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Biomedical subjects

C Vaughan

Publications and source records attributed to C Vaughan.

At least 19 recordsLinked to original sources
PubMed1996

Training for excellence in the inner city: an interview with Richard Savage and Clare Vaughan. Interview by Douglas Carnall.

Recruitment to general practice is at its lowest level for 30 years, and many vocational training schemes report difficulty in attracting new trainees. Spurred on by the aging population of south London, and with the advantage of pounds 1.3m of development money resulting from the Tomlinson report, the south London organisation of vocational training schemes (SLOVTS) has perhaps been able to cope better than most. Its chair, Richard Savage, a general practitioner and course organiser, and Clare Vaughan, an assistant adviser, have devised and implemented many innovative training posts for general practice over the past two years, and their approach seems to be bearing fruit: most of the doctors who have finished the training scheme are now entering practice in south London. They talked to Douglas Carnall about the causes of the crisis and the measures they have implemented to counter it. Clare Vaughan died in the week following the interview (see obituary, p 555).

Education, Medical, Continuing↗
PubMed1996

The role of DDAVP (desmopressin) in orthognathic surgery.

Desmopressin (1-deamino-8-D-argininevasopressin, DDAVP) is a synthetic analog of the antidiuretic hormone L-argininevasopressin. DDAVP has been shown to increase the plasma concentration of endothelial factor VIII, thus increasing coagulant activity. There is evidence from controlled clinical trials indicating that DDAVP can reduce blood loss and transfusion requirements for individuals with normal coagulation profiles undergoing various surgical procedures. This study was conducted to evaluate the efficacy of the DDAVP in reduction of blood loss during orthognathic surgery. Twenty patients, 15 females and 5 males, undergoing bimaxillary osteotomy were randomized into two groups of ten. Perioperatively, group 1 patients received 20 micrograms of DDAVP infused over one-half hour. Group II patients did not receive DDAVP. Hypotensive anesthesia (mean arterial pressure < 60 mm Hg) was routinely employed for both groups. On average, the blood loss in group I patients was 144 ml less per patient than group II patients (p < 0.50). Only 2 of 10 patients in group I lost in excess of 750 ml, while 6 to 10 group II patients experienced blood loss greater than 750 ml (p < 0.20). The average postoperative hematocrit for patients in group I dropped by 6.17 of the preoperative mean hematocrit (p < 0.001). The average drop in hematocrits among the group II patients was 11.61 (p < 0.001). When collated, this hematocrit drop of 11.61 for group II and 6.17 for group I (recipients of DDAVP) proved to be significantly different (p < 0.01). It is concluded from this study that patients receiving a standard dose of DDAVP prior to bimaxillary osteotomy would experience reduced intraoperative blood loss, providing that blood pressure is well controlled and fluid replacement is carefully managed. No significant adverse side effects of desmopressin acetate were observed.

Blood Loss, Surgical↗
PubMed1996

Comparison of polydioxanone and polyglactin 910 in intradermal repair.

A prospective clinical study was undertaken to compare the results of intradermal layer closure using two popular absorbable suture materials, polydioxanone and polyglactin 910. On an alternating basis, 6-0 polydioxanone and 6-0 polyglactin 910 were used to repair 80 surgical sites of the temple and occipital regions in 20 patients undergoing facial rhytidectomy. In all instances, the superficial skin layer was repaired with 6-0 plain catgut. These sites were evaluated by a double-blind method for erythema, induration, infection, scar spread, and hypertrophic scarring at approximately 5 months and at least 1 year postoperatively. Scar spread was indicated at widths greater than 1 mm. Any raised scar was labeled hypertrophic. Scar spread, as defined above, was observed in 6 of 38 incisions repaired with polyglactin 910, and 3 sites developed scar hypertrophy. Conversely, 3 of 38 incisions closed with polydioxanone revealed scar spread (p < 0.25), and 3 were hypertrophic (p < 0.35). Sixty-one sites healed with undiscernible scars. This study does not disclose any statistically significant difference in the quality of the scars when polyglactin 910 is used compared with polydioxanone.

Cicatrix↗
PubMed1996

Expression of the subtype 1A dopamine receptor in the rat heart.

