bluuebunny/crossref_metadata_2025 huggingface dataset:
Sodium/iodide‐symporter: distribution in different mammals and role in entero‐thyroid circulation of iodide
Authors: JOSEFSSON M. , GRUNDITZ T. , OHLSSON T. , EKBLAD E.
Published: March 2003

The sodium (Na+)/iodide (I–)‐symporter (NIS) is abundantly expressed and accumulates iodide in thyroid follicular cells. The NIS is also found in extrathyroidal tissues, particularly gastric mucosa. Controversies exist on the localization of extrathyroidal NIS. We have studied the presence of both NIS peptide and NIS messenger RNA (mRNA) in the digestive tract and thyroid from different mammals. The role of gastric NIS is enigmatic and we aimed to unravel its possible involvement in iodide transport. Methods:  Distribution and expression of NIS were studied using immunocytochemistry and in situ hybridization. Iodide transport in the gastrointestinal tract was measured after oral or intravenous (i.v.) administration of 125I to rats with or without ligation of the pylorus. Results:  All thyroid follicular cells in rat and mouse expressed NIS, whereas a patchy staining was noted in man, pig and guinea‐pig. Gastric mucosa surface epithelium in all species and ductal cells of parotid gland in guinea‐pig, rat and mouse expressed NIS. In parietal cells and in endocrine cells of intestines and pancreas NIS immunoreactivity but no NIS mRNA was found. Studies of 125I uptake showed marked iodide transport from the circulation into the gastric lumen. Conclusions:  The localization of NIS varies slightly among mammals. To establish expression of NIS in a particular cell type the need to correlate the presence of both NIS protein by immunocytochemistry and NIS mRNA by in situ hybridization is emphasized. An entero‐thyroidal circulation of iodide mediated principally by gastric NIS, but possibly also by NIS in salivary glands is suggested.
Collecting duct function in liver cirrhotic rats with early sodium retention
Authors: Jonassen T. E. N. , Heide A. M. , Janjua N. R. , Christensen S.
Published: March 2003

Liver cirrhosis is a chronic disease associated with sodium retention due to increased tubular sodium reabsorption. However, the exact tubular site of increased sodium reabsorption in uncertain. We have recently demonstrated selective hypertrophy of the inner stripe of the outer medulla (ISOM) in rats with liver cirrhosis induced by common bile duct ligation (CBL). The present study was designed in order to measure Na–K–ATPase activity in the two major tubular segments located in the ISOM: the thick ascending limb of henles (MTAL) and the collecting ducts (OMCD) in CBL rats. Sham‐operated rats were used as controls. In addition, the natriuretic response to amiloride (0.2 mg kg−1 h−1 i.v) was examined in conscious, chronically instrumented rats during conditions where amiloride‐induced volume losses were replaced continuously using a servo‐controlled i.v. volume replacement system. For 4–5 weeks after CBL, cirrhotic rats showed sodium retention relative to control rats without any sign of ascites. Plasma levels of sodium and aldosterone were normal, but plasma vasopressin was increased. Effective renal plasma flow was significantly increased, whereas glomerular filtration rate (GFR) and renal lithium handling were normal. The CBL rats showed a blunted natriuretic response to amiloride (ΔFENa: 1.17 ± 0.15% vs. 1.65 ± 0.13%; P < 0.05). In rats with CBL, Na–K–ATPase activity per mm tubular length was decreased in the OMCD and unchanged in the TAL segment. These results suggest that increased tubular sodium reabsorption in liver cirrhotic rats with early sodium retention is localized in segments proximal to the collecting ducts.
Localization of a protein inhibitor of carbonic anhydrase in pig tissues
Authors: Ridderstråle Y. , Fierke C. A. , Roush E. D. , Wistrand P. J.
Published: March 2003

The protein inhibitor of carbonic anhydrase (CA), pICA, was localized in pig tissues by an immunohistochemical technique, using rabbit antipICA IgG. Staining for pICA was found in liver sinusoids and kidney glomeruli, where phagocytic cells are located, i.e. Kupffer and mesangial cells, respectively. pICA was not found inside parenchymal cells, or in tissues from striated muscle, heart, eye or lung. It is concluded that the function of pICA is perhaps to bind the carbonic anhydrase isozymes CA I, II, and III, released from erythrocytes into the blood circulation by intravascular haemolysis. The complex of CA‐pICA in plasma may then be transported to the reticuloendothelial system, for degradation and reclamation of CA‐bound zinc. This would be similar to the fate of the haemoglobin–haptoglobin complex for the recycling of iron.
Regulation of Ca2+ channel and phosphatase activities by polyamines in intestinal and vascular smooth muscle – implications for cellular growth and contractility
Authors: Nilsson B.‐O. , Gomez M. F. , Swärd K. , Hellstrand P.
Published: March 2003

Polyamines added extracellularly to intestinal and vascular smooth muscle cells cause relaxation through inhibition of Ca2+ channel activity. Intracellularly applied polyamines also affect Ca2+ channel properties. Polyamines do not readily pass over the plasma membrane because of their positive charges but in permeabilized smooth muscle preparations they have free access to the cytoplasm. In this system they increase sensitivity of the contractile machinery to Ca2+ through inhibition of myosin phosphatase activity. The magnitude of Ca2+ channel and phosphatase inhibition depends on the number of positive charges on the polyamine molecule. Polyamines have an obligatory, but yet undefined, role in regulation of cell growth and proliferation. Several groups of protein kinases, such as tyrosine and mitogen activated protein (MAP)‐kinases transmit the growth signal from the plasma membrane to the cell nucleus where mitosis and protein synthesis are initiated. The data reviewed here show that polyamines may affect such signal transmission via inhibition of phosphatase activity.
Modulation of endothelial permeability by 1‐O‐alkylglycerols
Authors: Marigny K. , Pedrono F. , Martin‐Chouly C. A. E. , Youmine H. , Saiag B. , Legrand A. B.
Published: March 2003

