Biomedical subjects

G Grant

Publications and source records attributed to G Grant.

At least 109 records · Page 6Linked to original sources

PubMed1995

Inhibition of starch digestion by alpha-amylase inhibitor reduces the efficiency of utilization of dietary proteins and lipids and retards the growth of rats.

Digestion/absorption and nutritional utilization of starch, protein and lipids were studied in rats fed diets containing purified kidney bean alpha-amylase inhibitor at levels of 0, 1.6, 3.3 and 6.6 g/kg diet. At the two higher levels, the growth rate of rats and the apparent digestibilities and utilization of dietary starch and protein were significantly less than in control rats, and losses of nitrogen, lipids and carbohydrate resulted in a significant reduction in dry body weight. Some organs of the body were also affected: the relative dry weights of the intestines and the pancreas were higher, whereas liver and thymus weights were lower than in control rats. As starch digestion in the small intestine was negligible at higher inhibitor concentrations, the cecum was practically blocked by solidified digesta. This effect and the ensuing bacterial fermentation stimulated the growth of this tissue by hyperplasia and hypertrophy. However, as the distension was not always sufficient, the organ was occasionally ruptured and the rats had to be killed. Inhibitor doses in this work were comparable to those in clinical studies, implying that the use of the inhibitor is not without health risks. Moreover, diets rich in alpha-amylase inhibitor such as those containing transgenic plants with high levels of inhibitor gene expression cannot be recommended in intensive animal production.

Animals↗

PubMed1995

The utilization of lupin (Lupinus angustifolius) and faba bean globulins by rats is poorer than of soybean globulins or lactalbumin but the nutritional value of lupin seed meal is lower only than that of lactalbumin.

The effects of dietary sweet lupin (Lupinus angustifolius, Unicrop) seed meal or its insoluble fiber (nonstarch polysaccharides + lignin) on performance, digestibility and nitrogen utilization in growing rats were studied in four experiments. Globulin proteins isolated from lupin, faba bean (Vicia faba L. minor) or soybean (Glycine max) were also incorporated into purified diets as replacements for lactalbumin (control) and the nutritional effects were evaluated. Isocaloric, legume-based diets supplemented with amino acids were used. Final weight gain, gain:feed ratios, nitrogen retention and net protein utilization of the animals fed whole lupin meal-based diets for 10 d were inferior to those of controls. In contrast, adding lupin insoluble fiber to a control diet produced no adverse effects. Ileal starch and apparent nitrogen digestibilities, and fecal digestibility of starch in lupin-fed rats were higher than those of controls, but fecal true nitrogen digestibility was lower. Replacement of lactalbumin with globulin proteins from lupin or faba bean depressed food intake and protein utilization, but only performance was affected by consumption of soybean globulins. Rats consuming lupin or faba bean globulins excreted significantly more nitrogen, particularly as urea through the urine. This did not occur in rats fed soybean globulins. Urea concentration in plasma was higher in rats fed diets containing lupin meal or legume globulins. The concentrations of urea, arginine and ornithine in plasma increased significantly compared with control values after 3 to 9 h of a lupin diet. After 9 h, plasma lysine was also decreased. We concluded that the main reasons for the low nutritional value of sweet lupin seed meal are likely to be related to the chemical structure of the globulin proteins and their adverse effects on growth and nitrogen metabolism, and not to any known antinutritional factor or poor digestibility.

Amino Acids↗

PubMed1995

Developing a typology of family care: implications for nurses and other service providers.

The meanings attributed to the concept of care are considered. It is argued that whilst nursing has paid considerable attention to care in a professional (nursing) context, it has virtually ignored care as it is defined and construed by family carers. A new typology of family care is described which builds on the limited existing conceptual work in this area. It is further suggested that interventions which are intended to assist carers form a continuum ranging from services which are facilitative to those which are actually obstructive. In the light of these discussions, the implications of the new typology for nurses working with family carers are addressed briefly.

Caregivers↗

PubMed1995

Purified Pseudomonas aeruginosa PA-I lectin induces gut growth when orally ingested by rats.