The subtype 1A dopamine receptor (D1A) has recently been detected in the rat kidney. In the present study using light microscopic immunohistochemistry, electron microscopic immunocytochemistry, and in situ amplification of mRNA, we demonstrate the D1A receptor in Sprague-Dawley and Wistar Kyoto rat hearts. For immunohistochemistry and immunocytochemistry, anti-peptide polyclonal antibodies were directed toward amino acid sequences of the third extracellular and intracellular domains of the native receptor. Selectivity was validated by recognition of the D1A receptor expressed in stably transfected LTK- cells. D1A receptor mRNA was detected with a novel transcription-based isothermal in situ amplification system as well as with reverse transcription-polymerase chain reaction. D1A receptor protein was distributed throughout the atrium and ventricular myocardium. Preimmune and preabsorption controls were negative. Electron microscopic immunocytochemistry using the protein A gold method demonstrated the D1A receptor along the cellular membranes of coronary smooth muscle cells and ventricular myocytes and in the myosin thick filaments and M-lines. D1A receptor mRNA was present in coronary vessels and myocardium in amplified but not in unamplified sections. Western blot analysis showed specific D1A bands in transfected LTK- cells and the atrium but not in nontransfected LTK- cells and the ventricle. The selective D1-like receptor agonist SKF38393 stimulated adenylyl cyclase in ventricular myocardial plasma membranes in a dose-related fashion, and the response was abolished by the selective D1-like receptor antagonist SCH23390. These results demonstrate that the D1A receptor gene and protein are expressed in normal rat heart. The physiological and pathophysiological roles and predominant cell signaling mechanism or mechanisms of this receptor remain to be determined.

Animals↗
PubMed1995

Medical-grade tattooing to camouflage depigmented scars.

Scars are apparent, in part, as a result of the loss of cutaneous pigments. This disfigurement can be concealed successfully with medical-grade tattooing. This treatment was evaluated on 39 scars in 18 patients. The procedure was performed under local anesthesia on an outpatient basis, unless carried out in conjunction with other procedures. The medical-grade tattooing dye was selected during the initial consultation to match the skin color in a natural light ambiance. An electric tattooing machine was used to implant the medical-grade dye in the dermis. Successful concealment of the depigmented scars was achieved subsequent to the first procedure in all but 4 patients. Two of the 4 patients exhibited inadequate camouflage of scars, and 2 were judged to have excess pigmentation following treatment. Both these conditions required revision.

Adolescent↗
PubMed1994

Bladder wall tension and mechanoreceptor discharge.

Bladder wall mechanoreceptors are essential elements in micturition and continence reflexes. While they have been described as tension receptors, their response to bladder wall deformation has always been characterised in terms of pressure. The firing patterns of 10 bladder wall mechanoreceptors were determined during bladder distensions at a natural and a much faster rate. In all units firing rate was higher at any given pressure at the slower bladder distension rate. This inverse rate dependence was reduced when firing rate was related to a derived measure of bladder wall tension and abolished when multi-fibre recordings were used. We conclude that it is important to incorporate volume effects in studies of continence control systems.

Animals↗
PubMed1994

The Jarisch-Herxheimer reaction in leptospirosis.

Three patients with leptospirosis whose condition worsened after initiation of antibiotic therapy are reported. Their clinical deterioration appeared to be due to the development of the Jarisch-Herxheimer reaction rather than to progression of their underlying infection. Relevant aspects of the management of patients with leptospirosis are discussed.

Adolescent↗
PubMed1993

Prodromal contractions and contractility in the feline bladder.

In the cat there are at least two distinct contractile states of the bladder during urine storage, one when prodromal contractions are present and one when non-micturating contractions are present. It is proposed that prodromal contractions are myogenic. This proposition was examined by comparing prodromal contractions before and after hypogastric nerve section as well as comparing prodromal contractions with the contractions that remain after sectioning of the hypogastric nerves. Key contraction characteristics, such as amplitude, maximum gradient and the variance of the intercontraction interval were not significantly changed by hypogastric nerve section, providing volume effects were corrected for, which suggested that prodromal contractions have a myogenic origin.

Animals↗
PubMed1992

A comparison of absorbable and nonabsorbable suture materials for skin repair.