Regulation of endothelial barrier function often occurs through signalling involving phospholipase C activation which produces diacylglycerol (DAG), a lipidic second messenger activator of protein kinase C (PKC). Therefore, modification of lipidic composition of endothelial cell membranes might modify DAG production and, as a result, alter regulation of endothelial permeability. We investigated the in vitro effects of natural 1‐O‐alkylglycerols on porcine aortic endothelial cell permeability to dye‐labelled albumin. [3H]‐1‐O‐alkylglycerols (10 μm) were substantially incorporated into phosphatidylcholine (6.6%) and phosphatidylethanolamine (4.4%). Stimulation of endothelial cell monolayer with phorbol‐myristate‐acetate or with the calcium ionophore A23187 resulted in a raise in permeability to albumin. Pre‐treatment with 1‐O‐alkylglycerols (10 μm, 24 h) had no effect on basal albumin permeability but totally inhibited the effect of phorbol‐myristate‐acetate, and brought the permeability of A23187‐stimulated endothelial cell monolayers below control. After incubation of cells with [3H]‐1‐O‐alkylglycerols (10 μm, 24 h), we detected the production of the analogue of DAG, and PKC inhibitor, [3H]‐1‐O‐alkyl‐2‐acyl‐glycerol, in resting cells. This production was increased by 58% under A23187 stimulation while phorbol‐myristate‐acetate had no effect. Our data demonstrate that natural 1‐O‐alkylglycerols modify endothelial permeability, and suggest that this effect could be mediated through alteration of lipidic signalling.
Variable frequency trains enhance torque independent of stimulation amplitude
Authors: Slade J. M. , Bickel C. S. , Warren G. L. , Dudley G. A.
Published: March 2003

Abstract Aim:  Variable frequency trains have been reported to enhance force of fatigued human skeletal muscle. More rapid calcium turnover and/or enhanced stiffness may be responsible for the augmented torque–time integral during surface stimulation at moderate amplitude. In contrast, it has recently been suggested that variable frequency train enhancement occurs only at low forces as a result of preferential stimulation of fast fibres and/or altered motor unit recruitment. If correct, this would limit the practical benefit of variable frequency trains. Accordingly, we tested the hypothesis that torque augmentation by variable frequency trains in fatigued skeletal muscle was independent of stimulation amplitude.

Methods:  The m. quadriceps femoris of six males was stimulated with constant frequency trains (six 200‐μs square waves separated by 70 ms) or variable frequency trains (first interpulse interval 5 ms) at an amplitude that initially evoked ∼25 or ∼50% of maximal voluntary isometric torque.

Results:  After 180 constant frequency trains (50% duty cycle), isometric peak torque decreased ∼63%. In fatigued muscle, variable frequency trains enhanced the torque–time integral by ∼23% over that for constant frequency trains and this effect was independent of stimulation amplitude. This was due to greater peak torque and less slowing of rise time.

Conclusion:  These responses show that the torque–time integral can be enhanced at both moderate and high stimulation amplitudes. As such, it is suggested that neither recruitment nor preferential activation of fast muscle is responsible for the ‘catch‐like’ property that can be demonstrated in fatigued human skeletal muscle.
Effects of normobaric hyperoxia on water content in different organs in rats
Authors: Stuhr L. E. B. , Gjerde E.‐A. B. , Thorsen E. , Reed R. K.
Published: March 2003

Pulmonary oxygen toxicity is a dose‐dependent effect on alveolar epithelial and endothelial cells resulting in pulmonary oedema. Any concomitant effects on systemic capillary endothelium would be expected to result in capillary leakage and an increase in the tissues' water content. Total tissue water (TTW) in different organs was therefore studied in freely moving rats exposed to 100% O2 at normobaric pressure for 24 or 48 h, and compared to air‐breathing control rats. The TTW for the following tissues was measured: Trachea, left bronchus, left lung, left and right ventricle, left kidney, skin (left paw‐hindlimb), skin (back of the rat), left brain, left eye and thigh muscle left side. There was a significant increase in TTW of the lung accompanied by pleural effusion after 48 h of oxygen exposure as expected in all exposed animals. There was a small increase in TTW of the paw only, and a small decrease or no change in other tissues after 24 and 48 h of exposure. We conclude that there is no evidence of systemic capillary dysfunction as measured by tissue water content after exposure to hyperoxia in a dosage causing pulmonary oedema.
Functional organization of peripheral vasomotor pathways
Authors: Gibbins Ian L. , Jobling Phillip , Morris Judy L.
Published: March 2003

Aim:  In this article, we review the functional organization of the peripheral autonomic pathways regulating the vasculature.

