Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: lnterleukin-1β stimulates oxytocin and vasopressin release in conscious, male rats and causes a rise in blood pressure. These experiments were done to: A) examine the effect of i.c.v. interieukin-1 β (1 ng/μl) on circulating levels of vasopressin in female rats at different stages of lactation and B) determine if α-adrenergic mechanisms and/or prostaglandins were involved as mediators. Urethane-anaesthetized non-lactating rats and rats at Day 7, 10, 20 and 26 of lactation were set up for arterial blood sampling and i.c.v. injections. One mL blood samples were obtained in one min periods before, and at 1, 2.5, 5, 10, 30, 60 and 120 min after the following treatments: i.c.v. treatment with either interleukin-1β (1 ng in 1 μl PBS-BSA) or PBS-BSA (1 μl) as a vehicle control; or i.c.v. treatment with interleukin-1β following pretreatment with either phentolamine (1.7 ng/μl i.c.v.) or indomethacin (1 ng/μl i.c.v.). As blood was sampled, isotonic saline was infused (1 mL per min) and blood pressure was monitored to minimize any hypovolemic effects due to sampling. Extracted plasma was assayed using a specific vasopressin radioimmunoassay, lnterleukin-1 β i.c.v. stimulated the release of vasopressin above that elicited by PBS-BSA alone in non-lactating rats resulting in an approximate 1.2 to 2-fold increase in plasma hormone levels. Throughout the first half of lactation, vasopressin responsiveness to i.c.v. interleukin-1β treatment was markedly attenuated. In latter stages of lactation, the response recovered and resembled that of non-lactators around the time of weaning. Prostaglandins consistently mediate a stimulatory action of interleukin-1β on vasopressin release whereas α-adrenergic mechanisms mediate a depression of interleukin-1β-induced vasopressin release during the early to middle stages of lactation. It is possible that the depression in interleukin-1β-stimulation of vasopressin release in early to mid-lactation is conducive for nursing to occur and that the increase in vasopressin responsiveness towards the latter stages of lactation represents a component of the weaning process.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Journal of periodontal research 38 (2003), S. 0 
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  The ability of Helium–Neon (He–Ne) laser irradiation of a photosensitizer to induce localized phototoxic effects that kill periodontal pathogens is well documented and is termed photodynamic therapy (PDT).Objectives:  We investigated the potential of a conventional light source (red-filtered Xenon lamp) to activate toluidine blue O (TBO) in vitro and determined in vitro model parameters that may be used in future in vivo trials.Materials and methods:  Porphyromonas gingivalis 381 was used as the primary test bacterium.Results:  Treatment with a 2.2 J/cm2 light dose and 50 µg/ml TBO concentration resulted in a bacterial kill of 2.43 ± 0.39 logs with the He–Ne laser control and 3.34 ± 0.24 logs with the lamp, a near 10-fold increase (p = 0.028). Increases in light intensity produced significantly higher killing (p = 0.012) that plateaued at 25 mW/cm2. There was a linear relationship between light dose and bacterial killing (r2 = 0.916); as light dose was increased bacterial survival decreased. No such relationship was found for the drug concentrations tested. Addition of serum or blood at 50% v/v to the P. gingivalis suspension prior to irradiation diminished killing from approximately 5 logs to 3 logs at 10 J/cm2. When serum was washed off, killing returned to 5 logs for all species tested except Bacteroides forsythus (3.92 ± 0.68 logs kill).Conclusions:  The data indicate that PDT utilizing a conventional light source is at least as effective as laser-induced treatment in vitro. Furthermore, PDT achieves significant bactericidal activity in the presence of serum and blood when used with the set parameters of 10 J/cm2, 100 mW/cm2 and 12.5 µg/ml TBO.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1530-0358
    Keywords: Rectal cancer ; PDT ; Palliation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Photodynamic therapy (PDT) is a relatively new form of cancer therapy utilizing a photosensitizer such as hematoporphyrin derivative. We conducted a pilot study to determine the efficacy of its use in palliating advanced rectal cancer, to determine toxicity, and to establish objective outcome criteria. Six patients with very advanced, usually recurrent rectal cancer were treated with PDT after being photosensitized with Photofrin II®. A protocol was established to measure clinical and radiologic response to therapy. A new intraluminal delivery system was incorporated. Five patients had both clinical and radiologic responses to therapy. In two patients we observed such significant responses that they cannot be accounted for on a photobiologic basis alone. One patient developed a significant sunburn after discharge. There was no major toxicity of bleeding or sepsis even at maximum doses (200 J/cm2). We are confident that PDT has a role to play in rectal cancer and speculate as to future applications.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1435-604X
