Biomedical subjects

D M Anderson

Publications and source records attributed to D M Anderson.

At least 199 records · Page 11Linked to original sources

PubMedDate not supplied

Glycogen cycle enzymes and cyclic nucleotides in avian muscular dystrophy.

Fast-frozen pectoralis muscle samples were taken from normal chickens (lines 200 and 412) and chickens having hereditary muscular dystrophy (line 304). The glycogen phosphorylase activity ratio (activity without AMP/activity with AMP) was significantly greater in dystrophic muscles (0.306 +/- 0.046) than it was in normal muscles (0.090 +/- 0.023). Glucagon treatment did not cause any changes in phosphorylase activity ratios. Isoproterenol treatment of both normal and dystrophic muscles raised the phosphorylase activity ratio of normal muscles to 0.446 +/- 0.054, which was not significantly different from that of the dystrophic muscles. The dystrophic muscles had significantly less glycogen than normal muscles (23.3 +/- 2.8 compared with 36.8 +/- 2.8 mumoles glucosyl units/g of muscle). There was no relationship of muscular dystrophy to total phosphorylase activity (measured in the presence of 1 mM AMP) and to glycogen synthase activities measured without and with glucose 6-phosphate. Normal muscles had 28% less cAMP and 49% less cGMP than dystrophic muscles, but these differences were eliminated by treatment of the chickens with glucagon.

Adenylyl Cyclases↗

PubMedDate not supplied

Soil and water and its relationship to the origin of life.

Soils of the terrestrial planets form at the boundaries between lithosphere, atmosphere and hydrosphere. Biogenesis occurred in these zones; thus, it is axiomatic that some, perhaps many, stages of biogensis occurred in intimate association with the mineral constituents of soils. Because of a high surface to mass ration and, consequently, a high surface reactivity, the layer lattice clay minerals are the most important of these. According to the geological record, clay minerals appeared very early on the primordial Earth. Recent investigations have confirmed their presence in carbonaceous meteorites and have indicated their occurrence on Mars. In this paper we collect pertinent physico-chemical data and summarize the organic reactions and interactions that are induced or catalyzed by clays. Many clay-organic reactions that do not occur readily at high water contents proceed rapidly at adsorbed water contents corresponding to surface coverages of one or two molecular layers. One or two monolayers of adsorbed water correspond to extremely dry or cold planetary environments. Some consequences of these facts vis á vis biogenesis on Mars are considered.

Adsorption↗

PubMedDate not supplied

An endogenous annual clock in the toxic marine dinoflagellate Gonyaulax tamarensis.

Blooms of the toxic dinoflagellate Gonyaulax tamarensis (synonyms Protogonyaulax tamarensis and Alexandrium tamarense) cause outbreaks of paralytic shellfish poisoning (PSP) in coastal waters throughout the world. In the Gulf of Maine, episodes occur between April and November, a seasonality due in part to life-cycle alternations between motile, vegetative cells and resting cysts which overwinter in bottom sediments. Newly formed cysts have a mandatory 2-6 month dormancy period during which germination is not possible, but once mature, the resting state will continue if temperatures are unfavourable or oxygen is unavailable. We now report another factor controlling germination of cysts of G. tamarensis from deep coastal waters--an endogenous annual clock that can override an otherwise favourable environment for germination. Similar annual variability in germination has not been observed for cysts of this species from shallow estuaries. These results represent the first conclusive demonstration of an endogenous circannual rhythm in a marine plant. They are evolutionarily and ecologically significant because an endogenous annual clock can lead to the release of motile cells into deep and relatively invariant bottom waters at those times when temperature and light at the surface are suitable for growth. In shallow waters where seasonal variability is large and extends to bottom sediments, a strategy similar to that of the seeds of terrestrial plants would be more appropriate, namely a direct coupling between germination and the external environment.

Biological Clocks↗

PubMedDate not supplied

Ischemic bandage injuries: a case series and review of the literature.