Results:  The final motor neurones in vasomotor pathways tend to be smaller than neurones in other autonomic pathways. This suggests that they have relatively smaller target territories and receive fewer pre‐ganglionic inputs than non‐vasomotor neurones. Nevertheless, single vasomotor neurones project to large areas of the vasculature separated by up to 7 mm. Different functional pools of vasomotor neurones project to specific segments of the vasculature, allowing for the selective neural control of resistance in vessels in proximal or distal regions of the vascular bed. In many cases, each functional pool of vasomotor neurones utilizes a characteristic combination of cotransmitters. The various pools of final motor neurones in vasomotor pathways receive convergent synaptic input from different pools of pre‐ganglionic neurones, many of which also contain neuropeptides which enhance the excitability of the final motor neurones. The excitability of vasomotor neurones regulating gastrointestinal and mesenteric blood flow, also can be increased by the actions of peptides such as substance P that are released from visceral nociceptors.

Conclusions:  We propose that autonomic pathways regulating the vasculature are organized into ‘vasomotor units’. Each vasomotor unit consists of a pre‐ganglionic neurone, the final motor neurones it innervates, and the blood vessels that they regulate. The vasomotor units are likely to be grouped into functional pools that can be recruited as necessary to provide highly specific, graded control of blood flow both within and between vascular beds.
High diversity of tropical intertidal zone sponges in temperature, salinity and current extremes
Authors: Barnes David K. A.
Published: March 2003

The wide intertidal zone of the Quirimba Archipelago (Mozambique, East Africa) encompasses many different habitats, which all experience wide environmental variation. Large daily fluctuations in temperature occur when standing water is heated up at low tide to >10°C above ambient. Salinity may be high in the dry season and periodically almost fresh in the wet season. Very high current velocities (≈3 ms−1) may occur and the direction of water flow is often complex. Sponges were a major component of the fauna (and dominate the sessile forms) in most of the eight habitats studied: exposed reef, sheltered reef, sand‐rock, cave, reef boulders, boulders on sand, mangrove swamp and seagrass meadows. The highest number of sponge species occurred in the two reef habitats: from mean values of between ≈2.5 and ≈0.5 species/m2 (upper and lower shore, respectively). The diversity of species present yielded a high Shannon index value of H=2.95 for the total of 33 species. A rank‐abundance plot of the data showed a high level of equitability (J=0.84). Community similarity measurement using Bray–Curtis index showed two clusters; the exposed habitats of the reefs and sand‐rock and the refugia of cave, reef and sand boulders.
Notes and Records
Authors: Kennedy Andrew D.
Published: March 2003

Colophospermum mopane Kirk ex J.Leon (Fabaceae), commonly known as mopane, is an example of a tree species that is heavily browsed by elephants Loxodonta africana (Blumenbach) (
Ben‐Shahar, 1993). Young mopane leaves are favoured by elephants because of their high crude protein content of 17.5% (
Styles & Skinner, 1997). Stems are also browsed on account of their mineral value, particularly of phosphate and calcium (
Van Wyk, 1994). Being semideciduous, the tendency for C. mopane to retain some of its leaves during the dry season is considered crucial to sustaining high elephant populations through this resource‐deficient time of year.
Relative densities and habitat utilization of non‐utilized, terrestrial gamebird populations in a natural savanna, South Africa
Authors: Dörgeloh W. G.
Published: March 2003

The objective of this study was to determine the relative population densities and habitat utilization of gamebird species in relation to plant communities, the amount of ecotone, and vegetation structure. The distribution of five terrestrial gamebird populations was monitored for 12 months in the Nyslvley Nature Reserve, South Africa. Only three species, Swainson's francolin (40.44% of the total gamebird population), crested francolin (10.41%) and guineafowl (43.94%), were found in significant numbers. Group sizes of these gamebird populations were typical for the species. The high amount of edge or ecotone (total amount of edge (DI) = 0.26), the short (9.36 cm) and evenly structured grass layer (mean Foliage Height Diversity (FHD) = 0.38), and a mosaic of open areas and termitaria thickets rendered the Sporobolus ioclados–Acacia tortilis Savanna suitable for gamebirds. The adjacent seasonally inundated floodplain was also utilized to some extent, mainly by Swainson's francolin. It appears that visibility is more important for gamebirds than a high diversity in grass structure. Also, a mosaic of feeding areas and cover makes an area suitable for terrestrial gamebirds. Of the gamebird species found in the reserve, only the Swainson's francolin, crested francolin and guineafowl populations had the potential to be harvested.
Effects of browse availability and quality on black rhino (Diceros bicornis michaeliGroves 1967) diet in Nairobi National Park, Kenya
Authors: Muya S. M. , Oguge N. O.
Published: March 2003

Investigations were conducted to study the effects of browse availability and quality on black rhinoceros (Diceros bicornis michaeliGroves 1967) diet in Nairobi National Park, Kenya, between September 1994 and February 1995. Line intercept method was used to assess availability of browse. The ratios of browsed crowns to the total crown were applied in the estimate of browse use. Proximate analysis and extraction methods were used, respectively, to appraise browse nutritional quality and phytochemical status of twelve species. Thirty‐four plant species were identified as potential black rhino browse, whose availability differed significantly (P < 0.001). Lippia javanica (20.581 ± 3.101, n = 544) and Lannea cornuta (0.963 ± 0.529, n = 544) were the most and least available species, respectively. Only 32 species, however, were utilized, as L. cornuta and Rhynchosia hirta did not show any level of rhino feeding activity. Browse use was found to vary significantly (P < 0.001) during the study period. Grewia similis was most (20.564 ± 2.764, n = 544) and Commelina africana least (0.974 ± 0.974, n = 544) exploited, respectively. Differences in total alkaloids and phenols, crude fibre, crude protein and total ash contents among species investigated were highly significant (P < 0.001). Ether extract values were similar (P= 0.0933) across plant taxa. The study shows that the black rhino is a selective browser feeding on plants with low phenol and alkaloid contents and high fibre values. Of the nutritionally similar species, browsing was driven by availability. These findings suggest that a key habitat factor important in black rhinoceros conservation include diverse plant species with low levels of phenols and alkaloids.
Diet and distribution of elephant in the Maputo Elephant Reserve, Mozambique
Authors: De Boer Willem F. , Ntumi Cornelio P. , Correia Augusto U. , Mafuca Jorge M.
Published: March 2003

