Search PubMed⌕ Search

Biomedical subjects

C Vaughan

Publications and source records attributed to C Vaughan.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1987

Troop movement and food habits of white-faced monkeys in a tropical-dry forest.

Home-range, movement and activity patterns and diet of a group of 16 white-faced monkeys (Cebus capucinus) were studied in a Costa Rican tropical dry forest at the end of the dry season (March and April) of 1982. The troop used an area of .67 km2 and moved an average of 4.5 km +/- 0.6 daily. Three basic daily activities were identified: resting, moving and feeding. Resting was greatest between 1000-1500 hours. Movement, which was strongly correlated with feeding, occurred most between 0500-0900 hrs and 1300-1800 hrs. The primates were omnivores, feeding on parts of 27 species of plants, four species of insects and an Anolis lizard.

Animals↗
PubMed1986

13-cis-retinoic acid in the treatment of oral leukoplakia.

13-cis-Retinoic acid has been reported to be effective in treating oral leukoplakia. We randomly assigned 44 patients with this disease to receive 13-cis-retinoic acid (24 patients) or placebo (20), 1 to 2 mg per kilogram of body weight per day for three months, and followed them for six months. There were major decreases in the size of the lesions in 67 percent (16 patients) of those given the drug and in 10 percent (2 patients) of those given placebo (P = 0.0002); dysplasia was reversed in 54 percent (13 patients) of the drug group and in 10 percent (2 patients) of the placebo group (P = 0.01). The clinical response to the drug correlated with the histologic response in 56 percent (9 of 16) of the patients evaluated. Relapse occurred in 9 of 16 patients two to three months after treatment ended. The toxic effects of the drug were acceptable in all but two patients. Cheilitis, facial erythema, and dryness and peeling of the skin were common; conjunctivitis and hypertriglyceridemia also occurred. All adverse reactions could be reversed by reducing the dose or temporarily discontinuing the drug. We conclude that 13-cis-retinoic acid, even in short-term use, appears to be an effective treatment for oral leukoplakia and has an acceptable level of toxicity.

Aged↗
PubMed1985

Patterns of relapse in locally advanced head and neck cancer patients who achieved complete remission after combined modality therapy.

Relapse patterns in patients with locally advanced head and neck cancer who achieved complete remission were evaluated. After combined modality therapy with induction chemotherapy followed by surgery and/or radiotherapy, 71 of 103 patients were clinically free of disease. The 5-year recurrence rate was estimated at 51%, with a 39% local and 26% distant failure rate by 5 years. The factors significantly affecting the relapse patterns were: the site of the primary tumor (those with oral cavity lesions were more likely to fail locally, whereas hypopharynx patients had a higher risk of distant metastases); the type of definitive local treatment (those patients who received surgery and radiotherapy were at lower risk of pure local failure); TN Stage (patients with T4N3 or T3N3 tumor were at higher risk of both local and distant failure); and time to response and presence of oropharyngeal lesions (patients who had a longer period from diagnosis to final complete response [CR] and patients with oropharyngeal primaries were at higher risk for simultaneous local and distant failure). Type of chemotherapy, patient age, tumor differentiation, and response to induction chemotherapy did not significantly influence the patterns of relapse. A combined modality approach with induction chemotherapy, surgery, and/or radiotherapy does not seem to reduce the incidence of distant metastases significantly.

Adult↗
PubMed1985

Aerodynamic assessment of the Henley-Cohn tracheoesophageal prosthesis.

In vitro airway resistance measurements were performed for eight Henley-Cohn voice prostheses. The results of these measures demonstrated that the Henley-Cohn device offers substantially less resistance to the flow of air than either the Blom-Singer or Panje devices. The lower overall resistance of the Henley-Cohn device was shown to be due to both its larger inner cross sectional area and to an improved valve tip design. The lower airway resistance of the Henley-Cohn prosthesis should theoretically result in more "efficient" production of esophageal voice than would be the case when using the Blom-Singer or Panje devices. However, the results of this investigation also point to the need for the development of methods which will enable investigators to evaluate the in vivo performance of tracheoesophageal prostheses.