OBJECTIVE: To determine the prognosis and distribution of ischemic injuries caused by inappropriate bandaging of the lower limb in dogs and cats. STUDY DESIGN: Retrospective clinical study. ANIMAL POPULATION: Eleven client-owned animals, including 9 dogs and 2 cats with a history of injuries consistent with incorrect application of a bandage. METHODS: Medical records for dogs and cats referred to the Queen's Veterinary School Hospital with limb wounds between 1995 and 1999 were reviewed for clinical history and referring veterinary surgeons' reports, indicating that the injury was directly related to the application of a bandage to the limb. RESULTS: The indications for bandage application included 2 postoperative cruciate ligament ruptures, 2 lacerations, 3 internal fixations, an onychectomy, a shoulder dislocation, a dog bite, and a tendon strain. None of the patients had other body systems involved or underlying or concurrent diseases. Five different types of bandage were described (support, Robert Jones, pressure, splint, and Velpeau), and no particular age or breed was overrepresented. Of the 11 animals, 5 required full-thickness skin grafts, 3 had to have digits amputated, and 2 required limb amputations. Nine animals survived, but only 4 became fully functional on the affected limb. CONCLUSIONS: Bandage-related injuries are potentially serious sequelae to a routine procedure. A guarded prognosis should be given when there is loss of deeper structures. CLINICAL RELEVANCE: A review of bandaging principles is presented. Method of application, choice of materials, and close monitoring of the bandage are important factors in preventing iatrogenic injury.

Amputation, Surgical↗

PubMedDate not supplied

The absence of rhamnose in human urine following the ingestion of gum karaya (Sterculia).

Urinary rhamnose estimations following ingestion of gum karaya were requested by the Scientific Committee for Food (EEC) in July 1983. Five male volunteers have therefore made 24-h urine collections prior to, and following, the ingestion of 10 g gum karaya for 15 days, an intake ten-fold greater than that approved in terms of the present temporary ADI (0-12 X 5 mg/kg b.w.). Paper chromatographic separations, with two solvent systems, were made on the fresh urine specimens and also after ten-fold enrichments of all urinary constituents. Standard aqueous solutions of rhamnose, and urine to which rhamnose had been added, showed the detection limit to be 0.2 microgram rhamnose. Independent examinations in two laboratories failed to detect rhamnose at this level in any of the urine specimens, Had 1% of the rhamnose present in 10 g gum karaya appeared in the 24-h urine specimens, it would have been detected. This confirms previous evidence that dietary gum karaya is neither digested nor degraded by enteric bacteria and is not absorbed to any significant extent in Man.

Adult↗

PubMedDate not supplied

The amino acid composition of the proteinaceous component of guar gum (Cyamopsis tetragonolobus).

Guar gum, powdered endosperm from the seeds of the legume Cyamopsis tetragonolobus, is a galactomannan which contains 2.5-4.5% of a proteinaceous component. Data presented for 11 bulk commercial samples show that the most abundant amino acids are glycine, glutamic acid, aspartic acid, serine and alanine, but that their relative proportions vary considerably. The proportions of other amino acids, e.g. histidine, isoleucine, phenylalanine, threonine, tyrosine and valine are remarkably constant. There appear to be some correlations between viscosity and the glycine, arginine and proline contents. Data for the amino acid compositions of several chemical derivatives of a medium-viscosity gum guar sample indicate that the proteinaceous component is retained but suffers variable modification. The amino acid profile for guar gum differs extensively from those for gum arabic and gum karaya; this provides a useful analytical supplement to sugar determinations for studies of admixtures of these hydrocolloids.

Amino Acids↗

PubMedDate not supplied

The amino acid composition of the proteinaceous component of gum tragacanth (Asiatic Astragalus spp.).

Six Iranian and seven Turkish samples of commercial gum tragacanth, and a sample of Turkish 'gum traganton', have been studied. Their nitrogen content varied from 0.17 to 0.58%. Their amino acid compositions are characterized by the presence of very large but variable proportions of hydroxyproline and substantial proportions of serine, proline and valine. The data presented may be useful for extending the current specifications for identity and purity, at present based solely on polysaccharide parameters, for gum tragacanth (E413).

Amino Acids↗

PubMedDate not supplied

Immunogenicity, immunological cross reactivity and non-specific irritant properties of the exudate gums, arabic, karaya and tragacanth.

An animal model has been used to investigate the immunogenicity and non-specific irritant properties of exudate gums. The materials studied were four preparations of gum arabic (Acacia spp.), two of gum karaya (Sterculia spp.), two of gum tragacanth (Astralagus spp.) and a residue obtained after ethanol extraction of gum arabic. Groups of animals were intradermally immunized with the gum in complete Freund's adjuvant. Serum antibody levels were measured by an ELISA technique and delayed hypersensitivity responses by a footpad swelling test. Antigenic cross-reactivity within each gum species was tested in a crossover fashion. All gum preparations elicited systemic immune responses after immunization. Further processing reduced immunogenicity, although there was no evidence that systemic immunity to these complex polysaccharide antigens responses could be completely abolished by processing or purification. The ethanolic extract, and some of the gum preparations, particularly tragacanth and karaya, caused considerable footpad swelling when injected intradermally. It is concluded that processing and awareness of subspecies differences can reduce the inherent immunogenicity and potential irritant effects of exudate gums.