The distribution and diet of the elephants of the Maputo Elephant Reserve were studied using dung counts, satellite tracking and faecal analysis. The results were compared with earlier data from before the civil war in Mozambique. The elephant population decreased during the civil war, but 180 animals still remain. Earlier studies described the elephants as preferring the grass plains. Currently, the elephants prefer the dense forest patches over the high quality forage found in the grass plains. Water salinity affected distribution; elephant dung piles were found closer to fresh water in the dry season. A total of 95 different plant species were identified in the faeces. The percentage of grass was relatively low compared with other studies, increasing at the beginning of the rainy season. At the end of the dry season, elephants concentrated on the few available browse species with young leaves, but generally preferred grass species to browse species. Diet composition was mainly affected by season and less by habitat. The elephants have changed their habitat preference in reaction to poaching, and probably increased the contribution of browse species in the diet. The presence of forest patches has been vital for the survival of the elephants.
Mercury in tigerfish (Hydrocynus vittatus, Castelnau), green happy (Sargochromis codringtonii, Boulenger) and kapenta (Limnothrissa miodon, Boulenger) from Lake Kariba, Zimbabwe
Authors: Mhlanga Wilson
Published: March 2003

Concentrations of total mercury were determined in Hydrocynus vittatus (Castelnau), Sargochromis codringtonii (Boulenger), and Limnothrissa miodon (Boulenger) from two localities in Lake Kariba, Zimbabwe.

The mean concentrations of total mercury in H. vittatus from Basin 5 and Basin 2 were 0.08 mg kg−1 and 0.094 mg kg−1, respectively. In S. codringtonii, mean concentrations were 0.004 mg kg−1 and 0.026 mg kg−1 for Basins 5 and 2, respectively. No mercury was detected in L. miodon from Basin 2 while samples from Basin 5 had a mean concentration of 0.069 mg kg−1 (wet weight). Total mercury concentrations were also determined on a dry weight basis.

Within each sampling area, total mercury concentrations were significantly different among species (P < 0.05). For H. vittatus and S. codringtonii, total mercury concentrations (in the same species) were not significantly different between the two localities (P < 0.05).

The factors causing the observed differences in total mercury between similar species from different localities and among different species in the same locality (sampling area) are discussed. From the observed low levels of mercury in all three species, it was concluded that the mercury constituted ‘background levels’. These levels are below the maximum concentrations permissible in human fish foods.
Feeding habits of chimpanzees (Pan troglodytes), red‐tail monkeys (Cercopithecus ascanius schmidti) and blue monkeys (Cercopithecus mitis stuhlmanii) on figs in Budongo Forest Reserve, Uganda
Authors: Tweheyo Mnason , Obua Joseph
Published: March 2003

Feeding habits of chimpanzees, red‐tail and blue monkeys on figs (Ficus) were studied in compartment N3 of Budongo Forest Reserve, western Uganda, from September 1997 to March 1998. The aim was to examine the spatial and temporal foraging habits of chimpanzees, red‐tail monkeys and blue monkeys on figs in the forest reserve. Both scan and focal sampling methods were used to assess the foraging habits of the primates. It was found that the primates fed on emerging leaves of Ficus mucuso Ficalho, F. varifolia Warb. and F. exasperata Vahl. They also preferred ripe fruits to emerging, young and unripe fruits. The primates spent 78% of the morning eating fruits and leaves and inhabited fig trees with fruits for about 4 h. Fig trees with ripe fruits attracted larger numbers of primate groups. It is concluded that information on the feeding habits of chimpanzees and monkeys is required in order to have a clear understanding of the social behaviour and pattern of movement of the primates and to assist in predicting the likely impacts of poor forest management, forest degradation and loss of food resources on their populations.
The effects of fire and grazing pressure on vegetation cover and small mammal populations in the Maasai Mara National Reserve
Authors: Salvatori V. , Egunyu F. , Skidmore A. K. , De Leeuw J. , Van Gils H. A. M.
Published: March 2003

An extensive study of vegetation changes as a consequence of fire and grazing pressure and their effect on small mammal populations inside the Maasai Mara National Reserve, Kenya, was carried out during May–June 1997. Comparison of vegetation maps from 1979 and 1998 suggested that vegetation in 46% of the Reserve area converted from shrubland to grassland, possibly as a result of fire and grazing pressure. We tested the hypothesis that in areas with high fire and grazing impact the population of small mammals was negatively affected. A low density of rodents was recorded in all habitats except in areas of human activity, where artificial resources are constantly present. Capture efforts were unsuccessful in grasslands. Our results confirm those of Norton‐Griffiths (1979) and Dublin (1995), i.e. that fire and grazing pressure impact the vegetation of the Serengeti–Mara ecosystem and limit the natural regeneration of woodlands. This indirectly affects the small mammal community, which is limited in its long‐term establishment.
GPS telemetry of forest elephants in Central Africa: results of a preliminary study
Authors: Blake S. , Douglas‐Hamilton I. , Karesh W. B.
Published: March 2003