This prospective clinical study was conducted to compare the outcome of elective surgical wound repair in the occipital region during rhytidectomy using absorbable and nonabsorbable suture materials. On an alternative basis, 6-0 polypropylene and 6-0 plain catgut were used to repair the incisions on the upper and lower half of the surgical wounds in 80 sites. These sites were then compared for stitch marks, erythema, hypertrophic scars, infection, and wound necrosis. This study revealed slightly visible stitch marks in 4 of 40 (10 percent) sites repaired with catgut and in 10 of 40 (25 percent) sites repaired with polypropylene material (p less than 0.10); however, this was not statistically significant. There were five incidences of suture-site erythema (12.5 percent) noted in the group of catgut repairs in comparison with three incidences (7.5 percent) in the group repaired using polypropylene. Furthermore, there was no statistically significant difference in hypertrophic scarring or infection rate between these groups. The incidence of erythema following repair with catgut was higher, but this was also not statistically significant. Considering these findings, coupled with the avoidance of patient discomfort, suture removal, and time spared for the surgeon and staff when absorbable suture material is used, the superiority of plain catgut over nonabsorbable material becomes evident.

Catgut↗
PubMed1991

Rate of bladder distension and hypogastric nerve activity in the cat.

The effect of two rates of bladder filling on hypogastric efferent nerve activity was examined in cats anaesthetised with a continuous pentobarbitone infusion. At each level of bladder pressure the amount of hypogastric efferent nerve activity was less at the higher filling rate. This result may reflect a volume effect absent in pressure-nerve activity relationships. When volume effects were allowed for, variation in filling rate appeared to have little influence on hypogastric nerve activity.

Action Potentials↗
PubMed1991

The membranous portion of the interventricular septum and its relationship with the aortic valve in humans.

Investigation of the membranous portion of the interventricular septum (MPIS) and its relationship with the aortic valve was performed in 32 human hearts of adult individuals (19 Caucasians and 11 non-Caucasians). With transillumination of the MPIS the specimens were photographed and 35 mm slices obtained. These were digitized into Apple Macintosh II using a Dage Model 68 video camera and a Data Translations DT 2255 frame grabber. The areas and the distances were traced manually, using the NIH Image program (Wayne Rasband, NIH, Research Services Branch, NIHM). The following forms of MPIS were found: oval (31.3%), triangular (28.1%), quadrangular (18.8%), circular (15.6%) and semilunar (6.2%); its surface area varied from 5.65 mm2 to 142.63 mm2 (mean 48.82 +/- 29.17 mm2). The superior border of the MPIS was in close relationship with the aortic valve, and its upper part was usually (41%) in direct continuity with the attachments of both right (RAC) and posterior (PAC) aortic cusps, or with PAC (34%) or RAC (6%) only. Rarely (19%) the MPIS lay below the attachments of both cusps. The distance between the MPIS superior border and the attachment of the RAC was not greater than 5.89 mm (mean 1.69 mm +/- 1.9 mm). The distance between the superior border of the MPIS and the attachment of the PAC was not greater than 5.63 mm (mean 0.77 +/- 1.49 mm). Differences between sex, race and age groups were not statistically significant.

Aortic Valve↗
PubMed1990

Esophagography and esophagoscopy. Comparison in the examination of patients with head and neck carcinoma.

We carried out a prospective, double-blind study at three institutions, comparing esophagography with esophagoscopy for the detection of simultaneous cancer of the esophagus in patients with other squamous cell cancers of the head and neck. The goal was to determine whether esophagography and esophagoscopy are necessary for the examination of patients before treatment. One hundred eighty-two patients were studied; both examinations were done in 148 patients. Twenty-one patients could not undergo esophagoscopy; esophagography was inadequate in 9 patients; 4 patients could have neither examination. Concordance was noted between the two procedures in 86.5% of patients. Sixty-five percent were normal, and 21.5% were abnormal. One esophageal cancer was found in this series that was diagnosed by both methods. Our data suggest that esophagoscopy and esophagography may be complementary in evaluating squamous cell carcinoma of the head and neck in patients before treatment. Esophagography alone was useful in patients in whom esophagoscopy could not be performed.

Adult↗
PubMed1989

Objective assessment of vocal hyperfunction: an experimental framework and initial results.

