposition and a radial forearm flap transposition, failed to obliterate the fistula. Seven years after initial surgery the esophagocutaneous fistula was successfully treated by means of a minimally invasive joint endoscopic and radiological technique. A radiographic catheter was passed through the fistula. The catheter and the guide wire were manipulated into the esophageal defect and into the upper esophagus. Under endoscopic vision, the catheter was then advanced over the guide wire and out of the patient's mouth. A T-tube was sutured to the catheter outside the mouth, pulled down through the esophagus, and into the esophageal defect and out through the chest wall, leaving the T-part of the tube within the esophagus. The patient made a good recovery and was discharged 7 days later. He was able to resume oral intake 3 weeks after the procedure.

Aged↗
PubMed2006

Characteristics and smoking cessation outcomes of patients returning for repeat tobacco dependence treatment.

Previous studies of tobacco dependence treatment have reported very low cessation rates among smokers who relapse and return to make a subsequent formal attempt to quit. This retrospective cohort study examined 1745 patients who attended a tobacco dependence clinic between 2001 and 2005, and the characteristics and outcomes of those who relapsed and returned for repeat treatment. Patients who returned for repeat treatment showed higher markers of nicotine dependence and were more likely to have a history of treatment for mental health problems than patients who attended the clinic for only one treatment episode. Among patients who relapsed and returned for repeat treatment, the 26-week abstinence rates were similar for each consecutive quit attempt (23%, 22% and 20%). Clinicians should encourage smokers who relapse after an initial treatment episode to return for treatment, and repeat treatment should focus on addressing high nicotine dependence and potentially co-occurring mental health problems in order to improve cessation outcomes.

Adult↗
PubMed2005

Ultrasound scan-guided core sampling for diagnosis versus freehand FNAC of the thyroid gland.

BACKGROUND AND AIM: Freehand fine needle aspiration cytology (FNAC) is an obligatory investigation of the thyroid nodule. Between 5.0-43.1% of FNAC samples are reported as being initially unsatisfactory. In our unit, thyroid freehand FNAs are performed with a small needle (21 or 23G). Non-dominant nodules as part of multinodular goitres, difficult to palpate nodules or nodules with previously unsatisfactory freehand FNACs are sampled under ultrasound scan (USS) guidance with the larger 20G cutting core sampling technique. We aimed to compare the satisfactory sampling rate and safety of the two different methods. PATIENTS AND METHODS: Cytology forms were reviewed for 262 freehand FNACs and USS-guided core samples, performed in our unit over a two-year interval (1 July 1999 to 30 June 2001). RESULTS: Ultrasound-guided core samples for cytology were unsatisfactory (AC0-1) in 19/121 (15.6%) of the cases, compared with 66/141 (46.8%) of freehand FNACs (p value = < 0.0001). Ten out of eleven patients (91%) had a satisfactory USS-guided core after an unsatisfactory freehand FNA; 7/15 patients (46.7%) had satisfactory repeat freehand FNACs following an initial unsatisfactory freehand FNAC (p value = 0.0191). There were no complications as a result of either freehand FNAC or USS-guided core sampling. CONCLUSION: USS-guided cores provided more satisfactory samples for assessment than freehand FNACs. The USS-guided technique is safe despite the use of the larger cuffing needle. The USS-guided core sampling was also a useful tool for repeat thyroid nodule sampling after an unsatisfactory freehand FNAC.

Biopsy, Fine-Needle↗
PubMed2004

Prospective study of routine contrast radiology after total gastrectomy.

BACKGROUND: The practice of routine contrast radiology before recommencing oral nutrition after total gastrectomy is not evidence based. The aim of this prospective study was to evaluate the clinical role and timing of this investigation. METHODS: Seventy-six consecutive patients underwent total gastrectomy with a stapled oesophagojejunal anastomosis. A contrast swallow using non-ionic contrast and barium was performed routinely 5 and 9 days after surgery. The surgeon was blinded to the result of the first of these examinations. Patients with clinical evidence of a leak underwent contrast radiology and upper gastrointestinal videoendoscopy. RESULTS: Eight patients (11 per cent) developed a clinical leak from the oesophagojejunal anastomosis, seven before the first scheduled contrast swallow. Contrast radiology identified a leak in four of six patients. Endoscopy detected a leak in both patients with a false-negative swallow and in two patients who were not fit to undergo contrast radiology. Routine contrast radiology identified a subclinical leak in a further five patients (7 per cent), none of whom developed clinical signs. Four of seven in-hospital deaths were associated with an anastomotic leak. CONCLUSION: There is no role for routine contrast swallow after total gastrectomy with a stapled oesophagojejunal anastomosis, but patients with clinical suspicion of leakage should undergo urgent contrast radiology, plus endoscopy if the contrast examination is normal.