The effects of PA-I lectin isolated from the human pathogen Pseudomonas aeruginosa upon cellular metabolism in vivo have been studied using the rat gut as a model system. Orally ingested PA-I lectin stimulated metabolic activity and induced polyamine accumulation and growth in the small intestine, caecum and colon. The nature and extent of the changes induced by PA-I lectin were similar to those caused by dietary kidney bean lectin and were likely to lead to impaired epithelial cell function and integrity. This finding contributes to our understanding of the possible roles of these lectins in Pseudomonas aeruginosa infection.

Adhesins, Bacterial↗

PubMed1995

Salmonella typhimurium and Salmonella enteritidis induce gut growth and increase the polyamine content of the rat small intestine in vivo.

The effects of infection by Salmonella enteritidis and S. typhimurium on the small and large intestines, liver, spleen and mesenteric nodules of rats were studied in vivo. Both Salmonella serotypes persisted and proliferated in the gastrointestinal tract and invaded sub-epithelial tissues, mainly the ileum, leading to the systemic distribution of these pathogens. Coincidental with infection, the rate of crypt cell proliferation increased resulting in substantial growth of the small intestine. The extent of this and the accompanying accumulation of polyamines was particularly dramatic in the ileum where there was also some disruption of the villus epithelium. It is possible that these effects of the infection on the metabolism and morphology of the small bowel, which strongly resembled the changes induced by some plant lectins, may facilitate the colonisation and invasion of the gut by Salmonellae.

Animals↗

PubMed1995

Reversible effect of phytohaemagglutinin on the growth and metabolism of rat gastrointestinal tract.

The lectin, phytohaemagglutinin, present in beans survives passage through the gastrointestinal tract in a biologically and immunologically intact form. It is known that by binding to the brush border membranes of the small intestine phytohaemagglutinin induces its hyperplastic growth. However, its effect on the other parts of the gut are not known. This study considered the dose and time dependent changes in the gastrointestinal tract exposed to phytohaemagglutinin. Lectin binding was detected by polyclonal antibodies using PAP staining to the surface and the parietal cell region of the stomach, the brush border epithelium of the small intestine and to the surface membrane of the caecum and colon. To characterise the metabolic changes in the gut organ weights, protein, RNA, DNA, and polyamine contents were measured. While phytohaemagglutinin induced a dose and time dependent growth of the small intestine by lengthening the tissue and thickening the gut wall by increasing the number of crypt cells, the lectin also changed the size and metabolism of the large intestine and pancreas, but this growth was by hypertrophy. Phytohaemagglutinin in the diet influences the size, metabolism, and function of the entire digestive tract. The lectin induced changes were fully or partially reversed within three days.

Animals↗

PubMed1995

Growth factor effects on the expression of collagenase and TIMP-1 in periodontal ligament cells.

The fibroblast is a prominent cellular component of the periodontal ligament. It is believed to play an important role in collagen metabolism in health and disease. The turnover of collagen in the periodontal ligament is believed to be controlled by the balance between collagen synthesis and degradation. The family of matrix metalloproteinases and their inhibitors is one of the mechanisms which regulates this balance. The factors that regulate the synthesis of collagenase and its inhibitor, TIMP-1, by the periodontal ligament cell are poorly understood. The present study was undertaken to assess the effect of interleukin-1 beta (IL-1 beta), platelet-derived growth factor (PDGF), and transforming growth factor-beta 1 (TGF-beta) on the expression of collagenase (MMP-1) and TIMP-1 mRNA in periodontal derived fibroblasts using reverse transcription polymerase chain reaction (RT-PCR). Early passage periodontal ligament derived fibroblasts were treated with IL-1 beta (10 and 100 pg/ml), two isoforms of PDGF, -AA and -BB (4 and 20 ng/ml) and TGF-beta (1 and 10 ng/ml). Treatment with growth factors from 2 to 24 hours revealed that the largest effects on MMP-1 mRNA occurred after 24 hours. IL-1 beta induced a 5 to 9 fold increase in MMP-1 mRNA. The two isoforms of PDGF had less of an effect (3 to 5 fold) on MMP-1 mRNA whereas TGF-beta induced a 25 to 50% decrease in the expression of this message. None of the growth factors had an effect on TIMP-1 mRNA expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Becaplermin↗

PubMed1995

Responses of neurons in the central cervical nucleus of the rat to proprioceptive and vestibular inputs.

