Search PubMed⌕ Search

Biomedical subjects

D M Anderson

Publications and source records attributed to D M Anderson.

211 records · Page 12Linked to original sources
PubMedDate not supplied

Specifications for gum arabic (Acacia senegal); analytical data for samples collected between 1904 and 1989.

The regulatory specifications for gum arabic (Acacia senegal) are superficial and inadequate to ensure that it is not adulterated with non-permitted gums from other botanical sources. Moreover, the existing specifications do not give the consumer the essential assurance, fundamental to food safety evaluation principles, that the nature and quality of gum arabic used in foodstuffs always conforms to that of the Test Article selected for the toxicological studies which justified the current status ('ADI not specified') of gum arabic as a permitted food additive. The availability of well-preserved gum arabic samples, collected between 1904 and 1939, has enabled invaluable data to be added to those derived from samples from the most recent crops. The resulting analytical data substantiate and greatly extend the quantitative information available previously for the chemical characterization of gum arabic for regulatory and trade purposes. The data confirm that good-quality commercial gum arabic was used previously as the Test Article. There is no evidence that the specific rotation of gum arabic has become significantly less negative in recent years.

Amino Acids↗
PubMedDate not supplied

A follow-up study of the ingestion of gellan gum by humans, with special reference to the absence of eosinophilia.

Following a 7-day control period, during which sampling was carried out on two occasions (days 1 and 8), 10 female and 10 male healthy volunteers consumed a weight of gellan gum corresponding to 175 mg/kg body weight for 7 days (days 8-14) followed by 200 mg gellan gum per kg body weight for a further 14 days (days 15-28). The total period of ingestion (21 days) was followed by a further 7-day control period (days 29-36). 'Control' samples for haematology and plasma clinical chemistry were therefore secured on days 1, 8 and 36, and 'test' samples were secured on days 15, 22 and 29. In addition, 24 h samples were monitored by urinalysis, and 24 h faecal samples were monitored for occult blood three times each week. The major objectives were to supplement the data for gellan gum obtained previously, particularly in respect of changes in eosinophil concentrations, and to re-examine the responses of two male volunteers who had given indications of eosinophilia in a previous study. There was no such response by them, or by any of the other 18 volunteers, on this occasion.

Adult↗
PubMedDate not supplied

Dietary effects of propylene glycol alginate in humans.

Following a 7-day control period, five male volunteers consumed a weight of propylene glycol alginate corresponding to 175 mg/kg body weight for 7 days, followed by 200 mg propylene glycol alginate per kg body weight for a further 16 days. Measurements before and at the end of the 23-day period of dietary supplementation showed that propylene glycol alginate had little effect on faecal parameters (pH, water content, daily wet and dry weights). The dietary transit time remained constant for three volunteers, increased for one, and decreased for one. The ingestion of propylene glycol alginate had no significant effect on (a) haematological indices, (b) plasma biochemistry parameters, (c) urinalysis parameters, (d) blood glucose and plasma insulin concentrations, (e) breath hydrogen concentrations. No allergic responses were reported by, nor observed in, any of the volunteers. The study therefore indicates that the ingestion of propylene glycol alginate at a high level for 23 days caused no adverse dietary or physiological effects; in particular, the enzymatic and other sensitive indicators of adverse toxicological effects remained unchanged.

Adult↗
PubMedDate not supplied

Dietary effects of sodium alginate in humans.

Following a 7-day control period, five male volunteers consumed a weight of sodium alginate corresponding to 175 mg/kg body weight for 7 days, followed by 200 mg sodium alginate per kg body weight for a further 16 days. Measurements before and at the end of the 23-day period of dietary supplementation showed that sodium alginate acted as a faecal bulking agent for all volunteers, giving a significant (p less than 0.01) increase in daily wet weight, and also increases in the water content and daily dry weight, but no change in faecal pH. Although the dietary transit time remained constant for two volunteers, it decreased for two, and increased slightly for one, with little resulting change in the overall mean value. The ingestion of sodium alginate had no significant effect on (a) haematological indices, (b) plasma biochemistry parameters, (c) urinalysis parameters, (d) blood glucose and plasma insulin concentrations, (e) breath hydrogen concentrations. No allergic responses were reported by, nor observed in, any of the volunteers. The study therefore indicates that the ingestion of sodium alginate at a high level for 23 days caused no effects other than those normally associated with a polysaccharide bulking agent; in particular, the enzymatic and other sensitive indicators of adverse toxicological effects remained unchanged.

