ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

21

Electronic Resource

Echo-Planar Magnetic Resonance Imaging to Assess Water Volume in the Distal Small Bowel (1995)

Adkin, Dawn A. ; Gowland, Penny ; Spiller, Robin C. ; [et al.]

Springer

Pharmaceutical research 12 (1995), S. 1134-1139

add to mindlist on the mindlist

Details

ISSN: 1573-904X

Keywords: mannitol ; small intestinal transit ; echo-planar magnetic resonance imaging

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract Purpose. Assessment of fluid volumes and flow through the small intestine has in the past only been possible by means of invasive intubation studies on human volunteers. Intubation very likely disturbs gut motility and stimulates secretion. Methods. The aim of this study was to utilise the new technique of echo-planar magnetic resonance imaging in order to non-invasively visualise the changing volume of water in the small intestinal lumen. 200mls of test solution was ingested and water volume assessed using a multi-slice scanning technique on 3 separate days. The solutions were pure water, pure water plus 2.264 or l0g of mannitol. These were taken on separate days by 8 healthy male volunteers. Regions of interest were constructed in the area of the lower pelvis excluding retroperitoneal structures. Results. The water content of the lower small intestine did not change significantly over the 4 hours after the control solution. By contrast after both mannitol solutions there was an increase in the amount of water in the distal intestine as assessed by the area under the curve of the volume time profile (Control 51 ml.h (SD ±47); mannitol 2.264g/200ml 72ml.h (SD ±57); 10g/200ml mannitol 115ml.h (SD ±56)). Page's L Trend test showed that the trend for the volume to increase with increasing mannitol concentration to be statistically significant at the 1% level (L= 108). Conclusions. The study highlights the potential of echo-planar magnetic resonance imaging to visualise changes in gastrointestinal physiology in a non-invasive manner.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1016251624220

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

22

Electronic Resource

Effect of potassium on the tolerance to PEG-induced water stress of two white clover varieties (Trifolium repens L.) (1989)

Robin, C. ; Shamsun-Noor, L. ; Guckert, A.

Springer

Plant and soil 120 (1989), S. 153-158

add to mindlist on the mindlist

Details

ISSN: 1573-5036

Keywords: nitrogen fixation ; nodules ; stomatal resistance ; water potential

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract The response to water stress was studied on white clover grown hydroponically. Two varieties (Crau and Huia) were both subjected to a moderate and a more-severe stress, induced by polyethylene glycol (10 and 20% respectively), in the presence of a nutrient solution poor in potassium (K1=0.005 mM), or abundantly supplied (K2=5mM). Dawn water potential and nitrogen fixation (acetylene reduction activity) decreased with the increasing stress. Conversely, the stomatal resistance increased whenosmoticum was added. Crau had a lower stomatal resistance to the deficit, than did Huia. In relation with the K supply, treatment K2 confirmed the superiority of Crau. Crau also showed greater nodule mass and number than Huia. The data show relationships between dawn water potential, stomatal resistance and nitrogen fixation activity.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02377063

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

23

Electronic Resource

Comparison of methods for introducing vectors based on bovine papillomavirus-1 DNA into mammalian cells (1986)

Bostock, Christopher J. ; Allshire, Robin C.

Springer

Somatic cell and molecular genetics 12 (1986), S. 357-366

add to mindlist on the mindlist

Details

ISSN: 1572-9931

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Abstract The intracellular structure of several vectors based on BPV-1 DNA has been analyzed following transfection into mouse C127 cells by the calcium phosphate method or, for the first time, by microinjection directly into the nucleus. It is shown that the method of introduction markedly affects the fate of a BPV-1 based vector. In general, microinjection appears to do little damage to DNA and is more likely to result in a vector replicating extrachromosomally as a monomeric structure of the same size as the input DNA. The method of selection for transformed cells, e.g., focus formation versus resistance to the neomycin analog G418, can also affect the intracellular state of the BPV-1 vector DNA. The nature of the recipient mammalian cell also influences whether a vector can replicate extrachromosomally or whether it integrates. BPV-1 based vectors, which replicated predominantly as multicopy intact extrachromosomal forms in mouse C127 cells, were always found to have integrated at low copy number in mouse LtAp20 cells.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01570730

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

24

Electronic Resource

Thermoregulation in resting and active polar bears (1982)

Best, Robin C.

Springer

Journal of comparative physiology 146 (1982), S. 63-73

add to mindlist on the mindlist

Details

ISSN: 1432-136X

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine

Notes: Summary Polar bears (Ursus maritimus) regulate their body temperatures both physiologically and behaviourally proportional to their level of activity while within the thermoneutral zone. Core temperatures (T c=36.9±0.5°C at rest) varied with the 4th power of walking speed for the two subadult (220 kg) bears tested, whereas subcutaneous temperatures (T sk=35.3±2.2°C at rest) were closely correlated withT c but also varied with wind speed (v a) and ambient temperature (T a). Radiative fur temperatures (T r) were closely correlated withT a and negligibly withT sk. Predictive equations for these temperature relationships were derived by regression analysis. Maximum rates of heat storage (S max) were above that predicted from the literature implying that the polar bear is an energetically costly walker. Radiative heat losses of a resting polar bear amount to between 36–67% of the metabolism and assuming a respiratory heat loss of 7–10%, convective heat losses (by difference) would thus range from 33–64%. When walking, the cooling of the fur surface by forced convection and the ‘pendulum’ effect of the moving legs of the bear lead to estimated convective heat losses on the order of 75% of the heat production while radiative losses are reduced to 13–22%. Increasing wind speeds enhance further this reciprocal effect.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00688718

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

25

Electronic Resource

Phase II trial of 10 deaza-aminopterin in patients with bladder cancer (1986)

Ahmed, Tauseef ; Yagoda, Alan ; Scher, Howard I. ; [et al.]