Activity of neurons in the central cervical nucleus (CCN) was recorded extracellularly in decerebrate, immobilized rats. Neurons were identified by their antidromic response to electrical stimulation of the contralateral superior cerebellar peduncle. Stimulation of the ipsilateral dorsal neck muscles (m. biventer cervicis and complexus [BCC]; m. splenius [S]) by a single electric pulse evoked a short-latency (approximately 1 ms) excitatory response in the majority of CCN neurons. The response was usually followed by a period of inhibition of the resting discharge (approximately 20 ms). Stimulation of the contralateral BCC or S usually produced only inhibition of the resting discharge (approximately 20 ms). Mechanical stretching of BCC or S resulted in activation (about 100% increased firing rate) of the ipsilateral CCN neurons, lasting for the duration of the stretch. A pronounced dynamic component, i.e. an extra-excitation at the beginning of the stretch and inhibition after termination of the stretch, was also observed. Stroking and pinching of the skin in the neck region affected the tested CCN neurons, while cutaneous stimuli at other sites of the body were inefficient. Stimulation of the vestibular receptors was performed in two ways. (i) Unilateral galvanic stimulation of the labyrinths by constant current pulses through the external acoustic meatus affected all CCN neurons tested. Contralateral stimulation with negative current was found to be most efficient; it produced excitation followed by inhibition. (ii) Natural vestibular stimulation was performed by rotating the animal in the transverse plane (roll, +/- 10 degrees) or the sagittal plane (pitch, +/- 5 degrees). Sinusoidal movements (0.5-1 Hz) or trapezoid movements were applied. Sinusoidal roll tilt evoked responses in all neurons tested, with a peak discharge during contralateral rolling or at the moment of transition from the ipsi- to contralateral position. All tested CCN neurons also responded statically to roll tilt, i.e. their tonic activity increased with up to 65%, of which the majority (80%) responded in the continuously maintained contralateral roll tilt position compared to the ipsilateral. Sinusoidal pitch tilt also affected all tested neurons, although the reaction was smaller than compared to roll. They usually responded by increasing their firing rate when moving towards the nose-down position. A static response (40-60% difference in the firing rate between the extreme pitch positions) was observed in some neurons. No tested neurons showed any clear rhythmic modulation during either spontaneous or induced, real or fictive locomotion.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

PubMed1995

Consumption of diets containing raw soya beans (Glycine max), kidney beans (Phaseolus vulgaris), cowpeas (Vigna unguiculata) or lupin seeds (Lupinus angustifolius) by rats for up to 700 days: effects on body composition and organ weights.

Feeding trials have been done with rats to assess the effects of long-term (700 d) consumption of diets based on raw cowpeas (Vigna unguiculata; moderate Bowman-Birk inhibitor content, low lectin content), lupin seeds (Lupinus angustifolius; low lectin and protease inhibitor content) or soya beans (Glycine max; high Kunitz inhibitor content, moderate Bowman-Birk inhibitor content, moderate lectin content) or diets containing low levels of raw kidney bean (Phaseolus vulgaris; high lectin content, low Bowman-Birk inhibitor content) on body weight and composition and organ weights. All the legume-based diets reduced feed conversion efficiency and growth rates during the initial 250 d. However, after 250 d the weight gains by rats given legume-based diets were similar to those of controls given the same daily feed intake. Long-term consumption of diets containing low levels of kidney bean significantly altered body composition of rats. The levels of lipid in the body were significantly reduced. As a result, carcasses of these rats contained a higher proportion of muscle/protein than did controls. Small-intestine relative weight was increased by short- and long-term consumption of the kidney-bean-based diet. However, the increase in relative pancreatic weight observed at 30 d did not persist long term. None of the other legume-based diets caused any significant changes in body composition. However, long-term exposure to a soya-bean- or cowpea-based diet induced an extensive increase in the relative and absolute weights of the pancreas and caused an increase in the incidence of macroscopic pancreatic nodules and possibly pancreatic neoplasia. Long-term consumption of the cowpea-, kidney-bean-, lupin-seed- or soya-bean-based diets by rats resulted in a significant increase in the relative weight of the caecum and colon.