Few data exist on the ranging behaviour of forest elephants. A feasibility study on the use of GPS telemetry as a tool to study ranging, seasonal movements and distribution was implemented in the Dzanga‐Sangha and Nouabalé‐Ndoki National Parks Complex of Central African Republic and Congo. The study consisted of two parts – a thorough hand‐held testing of an elephant GPS telemetry collar under tropical forest conditions and the deployment of collars on two elephants. During the feasibility study the system performance was satisfactory; GPS fix acquisition success rate, VHF and UHF collar–researcher communications were adequate. Two elephants, a mature bull and an adult female, were immobilized and fitted with GPS collars in October 1998. After deployment, the female's GPS collar performed well initially, but in less than a month the GPS within the collar stopped acquiring fixes. She was subsequently located using VHF tracking. The male was never relocated strongly suggesting complete failure of the collar. Despite these setbacks, the small amount of data retrieved provide an important first insight into forest elephant ranging and daily activity patterns, with significant conservation implications. When technical difficulties of reliability are overcome, GPS telemetry will provide an exceptionally useful tool in forest elephant research and management.
Hermit crabs, humans and Mozambique mangroves
Authors: Barnes David K. A.
Published: March 2003

There is a complex interrelationship between upper shore hermit crabs (such as Coenobita sp. and Clibanarius sp.), coastal human populations and mangrove forests in Mozambique. The abundance, activity, shell selection and behaviour of three species of hermit crab are related to the level of mangrove cover. With increased density of mangrove trees, the study species of hermit crab changed in abundance, tended to become diurnal, spent more time feeding and were clustered in larger groups when doing so, and selected longer spired shells. All five of the same variables are also linked to the proximity and activity of humans through both direct and indirect actions. Direct effects included a tendency to nocturnal activity with proximity to human activity; indirect effects included increased and more clumped food supplies, and shell middens from intertidal harvesting and deforestation. Mangroves are important to local human populations as well as to hermit crabs, for a wide variety of (similar) reasons. Mangroves provide storm shelter, fisheries and fishery nursery grounds for adjacent human settlements, but they also harbour mosquito populations and their removal provides valuable building materials and fuel. Hermit crabs may be useful (indirectly) to coastal human populations by being a source of food to certain commercial species, and by quickly consuming rotting/discarded food and faeces (thereby reducing disease and pests). They can also cause minor problems to coastal human populations because they use shells of (fisheries) target mollusc species and can be more abundant than the living molluscs, thereby slowing down effective hand collection through confusion over identification. The mixture of positive and negative attributes that the three groups impart to each other in the Quirimba Archipelago, northern Mozambique, is discussed.
Sighting frequency and food habits of the leopard tortoise, Geochelone pardalis, in northern Tanzania
Authors: Kabigumila J.
Published: March 2003

Sighting frequency and food habits of the leopard tortoise (Geochelone pardalis) were studied in northern Tanzania from October 1993 to June 1996. Sighting frequency varied significantly between protected (0.22 mhr−1) and unprotected sites (0.59 mhr−1), and between Arusha (0.27 mhr−1) and Serengeti sites (0.56 mhr−1).

The tortoise diet comprised mostly plants (97.8%) and rarely inorganic matter (2.2%). A total of 47 plant species from 21 families was eaten. Forbs made up 74.5% of the plant items and monocots the remainder. Succulents contributed 51.0% of the plant items eaten while grasses and legumes accounted for 16.8% and 13.5%, respectively. Some plant items were eaten more frequently than their occurrence in the habitats.
Introduction of giraffe changes acacia distribution in a South African savanna
Authors: Bond William J. , Loffell Debbie
Published: March 2003

Large mammal herbivores can have significant effects on the structure and composition of plant communities. We studied the impacts of an introduced giraffe population on Acacia species at Ithala Game Reserve in South Africa. Browse intensity and Acacia mortality were assessed in field transects, and in road transects covering the reserve road network. Several Acacia species occurring in high‐density giraffe areas had high levels of mortality. Populations of Acacia davyi were extinct in areas accessible to giraffe. Most A. caffra trees within giraffe browse height were dead and A. karroo, the most common species, was also heavily affected. Some species, including A. tortilis, showed no or very low mortality attributable to giraffe browsing. Healthy populations of sensitive species occurred in areas within, and adjacent to, the reserve in areas with low or no giraffe browsing. Areas too steep for giraffe access formed spatial refuges for these trees. The differential mortality that is occurring as a consequence of giraffe browsing is altering species composition and species distribution in this savanna landscape.
Aspects of the feeding habits and reproductive biology of the Ghana mole‐rat Cryptomys zechi (Rodentia, Bathyergidae)
Authors: Yeboah S. , Dakwa K. B.
Published: March 2003

The feeding habits and reproductive biology of the Ghana mole‐rat, Cryptomys zechi (Matchie), were studied in a Guinea savanna woodland in Ghana.

Both tunnel contents and stomach content analysis indicated that bulbs and tubers constituted the commonest and most preferred food items, although some animal food materials were also consumed.