Springer

Investigational new drugs 4 (1986), S. 171-174

add to mindlist on the mindlist

Details

ISSN: 1573-0646

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology , Medicine

Notes: Summary Deaza-aminopterin is a folate analog which is transported more rapidly than methotrexate into cells and appears to be more active than methotrexate against human and animal tumor in vitro. Fifteen patients with advanced urothelial tract cancer were given deaza-aminopterin 30–37.5 mg/m2 IV QW. In responding patients drug was given QOW after 4–6 consecutive doses. Doses were escalated or de-escalated by 7.5 mg/m2 depending on toxicity. Twelve patients had received prior chemotherapy which included methotrexate in nine. Three patients achieved a partial remission lasting 1, 3, and 3 months respectively: all responders had previously failed methotrexate after an initial response to a methotrexate containing regimen. None of the six patients who were methotrexate naive responded to deaza-aminopterin; 3 subsequently received methotrexate without response. Mild mucositis was universal and in 5 was severe. Six patients had an increase in liver transaminases probably secondary to anti-folate hepatotoxicity. Other toxicities included diarrhea, nausea, skin rash and fever. Further studies are needed to define the precise efficacy of deaza-aminopterin in patients with urothelial tract cancers.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00194598

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

26

Electronic Resource

Regional Differences in Quinine Absorption from the Undisturbed Human Colon Assessed Using a Timed Release Delivery System (1999)

Hebden, John M. ; Wilson, Clive G. ; Spiller, Robin C. ; [et al.]

Springer

Pharmaceutical research 16 (1999), S. 1087-1092

add to mindlist on the mindlist

Details

ISSN: 1573-904X

Keywords: transcellular ; paracellular ; absorption ; gastrointestinal

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract Purpose. To investigate the regional absorption characteristics of the distal gut using two markers of permeability, quinine (a transcellular probe) and 51CrEDTA (a paracellular probe). Methods. The permeability markers were delivered to the undisturbed gastrointestinal tract in 39 healthy volunteers using an oral timed-release delivery vehicle which allowed pulsed release within a particular site of the gut. Site of release was identified using gamma scintigraphy. Absorption of quinine and 5lCrEDTA was assessed by measuring the percent excretion in the urine using HPLC and gamma counting respectively. Serial plasma samples allowed time-concentration curves for quinine to be plotted. Results. There was a significant trend for diminished absorption with more distal delivery of the transcellular probe, quinine, which was: 6.26 ± 0.87% (small intestine, n = 10); 4.65 ± 0.93% (ascending colon, n = 16); and 2.59 ± 0.52% (transverse colon, n = 10) of the ingested dose excreted respectively (p 〈 0.001). No such gradient was seen with the paracellular marker, 5lCrEDTA. Conclusions. These results suggest that delayed release formuations should aim for release in the distal small bowel and proximal colon if absorption is to be miximised. Absorption by the transcellular route diminishes in the more distal colon, a fact which has implications for delayed or sustained release formulations.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1018948102778

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

27

Electronic Resource

Stool Water Content and Colonic Drug Absorption: Contrasting Effects of Lactulose and Codeine (1999)

Hebden, John M. ; Gilchrist, Peter J. ; Perkins, Alan C. ; [et al.]

Springer

Pharmaceutical research 16 (1999), S. 1254-1259

add to mindlist on the mindlist

Details

ISSN: 1573-904X

Keywords: colon ; absorption ; EDTA ; quinine ; lactulose ; codeine

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract Purpose. By varying stool water content using lactulose and codeine, we investigated the influence of luminal water content on the absorption of quinine, a transcellular probe, and 5lCr-EDTA, a paracellular probe, from the distal gut. Methods. Sixteen volunteers entered a three-way cross-over trial in which absorption of probe markers from a timed-release delivery system was determined following treatment with lactulose 20 mls tds (increasing water content), or codeine 30 gms qds (decreasing water content), and compared with control untreated values. Stool water content was assessed by freeze drying stool samples. Site of release was determined by gamma scintigraphy, and absorption was measured by plasma levels and urinary recovery of the marker probes. Results. Lactulose accelerated ascending colon transit (3.7 ± 0.8 vs 4.5 ± 1.4 hrs, p 〈 0.05), increased stool water content (75 ± 2 vs 71 ± 2%, p 〈 0.01), caused greater dispersion of released material (dispersion score 3.4 ± 0.3 vs 1.8 ± 0.2, p 〈 0.01), and enhanced absorption of the transcellular probe quinine (4.66 ± 0.78 vs 3.02 ± 0.63%, p 〈 0.05) compared to control. Conversely codeine slowed ascending colon transit (8.9 ± 1.8 hrs), reduced stool water content (61 ± 2 vs 71.2%, p 〈 0.05), and tended to diminish absorption (2.60 ± 0.77 vs 3.02 ± 0.63%, p = 0.20). Within the ascending colon specifically, there was a significant trend for treatments increasing luminal water content to enhance quinine absorption (medians: codeine = 1.2%, [n = 8] 〈 control = 2.3%, [n = 5] 〈 lactulose = 3.2%, [n = 7], p 〈 0.01). Delivery site also had an important influence on absorption, with more distal release resulting in less absorption in the control arm (medians: small intestine = 4.4% [n = 5] 〉 ascending colon = 2.3% [n = 5] 〉 transverse colon = 1.5% [n = 6], p 〈 0.005). Conclusions. Lactulose accelerates transit, increases stool water content, and enhances drug absorption from the distal gut whilst codeine slows transit, decreases stool water content, and tends to diminish absorption, compared to controls. We conclude that water content may be an important determinant in colonic drug absorption.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1014805815499

Permalink