Adult↗
PubMed2001

TIGRFAMs: a protein family resource for the functional identification of proteins.

TIGRFAMs is a collection of protein families featuring curated multiple sequence alignments, hidden Markov models and associated information designed to support the automated functional identification of proteins by sequence homology. We introduce the term 'equivalog' to describe members of a set of homologous proteins that are conserved with respect to function since their last common ancestor. Related proteins are grouped into equivalog families where possible, and otherwise into protein families with other hierarchically defined homology types. TIGRFAMs currently contains over 800 protein families, available for searching or downloading at www.tigr.org/TIGRFAMs. Classification by equivalog family, where achievable, complements classification by orthology, superfamily, domain or motif. It provides the information best suited for automatic assignment of specific functions to proteins from large-scale genome sequencing projects.

Databases, Factual↗
PubMed2001

Diagnosis and management of a mediastinal leak following radical oesophagectomy.

BACKGROUND: The aim of this study was to evaluate the diagnosis, management and outcome of mediastinal leaks following radical oesophagectomy with a stapled intrathoracic anastomosis. METHODS: Some 291 consecutive patients underwent two-phase subtotal oesophagectomy with gastric interposition for malignancy. Patients with clinical suspicion of a leak were investigated with contrast radiology and flexible upper gastrointestinal endoscopy. RESULTS: Nineteen patients (6.5 per cent) developed a proven mediastinal leak at a median of 8 (range 3-30) days following surgery. Contrast radiology and flexible upper gastrointestinal endoscopy identified that 13 patients had an isolated leak from the oesophagogastric anastomosis and two had widespread leakage secondary to gastrotomy-line dehiscence. Endoscopy revealed a further four patients with gastric necrosis in whom contrast radiology was normal. In six patients the diagnosis of leakage followed an apparently normal routine contrast examination on day 5-8. All 13 isolated anastomotic leaks were managed non-operatively with targeted mediastinal drainage, intravenous antibiotics and antifungal therapy, nasogastric decompression and enteral nutrition; the mortality rate was 15 per cent (two of 13). Patients with gastrotomy dehiscence or gastric necrosis had a more severe clinical picture; they were managed with repeat thoracotomy and either revision of the conduit or resection and exclusion. Despite early intervention four of the six patients died. CONCLUSION: Routine postoperative contrast radiology cannot be recommended. On clinical suspicion of a leak patients require both contrast radiology and endoscopic evaluation. Isolated anastomotic leaks can be managed successfully with non-operative treatment, whereas more extensive leaks from the gastric conduit require revisional surgery which carries a high mortality rate.

Aged↗
PubMed1999

Genome sequence of the radioresistant bacterium Deinococcus radiodurans R1.

The complete genome sequence of the radiation-resistant bacterium Deinococcus radiodurans R1 is composed of two chromosomes (2,648,638 and 412,348 base pairs), a megaplasmid (177,466 base pairs), and a small plasmid (45,704 base pairs), yielding a total genome of 3,284, 156 base pairs. Multiple components distributed on the chromosomes and megaplasmid that contribute to the ability of D. radiodurans to survive under conditions of starvation, oxidative stress, and high amounts of DNA damage were identified. Deinococcus radiodurans represents an organism in which all systems for DNA repair, DNA damage export, desiccation and starvation recovery, and genetic redundancy are present in one cell.

Bacterial Proteins↗
PubMed1997

The complete genome sequence of the hyperthermophilic, sulphate-reducing archaeon Archaeoglobus fulgidus.

Archaeoglobus fulgidus is the first sulphur-metabolizing organism to have its genome sequence determined. Its genome of 2,178,400 base pairs contains 2,436 open reading frames (ORFs). The information processing systems and the biosynthetic pathways for essential components (nucleotides, amino acids and cofactors) have extensive correlation with their counterparts in the archaeon Methanococcus jannaschii. The genomes of these two Archaea indicate dramatic differences in the way these organisms sense their environment, perform regulatory and transport functions, and gain energy. In contrast to M. jannaschii, A. fulgidus has fewer restriction-modification systems, and none of its genes appears to contain inteins. A quarter (651 ORFs) of the A. fulgidus genome encodes functionally uncharacterized yet conserved proteins, two-thirds of which are shared with M. jannaschii (428 ORFs). Another quarter of the genome encodes new proteins indicating substantial archaeal gene diversity.