Five plant species, Urgenia altissima, Manihot utilisima, Curuligo sp., Oxalis corniculata and Archis hypogea, were the most popular plant food source.

Breeding occurred during the rainy season (March–August) and was at its peak in July. There is evidence that the species is capable of producing two litters in a year.

In a colony, reproduction is restricted to one female and one male. Males reached sexual maturity at a lower body weights (105 g) than females (155 g).

Estimated mean litter size was 1.5 (range 1–2), the smallest among the bathergids. Available data on birth weights of three other species of social Cryptomys indicate that C. zechi has the highest birth weight, which is comparable to that of solitary bathyergids.
Demography of lions in relation to prey and habitat in the Maasai Mara National Reserve, Kenya
Authors: Ogutu J. O. , Dublin H. T.
Published: March 2003

We studied lion demography in the Maasai Mara National Reserve between September 1990 and April 1992, with a special emphasis on the spatial and seasonal variation in demographic characteristics. Lion density (0.2–0.4 lions km−2) and pride size (range 8–48) were high because of a high resident prey biomass (10 335 kg km−2) augmented by migrant prey to 26 092 kg km−2 in the dry season. Overall, their sex ratio was almost at parity and varied neither spatially nor seasonally. Sex ratio was even among subadults but skewed toward males and females among cubs and adults, respectively. This implies an increasing differential mortality of males with age through subadulthood. The age ratio varied seasonally because of a birth peak in March–June and an influx of subadults into the reserve during July–August, coincident with increases in migrant prey. The birth peak was apparently preceded by another peak in mating activity falling between November and May. Further research should investigate the precise causes of the biased cub sex ratio, low lion density in the Mara Triangle and the higher ratio of subadults in Musiara than in the Mara Triangle or Sekenani.
The histology of mature gonads of Oreochromis (Nyasalapia) karongae (Trewavas)
Authors: Msiska O. V.
Published: March 2003

Histology of gonads of Oreochromis karongae was undertaken to study internal cell characteristics during maturation. This study was necessitated by low spawning output of the fish species. Several oocyte stages, ranging from primary forms to vitellogenesis, suggest that the maturation was generally succesfully attained in the fish ponds. Pre‐vitellogenesis oocytes (oogonia to perinuclear stage) and more advanced vitellogenesis (primary vesicle to tertiary yolk vesicle) oocyte stages were all found in the same gonads. However, there were some discontinuities observed during stages 3 and 4, suggesting selective maturation. Failure of gonads to mature normally is attributed to an ecological crunch that was in a previous study associated with environmental factors. Atretic oocytes were also recorded in the same gonads, a sign that some oocytes failed to mature normally. This indicates insufficient stimuli for normal gonad development. Several stages of spermatogenesis (spermatocytes, spermatid and spermatozoa) were also found in the same gonads. Selective recrudescence was more pronounced in O. karongae because generally less oocytes attained final maturation stages compared to Oreochromis niloticus and other tilapias. This could be the main reason for low natural breeding that has been observed in both wild and captive stocks, and led to the abandonment of its use in aquaculture. This study corroborates findings of previous studies that depended solely on external gonad characteristics. Histology provides conclusive evidence from internal cell characteristics that other techniques are unable to show.
Helicobacter pylori infection from pathogenesis to treatment – a critical reappraisal
Authors: Vaira D. , Holton J. , Ricci C. , Basset C. , Gatta L. , Perna F. , Tampieri A. , Miglioli M.
Published: March 2003

The main areas of this review are Helicobacter pylori and disease pathogenesis; the relationship of H. plyori to lower gastrointestinal diseases, liver disease and extra‐gastrointestinal conditions; the relationship of H. plyori to gastro‐oesophageal reflux disease; infection in the very young and very old; diagnostic techniques; and management of H. plyori infections with particular emphasis on eradication regimens and antibiotic resistance.
Iron absorption in patients with Zollinger–Ellison syndrome treated with long‐term gastric acid antisecretory therapy
Authors: Stewart  , Termanini  , Sutliff  , Serrano  , Yu  , Gibril  , Jensen
Published: March 2003

Background:

Gastric acid secretion is important for absorption of dietary non‐haem iron, and iron deficiency is common in gastric hyposecretory states such as after gastric resection. It is not known if prolonged, continuous treatment with potent acid suppressants such as omeprazole will lead to iron deficiency or lower body iron stores.

Aim:

To assess iron stores and the occurrence of iron deficiency anaemia in patients with Zollinger–Ellison syndrome (ZES) treated long‐term with gastric antisecretory drugs.

Methods:

One hundred and nine patients with ZES but without previous gastric resections were studied. All patients underwent assessment of acid control on antisecretory agents, determination of tumour extent, evaluation of haematological parameters (Hct, haemoglobin, WBC, MCV, MCHC), and determination of serum iron parameters (iron, ferritin, transferrin, iron/transferrin ratio). Acid control values for the last 4 years were reviewed, the presence or absence of acid hyposecretion determined using three different criteria and this result correlated with haematological and iron parameters.

Results:

Eighty‐nine patients were taking omeprazole, nine patients were taking histamine H2‐antagonists and 11 patients were taking no drugs following curative resection. The mean duration of omeprazole treatment was 5.7 years (range 0.7–12.5 years) and total duration of any treatment was 10.1 years (range 0.7–21 years). Acid hyposecretion was present by at least one criterion in 45% of patients. There were no significant differences between patients with or without acid hyposecretion, taking or not taking omeprazole, having different durations of omeprazole treatment or different durations of total time receiving any antisecretory treatment, for any serum iron parameter, haematological parameter, or for the frequency of iron deficiency. Males and females did not differ in percentage with low ferritin levels or percentage with iron deficiency.