    Keywords: Tissue optics ; Absorption ; Scattering ; Fluence distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract This paper is the second of two reviewing the propagation of electromagnetic radiation of wavelength 0.25–10μm in tissue. This part begins with a discussion of how the fundamental optical interaction coefficients of tissue may be measured. Both direct methods, in which the coefficients are measured for optically thin samples, and indirect methods, in which the coefficients are inferred from measurements on bulk samples are described. The difficulties inherent in both types of measurement are outlined. Next the wavelength dependence of the scattering and absorption coefficient is discussed, both from a heuristic point of view and by illustration from current literature. We illustrate how the optical spectrum can be divided into regions where the propagation of light is dominated by absorption or scattering effects. Finally we show how the distribution of light fluence in these spectral regions is dramatically different and illustrate the important features of these distributions.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1435-604X
    Keywords: Light propagation ; Radiation transport ; Tissue optics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract This paper is the first of two reviewing the propagation of electromagnetic radiation of wavelength 0.25–10μm in tissue. After a brief discussion of light/tissue interactions, a mathematical description of light propagation in terms of radiative transfer is developed. Formal solutions of the resulting equation are outlined, but the emphasis is on approximate method of solution—namely the discrete ordinates method, the technique of functional expansion and Monte Carlo simulation. The application of the simplest of these approximate methods, namely the 2-flux and diffusion models, to tissue optics is discussed in some detail. The second paper deals with the optical properties of tissue and the salient characteristics of light fluence distributions in these tissues.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 6 (1981), S. 309-315 
    ISSN: 1619-7089
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A method is described for generating regional ventilation/perfusion (V/Q) images of the lung to aid assessment of suspected pulmonary embolism, especially in patients with obstructive airways disease. The radionuclide scans used for this are stored on a computer and comprise: lung perfusion (P) with Tc-99 m MAA, lung ventilation at equilibrium (E) with Xe-127, and the sum of the Xe-127 washout images (W). A functional ventilation image is calculated as V=E/W and a functional perfusion image as Q=P/E. Finally a ventilation perfusion ratio image is obtained by taking V/Q. This is normalised by a factor determined from the cumulative frequency distributions of the counts per pixel in the Q and V images so that areas which are well ventilated and perfused are given a V/Q value of 1.0. Areas with normalised V/Q values〉1.5 suggest pulmonary embolism. In 100 studies on patients with abnormal perfusion scans this method proved very helpful by assisting the recognition or exclusion of areas with abnormally high V/Q values.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of network and systems management 2 (1994), S. 95-123 
    ISSN: 1573-7705
    Keywords: Network Restoration ; Digital Cross-Connect System (DCS) ; routing algorithms ; multicommodity flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A crucial issue in the management of telecommunications networks is restoration after a network failure. We compare the capacity efficiency (the amount of traffic restored over fixed capacity) of several types of restoration methods for Digital Crossconnect Systems (DCSs) under both node or link failures in metropolitan networks. These restoration methods can be broadly categorized based on the type of control of the restoration process and the type of procedure for rerouting traffic around the failure. It is easily shown that point-to-point methods (where traffic is rerouted end-to-end) restore a higher percent of traffic than patch methods (where traffic is rerouted only around the failed segment). However, quantification of the difference in efficiency among the methods is important to fully evaluate other trade-offs, such as cost and speed of restoration. To evaluate the efficiency difference, we generated random network traffic distributions by simulation and then failed links and nodes for each simulation sample. Statistics were generated on the expected amount of restored traffic for each restoration method. In particular, we found that the efficiency advantage of point-to-point methods over patch methods is greater for link failure than for node failure. Also, the difference was not statistically significant in low levels of network congestion (i.e., networks with large amounts of excess capacity) and became more significant as network congestion increased.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Higher education 13 (1984), S. 1-22 