Animal Feed↗

PubMed1994

Decreased GABA immunoreactivity in spinal cord dorsal horn neurons after transient spinal cord ischemia in the rat.

The number of GABA-like immunoreactive (LI) cells in lamina I-III of the rat spinal cord was significantly decreased bilaterally 48-72 h after photochemical induction of transient spinal cord ischemia compared to sham-operated controls. No significant changes in the number of GABA-LI cells were observed at cervical level. The number of GABA-LI cells was restored 2 weeks after ischemia. These data, together with recent behavioral and electrophysiological findings, suggest that decreased intraneuronal GABA levels after spinal cord ischemia may underlie the development of the temporary pain-like response to innocuous mechanical stimuli (allodynia) in rats after transient spinal cord ischemia.

Animals↗

PubMed1994

Course of spinocerebellar axons in the ventral and lateral funiculi of the spinal cord with projections to the anterior lobe: an experimental anatomical study in the cat with retrograde tracing techniques.

The fiber course of the spinocerebellar tracts in the ventral and lateral funiculi of the cat spinal cord were studied by a new approach, making cordotomies at different spinal levels or lesions of the restiform body followed by injections of HRP or WGA-HRP into the anterior cerebellar lobe. The retrogradely labeled axons showed characteristic distribution patterns related to the level and extent of the lesions. The results show the following. 1) The dorsal spinocerebellar tract (DSCT) originating ipsilaterally from the thoracic and upper lumbar segments ascends in the dorsolateral fasciculus. It undergoes a dorsal shift during its rostral course. The tract is topically arranged and passes through the restiform body. 2) The ventral spinocerebellar tract (VSCT) arising contralaterally from lower thoracic, lumbar, and more caudal segments passes via the ventral funiculus and ascends in the ventrolateral fasciculus. This tract is also topically arranged. It makes a lateral and then a dorsal shift during its ascending course. The main portion of the VSCT enters the cerebellum via the superior cerebellar peduncle. A minor portion originating from the sacrococcygeal region enters via the restiform body. 3) The spinocerebellar fibers originating ipsilaterally from the cervical enlargement ascend in the lateralmost part of the lateral funiculus in the area between the dorsolateral and ventrolateral fasciculi. These fibers form two groups, one passing through the restiform body, the other through the superior cerebellar peduncle. 4) The spinocerebellar fibers originating contralaterally from the central cervical nucleus pass through the ventral funiculus and ascend in the lateralmost part of the lateral funiculus, mainly in the ventrolateral fasciculus. Most of the fibers seem to pass through the superior cerebellar peduncle.

Animals↗

PubMed1994

Protection against focal cerebral ischemia following exposure to a pulsed electromagnetic field.

There is evidence that electromagnetic stimulation may accelerate the healing of tissue damage following ischemia. We undertook this study to investigate the effects of low frequency pulsed electromagnetic field (PEMF) exposure on cerebral injury in a rabbit model of transient focal ischemia (2 h occlusion followed by 4 h of reperfusion). PEMF exposure (280 V, 75 Hz, IGEA Stimulator) was initiated 10 min after the onset of ischemia and continued throughout reperfusion (six exposed, six controls). Magnetic resonance imaging (MRI) and histology were used to measure the degree of ischemic injury. Exposure to pulsed electromagnetic field attenuated cortical ischemia edema on MRI at the most anterior coronal level by 65% (P < 0.001). On histologic examination, PEMF exposure reduced ischemic neuronal damage in this same cortical area by 69% (P < 0.01) and by 43% (P < 0.05) in the striatum. Preliminary data suggest that exposure to a PEMF of short duration may have implications for the treatment of acute stroke.

Animals↗

PubMed1994

Transganglionic transport and binding of the isolectin B4 from Griffonia simplicifolia I in rat primary sensory neurons.

