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Biomedical subjects

K Kowalski

Publications and source records attributed to K Kowalski.

At least 37 records · Page 2Linked to original sources
PubMed1994

Tyrosine reverses a cold-induced working memory deficit in humans.

Acute exposure to cold stress has been shown to impair short-term, or working, memory, which may be related to reduction in, or disruption of, sustained release of brain catecholamines. Administering a supplemental dose of the catecholamine precursor tyrosine may alleviate cold stress-induced memory impairments by preventing cold-induced deficits in brain catecholamine levels. The present experiment determined whether administration of tyrosine would prevent a cold-induced working memory deficit, using a computer-based delayed matching-to-sample (DMTS) memory task. Eight male volunteers performed the DMTS task for 30 min at an ambient temperature of either 4 degrees C (cold) or 22 degrees C following a 30-min preexposure period and 2 h after ingesting 150 mg/kg of L-tyrosine or placebo. Subjects demonstrated a decline in matching accuracy on the DMTS task as delay interval increased, such that matching accuracy following a 16-s delay between sample and comparison stimuli was lower than that following a delay of 2 or 8 s. Consistent with previous research, and relative to 22 degrees C exposure sessions, matching accuracy during 4 degrees C exposure sessions was reduced significantly following placebo administration, which is attributed to the effect of cold exposure on short-term, or working, memory. Administration of tyrosine significantly improved matching accuracy at the longest delay interval most affected by cold exposure, such that matching accuracy in the cold following tyrosine was at the same level as matching accuracy following placebo or tyrosine administration at 22 degrees C. Tyrosine administered prior to 22 degrees C exposure had no effect on DMTS performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

LOCALIZATION OF ANGIOTENSIN II RESPONSES IN THE TROUT CARDIOVASCULAR SYSTEM

The renin/angiotensin system (RAS) is a tonic anti-drop regulator of arterial blood pressure in many teleosts. In trout, angiotensin II (ANG II) has no direct constrictor effect on large arteries or veins and the identity of specific cardiovascular pressor effectors is unknown. Potential targets of angiotensin activation were examined in the present experiments using perfused organs and isolated tissues from the rainbow trout Oncorhynchus mykiss. Perfused gill (arches 2 and 3), perfused skeletal muscle-kidney (via the dorsal aorta; PDA) and perfused splanchnic (via the celiacomesenteric; PCM) circulations vasoconstrict in response to salmonid ANG II in a dose-dependent manner. ANG II was significantly (P¾0.05) more potent in the PCM than in the PDA, and both preparations were more responsive than the gills: pD2=8.0±0.20 (10) for PCM; pD2=7.5±0.07 (13) for PDA; pD2=6.9 ±0.21 (8) for gill arch 3; pD2=6.7±0.23 (8) for gill arch 2; mean ± s.e.m. (N), respectively. Salmonid angiotensin I (ANG I) also produced a dose-dependent constriction of the PDA and PCM. Angiotensin converting enzyme (ACE) activated nearly 100 % of ANG I to ANG II in a single pass through the PDA, whereas PCM conversion was estimated to be less than 10 %. Inhibitors of adrenergic constriction partially prevented ANG II responses in the PDA but did not affect PCM responses. ANG II did not affect paced rings of ventricular muscle in the presence of high or low [Ca2+] or epinephrine concentrations, nor did it have any inotropic or chronotropic effects in the in situ perfused heart. Red blood cell swelling was unaffected by ANG II. Similarly, the effects of ANG II on gut, urinary bladder and gall bladder smooth muscle were negligible or non-existent; thus, an increase in splanchnic resistance due to extravascular compression can be discounted. These results indicate that, in trout, the systemic microcirculation is the major cardiovascular effector of angiotensin-mediated pressor responses. In addition, the RAS has little direct effect on non-vascular smooth muscle or the heart. From an evolutionary perspective, the initial site of direct systemic RAS action appears to be the vascular microcirculation.

Journal Article↗
PubMed1994

Antidromic field potentials recorded from cell groups of S2 spinal cord segment with axons in the opposite Th13 dorsolateral funiculus in the cat.

