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Biomedical subjects

R Shepherd

Publications and source records attributed to R Shepherd.

At least 37 records · Page 2Linked to original sources
PubMed1997

Chitosan functional properties.

Chitosan is a partially deacetylated polymer of N-acetyl glucosamine. It is essentially a natural, water-soluble, derivative of cellulose with unique properties. Chitosan is usually prepared from chitin (2 acetamido-2-deoxy beta-1,4-D-glucan) and chitin has been found in a wide range of natural sources (crustaceans, fungi, insects, annelids, molluscs, coelenterata etc.) However chitosan is only manufactured from crustaceans (crab and crayfish) primarily because a large amount of the crustacean exoskeleton is available as a by product of food processing. Squid pens (a waste byproduct of New Zealand squid processing) are a novel, renewable source of chitin and chitosan. Squid pens are currently regarded as waste and so the raw material is relatively cheap. This study was intended to assess the functional properties of squid pen chitosan. Chitosan was extracted from squid pens and assessed for composition, rheology, flocculation, film formation and antimicrobial properties. Crustacean chitosans were also assessed for comparison. Squid chitosan was colourless, had a low ash content and had significantly improved thickening and suspending properties. The flocculation capacity of squid chitosan was low in comparison with the crustacean sourced chitosans. However it should be possible to increase the flocculation capacity of squid pen chitosan by decreasing the degree of acetylation. Films made with squid chitosan were more elastic than crustacean chitosan with improved functional properties. This high quality chitosan could prove particularly suitable for medical/analytical applications.

Animals↗
PubMed1997

The elaboration likelihood model and communication about food risks.

Factors such as hazard type and source credibility have been identified as important in the establishment of effective strategies for risk communication. The elaboration likelihood model was adapted to investigate the potential impact of hazard type, information source, and persuasive content of information on individual engagement in elaborative, or thoughtful, cognitions about risk messages. One hundred sixty respondents were allocated to one of eight experimental groups, and the effects of source credibility, persuasive content of information and hazard type were systematically varied. The impact of the different factors on beliefs about the information and elaborative processing examined. Low credibility was particularly important in reducing risk perceptions, although persuasive content and hazard type were also influential in determining whether elaborative processing occurred.

Adult↗
PubMed1996

Development of hearing and vocalization in a marsupial, the Northern Quoll, Dasyurus hallucatus.

The development of hearing was studied in the Northern Quoll, a nocturnal marsupial carnivore whose young are born into a pouch in an immature state after about 21 days in utero. Startle responses to noise bursts of 105 dB sound pressure level first appeared at 60 days after arrival in the pouch, but only to occasional stimuli; forelimb rather than whole body twitches were evoked. The latter were elicited regularly at 67 days onward. Auditory brainstem response (ABR) audiograms were measured during the period when startle responses first appeared. At 68 days responses were elicited between 1 and 16 kHz with thresholds in excess of 55 dB. At 81-88 days responses occurred over the adult range at lower thresholds than observed in the adult. The waveform of the ABR increased in complexity and decreased in latency during development. Pouch-young emitted acoustically well-defined isolation cells when separated from their mothers. Fourier analysis of these calls revealed peak energy at 8-11 kHz irrespective of the sex of the pouch-young. The isolation call first became evident at about 35 days, when the young were deliberately removed from the nipple, and ceased being emitted beyond about 80 days, some 5 or so days after the eyes open, when the young leave the pouch for substantial amounts of time. The spectrum of the call was similar at all ages within this 45 day period, and its peak frequency correlated closely with the best frequency in the adult quoll's ABR audiogram. At approximately 80 days of age the calls developed major low frequency components, similar to those measured in adult vocalizations, and the contributions of frequencies between 8-11 kHz waned in importance. The results indicate that the onset of hearing in quolls occurs at a relatively early time in the course of their development, but prior to this time the pouch-young emit characteristic isolation calls easily detectable by the mother.