The isolectin B4 from Griffonia simplicifolia I binds to a subpopulation of rat small-diameter dorsal root ganglion neurons, and to fibres and presumed terminals in laminae I-II of the spinal cord dorsal horn. In the present study we investigated B4 and B4 conjugated to horseradish peroxidase as potential transganglionic tracers of somatic primary afferent neurons after injection into a peripheral nerve. We also tried to identify the specific subpopulation of dorsal root ganglion neurons that bind and ganglion neurons that bind and transport B4. Following injection of B4 or B4-horseradish peroxidase into the sciatic nerve, labelled presumed terminals that reached peak labelling at two days were found exclusively in regions of the spinal cord gray matter known to receive unmyelinated primary afferent fibres. Almost all dorsal root ganglion cells that transported B4-horseradish peroxidase also bound B4. Cell counts showed that 51% of the dorsal root ganglion neurons were B4-positive and cell area measurements that these were all in the small size range. An extensive overlap was found between B4 and fluoride-resistant acid phosphatase (85%), and between B4 and calcitonin gene-related peptide (59%). Seventeen per cent of the B4-positive cells were substance P-immunoreactive and 9% were immunoreactive to somatostatin. Minimal overlap was seen between B4-positive cells and cells positive for RT97 (3%), a selective marker of primary afferent neurons with myelinated axons. All somatostatin-immunoreactive cells and almost all (95%) of the fluoride-resistant acid phosphatase-positive cells were contained within the B4-positive population. This comprised also 58% of the cells immunoreactive to calcitonin gene-related peptide and 42% of those immunoreactive to substance P. The results obtained show that B4 binds to a subpopulation of unmyelinated primary afferent neurons, and that B4 and B4-horseradish peroxidase can be used as selective transganglionic tracers of this specific cell subpopulation.

Animals↗

PubMed1994

The intestinal true absorption of 65Zn in rats is adversely affected by diets containing a faba bean (Vicia faba L.) nonstarch polysaccharide fraction.

The effects on the absorption of 65Zn by two varieties of raw faba bean (Vicia faba L., minor) or seed components that may interfere with mineral metabolism in the gut, have been studied in growing rats. In bean diets all protein was supplied by the meals, and the fractions were tested by incorporating them in control diet at the same levels as they occur in the seeds. Absorption of 65Zn was also measured in rats fed dephytinized bean meal produced by including phytase in the diet. Rats were pair-fed diets supplemented with amino acids and minerals to target requirements and containing 40 mg Zn/kg diet. True absorption of Zn was 50-70% lower in rats fed diets containing both cultivars of faba bean meals than in those fed the control diet. Although soluble nonstarch polysaccharides caused a significant reduction in the absorption of Zn, this effect disappeared after the removal of phytate by demineralization. In contrast, despite its negligible content of phytate, the insoluble nonstarch polysaccharides in the cell wall fraction of the cotyledon accounted for most of the reduction in Zn absorption in rats fed the faba bean diets. Addition of phytic acid to the control diet significantly reduced the absorption of 65Zn but only from 44 to 36%. Moreover, the increase in the absorption of Zn was similarly small, from 21% to 29%, with the addition of phytase to the faba bean diet.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Phytase↗

PubMed1994

The significance of anterior chamber depth in Fuchs' corneal dystrophy and cornea guttata.

It is sometimes claimed that a relationship exists between Fuchs' dystrophy and angle closure glaucoma and that this is an indication for the simultaneous performance of keratoplasty and cataract extraction in patients with Fuchs' dystrophy. If such a relationship exists, then the anterior chamber depth in Fuchs' dystrophy should resemble that in angle closure glaucoma and a significant degree of cornea guttata might be expected to be common in angle closure glaucoma. In 88 patients with angle closure glaucoma we found that the anterior chamber depth was significantly shallower than in cornea guttata or Fuchs' dystrophy for acute (p < 0.001), chronic (p < 0.002) or incipient angle closure glaucoma (p < 0.001). Cornea guttata and Fuchs' dystrophy were very infrequent in these patients with angle closure, only two having cornea guttata and one Fuchs' dystrophy. These results do not support a relationship between angle closure glaucoma and Fuchs' dystrophy or cornea guttata and do not justify performing combined cataract surgery and keratoplasty in all cases of cornea guttata or Fuchs' dystrophy undergoing keratoplasty. Each case should be assessed on its merits and combined surgery should be reserved for patients shown to have a shallow anterior chamber or significant cataract.