Location of cell groups within gray matter of S2 spinal cord segment, whose axons are running in the opposite Th13 dorsolateral funiculus, were studied by means of antidromic field potentials recorded in chloralose anaesthetized cats. The cell bodies are forming six separate groups occupying medial laminae II and III, medial laminae IV and V, medial lamina VII, medial lamina VIII, lateral laminae V and VI and lateral laminae VIII and IX. Properties of main components in antidromic field potentials recorded in each of areas have been described. The presumable termination sites of axons of investigated cellular groups are considered.

Anesthesia↗
PubMed1993

Fluctuations in the mass-action model for ligand-receptor binding.

The fluctuation kinetics of the mass-action model for ligand-receptor binding is investigated. The approximate solution to the model in the case with an excess number of receptors is found. The classical results concerning the stochastic approach to the mass-action model are also presented.

Kinetics↗
PubMed1993

Load compensatory response of external intercostal muscles during assisted ventilation in rabbits.

Phrenic and external intercostal motor responses to inspiratory load were studied in anaesthetized rabbits and after bilateral vagotomy. Animals were ventilated with a phrenic nerve driven respirator set at different gains, i.e. volume to phrenic-signal ratio. Load was imposed by occluding the trachea at the end of expiration for the period of one breath. It was found that vagally mediated low threshold facilitation may be observed in rabbits on late-inspiratory external intercostal motor units. After vagotomy, external intercostal EMG response to load depended on the given of the servorespirator set during the period of assisted ventilation.

Adaptation, Physiological↗
PubMed1991

Functional properties of crossed spinocerebellar tract neurones with cell bodies in the S1 segment.

Functional properties of a crossed spinocerebellar tract with cell bodies located in laminae VII and IX of the S1 segment were investigated using intracellular recording. The neurones were found to be excited by group I and II muscle afferents and afferents of skin, joint and interosseus nerves. Volleys from group II muscle afferents and cutaneous afferents evoked inhibition in these cells. It is concluded that S1 spinocerebellar neurones convey a similar type of information to that of dorsal spinocerebellar tract and ventral spinocerebellar tract neurones but integrate it in a different way.

Animals↗
PubMed1991

Dynorphin expression and Fos-like immunoreactivity following inflammation induced hyperalgesia are colocalized in spinal cord neurons.

Fos and Fos-related proteins are increased in spinal dorsal horn neurons following noxious stimulation. The laminar location of neurons that exhibit this increase is coincident with those that exhibit an increase in dynorphin in a rat model of peripheral inflammation and hyperalgesia. In order to determine whether the increase in Fos or related proteins and dynorphin occurs in the same dorsal horn neurons, two kinds of double-labeling methods were used: in situ hybridization histochemistry to label dynorphin mRNA autoradiographically, and immunocytochemistry to label Fos and Fos-related proteins, or a double immunocytochemical method that labeled Fos and Fos-related proteins and dynorphin peptide with distinct chromagens. With both methods more than 80% of the neurons in laminae I, II, V and VI exhibiting an increase in either dynorphin mRNA or peptide following peripheral inflammation also colocalized increased nuclear Fos-like immunoreactivity. However, the number of neurons displaying increased Fos-like immunoreactivity was substantially greater than the number of neurons colocalizing increased dynorphin. These data suggest that the activation of nuclear Fos and Fos-related proteins may be related to the induction of dynorphin gene expression in a subpopulation of spinal cord neurons following peripheral inflammation and hyperalgesia.

Animals↗
PubMed1991

No happy ending: pregnancy loss and bereavement.

Bleeding in pregnancy signals not only danger but often failure and loss and the start of bereavement. This chapter identifies types of loss experienced in pregnancy and the bereavement process. In addition, the social aspects of bereavement as they concern marital relationships are identified. The impact of the personal losses of those in the helping profession also are discussed. Working with parents experiencing perinatal death should include interventions involved with physical care, psychological support, and aspects of perinatal death education. Follow-up care is critical to the ongoing assessment and evaluation of parents' progress through the bereavement process. Specific aspects of follow-up care are suggested, including data and information regarding parent support groups.

