Biomedical subjects

C Ray

Publications and source records attributed to C Ray.

At least 55 records · Page 3Linked to original sources

PubMed1989

The myth of the yo-yo: consistent rate of weight loss with successive dieting by VLCD.

Four subjects in a recent trial of eight weeks dieting with the 405 kcal/day, 42 g protein formula (Cambridge diet extra), had participated 18 months previously in an 8-week trial using the 330 kcal/day Cambridge diet formula. This permitted a quantitative comparison of two similar dieting episodes, but following substantial weight loss and variable weight regain after a successful experience with a very low calorie diet. Within the reasonable bounds of comparison between outpatient dieting experiences, there was no suggestion of impairment in ability to lose weight in subsequent dieting after weight loss on a VLCD. The experience of these subjects would not support the contention that lasting metabolic debilitation had occurred that could be attributed to repeated dieting experiences with VLCD.

Diet, Reducing↗

PubMed1988

An automated mechanism for protection of mass spectrometry sampling tubing.

The usefulness of medical mass spectrometers in intensive care units can be limited by too frequent obstruction of the tubing that transports gases from the patients to the analyzing unit. To overcome this problem, we developed an automated system consisting of an infrared light sensor and a three-way valve. One port of the three-way valve connects to 2.4-m disposable tubing that collects gases from the patient's airway. The second port is connected to a mass spectrometer analyzing unit through 30-m permanently installed tubing. The third port is connected to a pressurized oxygen source. An infrared light sensor is placed on the shorter tubing, between the patient and the three-way valve. When increased optical density is detected, due to entrainment of respiratory secretions, the three-way valve is activated. Gas flow is closed between the patient and the mass spectrometer and opened between the pressurized oxygen source and patient tubing to flush its contents. During the six years that the protection system has been in use, the frequency with which the disposable gas collection tubing is changed has been halved. Furthermore, periodic tests of delay and response times, performed at each bedside station, indicate that permanent connection tubing only needed cleaning at 2- to 3-year intervals. The system has decreased the cost of operating our mass spectrometers while also reducing periods of unavailability due to equipment failure.

Anesthesiology↗

PubMed1988

Capnography in mechanically ventilated patients.

Capnography, the science of CO2 waveforms analysis, can play a role in the management of mechanically ventilated patients. Mass spectrometers are the devices most commonly used to collect sequentially and examine CO2 waveforms from multiple patients in the ICU or operating rooms. We present here a review of some clinical and technical problems, which may be resolved efficiently and expeditiously through the use of mass spectrometry and capnography. Mechanical failures, especially those that lead to rebreathing of exhaled gases, can be readily detected. The patient's progress during weaning and the consequences of changes in mechanical assistance can be virtually and noninvasively determined. An expanded role of capnography in mechanically ventilated patients can increase the use of mass spectrometers in the ICU.

Carbon Dioxide↗

PubMed1988

Suppression of ctc promoter mutations in Bacillus subtilis.

Transcription from the Bacillus subtilis ctc promoter is induced as cells enter stationary phase under conditions in which the enzymes of the tricarboxylic acid cycle are repressed. This transcription requires the presence of a secondary form of RNA polymerase, E sigma B, that is found in exponentially growing cells and in early-stationary-phase cells. Starting with a defective ctc promoter that had either a base substitution at position -15 or a base substitution at position -36, we were able to identify four independent second-site mutations within these mutated promoters that suppressed the effect of the original mutations and thereby restored function to the ctc promoter. Three of these mutated promoters had an additional base substitution(s) at positions -5, -9, or both -5 and -9 that enhanced their utilization in vivo by E sigma B, whereas one of the promoters had a single-base-pair deletion in the -15 region that placed it under a completely different form of regulation than that of the wild-type ctc promoter. In addition to mutations in the ctc promoter region, we also isolated three classes of mutants that exhibited increased ctc expression. The effects of the mutations in these strains were not allele specific, since they increased expression from both mutant and wild-type ctc promoters. One class of mutants which affected expression from the ctc promoter carried mutations that blocked the activity of the tricarboxylic acid cycle. A second class of mutations mapped near cysA and was unable to sporulate. Three-factor transformation crosses and complementation analysis indicated that one of these mutations was an allele of spo0H. The third class of mutations is closely linked to dal and may define a regulatory gene for sigB, the sigma B structural gene.

Acetyltransferases↗

PubMed1987

Indirect calorimetry in the mechanically ventilated patient.