    ISSN: 1573-174X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract A considerable amount of information is available concerning the adjustment problems that students from developed countries experience when they transfer from school to university. Comparatively little is known about the problems of African students, despite the existence of a number of factors which might be expected to produce large numbers of problems and relatively severe problems. Having adopted certain criteria regarding the “acceptability” or otherwise of adjustment problems, a preliminary survey was conducted at the University of Zambia in order to see whether adjustment problems existed and to give some insight into the type of problem experienced. The survey indicated the presence of a large number and wide variety of problems and a questionnaire was subsequently developed in order to test the potency, generality and persistency of the student's difficulties. The results obtained with a representative sample of 242 first-year and 60 fourth-year students showed that there are problems which are sufficiently potent, general and/or persistent to be a cause for concern to the university authorities.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 1 (1986), S. 235-244 
    ISSN: 1435-604X
    Keywords: Dihaematoporphyrin ether ; Aluminium chlorosulphonated phthalocyanine ; Penetration depth ; Diffusion theory ; Photodynamic therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The additional optical absorption in tissue resulting from the uptake of exogenous photosensitizers increases the effective attenuation of photoactivating light. This may be significant for the irradiation of solid tumours in photodynamic therapy, since it reduces the depth or volume of tissue treated. The effect has been studied in vitro by using dihaematoporphyrin ether (DHE) and 630 nm light in tissues representing a wide range of absorption and scattering conditions. While the attenuation may be markedly changed by small concentrations of DHE in pure scattering media, tissues with significant inherent light absorption are little affected by the additional absorption of DHE at concentrations relevant to clinical photodynamic therapy. However, it is shown that for other potential photosensitizers such as the phthalocyanines, which have substantially greater absorption at the treatment wavelength than DHE, the penetration of light in tissues may be significantly reduced.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 5 (1990), S. 245-252 
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Supratentorial tumours ; Cerebral gliomas ; Cerebral metastasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Experience with intraoperative PDT in 50 patients with malignant supratentorial tumours is reported; in 33 cases the tumour was recurrent. In 45 patients the tumour was a cerebral glioma and in five cases a solitary cerebral metastasis. There were 29 males and 17 females with an age range of 17–73 (mean 48) years. All patients received either haematoporphyrin derivative (HPD) or dihaematoporphyrin ether (DHE) 18–24 h preoperatively. A photoilluminating device, of the authors' design, was coupled to an argon dye pump laser in order to deliver light at 630 nm to a tumour cavity created by radical tumour resection and/or tumour cyst drainage. The total light energy delivered ranged from 440 to 3888 J and the light energy density ranged from 8 to 175 J/cm2. In eight patients a line fibre(s) was used to administer interstitial light as a supplement to the cavitary photoillumination. The additional light dose ranged from 60 to 945 J/cm. There were two postoperative deaths as the consequence of haematoma accumulation in the tumour resection cavity. In three patients neurological function was worse postoperatively and did not recover. Postoperative cerebral oedema was pronounced in some cases and required second craniotomy in two patients (the histology from both showed haemorrhagic necrosis of residual tumour). Four patients developed wound infections; two of these required surgical treatment. Four patients, two of whom were hemiparetic, developed deep vein thrombosis and required anticoagulant therapy. There were no adverse systemic reactions to the administration of either photosensitizer and only three skin photosensitivity reactions. Follow up ranged from 1 to 30 months. In the group of 45 patients with gliomas the death rate per observation year was 0.92 for the interval between PDT and death. For the interval between first diagnosis and death the rate was 0.41 deaths per observation year. The median survival was 8.6 months with a 1 and 2 year actuarial survival rate of 32% and 18%, repectively. In 12 patients a complete or near complete CT scan response was identified post PDT. These patients tended to have a tumour geometry (e.g. cystic) that allowed complete or near complete light distribution to the tumour. The median survival for this group was 17.1 months with a 1 and 2 year actuarial survival of 62% and 38%, respectively. In the 33 cases without a complete response the median survival was 6.5 months with a 1 and 2 year actuarial survival of 22% and 11%, respectively. Photodynamic therapy of malignant brain tumours can be carried out with acceptable risk. Good responses appear to be related to adequate light delivery to the tumour.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...