Airway Resistance↗
PubMed1984

Complications of CO2 laser surgery of the aerodigestive tract: experience of 4416 cases.

The CO2 laser was first introduced for surgery of the aerodigestive tract in 1971. Since that time, great advances in application have been made in both the adult and pediatric population. Recent reports of isolated complications have appeared in the literature. However, a realistic complication rate in a large series of patients has yet to be reported. This report relates the combined experience of the authors in a total of 4416 cases during the 11-year period from 1971 to 1982. There were nine instances of complications, representing a complication rate of 0.2%. These complications provided a unique learning experience for the authors, and led to the establishment of certain basic principles that should be followed in all laser operations. This survey indicates that the CO2 laser is a safe, extremely useful surgical modality in the aerodigestive tract.

Adolescent↗
PubMed1984

Evaluation of Blom-Singer voice prosthesis.

Tracheoesophageal puncture and use of a silicone prosthesis is becoming a common and highly effective procedure for voice rehabilitation in the alaryngeal patient. Radiologic evaluations were reviewed of 31 patients scheduled for tracheoesophageal puncture at this institution over the past 3 years. Barium swallow examinations were performed preoperatively to assess anatomy and muscular activity of the pharyngoesophagus. Examinations were performed postoperatively when complications were suspected, phonation was unsatisfactory, or as routine oncologic follow-up. Postoperative complications included neck abscess, cervical osteomyelitis, and feeding tube dissection into the anterior wall of the thoracic esophagus. This method of pre- and postoperative radiologic evaluation of these patients is presented, along with the radiologic manifestations of the complications.

Aged↗
PubMed1983

A prospective randomized trial of methotrexate versus cisplatin in the treatment of recurrent squamous cell carcinoma of the head and neck.

A prospective randomized study was conducted to determine the relative effectiveness, toxicity and tolerance of methotrexate (MTX) versus cisplatin (DDP) in patients with recurrent head and neck squamous cell carcinoma. Forty-four patients were randomized to receive either MTX, 40 mg escalated to 60 mg/m2 IV push weekly, or DDP, 50 mg/m2 6 hour infusion days 1 and 8 every 4 weeks. All patients had objectively measurable disease and a performance status greater than 60% (Karnofsky scale). All had been treated with surgery and/or radiotherapy. No patients had prior chemotherapy. Prior treatment, performance status, and site of primary disease were comparable in both groups. Complete and partial objective responses were achieved in 23.5% of the MTX group and 28.6% of the DDP group (P = 0.51). Median duration of response was 84 days in the MTX group and 92 days in the DDP group. Median survival of patients was 6.1 months with MTX and 6.3 months with DDP. Mucositis was noted in 38% of patients in the MTX group (P = 0.001) compared to none in the DDP group. Vomiting occurred in 87% of patients in the DDP group (P less than .0001) compared to 10% of patients in the MTX group. This study demonstrates that in the treatment of recurrent head and neck squamous cell carcinoma, MTX and DDP are equally effective, although MTX appears to be better tolerated.

Carcinoma, Squamous Cell↗
PubMed1983

Applications of carbon dioxide laser surgery and radiation. A preliminary report.

Ten patients with advanced or recurrent squamous cell carcinomas of the upper airway were treated with a combination of carbon dioxide laser surgery and radiation therapy to evaluate the tolerance to rapid sequencing of both modalities in a variety of clinical situations. Other considerations were to accurately stage infiltrating tumors, to provide cytoreduction for T3 and T4 tumors, and to facilitate the optimal placement of intracavitary radium applicators. Because of minimal postoperative pain or dysfunction associated with the laser, patients were able to receive irradiation considerably sooner than with conventional surgery. Local tolerance was good to excellent in seven of the ten patients treated and, based on preliminary results, the combination would appear to offer advantages in curative approaches to advanced head and neck tumors.

Adult↗