Acute Disease↗

PubMed1993

Expression of mRNAs for neurotrophin receptors in the dorsal root ganglion and spinal cord during development and following peripheral or central axotomy.

Expression of mRNAs for the protein tyrosine kinases trk, trkB and trkC, encoding essential components of high-affinity neurotrophin receptors, was studied in the spinal cord and dorsal root ganglion during normal development and in the adult rat following peripheral and central axon injury. Northern blots revealed multiple trkB transcripts in the embryonic, early postnatal and adult spinal cord with different patterns of expression during development. The levels of 9.0 kb and 4.8 kb trkB transcripts, encoding a full-length trkB receptor, increased progressively during embryonic development with maximal levels around birth, followed by a decline at adulthood. In contrast, the level of 7.5/7.0 kb trkB transcripts, encoding a truncated trkB receptor, reached maximal levels shortly after birth and similar levels remained in the adult animal. In the spinal cord a 4.7kb trkC transcript was detected with maximal levels shortly after birth. In situ hybridization revealed a uniform labeling throughout the spinal cord for both trkB and trkC mRNAs with maximal intensities of labeling shortly after birth. The level of the 2.4 kb trkB transcript in the spinal cord increased 5-fold 8 days after a crush lesion of the sciatic nerve or the dorsal root, while no change was seen in the levels of the other trkB transcripts. No change in the 4.7 kb trkC mRNA was seen following these two injuries, although increased levels of several smaller size trkC transcripts were observed. For both trkB and trkC, similar size transcripts as seen in the spinal cord were also detected in adult rat dorsal root ganglia. Consistent with previous observations of decreased levels of cytoskeletal proteins after peripheral and central axotomy, the level of neurofilment light chain mRNA decreased markedly in the dorsal root ganglia following a crush lesion of the sciatic nerve or of the dorsal root. A small decrease was also seen in the level of preprotachykinin-A mRNA encoding the protein precursor of substance P. In the same animals, the levels of all five trkB transcripts increased 3-fold in the dorsal root ganglia in response to these two injuries. A small increase was also seen in the level of trkC mRNA. The level of brain-derived neurotrophic factor (BDNF) mRNA increased two-fold in the dorsal root ganglia following either of the two lesions, while no change was detected in trk mRNA following these two injuries.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1993

Projection patterns of primary sensory neurons studied by transganglionic methods: somatotopy and target-related organization.

The anatomical organization of the centrally projecting branches of different peripheral sensory nerves was not possible to investigate efficiently until the development of the axonal tracing methods. Horseradish peroxidase applied peripherally could be visualized in central projection areas provided a sensitive histochemical method was used; this created the basis for transganglionic tracing from the periphery. This has permitted the investigation of large-scale projections from peripheral sensory nerves. The use of conjugates of horseradish peroxidase and lectins with affinities for different populations of primary sensory neurons, as well as the use of different postoperative survival times, has offered the possibility for selective visualization of projections from subsets of primary sensory neurons. For detailed studies of single afferent fiber projections, a combined physiological-anatomical approach using single-unit recording followed by intraaxonal application of horseradish peroxidase, has become the method of choice. This chapter will focus on results which have been achieved by transganglionic tracing methods, in regard to the organization of the central projections of peripheral sensory nerves.

Animals↗

PubMed1993

Analysis of lectin binding sites in the gut of hooded Lister rats with special emphasis on recently detected lectins.

Seven recently isolated lectins were tested for their ability to bind to tissue sections of rat gut. Binding sites for N-Acetylgalactosamine specific lectins were found in mucins, in the brush border membrane and in goblet cells. Non-reducing terminal mannose residues were absent from cell surface membranes but were detected in the supranuclear region of goblet cells and enterocytes. The results of lectin binding obtained in this study were generally similar to lectin-gut interactions observed in vivo.

Acetylgalactosamine↗