Conclusions:

Continuous treatment with omeprazole for 6 years or continuous treatment with any gastric antisecretory drug for 10 years does not cause decreased body iron stores or iron deficiency. These results suggest that, in contrast to recent results which show yearly monitoring of vitamin B12 in such patients is needed, such monitoring for iron parameters is not necessary.
Patterns of food and acid reflux in patients with low‐grade oesophagitis—the role of an anti‐reflux agent
Authors: Washington  , Steele  , Jackson  , Washington  , Bush
Published: March 2003

Background:

Food and acid have been shown to be refluxed independently of each other in healthy volunteers, and anti‐reflux agents decrease the reflux of both parameters. Until now this phenomenon had not been studied in patients with low‐grade oesophagitis, who are the group most likely to use anti‐reflux medication.

Aim:

To assess patterns of gastro‐oesophageal reflux of acid and food in 12 ambulant patients with endoscopically proven oesophagitis of between grades I and II, but who were otherwise healthy. Also to assess the effectiveness of a single dose of an alginate‐containing anti‐reflux agent in controlling food and acid reflux in this patient group.

Methods:

Oesophageal pH monitoring and external ambulatory gamma detection were used to study food and acid reflux. A pH electrode was positioned 5 cm above the cardia and the gamma detector was positioned externally over the pH electrode. The patients then received a technetium‐99m labelled meal designed to provoke reflux. Thirty minutes later the patients were given a 20 ml dose of alginate (Liquid Gaviscon), or 20 ml of tap water. Incidence of reflux was monitored for approximately 4 h from the end of the meal. Allocation to treatment group was randomized, with patients receiving the alternative treatment on the second study day after approximately a 7‐day washout period.

Results:

The mean percentage time oesophageal pH remained below 4 was 16.3 min for the control group and 5.4 min for the treatment group (P=0.03). Food reflux was detected 23.7% of the time in the control group compared to 12% of the time in the treatment group (P=0.02). The anti‐reflux agent was also successful in decreasing the number of events, but the duration of the reflux events was not significantly different.

Conclusions:

Patients with grades I and II oesophagitis reflux food and acid independently, and are predominantly either food refluxers or acid refluxers, but not both. Liquid alginate decreases the number of both food and acid reflux events, but does not change their duration.
The effect of rectally administered steroids on bone turnover: a comparative study
Authors: Robinson  , Iqbal  , Wolfe  , Patel  , Abrams  , Mayberry
Published: March 2003

Background:

Oral glucocorticoids contribute significantly to the risk of osteoporosis in patients with inflammatory bowel disease. Less well established are the effects of rectally administered steroids on bone metabolism.

Aim:

To investigate the effects of two widely used rectal foam preparations (prednisolone metasulphobenzoate and hydrocortisone acetate) on biochemical markers of bone turnover.

Methods:

Twenty‐four patients with active inflammatory bowel disease randomly received a standard course of either prednisolone metasulphobenzoate or hydrocortisone acetate for 2 weeks. Biochemical markers of bone turnover were measured before, during and after treatment. Bone formation markers measured were serum osteocalcin (BGP) and bone‐specific alkaline phosphatase (BALP). Urinary deoxypyridinoline (DPD) was measured to assess bone resorption.

Results:

Disease activity scores improved during treatment (difference in mean Powell–Tuck score = 3.4, 95% CI: 2.0–4.8, P < 0.0001) and were similar in both hydrocortisone and prednisolone‐treated groups. There was no significant reduction in BALP or BGP during treatment with either steroid preparation, and urinary DPD did not change significantly during treatment.

Conclusions:

During a 2‐week course of rectal hydrocortisone acetate or prednisolone metasulphobenzoate, there was no significant change in biochemical markers of bone formation or resorption. These results suggest that pharmacological doses of rectal steroid foam preparations do not significantly impair bone turnover in patients with inflammatory bowel disease.
Omeprazole and sucralfate in the treatment of NSAID‐induced gastric and duodenal ulcer
Authors: Porro G. Bianchi , Lazzaroni  , Manzionna  , Petrillo
Published: March 2003

Aim:

To establish the healing efficacy of two drugs, omeprazole and sucralfate, when given to patients who had developed gastric or duodenal ulcer while undergoing chronic treatment with non‐steroidal anti‐inflammatory drugs (NSAIDs).

Methods:

Ninety‐eight patients with arthritis or arthrosis and NSAID‐related gastric or duodenal ulcer were admitted to the endoscopic, single‐blind study. They were randomized to receive either omeprazole 20 mg o.m. or sucralfate 2 g b.d. for 4–8 weeks. The patients continued to receive the same NSAID during the trial. Upper gastrointestinal endoscopy was performed at entry and after 4 or 8 weeks.