Acoustic Stimulation↗
PubMed1996

Current therapy for Crigler-Najjar syndrome type 1: report of a world registry.

This study represents a multicenter survey on the management of patients with Crigler-Najjar syndrome (CNS) type 1. The aim of the survey was to find guiding principles for physicians in the care of these patients. Fifty-seven patients were included. At the time of inclusion, 21 patients had received a liver transplant (37%). The average age at transplantation was 9.1 +/- 6.9 years (range, 1-23 years); the age of the patients who had not been transplanted at the time of inclusion was 6.9 +/- 6.0 years (range, 0-23 years). Brain damage had developed in 15 patients (26%). Five patients died, and 10 are alive with some degree of mental or physical handicap. In 2 patients, ages 22 and 23 years, early signs of bilirubin encephalopathy could be reversed, in 1 by prompt medical intervention followed by liver transplantation and in the other by prompt liver transplantation. Seven patients underwent transplantation with some degree of brain damage at the time of the surgery; 1 of these died after retransplantation, 2 improved neurologically, and 4 remained neurologically impaired. The age of 8 patients with and 13 without brain damage at or before transplantation was 14.3 +/- 5.9 and 5.9 +/- 5.4 years (P < .01), respectively. Therapy of CNS type 1 consists of phototherapy (12 h/d), followed by liver transplantation. Phototherapy, although initially very effective, is socially inconvenient and becomes less efficient in the older age group, thus also decreasing compliance. Currently, liver transplantation is the only effective therapy. This survey shows that, in a significant number of patients, liver transplantation is performed after some form of brain damage has already occurred. From this, one must conclude that liver transplantation should be performed at a young age, particularly in situations in which reliable administration of phototherapy cannot be guaranteed.

Adolescent↗
PubMed1996

Controlled trial of nimodipine in amyotrophic lateral sclerosis.

Calcium channel blocking drugs antagonize excitatory amino acid receptor activation, decrease calcium entry into damaged neurons, and might help to slow or reverse amyotrophic lateral sclerosis (ALS). We enrolled 87 patients with ALS in a randomized, placebo-controlled, prospective, double-blind crossover study of nimodipine therapy. Monthly measures of isometric muscle strength and respiratory function compared the effects of drug and placebo. No difference in adverse events occurred in placebo vs drug-treated patients, but diarrhoea, nausea, and lightheadedness were more common with nimodipine. There was no significant difference in the rate of decline of pulmonary function or limb strength during treatment with drug or placebo. Nimodipine was ineffective in slowing the progress of ALS.

Amyotrophic Lateral Sclerosis↗
PubMed1996

Developing a subject-derived terminology to describe perceptions of chemicals in foods.

Risk perception may be influenced by a number of factors, such as unfamiliarity, lack of control, perceived consequences, and hazards being seen as catastrophic and having risk for future generations. Risk perception researchers have typically used such investigator-selected characteristics to assess hazards. In the first study reported here, the repertory grid method was used to elicit the terminology that subjects (n = 30) use to distinguish between 30 different chemicals. The data were submitted to generalized Procrustes analysis. The first principal axis of the resulting consensus plot separated the chemicals ranging from "poisonous or toxic," "harmful or dangerous," and "sounds negative" at one end, to "positive effect on health," "often present in food nowadays," and "sounds positive" at the other end. The second principal axis ranged from "familiar with or knowledge of" and "chemical" to "natural." A second study (n = 226) was carried out to look at the general validity of the results of the repertory grid interviews using a fixed questionnaire. The data were submitted to principal components analysis and internal preference mapping. The first principal component ranged from "safe" and "healthy" at one end, to "poisonous" and "harmful" at the other end. The chemicals also separated in terms of "familiar," "chemical," and "natural." All three methods of data collection and analysis yield essentially similar results.

Attitude↗
PubMed1996

What determines trust in information about food-related risks? Underlying psychological constructs.

