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Biomedical subjects

M Pawlowski

Publications and source records attributed to M Pawlowski.

At least 19 recordsLinked to original sources
PubMed2006

[Retropharyngeal tendinitis. Differential diagnosis in the management of acute neck pain].

Neck pain is frequent and can be a symptom of numerous differential diagnoses with quite different diagnostic and therapeutic consequences. A 37-year-old woman reported acute neck pain aggravated by movements of the cervical spine and head and by swallowing. Clinical examination showed pronounced neck stiffness. T2-weighted MRI demonstrated high-intensity edema and effusion localized prevertebrally in the area of the superior part of the longus colli muscle. Computed tomography of this region demonstrated prevertebral calcification leading to the diagnosis of retropharyngeal tendinitis. Nonsteroidal antiphlogistic drugs led to rapid improvement of clinical signs and symptoms. Retropharyngeal tendinitis should be considered in patients with acute neck pain.

Acute Disease↗
PubMed2001

The impact of ultraviolet radiation on the vertical distribution of zooplankton of the genus Daphnia.

The vertical migration of zooplankton into lower and darker water strata by day is generally explained by the avoidance of visually orienting predators, mainly fish; however, it is unclear why daily zooplankton migration has been maintained in fishless areas. In addition to predation, ultraviolet radiation-a hazardous factor for zooplankton in the surface layers of marine and freshwater environments-has been suspected as a possible cause of daytime downward migration. Here we test this hypothesis by studying several Daphnia species, both in a controlled laboratory system and under natural sunlight in an outdoor system. We selected Daphnia species that differed in their pigmentation as both melanin and carotenoids have been shown to protect Daphnia from ultraviolet light. All Daphnia species escaped into significantly deeper water layers under ultraviolet radiation. The extent to which the daphnids responded to this radiation was inversely linked to their pigmentation, which reduced ultraviolet transmission. These results suggest that ultraviolet avoidance is an additional factor in explaining daytime downward migration. Synergistic benefits might have shaped the evolution of this complex behaviour.

Animals↗
PubMed1997

Aza-analogs of 8-styrylxanthines as A2A-adenosine receptor antagonists.

In the present study we synthesized aza-analogs of 8-styrylxanthines, in which the ethenyl bridge is replaced by an imine, amide, or azo function, in order to investigate structure-activity relationships of the 8-substituent of A2A-selective xanthine derivatives. Thus, various 8-substituents were combined with theophylline or caffeine, respectively, and affinities of the novel compounds for adenosine A1- and A2a-receptors were determined and compared with those of analogous 8-styrylxanthine derivatives. 8-(Benzylideneamino)caffeine derivatives exhibited high affinity and selectivity for A2A-adenosine receptors, but were unstable in aqueous buffer solution at physiological pH values. 8-(Phenylazo)caffeine derivatives were less potent than corresponding 8-styrylcaffeine derivatives at adenosine receptors. The most potent azo compound of the present series was 8-(m-chlorophenylazo)caffeine (14b) exhibiting a Ki value of 400 nM at A2A-adenosine receptors and 20-fold selectivity versus A1-receptors. Due to the facile synthetic access to 8-(phenylazo)xanthine derivatives, which are obtained by coupling of 8-unsubstituted xanthines with phenyldiazonium salts, 14b may be an interesting new lead compound for the development of more potent and selective A2A-antagonists with azo structure.

Adenosine↗
PubMed1997

Intravascular oxygen distribution in subcutaneous 9L tumors and radiation sensitivity.