Archaeoglobus fulgidus↗
PubMed1997

Tn916 transposition in Haemophilus influenzae Rd: preferential insertion into noncoding DNA.

The availability of completely sequenced genomes has created an opportunity for high throughput mutational studies. Using the conjugative transposon Tn916, a pilot project was initiated to determine the efficiency of gene disruption in the first completely sequenced bacterium, Haemophilus influenzae Rd strain KW20. DNA was isolated from Tn916-mutagenized cells, and the point of transposon insertion was determined by inverse PCR, DNA sequencing, and mapping to the wild-type genome sequence. Analysis of the insertion sites at the nucleotide level demonstrated a biased pattern of insertion into regions rich in stretches of A's and T's. Although Tn916 integrated at multiple dispersed positions throughout the chromosome, 9 of 10 insertion events occurred in noncoding, intergenic DNA. It was determined that the intergenic DNA was over 5% more A + T-rich than that of protein coding sequences. This suggests that A + T-rich sequences similar to the Tn916 insertion site would be more likely to reside in the intergenic DNA. In an effort to identify other likely sites for transposon integration, a hidden Markov model of the consensus target insertion site was derived from the Tn916-H. influenzae junction fragments and searched against the entire genome. Eighty percent of the 30 highest-scoring predicted Tn916 target sites were from intergenic, nonprotein-coding regions of the genome. These data support the hypothesis that Tn916 has a marked preference for insertion into noncoding DNA for H. influenzae, suggesting that this mobile element has evolved to minimize disruption of host cell function on integration.

Base Sequence↗
PubMed1995

How reliable are ultrasound measurements of renal length in adults?

Ultrasound assessment of patients with renal impairment commonly includes measurement of bipolar renal length. Reduction in length is considered to indicate chronic renal disease and is a factor in deciding whether to proceed to renal biopsy. To date, no published data are available on interobserver and intraobserver variation in sonographic renal length measurement in adults. Bilateral renal lengths were measured in 20 adult subjects, with no history of renal disease, by three experienced operators, on two separate occasions. Limits of agreement for replicate measurements by each ultrasonographer and for replicate measurements by each pair of ultrasonographers were determined. Values of repeatability (a measure of intraobserver variation) and reproducibility (a measure of interobserver variation) were calculated for all renal length measurements, and for right and left renal lengths separately. Results indicate that replicate renal length measurements differ by less than 1.85 cm in 95% of cases, and the magnitude of variations is similar when measurements are made by either single or different ultrasonographers, and are similar for right and left renal length measurements. This suggests that sonographic bipolar renal length measurements in normal adult kidneys are reasonably reliable. In diseased kidneys, however, in which identification of renal poles is difficult, interobserver and intraobserver variation may be much greater.

Adult↗
PubMed1994

Expression of cAMP-dependent protein kinase in prespore cells is sufficient to induce spore cell differentiation in Dictyostelium.

The activity of cAMP-dependent protein kinase (PKA) is required for proper development at several stages during the Dictyostelium life cycle. We present evidence that activation of PKA is rate-limiting for the differentiation of prespore cells to spores and that PKA activation may be the developmental trigger for sporulation. Strains that overexpress the gene encoding the catalytic subunit of PKA (PKAcat) or lack a functional regulatory subunit (rdeC strains) undergo rapid, heterochronic development. We show that overexpression of PKAcat in prespore cell is sufficient to directly induce expression of the spore maturation marker spiA and differentiation to spores, in a cell-autonomous manner. Moreover, overexpression of PKAcat in prespore cells can bypass a mutation that blocks an earlier developmental step to induce spiA expression. Our results suggest that the regulatory pathway in prespore cells between the activation of PKA and spiA induction/spore maturation is quite short and that PKAcat expression in prespore cells may mediate spore differentiation at the level of transcription. This induction of sporulation requires the prior activation of the prespore cell pathway. In addition, we show that beta-galactosidase activity expressed from a PKAcat promoter/lacZ reporter construct is highly enriched in the anterior prestalk A region during the tipped aggregate, slug, and early culminant stages and that this pattern switches abruptly to a prespore pattern at the time of spore maturation, supporting the proposed role of PKA in this process.

Animals↗