Adult↗
PubMedDate not supplied

Gum arabic (Acacia senegal): unambiguous identification by 13C-NMR spectroscopy as an adjunct to the Revised JECFA Specification, and the application of 13C-NMR spectra for regulatory/legislative purposes.

The JECFA Specification for gum arabic was revised in 1990 to reflect more closely the specification of the Test Article used in evaluations that led to its classification 'ADI not specified' in 1982/83. Some producers and traders have objected to the Revised Specification; in contrast, consumer-protection groups consider that it remains too lax to provide the degree of safety assurance expected. This paper presents analytical data that confirm the mean values previously established for nitrogen and the specific rotation of bulk commercial gum arabic from Acacia senegal. The data also establish that natural gum arabic imported into the USA and Europe in 1989/91 met the Revised Specification, but that a disturbingly high proportion of spray-dried, processed gums sold as 'gum arabic' did not. NMR spectroscopy has (a) indicated that some such samples are based on non-permitted gums and (b) confirmed that the 1983 Test Article represents not only typical 1990/91 shipments but also a wide range of reference gum arabic samples from other reputable sources. Details of a representative 13C-NMR spectrum, derived by averaging the relative intensities for the characteristic resonances of 35 gum arabic samples, are given for future regulatory/legislative purposes. Some limitations of the Revised Specification and its susceptibility to commercial exploitation are discussed.

Carbon Isotopes↗
PubMedDate not supplied

The gum exudate from Combretum nigricans gum, the major source of West African 'gum combretum'.

Gum samples from six individual Combretum nigricans trees and two additional reference samples have been characterized. 13C Fourier-transform NMR spectra show that all have the same structure and confirm that the variations observed in their analytical parameters reflect only small fine-structural differences. NMR spectra also reveal that eight West African 'gum combretum' samples from reputable commercial sources originated from Combretum nigricans. This identification is important because gum combretum, which is not permitted as a food additive, has been exploited as an adulterant and misrepresented as gum arabic, for which not even the 1990 Revised Specification is sufficiently rigorous to detect such commercial deceptions. NMR spectroscopy has also shown that the rhamnose and uronic acid contents of gum combretum are located within internal polysaccharide chains. This explains the well-known difference in emulsification functionality between gum arabic, in which all rhamnose and uronic acid groups chain-terminal, and gum combretum which is, in addition, markedly hygroscopic and characterized commercially by its tendency to 'block' in transit and storage.

Africa, Western↗
PubMedDate not supplied

Videoendoscopic techniques for collection of multiple, serial intra-abdominal biopsy specimens in HIV-negative and HIV-positive pigtail macaques (Macaca nemestrina).

Tissue biopsy sampling by laparotomy is considered major surgery, which precludes serial sampling. This increases variability and requires a larger n value for pathogenesis studies. To address this problem, a study was conducted to develop and validate the feasibility of performing multiple, serial biopsy sampling by laparoscopy in pigtail macaques. Tissues were obtained laparoscopically from 2 HIV-negative and 2 HIV-positive (late postinoculation) macaques on days 0, 3, and 7, followed by necropsy on day 21. Anesthesia was induced with ketamine and atropine and maintained with isoflurane. Carbon dioxide pneumoperitoneum was maintained at 6 mm Hg. A triangulated threeport technique was used for insertion of pediatric (3.5-5.0 mm) laparoscopic instrumentation. Biopsies of kidney and spleen were obtained with a core-sampling biopsy needle, of small intestine and mesenteric lymph node with a pretied loop, and of liver with 3.5-5.0 mm biopsy forceps. Analgesics were administered for 24 h post operation, and animals were evaluated for postoperative complications. All monkeys maintained a good appetite. Mild postoperative pain was observed in one animal after the second surgery. There was no excessive bleeding or intestinal stenosis at biopsy sites. Skin infection, observed in 1/36 (2.8%) port sites, resolved with systemic antibiotics. Significant adhesions formed at 23/114 (20.2%) sites. Out of 34 samples evaluated for histopathology, 29 (85.3%) were satisfactory (minimal to mild tissue crushing). In situ hybridization results revealed few (4 of 29 samples tested) positive cells, which is consistent with the low level of HIV-2 virus found in cells late in the postinoculation period in pigtail macaques. The results of this study suggest that laparoscopic serial abdominal biopsy collection in healthy and immunocompromised pigtail macaques may be considered a minor procedure, and can be used to expedite serial tissue collection in survival studies.