We used indirect calorimetry to measure oxygen consumption (VO2) and carbon dioxide production in 29 mechanically ventilated patients. These data were compared to VO2 measured simultaneously by a standard thermodilution technique. A good correlation was demonstrated between the methods, but VO2 measured by indirect calorimetry was 15% higher than VO2 measured by thermodilution.

Adolescent↗

PubMed1987

Genetic analysis of RNA polymerase-promoter interaction during sporulation in bacillus subtilis.

The discovery of secondary sigma factors in Bacillus subtilis that enable RNA polymerase to transcribe cloned sporulation genes in vitro has led to the proposal that the appearance of new sigma factors during sporulation directs RNA polymerase to the different temporal classes of sporulation genes. One sigma factor, which appears 2 h after the initiation of sporulation, is sigma E (formerly sigma 29). Mutations that inactivate the structural gene for sigma E prevent transcription from promoter G4. To determine whether sigma E-RNA polymerase interacts with the G4 promoter in vivo, we examined the effects of six single-base-pair substitutions in the G4 promoter on its utilization in vivo and in vitro by sigma E-RNA polymerase. The mutations in the G4 promoter affected utilization of the promoter in vivo in the same way that they affected its utilization in vitro by purified sigma E-RNA polymerase; therefore, we conclude that this polymerase interacts directly with the G4 promoter in vivo. The effects of these mutations also support the model in which sigma E-RNA polymerase utilizes promoters by interacting with two distinct sets of nucleotides located 10 and 35 base pairs upstream from the start point of transcription.

Bacillus subtilis↗

PubMed1987

Genetic studies of a secondary RNA polymerase sigma factor in Bacillus subtilis.

sigma B (sigma 37) is a secondary species of RNA polymerase sigma factor found in the gram-positive bacterium Bacillus subtilis. To study the function of sigma B genetically, we sought mutations that block the expression of a gene (ctc) known to be transcribed by sigma B-containing RNA polymerase in vitro. One such mutation, called crl, was found to map in or near the structural gene (sigB) for sigma B. To determine directly whether mutations in sigB would prevent transcription of ctc, we replaced sigB in the B. subtilis chromosome with insertion and deletion mutations that disrupted the sigma B coding sequence. Like crl, these in vitro-constructed mutations blocked expression of ctc, but had little or no effect on viability, sporulation, expression of the sporulation gene spoVG, or production of sporulation-associated alkaline protease. Using fusions of ctc to the reporter genes xylE and lacZ, we also identified mutations that enhanced ctc expression. One such mutation, called socB, was found to be located in an open reading frame immediately downstream of sigB.

Bacillus subtilis↗

PubMed1986

Dental and social effects of malocclusion and effectiveness of orthodontic treatment: a strategy for investigation.

Study of the effectiveness of orthodontic treatment is complicated by a variety of factors, including the need for longitudinal, multidisciplinary appraisal and difficulties of randomisation, control and sample composition. This report outlines a recent initiative adopting a longitudinal, observational approach with a cohort of approximately 1000 12-yr-olds, selected by disproportionate stratified sampling in order that occlusal features of low prevalence, but high orthodontic interest, would be well represented. In the event, 4810 subjects were listed and after certain exclusions, 3420 children were screened. Using preselected screening criteria, 663 with specific occlusal features were selected and an additional 355 children with nonspecific features were randomly allocated on a pro-rata basis. This gave a final study population of 1018. Baseline dental data included the recording of caries, periodontal status and mandibular function. Study models were obtained and analysed using a new standardised technique for recording the alignment of individual teeth. Photographs of the face and dentition were collected and a rating system developed to score dental and facial attractiveness. Social-psychological data were recorded via self-rating questionnaires, interviews, parental questionnaires, teacher questionnaires and peer ratings.

Child↗

PubMed1986

Regional isolated limb perfusion of melanoma intransit metastases using mechlorethamine (nitrogen mustard).