Animals↗

PubMedDate not supplied

Evidence for the safety of gum arabic (Acacia senegal (L.) Willd.) as a food additive--a brief review.

Scrutiny of the experimental evidence of safety demanded by the international food safety authorities has led them to conclude that no limitation to the use of gum arabic as a food additive need be specified when it conforms to the established criteria of identity and purity. This brief review collates the dietary, toxicological, immunological, chemical and other studies available.

Animals↗

PubMedDate not supplied

Nitrogen conversion factors for the proteinaceous content of gums permitted as food additives.

Nitrogen conversion factors for gum arabic (Acacia senegal (L.) Willd.), gum tragacanth (Asiatic Astragalus spp.), gum karaya (Sterculia spp.), guar gum (Cyamopsis spp.), locust bean (carob) gum (Ceratonia spp.), tara gum (Caesalpinia spp.), and xanthan gum (Xanthomonas campestris) have been calculated from data for the amino acid compositions of their proteinaceous components. The factors derived differ from the arbitrary values (5.7 or 6.25) at present specified by international regulatory authorities for some emulsifiers, stabilizers and thickeners.

Dietary Proteins↗

PubMedDate not supplied

The dietary effects of xanthan gum in man.

Following a 7-day control period, 5 male volunteers consumed, on each of 23 consecutive days, a weight of xanthan gum equal to 15 times the current acceptable daily intake (10 mg/kg b.w.) approved by the EEC and by the Joint FAO/WHO Expert Committee on Food Additives; thus, the lightest and heaviest of the volunteers consumed 10.4 g and 12.9 g respectively of xanthan daily. Measurements before and at the end of the test period showed that the ingestion of xanthan, as a pre-hydrated gel, acted as a bulking agent in terms of its effects on faecal wet and dry weight and intestinal transit time but had no significant effect on plasma biochemistry, haematological indices, urinalysis parameters, glucose tolerance and insulin tests, serum immunoglobulins, triglycerides, phospholipids and HDL cholesterol, breath hydrogen and breath methane concentrations. There was a moderate (10%) reduction in serum cholesterol and a significant increase in faecal bile acid concentrations. The data indicate that the ingestion of xanthan caused no adverse dietary nor physiological effects in any of the subjects. In particular, all of the enzymatic and other parameters that act as sensitive indicators of adverse toxicological effects remained unchanged.

Adult↗

PubMedDate not supplied

The amino acid composition and quantitative sugar-amino acid relationships in sequential Smith-degradation products from gum talha (Acacia seyal Del.).

Data are presented for the amino acid and sugar compositions of gum talha (tahl), i.e. the exudate from Acacia seyal Del., and for four sequential Smith-degradation (SD) products (0.10, 0.19, 0.38, 1.60 and 2.22% N respectively). Gum talha, which is not permitted as a food additive, is liable to occur as a contaminant of shipments of legitimate gum arabic (Acacia senegal (L.) Willd.). The molar polysaccharide/protein ratio in the whole gum (113:1) decreased to 58:1, 27:1, 5.5:1 and 4:1 in the first, second, third and fourth SD products respectively. From previous studies, SD-IV is known to be a branched galactan; hydroxyproline, aspartic acid, serine, valine, proline, and leucine account jointly for 70% of its amino acids. The first SD eliminated large amounts of sugars (ca 50%, including all of the rhamnose and glucuronic acid present) but only very small amounts of amino acids (molar ratio 807/1). The second and third degradations eliminated all of the arabinose and 99% of the galactose originally present. The very small yield of the final SD product is an established characteristic of dextrorotatory Acacia exudates of the A. seyal type (Bentham's Gummiferae). Overall (four SD stages), 99.7% of the original sugars but only 91.3% of the amino acids were eliminated. Hydroxyproline accounts for ca 25% of the low amino acid content of A. seyal gum and each of its SD products; the proteinaceous enrichment of the branched galactan core also involves aspartic acid, glutamic acid and iso-leucine.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

PubMedDate not supplied

The dietary effects of gellan gum in humans.