Trust in risk information about food related-hazards may be an important determinant of public reactions to risk information. One of the central questions addressed by the risk communication literature is why some individuals and organizations are trusted as sources of risk information and others are not. Industry and government often lack public trust, whereas other sources (for example, consumer organizations, the quality media, medical doctors) are highly trusted. Problematically, previous surveys and questionnaire studies have utilized questions generated by the investigators themselves to assess public perceptions of trust in different sources. Furthermore, no account of the hazard domain was made. In the first study reported here, semistructured interviewing was used to elicit underpinning constructs determining trust and distrust in different sources providing food-related risk information (n = 35). In the second study, the repertory grid method was used to elicit the terminology that respondents use to distinguish between different potential food-related information sources (n = 35), the data being submitted to generalised Procrustes analysis. The results of the two studies were combined and validated in survey research (n = 888) where factor analysis indicated that knowledge in itself does not lead to trust, but that trusted sources are seen to be characterised by multiple positive attributes. Contrary to previous research, complete freedom does not lead to trust-rather sources which possess moderate accountability are seen to be the most trusted.

Adult↗
PubMed1996

X-linked immune dysregulation, neonatal insulin dependent diabetes, and intractable diarrhoea.

Four related male infants presented with neonatal diabetes mellitus, immune dysregulation with extremely high concentrations of immunoglobulin E, and intractable diarrhoea. They were all from one family, and all of them died. As far as is known this X-linked recessive disorder has not been described before. It is suggested that this is a new immunodeficiency in which type 2 T helper responses predominate.

Diabetes Mellitus, Type 1↗
PubMed1995

Novel bioemulsifiers from microorganisms for use in foods.

The main objective of this study was to test the range of microorganisms for production of extracellular, high molecular weight emulsifiers for potential use in foods. A standard emulsification assay developed specifically for assessing food emulsifiers was used to examine 24 extracellular microbial products from bacteria, yeasts and algae. Of the 24 products tested, nine had emulsification ability that was as good as and eight had emulsifying properties that were better than those of the commonly used food emulsifiers gum arabic and carboxymethylcellulose. The eight good producer organisms included the yeasts Candida utilis, Candida valida, Hansenula anomala, Rhodospiridium diobovatum and Rhodotorula graminis, the red alga Porphiridium cruentum, and the bacteria Klebsiella spp. and Acinetobacter calcoaceticus. Of these, C. utilis was selected for further study due to the excellent emulsification properties of its extracellular products and food-grade status of the organism. Crude preparations of the bioemulsifier from C. utilis exhibited low viscosity and had a carbohydrate content of over 80%. Preliminary trials showed that the bioemulsifier from this organism had potential for use in salad cream.

Acinetobacter calcoaceticus↗
PubMed1995

Perceived behavioural control, unrealistic optimism and dietary change: an exploratory study.

In the context of five dietary changes conducive to reductions in fat consumption, a short questionnaire was constructed to examine the applicability of the theory of planned behaviour and to assess the presence of the phenomenon of "unrealistic optimism". An extension to the theory of planned behaviour was also included, in the form of a "self-identity" measure assessing identification with concern about the health consequences of diet. The questionnaire was completed by 612 members of the general public at three different locations in the U.K. The findings indicate some support for the applicability of the theory of planned behaviour, with the measure of "self-identity" producing some additional independent effects. Evidence of unrealistic optimism concerning diet-related health risks was found, with greater optimism being significantly related to lower relative consumption estimates of "unhealthy" foods. The findings are discussed in the context of implications for health promotion.

Adolescent↗
PubMed1995

The influence of dietary advice on nutrient intake during pregnancy.