Forty-two patients with intransit metastases of melanoma in a limb were treated by isolated regional perfusion chemotherapy using mechlorethamine (nitrogen mustard). Group 1 (n = 12) underwent treatment at low dose, less than 0.35 mg/kg, or low temperature, less than 38 degrees C. Group 2 (n = 30) received higher doses, 0.35 to 0.6 mg/kg, plus heat at 38 degrees C to 41 degrees C. No patient had evidence of disease outside the limb at the time of perfusion. The median follow-up time was 48 months (range, 1 to 9 years). Of the 42 patients, 29 had measurable lesions that responded as follows: group 1, complete response (CR) in two of ten and partial response (PR) in none; group 2, CR in six of 19 and PR in six of 19. The combined CR and PR rate of 12 of 19 in group 2 was significantly higher than that of group 1 (P less than .05). CR lasted only 2 months in the two patients of group 1, but persisted in the six patients of Group 2, four of whom are still alive free of disease at 16, 21, 33, and 40 months. Relapse-free control of disease in the limb was achieved in 36% of the patients in group 2 at 24 months, compared with 0% in group 1 (P less than .05). An overall survival of 74% at 48 months was observed in group 2, significantly higher than that of 64% for group 1 (P less than .05). The status of the regional lymph nodes (RLN) and the number of metastases did not affect tumor response. However, 77% of RLN-negative patients survived 48 months, in contrast to only 38% of RLN-positive patients (P less than .05). One patient died postoperatively of myocardial infarction. No serious systemic toxicity developed. Two patients who underwent repeat salvage perfusions developed a reversible peripheral neuropathy in the limb. Limb function was good after treatment, and dramatically improved in patients who had advanced satellitosis that responded to treatment. These results suggest that heated limb perfusion using mechlorethamine at an adequate dose can offer long-term control of intransit metastases in approximately one third of these patients, with preservation of good limb function and possible prolongation of survival.

Adult↗

PubMed1985

Effect of indomethacin on urine concentration and dilution in the rat.

The precise role of prostaglandins in modulating urine concentration and dilution is unclear. Evidence in vitro has recently cast doubt on the accepted theory that renal prostaglandins inhibit the hydro-osmotic effect of vasopressin. Urine clearance studies were performed on indomethacin treated (prostaglandin deficient) and control anaesthetized water diuretic rats both before and during the addition of vasopressin in maximal (10 m-units) and supramaximal (100 m-units) concentrations. Before the addition of vasopressin, indomethacin treatment inhibited the excretion of a water load by 48.7%. The mean papillary sodium concentration was also greater in this group of rats. Vasopressin (10 m-units) increased the urine osmolality in control and indomethacin treated rats; however, the mean urine osmolality was greater in the indomethacin group (1521 +/- 103 compared with 1120 +/- 98 mosmol/kg; P less than 0.01), as was the papillary sodium concentration. A ten-fold increase in vasopressin depressed the papillary sodium concentration to a level similar to that in the control group and produced a marked natriuresis. Consequently, the mean urine osmolalities and urine flows were similar in control and indomethacin treated rats. These experiments suggest that a major function of renal prostaglandins is to increase the ability of the kidney to excrete a water load. Renal prostaglandins do not interfere with the vasopressin induced increase in distal nephron water permeability.

Animals↗

PubMed1985

Mutations that affect utilization of a promoter in stationary-phase Bacillus subtilis.

Transcription of the ctc gene in Bacillus subtilis is activated only after exponentially growing cells enter stationary phase. The promoter of the ctc gene is utilized in vitro by two minor forms of RNA polymerase, E sigma 37 and E sigma 32, but not by the most abundant form of RNA polymerase, E sigma 55. We have used the ctc promoter to direct transcription of the xylE gene on plasmid pLC4 and observed that xylE was expressed only in stationary-phase B. subtilis. We also have constructed a series of homologous plasmids that differ only by specific base substitutions in the ctc promoter. We observed that the base substitutions that affected utilization of the ctc promoter in vivo (xylE expression) were the same as those that we had previously shown to affect utilization of the promoter in vitro by E sigma 37 and E sigma 32. We conclude that it is likely that the ctc promoter is utilized in vivo by E sigma 37 or E sigma 32.

Acetyltransferases↗

PubMed1984

Nurses' perceptions of early breast cancer and mastectomy, and their psychological implications, and of the role of health professionals in providing support.

The literature on the psychological precursors and outcomes of cancer and the role of the surgeon and nurse in the psychological management of early breast cancer, is briefly reviewed. A questionnaire study tapped nurses' perceptions of the disease and its treatment, patients' problems and the provision of psychological support. Their responses indicated mixed attitudes toward treatment outcomes, but a general enthusiasm for health education. Mastectomy itself was seen as posing serious social problems by half the sample, and serious sexual problems by more than three-quarters, and many felt that the support currently provided for patients is inadequate. While nurses saw themselves as having a key role in giving comfort, they were less likely to see themselves in the role of counsellor. Many of the sample felt that they had not been trained to provide psychological care at this level. Here, the skills of a specialist nurse were looked for, in the case of counselling the patient herself, or the authority of the doctor, when counselling husbands.