Following a 7-day control period, five female and five male volunteers consumed a weight of gellan gum corresponding to 175 mg/kg body weight for 7 days, followed by 200 mg gellan gum per kg body weight for a further 16 days. Measurements before and at the end of the 23-day test period showed that the gellan gum acted as a faecal bulking agent for the male volunteers and for four of the females. Dietary transit time increased for 2 females and 2 males, and decreased for 3 females and 3 males. Faecal bile acid concentrations increased for 4 females and for 4 males; the average increases were from 0.69 to 0.83 mmol/24 h (females) and from 1.22 to 1.44 mmol/24 h (males). Gellan gum ingestion had no significant effect on (a) plasma biochemistry parameters; (b) haematological indices; (c) urinalysis parameters; (d) blood glucose and plasma insulin concentrations; (e) breath hydrogen concentrations. There were no significant changes in HDL cholesterol, triglyceride or phospholipid concentrations. Serum cholesterol concentrations decreased significantly (P less than 0.1) by 13% on average for females, and by 12%, on average, for males. The data indicate that the ingestion of gellan gum at a high level for 23 days caused no adverse dietary or physiological effects in any of the volunteers. In particular, the enzymatic and other indicators of adverse toxicological effects remained unchanged.

Adult↗

PubMedDate not supplied

Evidence for the safety of gum tragacanth (Asiatic Astragalus spp.) and modern criteria for the evaluation of food additives.

Gum tragacanth (GT), affirmed as GRAS within the USA since 1961, was evaluated as 'ADI not specified' by JECFA in 1985. Within the EEC, GT has been permitted temporarily as a food additive (E413), without an ADI, since 1974; a decision regarding its permanent status must be reached before the end of 1988. This review collates the dietary, toxicological, immunological and chemical data available and presents the pre-requisite data concerning the 'Need' and low levels of utilization of GT.

Abnormalities, Drug-Induced↗

PubMedDate not supplied

Evidence for the safety of gum karaya (Sterculia spp.) as a food additive.

Gum karaya (GK), accepted as Generally Recognised as Safe (GRAS) in the USA since 1961, was accepted temporarily (Annex II) as a food additive by the EEC in 1974. Since then no adverse incident involving human health has been attributed to the ingestion of GK, which is used in extremely small amounts in foods. This report collates the evidence of safety now available and presents the data on Need, production tonnages and dietary intake levels.

Food Additives↗

PubMedDate not supplied

The effects of dietary methylcellulose in man.

Following a 7-day control period, five male volunteers consumed, on each of 23 consecutive days, a weight of methylcellulose (MC) equal to ten times the acceptable daily intake (25 mg/kg b.w.) approved by the EEC and the Joint FAO/WHO Expert Committee on Food Additives (JECFA). The MC was well tolerated; no allergic responses were reported. Measurements before and at the end of the test period showed that the ingestion of MC, as a pre-hydrated gel, acted as a bulking agent in terms of increased faecal wet (p less than 0.05) and dry weight, with intestinal transit time increasing for three but decreasing for two of the volunteers. Small changes, well within the normal ranges, occurred in some haematological indices, serum lipids and a few plasma biochemistry parameters. There were no changes in urinalysis parameters or breath hydrogen concentrations. There were small (p less than 0.05) reductions in faecal volatile fatty acids and neutral sterols (mumol/g dry weight). The decreases in blood glucose and plasma insulin after 60 min were also within the normal clinical range. The data provide no indications of any adverse effects of methylcellulose resulting from its ingestion for 23 days at the level of 250 mg/kg b.w.

Adult↗

PubMedDate not supplied

Identification of Albizia gum exudates which are not permitted food additives.

Trees of the genus Albizia have frequently been confused with Acacia species. The genus Albizia has been recommended for more extensive arid zone development; its species are sources of tannins and gum exudates, which are not included in any of the regulatory lists of permitted food additives. Analytical data permitting their identification are therefore required to allow food law compliance to be monitored. This paper presents data which serve to characterize the gums from seven Albizia species, making a total of eleven Albizia species for which data are available. The presence of tannins, and high proportions of aluminium and heavy metals, indicates that gum importers and food processors must be vigilant to ensure that Albizia gums do not enter human food chains as adulterants or contaminants.

Amino Acids↗

PubMedDate not supplied

The identification of Combretum gums which are not permitted food additives, II.

Combretum gums, readily available at low prices in East and West Africa, may be offered for sale as 'gum arabic'. Vigilance is necessary to detect such misrepresentations because Combretum gums differ greatly from gum arabic (Acacia senegal (L.) Willd.) in terms of quality, solution properties and value. Moreover, because there is no toxicological evidence for their safety in use, Combretum gums are not included in any of the international lists of permitted food additives. Food manufacturers and regulatory authorities therefore require data that characterize Combretum gums so that their use in foodstuffs can be prevented. This paper presents such data for the gums from a further six Combretum species. All of these have negative optical rotations similar to that of food grade gum arabic. It is no longer sufficient, therefore, to rely solely on an optical rotation measurement to confirm the identity of gum arabic. The additional analyses necessary to differentiate between Combretum gums and gum arabic are discussed.

Amino Acids↗