To assess the effect of an antenatal nutrition programme designed specifically for the local population, questionnaires on nutrition knowledge, attitudes to healthier eating and 4 d diet diaries were completed by women attending routine antenatal clinics. Women who received the nutrition education programme were allocated into an Intervention Education Group whilst those women who did not were allocated into a Routine Education Group. The results showed that knowledge about nutrition was significantly higher in the intervention group. However, no significant differences were detected between the two groups for attitude variables or nutrient intake. It is concluded, therefore, that the most-widely-read form of nutrition advice for pregnant women may have some impact on nutrition knowledge but has little effect on nutrient intake during pregnancy.

Adolescent↗
PubMed1995

Clinical, pathophysiologic, and microbiologic characterization of bronchiectasis in an aging cohort.

STUDY OBJECTIVE: Awareness of bronchiectasis on the part of clinicians has been low in recent years, although it was previously well recognized. We believe that bronchiectasis is underdiagnosed, and that current literature is skewed toward the esoteric etiologies of bronchiectasis. DESIGN: We reviewed the clinical, radiologic, microbiologic, and physiologic findings in 123 well-studied patients with proved bronchiectasis. SETTING: The University of Texas Health Center at Tyler Hospital and Clinics. MEASUREMENTS AND RESULTS: There were 38 men and 85 women with a mean (+/- SD) age of 57.2 +/- 16.7 years; 55% were lifetime nonsmokers. Diagnosis was confirmed with CTs of the chest in 56%, by bronchogram in 28%, and surgery with the remainder. Seventy percent of patients gave a history of an antecedent potentially causative event for the bronchiectasis, usually pneumonia. Symptoms of bronchiectasis included chronic cough with the production of purulent sputum, hemoptysis, recurrent fever, and pleurisy. The finding of crackles on chest examination was the rule (70%) with wheezing present in 34% of the group. Pulmonary function studies documented airway obstruction to be present in 54% of the lifetime nonsmokers. The chest radiographs were abnormal in 91.3%, showing fibrotic stranding and infiltrates. A variety of pathologic microbial flora, particularly Pseudomonas aeruginosa and other opportunistic organisms, were isolated from the sputum. Patients who had smoked had much the same picture as nonsmokers, although they had a greater degree of airway obstruction. CONCLUSIONS: A characteristic clinical picture of bronchiectasis emerges after review and evaluation of these data. Knowledge of this picture should allow ready recognition of the disease.

Adult↗
PubMed1995

Education and audit can improve the identification of excessive drinkers among medical inpatients.

This study investigated the effect of education and audit on the identification and management of medical inpatients with excessive alcohol consumptions by use of a cross-sectional survey of medical and nursing notes, compared with historical controls. We report the proportion of medical and nursing notes containing qualitative and quantitative drinking histories, the use of the CAGE questionnaire, and notification of alcohol consumption in discharge summaries. A total of 1,979 out of 2,680 (74%) notes of eligible patients were examined. The number of medical notes containing quantitative alcohol histories rose from 175/792 (22%) among historical controls, to 242/690 (35%) after training of junior medical and nursing staff, and to 241/497 (48%) after feedback of results in a clinical audit meeting. The number of medical notes with no recorded alcohol history changed from 309/792 (39%) to 287/690 (42%) to 152/497 (31%), respectively (chi 2 for trend = 97.2, p < 0.0001). The number of nursing notes containing quantified alcohol histories rose from 31/792 (4%) among historical controls, to 123/690 (18%) after training, and to 237/497 (48%) after feedback of results in a clinical audit meeting. The number of nursing notes with no recorded alcohol history fell from 309/792 (90%), to 512/690 (74%), to 205/497 (41%) respectively (chi 2 for trend = 353.7, p < 0.0001). The proportion of patients found to be drinking excessively rose from 40/792 (5.1%) to 57/690 (8.3%) to 45/497 (9.1%) (chi 2 for trend = 8.25, p = 0.004). There was little worthwhile improvement in use of the CAGE questionnaire and in discharge summaries. Education and audit are effective ways of improving the identification of excessive drinkers by both junior doctors and nurses alike. Other aspects of management are less responsive.

Alcoholism↗