Phosphorescence quenching was evaluated as a technique for measuring PO2 in tumors and for determining the effect of increased PO2 on sensitivity of the tumors to radiation. Suspensions of cultured 9L cells or small pieces of solid tumors from 9L cells were injected subcutaneously on the hindquarter of rats, and tumors were grown to between 0.2 and 1.0 cm in diameter. Oxygen-dependent quenching of the phosphorescence of intravenously injected Pd-meso-tetra-(4-carboxyphenyl) porphine was used to image the in vivo distribution of PO2 in the vasculature of small tumors and surrounding tissue. Maps (512 x 480 pixels) of tissue oxygen distribution showed that the PO2 within 9L tumors was low (2-12 Torr) relative to the surrounding muscle tissue (20-40 Torr). When the rats were given 100% oxygen or carbogen (95% O2-5% CO2) to breathe, the PO2 in the tumors increased significantly. This increase was variable among tumors and was greater with carbogen compared with 100% oxygen. Based on irradiation and regrowth studies, carbogen breathing increased the sensitivity of the tumors to radiation. This is consistent with the measured increase in PO2 in the tumor vasculature. It is concluded that phosphorescence quenching can be used for noninvasive determination of the oxygenation of tumors. This method for oxygen measurements has great potential for clinical application in tumor identification and therapy.

Administration, Inhalation↗
PubMed1994

Synergy between tumor necrosis factor alpha and interleukin-1 in the induction of sickness behavior in mice.

Like interleukin-1, recombinant human tumor necrosis factor alpha (TNF alpha) has been found to decrease social exploration and induce weight loss in mice in a dose and time-dependent manner. The present study was carried out to study the interaction between these two cytokines. Mice were injected IP with subthreshold doses of TNF alpha (2.5 micrograms/mouse) and IL-1 beta (50 ng/mouse). Social exploration was decreased 2 and 4 h after injection of TNF and IL-1, but body weight was not affected. Subthreshold doses of TNF alpha (90 ng/mouse) and IL-1 beta (100 pg/mouse) were also injected intracerebroventricularly (ICV). Social exploration was decreased 1.5 and 3 h after injections of the two cytokines and body weight was decreased for 6 h. To test the possibility of central induction of IL-1 by TNF alpha, mice pretreated with IL-1 receptor antagonist (IL-1ra, 1.8 micrograms/mouse, ICV) were injected with 90 ng TNF alpha. Pretreatment with IL-1ra antagonized the depressive effect of TNF alpha on behavior, but had no effect on weight loss induced by this cytokine. These results suggest that TNF alpha-induced behavioral alterations are mediated by endogenously released IL-1, whereas metabolic changes are dependent on the release of other cytokines.

Animals↗
PubMed1994

Oxygen pressure distribution in the heart in vivo and evaluation of the ischemic "border zone".

Quantitation of the oxygen pressure distribution in the heart provides an accurate definition of metabolically viable cells adjacent to ischemic injury. By injection of a phosphorescent oxygen probe into the blood of newborn piglets and illumination of the heart with monochromatic light, a series of images of the heart were collected with use of a gated intensified CCD camera. These sets of images were used to calculate two-dimensional maps of the oxygen pressure in the epicardial microvasculature. Occlusion of a distal arterial vessel resulted in a hypoxic area containing a central focus of near-zero oxygen pressure bordered by tissue with diminished but nonzero oxygen pressures. These border zones extended for several millimeters from the hypoxic core, with the oxygen pressures progressively increasing from the focus to the normoxic region. The maps of oxygen distribution obtained by phosphorescence imaging provide rapid and quantitative measure of the oxygen pressures in the beating heart in vivo. They accurately show the degree of oxygen deprivation and the extent of an ischemic border zone that may respond to treatment.

Animals↗
PubMed1992

Monitoring of the oxygen pressure in the blood of live animals using the oxygen dependent quenching of phosphorescence.

Oxygen dependent quenching of phosphorescence is a powerful new method for measuring oxygen pressure in biological systems (see Vanderkooi et al, J. Biol. Chem. 262 (1987) 5476; Wilson et al, J. Biol. Chem. 263 (1988) 2712). This technology has now been extended to include measurements of the phosphorescent of oxygen probes dissolved in the blood as a complex with albumin. In this communication, we report on a new microcomputer controlled phosphorimeter in which the tissue is illuminated by a flash lamp and the phosphorescence observed through flexible light guides designed to make measurements in regions down to approximately 1 mm in diameter. Measurements of the phosphorescence lifetimes of these probes in regions of tissue necessarily report a distribution of oxygen pressures due to the presence of blood in veins and arteriols as well as that present in the capillaries. Thus the phosphorescence decay is the sum of a continuum of exponentials with different decay constants and initial intensities. The complete phosphorescence decay curve is digitized using a 12 bit, 1 MHz A/D board and deconvoluted using numerical methods to yield a distribution of exponentials contributing to the total decay curve.