Abdomen↗
PubMedDate not supplied

Videoendoscopy: an effective and efficient way to perform multiple visceral biopsies in small animals.

Because major surgery is usually required to obtain biopsies of abdominal organs, regulations tend to limit the number of procedures on individual animals to one. This study was conducted to develop a more humane, minor, comparatively cost-effective, minimally invasive surgical procedure, which reduces surgical trauma and the number of animals used. Biopsy techniques were developed in two nonsurvival rabbit surgeries. Safety and efficacy of multiple procedures were assessed in survival studies on four rabbits. Anesthesia was induced with ketamine/xylazine and maintained with isoflurane. Initial carbon dioxide insufflation (6 mmHg) was achieved through a Veress needle. A triangulated 5-mm port technique allowed introduction of pediatric 3.5- to 5.0-mm laparoscopic instruments. Biopsies of liver, spleen, kidney, and full-thickness bowel were obtained and evaluated for suitability (size) for polymerase chain reaction, in-situ hybridization, and histopathology studies. Animals in survival studies were assessed for infection, pain, bleeding, adhesion development, bowel function, and intestinal stenosis. All had normal appetite and stools within 48 h postoperatively. Biopsies obtained from either a Tru-Cut Biopsy Needle, 3.5- to 5.0-mm biopsy cups, or with the aid ofa pre-tied loop were adequate for all studies. There was no postoperative bowel obstruction, wound infection, or bleeding. Mean hematocrit decrease at 24 h postoperative was 3.4% +/- 6.7%. Adhesions formed at 9/52 (17%) evaluable sites. Multiple visceral organ biopsy under videoendoscopic guidance constitutes a minor procedure and is a promising means for longitudinal studies in animals. Utility for ill animals remains to be determined.

Abdomen↗
PubMedDate not supplied

Beneficial effect of beta-mannanase feed enzyme on performance of chicks challenged with Eimerla sp. and Clostridium perfringens.

Two experiments were conducted to determine the effect of a beta-mannanase feed enzyme on the performance of broiler chicks subject to a necrotic enteritis disease challenge model involving oral inoculation of Eimeria sp. and Clostridium pefringens. Beta-mannanase is known to improve productive performance when added to poultry and swine diets. In both experiments, disease challenge in the absence of feed additives demonstrated significant reductions in performance as measured by weight gain, feed conversion, and the incidence of coccidial lesion scores. Significant mortality was also observed in challenged groups in Experiment 1. The disease challenge model was therefore judged as highly effective. Additions of a commonly used antibiotic, bacitracin methylene disalicilate (BMD), and coccidiostat, salinomycin, were highly effective in partially counteracting negative effects of the disease challenge. In both experiments, addition of beta-mannanase significantly improved performance and reduced lesion scores in disease-challenged groups. The degree of improvement was somewhat less than that afforded by a combination of BMD and salinomycin in Experiment 1 but was not different from that afforded by BMD alone in Experiment 2. We conclude that the beta-mannanase enzyme can play a role in circumstances where the use of antibiotics is not desired.

Animal Feed↗
PubMedDate not supplied

Cancer prevention counseling on telephone helplines.

Since 1983, the National Cancer Institute (NCI) has collected data by means of its Cancer Information Service (CIS), a toll-free telephone helpline for health care professionals and members of the public who have questions about cancer treatment, diagnosis, and prevention. These data reveal information about the characteristics of callers and their questions and about how inquiries reflect mass media promotions and secular trends. A request for a publication is the most common type of inquiry, followed by information about specific cancer sites, smoking prevention and cessation, other types of prevention, cancer treatment, cancer symptoms, referrals to physicians, NCI clinical trials, hospital and clinic-based screening programs, and general counseling or coping. Breast cancer is the most common cancer of interest, followed by respiratory system cancers, colon and prostate cancers, leukemia, melanoma, nonHodgkin's lymphoma, cervical cancer, general or unspecified skin cancer, and ovarian cancer. Responding to these other caller inquiries, CIS counselors may proactively guide callers to a desirable goal, such as screening mammography. Protocols have been developed to assist counselors' proactive efforts, and preliminary results are beginning to support this approach. The findings gathered in this study underscore the health education potential of telephone helplines and point to the need for controlled evaluation research on the effectiveness of proactive counselor advice.

Adult↗
PubMedDate not supplied

Is it worth it?

Explore the source record for details and available documents.

Allied Health Personnel↗
PubMedDate not supplied

Epistaxis.

Explore the source record for details and available documents.

Epistaxis↗