Abortion, Spontaneous↗
PubMed1989

Dynamics of the Adair model for ligand-receptor binding.

The dynamics of the Adair model for ligand-receptor binding involving the case with interacting receptors is investigated. Using the methods of formal reaction kinetics, the existence, uniqueness, and asymptotic stability of equilibria within the model are demonstrated. The approximate solutions to the Adair model are found.

Kinetics↗
PubMed1988

The pontocerebellar efferents from the pontine reticular tegmental nucleus in the rabbit: differential projections to the paramedian sublobules as revealed with tracing of retrograde axonal transport of horseradish peroxidase.

Projections from the nucleus reticularis tegmenti (NRTP) pontis to the cerebellar paramedian lobule were studied using a horseradish peroxidase retrograde transport technique. The rabbit's NRTP consists of a medial principal part (the nucleus papillioformis: PLF) and smaller lateral part (the processus tegmentosus lateralis: PTL). The PLF can be subdivided into a dorsomedial part--zone A, a ventrolateral part--zone C, and a main part--zone B. Zone B is furthermore divisible into the subzones: B1, B2, and B3. In addition, some cells of zone B3 invade the fiber bundles of the medial lemniscus. Experimental data have indicated a topographically organized bilateral projection from the NRTP to the anterior, the middle and the posterior folia of the paramedian lobule with some degree of contralateral dominance. In contrast to an earlier report in cats we find that not only the ventral, but also the dorsal region of the NRTP send projections onto the paramedian lobule. The neurons sending axons to the paramedian lobule are localized mainly in the middle and to a some degree in the posterior thirds of the NRTP. Zones A, B1 and B3 project onto all of sublobules of the paramedian lobule. While zone A projects primarily onto the anterior sublobules (e, f), zone B1 emanates to the middle paramedian sublobules (c, d), Zone B3 sends fibers mainly into the posterior sublobules (a, b) and to a some degree to the middle paramedian sublobules. Zone B2 distributes a few axons exclusively to the middle folia of the paramedian lobule, while the middle part of the PTL gives rise to small bilateral projection to sublobules c and d of the paramedian lobule. Neurons of zone C send projections into the middle folia of the paramedian lobule. These findings are discussed in relationship to other morphological and physiological data on neurons of the pontine reticular tegmental nucleus.

Animals↗
PubMed1988

Twitch force and action potentials of single motor units in medial gastrocnemius muscle of the rat.

On the basis of a sag test in unfused tetanus we classified fast and slow motor units (MUs) in medial gastrocnemius muscle of the rat. The following parameters of motor units were investigated: single twitch force, duration of the action potentials, maximum-minimum amplitude time (M-MAT), action potentials amplitude and their latencies after stimulus (to the onset of potentials) and the diameter of MU territory in muscle medio-lateral direction. Differences were found between fast and slow MUs in all of the properties. A correlation was found between MU twitch forces and the diameters of territories and amplitudes of action potentials in the whole investigated MU population, as well as between the duration and the M-MAT of the action potentials.

Action Potentials↗
PubMed1985

[New data on the fleas (Insecta, Siphonaptera) of Algeria].

28 species or subspecies are noted; 6 are new for this country [Echidnophaga gallinacea (Westwood, 1875), Xenopsylla blanci Smit, 1957?, Ischnopsyllus intermedius (Rothschild, 1898), I. octactenus (Kolenati, 1856), Nycteridopsylla ancyluris Jordan, 1942 and N. pentactena (Kolenati, 1856)]. A new Caenopsylla is described in another paper.

Algeria↗
PubMed1985

Enterobius vermicularis and acute appendicitis.

The relationship between Enterobius vermicularis and acute appendicitis has been discussed for more than 80 years. The latest histological examinations show that the parasites do invade the wall of the vermiform appendix, and related to these are inflammatory reactions. This invasion causes the symptoms that lead to appendectomy. A case report of a patient with symptoms of acute appendicitis and a histological finding of intramural parasites is presented.

Acute Disease↗