Breast Neoplasms↗

PubMed1984

Social, sexual and personal implications of paraplegia.

Paraplegia can lead to social stigmatisation, sexual difficulties, and emotional maladjustment. The specific nature of problems experienced in these areas were investigated in an interview study of 22 male and female paraplegics. These interviews were followed up by a postal questionnaire and both qualitative and quantitative data are presented in this report. Effective counselling can only be offered on the basis of an understanding of problems as they are subjectively experienced, and with an acknowledgement of the wide differences that exist between individuals in the way that they view and react to their situation.

Adaptation, Psychological↗

PubMed1984

II. Coping with spinal cord injury.

Paraplegia creates social, sexual and emotional problems, and the impact of these was investigated in an interview study of 22 male and female paraplegics. Of particular concern was the way in which individuals were coping with the difficulties confronting them. People used a number of strategies for dealing with other people and their attitudes, and for readjusting sexually. In dealing with their own personal feelings about their disability, ways of coping were varied and included suppression, denial and repression, resignation and acceptance, positive thinking and independence and assertiveness. No specific recommendations can be made about ways of coping that will be most adaptive, since these will depend upon the individual and his or her circumstances. What is important for counselling, however, is to recognise the range of coping strategies that are available, and to be able to guide the individual toward those which effect the best match between their needs and the demands of the situation.

Adaptation, Psychological↗

PubMed1984

Pneumatic-to-electrical analog for high-frequency jet ventilation of disrupted airways.

A pneumatic-to-electrical circuit analog is used to describe 2 separate mechanisms by which high-frequency jet ventilators sustain ventilation and oxygenation in the presence of large airway disruptions. The frequency-dependent mechanism is based on variations in the pneumatic equivalent to capacitive reactance. The pressure-dependent mechanism models lung defects on a voltage-controlled resistor. The electrical circuit model is also used to explain the factors leading to gas trapping and inadvertent positive end-expiratory pressure during high-frequency jet ventilation.

Airway Resistance↗

PubMed1984

High-frequency jet ventilation: technical implications.

A variety of technical decisions are required for the proper selection and safe and efficacious application of high-frequency jet ventilation (HFJV). Criteria for analyzing the performance of an HFJV system are presented, along with discussions of some of the more common respiratory measurements and their applicability to HFJV.

Equipment Safety↗

PubMed1984

Experimental evaluation of high-frequency jet ventilation.

The consensus of available studies indicates that high-frequency jet ventilation (HFJV) can adequately ventilate animals in respiratory failure, although a clear superiority to volume-cycled ventilation (VCV) cannot be established. HFJV is probably useful in the presence of airway disruption and in tracheal or pulmonary surgery. Clinical trials and additional bench and animal studies must be performed, to reach a full understanding of the potential benefits of this technique.

Animals↗

PubMed1984

Early prediction of outcome of respiratory failure. Comparison of high-frequency jet ventilation and volume-cycled ventilation.

Data from a prospective randomized investigation comparing volume-cycled ventilation and high-frequency jet ventilation were reexamined to determine whether improvement of respiratory and hemodynamic function, as well as ultimate outcome (death or survival), could be predicted early in the course of the disease. End points were selected for the ratio of the arterial oxygen pressure over the fractional concentration of oxygen in the inspired gas (PaO2/FIO2), the arterial oxygen saturation (SaO2), the arterial carbon dioxide tension (PaCO2), and the cardiac index. Patients were assigned to "success" or "failure" groups, according to the values recorded for those end points 24 hours after institution of mechanical ventilation. Values obtained from initiation of mechanical ventilation to 16 hours later were divided into four time groups. Differences between patients who "succeeded" and "failed" were compared at each time interval. Ultimate outcome was also compared. The PaCO2 and cardiac index were poor predictors of survival. Early values did not foretell the progression of these variables. The PaO2/FIO2 and SaO2 effectively discriminated, at all time intervals, between patients who succeeded and failed on volume-cycled ventilation. On high-frequency jet ventilation, significant differences were evident only after eight hours of support. With both types of ventilator, patients who reached the end point of oxygenation at 24 hours survived in far greater numbers than those who did not. On the basis of this investigation, it appears justified to attempt high-frequency jet ventilation in patients who do not rapidly improve on volume-cycled ventilation. Institution of high-frequency jet ventilation as the initial support method may not be advisable, since failure does not become apparent for many hours.

Cardiac Output↗