Animals↗
PubMed1992

Effect of hyperventilation on oxygenation of the brain cortex of neonates.

A new phosphorescence imaging method (Rumsey et al, Science (1988) 1649) has been used to continuously monitor the oxygen pressure in the blood of the cerebral cortex of newborn pigs. The animals' blood pressure was continuously measured and PaCO2, PaO2 and arterial blood pH were measured periodically. The oxygen pressure in the blood was quantitatively determined for regions of about 100 um square within the image (from a total field of about 3 mm diameter). It was observed that during hyperventilation, which lowered PaCO2 and increased pH of the blood, oxygen pressure decreased in proportion to the decrease in PaCO2. For example, hyperventilation which decreased PaCO2 from its normal value of 40 Torr to 10 Torr caused a rapid (within 5 minutes) decrease in oxygen pressure in the blood of capillaries and veins to approximately 1/4 of normal.

Animals↗
PubMed1992

Anxiolytic-like effects of a selective 5-HT1A agonist, S20244, and its enantiomers in mice.

The action of a selective 5-HT1A agonist S20244 and its two enantiomers (+)-S20499 and (-)-S20500 were assessed in mice. The animals were confronted with a free exploratory test especially adapted to reveal behavioural sedation, and with a two-box light/dark choice situation validated for the detection of anti-anxiety agents. These drugs were found to have anxiolytic properties at low doses, like benzodiazepines. Furthermore, the drugs exhibited sedative effects at higher doses. These results closely resemble those we found after administration of two other 5-HT1A agonists, 8-OH-DPAT and MDL 73005EF (NeuroReport, 1, 267-270, 1990).

Animals↗
PubMed1991

m-Chlorophenylpiperazine enhances neophobic and anxious behaviour in mice.

1-(3-Chlorophenyl)piperazine (mCPP) reduced novelty-seeking behaviour as well as the number of rears in mice confronted with a free exploratory test. Moreover, mCPP was found to decrease the time spent by mice in the lit box and the number of transitions in a two-box light/dark choice situation validated for the detection of anxiolytic or anxiogenic drugs. These results suggest that mCPP enhances emotional responses towards novel and aversive places. Since mCPP has been reported as a 5-HT1C receptor agonist, it can be hypothesized that increased activity of serotonin may play a role in regulating certain forms of emotional behaviour in animals.

Analysis of Variance↗
PubMed1991

Effect of hyperventilation on oxygenation of the brain cortex of newborn piglets.

A new phosphorescence imaging method (Rumsey et al. Science Wash. DC 241: 1649-1651, 1988) has been used to continuously monitor the PO2 in the blood of the cerebral cortex of newborn pigs. A window was prepared in the skull and the brain superfused with artificial cerebrospinal fluid. The phosphorescent probe for PO2, Pd-meso-tetra(4-carboxyphenyl)porphine, was injected directly into the systemic blood. The phosphorescence of the probe was imaged, and the lifetimes were measured using flash illumination and a gated video camera. The PO2 in the blood of the veins and capillary beds of the cortex was calculated from the lifetimes. Systemic blood pressure was continuously monitored while the systemic arterial PCO2, PO2, and blood pH were measured periodically. The PO2 in the blood was quantitated for 60- to 200 microns2 regions within the image (from a total field of approximately 3 mm diam). The PO2 in the microvasculature was not uniform across the viewing field but increased or decreased in each region independently of the other regions. Thus at any point in time the PO2 in a region could be substantially above or below the average value. During hyperventilation, which lowered arterial PCO2 and increased pH of the blood, the average PO2 decreased in proportion to the decrease in arterial PCO2. For example, hyperventilation, which decreased arterial PCO2 from its normal value of 40 Torr to 10 Torr, caused a rapid (within 5 min) decrease in PO2 in the blood of capillaries and veins to approximately one-third of normal.

Animals↗