Results:

Eighty‐eight patients completed the 4‐week study, but only 81 were available for final analysis at 8 weeks. Omeprazole was significantly superior to sucralfate in inducing gastric ulcer healing after both 4 (87 vs. 52%, P = 0.007) and 8 weeks (100 vs. 82%, P = 0.04). No statistically significant difference in duodenal ulcer healing rates emerged between the two groups either at 4 (79 vs. 55%) or 8 weeks (95 vs. 73%). The healing rates in patients with combined gastric and duodenal ulcer were 67 vs. 33% after 4 weeks and 67 vs. 67% after 8 weeks of treatment. The percentages of asymptomatic patients were similar in the two treatment groups both at 4 (70 vs. 73%) and 8 weeks (70 vs. 75%). H. pylori infection did not influence healing rates, but significantly more H. pylori‐positive patients healed with omeprazole.

Conclusions:

The results of this study show that omeprazole is superior to sucralfate in healing NSAID‐induced gastroduodenal ulcer in patients who continue to take anti‐inflammatory drugs. The good results observed were unrelated to H. pylori status.
One‐week triple therapy using omeprazole, amoxycillin and clarithromycin for the eradication of Helicobacter pylori in patients with non‐ulcer dyspepsia: influence of dosage of omeprazole and clarithromycin
Authors: Bigard  , Delchier  , Riachi  , Thibault  , Barthelemy
Published: March 2003

Background:

Triple therapy based upon omeprazole, amoxycillin and clarithromycin for 7 days is the reference treatment used in France for the eradication of Helicobacter pylori. However, optimal dosages of omeprazole and clarithromycin have not been determined.

Aim:

To compare four eradication regimens using this treatment in patients with non‐ulcer dyspepsia.

Methods:

Two hundred and seventy‐four patients with symptoms of dyspepsia, normal upper GI endoscopy and a positive urease test were included in the study. A 13C‐urea breath test (UBT) was obtained before and 6 weeks after treatment. Patients were randomized to one of the following 7‐day regimens: 20 mg omeprazole o.m. plus amoxycillin 1000 mg b.d. plus clarithromycin 250 mg b.d. (O20AC500) or 20 mg omeprazole o.m. plus amoxycillin 1000 mg b.d. plus clarithromycin 500 mg b.d. (O20AC1000) or 20 mg omeprazole b.d. plus amoxycillin 1000 mg b.d. plus clarithromycin 250 mg b.d. (O40AC500) or 20 mg omeprazole b.d. plus amoxycillin 1000 mg b.d. plus clarithromycin 500 mg b.d. (O40AC1000). Compliance was assessed by returned tablet counts. Eradication was defined as conversion from positive 13C‐UBT at entry to negative 13C‐UBT 6 weeks after cessation of therapy.

Results:

Two hundred and fifty‐eight patients were included in the intention‐to‐treat (ITT) analysis. From the least to the most effective regimen, eradication rates were: O20AC1000: 60.0% (95% CI: 47.6–72.4), O20AC500: 64.1% (52.3–75.8), O40AC1000: 64.2% (52.7–75.7), O40AC500: 74.6% (64.2–85.0) (N.S.). Overall compliance was good in 92% of patients. The most frequent adverse events were diarrhoea and taste impairment, occurring mainly in the high‐dose clarithromycin groups.

Conclusions:

Eradication rates obtained in this study were lower than those expected on the basis of previously reported studies. This study supports the use of a double dose of omeprazole, although the difference between groups was non‐significant, but provides no argument in favour of a high dose of clarithromycin.
Localization of the β(beta)3‐adrenoceptor in the human gastrointestinal tract: an immunohistochemical study
Authors: Anthony  , Schepelmann  , Guillaume  , Strosberg  , Dhillon  , Pounder  , Wakefield
Published: March 2003

Background:

Activation of human and non‐human colonic β(beta)3‐adrenoceptors causes smooth muscle relaxation. β3‐Adrenoceptor agonists protect against experimental indomethacin‐induced jejunal ulceration. The mechanism of protection may involve spasmolytic/vasodilatory agonist activity. The precise localization of β3‐adrenoceptors in the human gut is not known.

Aim:

To localize the β3‐adrenoceptor within the human gastrointestinal tract using the immunohistochemical technique.

Methods:

Human β3‐adrenoceptors were immuno‐localized in paraffin sections of human oesophagus (OS), stomach (ST), duodenum (DU), ileum (IL), sigmoid colon (SC), rectum (R) and gall‐bladder (GB) using the rabbit polyclonal antibody anti‐P12. Staining was graded +++, ++, + and 0. Immunostaining of SC was also done with pre‐incubation of anti‐P12 with P12 peptide. Western blotting of anti‐P12 on human and murine IL and SC isolated membrane proteins was performed.

Results:

All epithelia, vascular endothelial cells and ganglia scored 0. Smooth muscle of the vasculature, muscularis propria, muscularis mucosae and mucosa was graded, respectively, as follows; OS (+++, +++, +++,‐), ST (++, +++, ++, ++), DU (++, +++, +++, +), IL (++, ++, ++, +), SC (+++, ++, ++, ++), R (++, ++, +, +), GB (+++, +++, –, 0). Pre‐incubation of anti‐P12 with P12 peptide almost abolished SC smooth muscle positivity. Western blot analysis using anti‐P12 on human, but not murine, IL and SC membrane proteins revealed a single 55 kDa band, a size consistent with the predicted size of a partially glycosylated form of the human β3‐adrenoceptor.

Conclusions:

This immunohistochemical study has localized the β3‐adrenoceptor to vascular and non‐vascular smooth muscle in the human gastrointestinal tract. These findings support a role for the β3‐adrenoceptor in the control of blood flow and motility in the human gastrointestinal tract.