This report describes the experimental design and initial results of an ongoing clinical investigation of voice disorders. Its major focus is the development and use of quantitative measures to provide objective descriptions of conditions referred to as "vocal hyperfunction." The experimental design for this project is based on a descriptive theoretical framework, which holds that there are different types and stages of hyperfunctionally related voice disorders. Data consist of indirect measures derived from noninvasive aerodynamic and acoustic recordings including (a) parameters derived from inverse filtered approximations of the glottal air flow waveform; (b) estimates of transglottal pressure, average glottal air flow, glottal resistance and vocal efficiency; and (c) measures of vocal intensity and fundamental frequency. Initial results (based on comparisons among 15 voice patients and 45 normal speakers) support major assumptions that underlie the theoretical framework, and indicate that the measurement approach being utilized is capable of differentiating hyperfunctional from normal voices and hyperfunctional conditions from one another. Organic manifestations of vocal hyperfunction (nodules, polyps, contact ulcers) are accompanied by abnormally high values for the glottal waveform parameters of AC flow and maximum flow declination rate, suggesting increased potential for vocal fold trauma due to high vocal fold closure velocities and collision forces. In contrast, nonorganic manifestations of hyperfunction (functional disorders) tend to be associated with abnormally high levels of unmodulated DC flow, without high values for AC flow and maximum flow declination rate, suggesting reduced potential for vocal fold trauma. Measures also suggest different underlying mechanisms for nodules and polyps as compared to contact ulcers. Results are discussed relative to predictions based on the theoretical framework for vocal hyperfunction.

Adult↗
PubMed1989

Efferent pelvic nerve activity, ganglionic filtering, and the feline bladder.

Ganglionic "filtering" may be responsible for muting the parasympathetic drive to the bladder during urine storage. For this process to be significant, there must be activity in preganglionic parasympathetic nerve fibers during continence. In cats, anesthetized with pentobarbital sodium, pelvic efferent nerve activity was recorded while the bladder was filled at a physiological rate. In one-half of the animals, there was no nerve activity during continence. Pelvic efferent nerve activity was observed in some animals, particularly in those with larger nonmicturating contractions. In these animals, multiple recordings from different sites in the pelvic plexus failed to provide evidence of ganglionic filtering. Ganglionic modulation of the excitatory motor drive to the bladder could not be observed during the continence process.

Animals↗
PubMed1988

Hypogastric nerve activity to the feline bladder during slow filling.

Hypogastric efferent nerve activity was measured in cats anaesthetised with a continuous pentobarbitone infusion while the bladder was filled at a physiological rate. Pelvic efferent nerve recording was used to determine the end of the continence process. The point in the continence process at which non-micturating contractions commenced was usually the point at which sympathetic nerve activity began to increase. By the time the continence process was half over, sympathetic nerve activity had increased from the resting level by 21%. There is disagreement about the role of the sympathetic innervation in the process of urine storage. In the present study, there appears to be significant sympathetic drive to the bladder for much of the continence process.

Action Potentials↗
PubMed1988

Effect of dietary manipulations (fasting, hypocaloric feeding, and subsequent refeeding) on rat muscle energetics as assessed by nuclear magnetic resonance spectroscopy.

31P nuclear magnetic resonance (NMR) spectroscopy in vivo and fluorometry were used to measure muscle ATP, total creatine, pH, and Mg2+ in vivo; and to calculate creatine phosphate (CrP), the ratios of CrP/inorganic phosphate (Pi), CrP/ATP, free ADP levels, and the free-energy change in ATP hydrolysis so nutritional effects could be ascertained. These parameters were determined in vivo in resting control, 2-d-fasted, and hypocalorically fed rats and in animals similarly hypocalorically fed and then refed. The ATP, Pi, and intracellular Mg2+ levels were comparable in the four groups. When the fasted and underfed animals were compared with the control and refed animals, there were falls in the ratios of CrP/Pi and CrP/ATP, in the calculated CrP, and the free-energy change of ATP hydrolysis, but a rise in the calculated free ADP. In the hypocaloric group, intracellular pH fell significantly and a large peak was noted in the phosphodiester region. The data are consistent with the hypothesis that ATP levels are maintained at the cost of CrP, suggesting that ATP production is disturbed by aerobic and anaerobic mechanisms.

Adenosine Diphosphate↗