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  1. 16 Folia Histochemica et Cytobiologica

  2. 6 Polish Journal of Veterinary Sciences

  3. 5 Acta Biologica Cracoviensia. Series Botanica. Supplement

  4. 5 Medycyna Weterynaryjna

  5. 4 Folia Morphologica

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  1. 55 Lewczuk B.

  2. 28 Przybylska-Gornowicz B.

  3. 12 Prusik M.

  4. 8 Wyrzykowski Z.

  5. 6 Nowicki M.

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  1. 1 2019

  2. 4 2018

  3. 1 2017

  4. 2 2016

  5. 2 2015

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1

Stosunki demograficzne w wybranych gminach wiejskich w 1996 r. [zatrudnienie i bezrobocie]

100%
Lewczuk B.
Zeszyty Naukowe. Seria Ekonomika i Organizacja Rolnictwa. Wyższa Szkoła Rolniczo-Pedagogiczna w Siedlcach
|
1998
|
tom 54
81-91
2

Infrastruktura i przemysl rolno-spozywczy w gminie jako warunek rozwoju przedsiebiorczosci

100%
Lewczuk B.
Zeszyty Naukowe. Seria: Ekonomika i Organizacja Rolnictwa. Akademia Podlaska
|
2000
|
tom 58
87-97
3

Bezrobocie a rozwoj obszarow wiejskich

100%
Lewczuk B.
Zeszyty Naukowe Akademii Rolniczej w Krakowie. Sesja Naukowa
|
2001
|
tom 76.2
245-251
4

Agroturystyka na terenie Nadbużańskiego Parku Krajobrazowego

100%
Lewczuk B.
Roczniki Naukowe Stowarzyszenia Ekonomistów Rolnictwa i Agrobiznesu
|
2000
|
tom 02
|
nr 2
Obszar Nadbużańskiego Parku Krajobrazowego posiada bardzo duże dotychczas wykorzystywane w niewielkim stopniu walory turystyczne. Położenie w bezpośrednim sąsiedztwie Warszawy oraz w pobliżu ważnych szlaków komunikacyjnych sprzyja turystycznemu wykorzystaniu tego atrakcyjnego terenu. Znaczną rolę w propagowaniu i rozwijaniu gospodarstw agroturystycznych odgrywa Ośrodek Doradztwa Rolniczego w Siedlcach i jego placówki terenowe. Na uwagę przede wszystkim zasługuje działalność doradcza, szkoleniowa i promocyjna. Dynamiczny rozwój agroturystyki nie jest jednak możliwy bez umiejętnego kreowania i wspierania ze strony samorządów lokalnych, dlatego trzeba szerzej ujmować ją w programach działania różnych podmiotów gospodarczych działających na terenach atrakcyjnych gmin.
5

Siatkowka, jadro skrzyzowania oraz szyszynka jako elementy zegara biologicznego ssakow

100%
Lewczuk B.
Medycyna Weterynaryjna
|
2007
|
tom 63
|
nr 05
506-511
The article presents the most important mechanisms related to the functioning of the retina, the suprachiasmatic nucleus (SCN) and the pineal gland as components of the mammalian biological clock. Environmental light influences the biological clock in mammals via light-sensitive, retinal ganglion cells containing a photo pigment - melanopsin. The axons of these neurons form the retionohypothalamic tract, which terminates in SCN. Neurons located in SCN generate cyclic, circadian changes in their activity due to a system of clock genes, the transcription of which is mutually controlled by an auto regulatory feedback loop. Glutamate and pituitary adenylate cyclase activating peptide (PACAP) - neurotransmitters released from terminals of the retionohypothalamic tract, synchronize the activity of the SCN neurons with environmental light conditions. The neuronal cells located in SCN influence the pineal activity via a paired, mulisynaptic pathway, composed of neurons of the paraventricular nucleus, the intermediolateral nuclei of the spinal cord and the cranial cervical ganglion, which supply the pineal gland with sympathetic nerve fibers. Norepinephrine, released from these fibers at night, stimulates melatonin secretion. The intracellular mechanisms controlling melatonin synthesis in the pinealocytes have significant variations between species, which accounts for differences in the diurnal patterns of pineal hormone secretion.
6

Mechanizmy adrenergicznej regulacji sekrecji melatoniny w szyszynce swini - badania in vitro

100%
Lewczuk B.
Rozprawy i Monografie. Uniwersytet Warmińsko-Mazurski w Olsztynie
|
2002
|
tom 60
1-157
7

Regulacja sekrecji melatoniny w szyszynce ptakow

63%
Prusik M., Lewczuk B.
Medycyna Weterynaryjna
|
2008
|
tom 64
|
nr 05
639-645
The avian pineal gland releases melatonin in a cyclic manner, with the highest level at night and the lowest level during the daytime. Mechanisms regulating melatonin secretion in birds are very complex, probably due to the phylogenetic position of the avian pineal gland as an intermediate form between the pineals of lower vertebrates and mammals. Avian pinealocytes possess an endogenous oscillator, formed by a self-regulated system of cock genes, that controls the transcription of several enzymes, among them arylalkylamine N-acetyltransferase (AA-NAT), the enzyme limiting melatonin synthesis. These cells are also directly photosensitive due to the presence of photopigments, pinopsin and melanopsin, as well as corresponding signal transduction systems. Light acting via pinopsin induces a cascade of events that leads to the decrease in cGMP and cAMP levels, AA-NAT activity and melatonin secretion. Melanopsin is probably involved in an entrainment of the circadian oscillator to the environmental light conditions. The function of the avian pineal gland is also regulated by light acting indirectly via the retina as well as by the extrapineal oscillator located in the suprachiasmatic nucleus. Both structures influence the pinealocyte activity via a common multisynaptic pathway, which ends in the gland as the sympathetic nerve fibers. Norepinephrine released from these fibers stimulates α₂-adrenoreceptors in pinealocyte plasmalemma and inhibits adenylate cyclase activity and melatonin secretion. The significance of direct and indirect routes of light perception as well as intra- and extra-pineal oscillators in the regulation of melatonin secretion may differ between species, but this problem is poorly recognized.
8

Innervation of the pineal gland in the Arctic fox (Vulpes lagopus) by nerve fibres immunoreactive to substance P and calcitonin gene-related peptide

63%
Bulc M., Lewczuk B.
Folia Morphologica
|
2019
|
tom 78
|
nr 4
Background: The study demonstrates, for the first time, the presence of substance P (SP) and calcitonin gene-related peptide (CGRP) in the nerve fibres supplying the pineal gland in the Arctic fox. Materials and methods: The expression and distribution pattern of the studied substances were examined by double-labelling immunofluorescence technique. Results: The SP-positive fibres enter into the pineal gland through the capsule as the nervi conarii. The fibres formed thick bundles in the capsule and connective tissue septa, from where they penetrated into the pineal parenchyma. Inside the parenchyma, the nerve fibres created basket-like structures surrounding clusters of pinealocytes. The density of intrapineal SP positive fibres was slightly higher in the distal and middle parts of the gland than in the proximal one. Double immunostaining with antibodies against SP and CGRP revealed that the vast majority of SP positive fibres were also CGRP positive. The fibres showing a positive reaction to SP and negative to CGRP were scattered within the whole gland. The fibres immunopositive to CGRP and immunonegative to SP were not observed. In the habenular and posterior commissural areas adjoining to the pineal gland the immunoreactive nerve fibres were not found. Moreover, no immunopositive cell bodies were observed in both the pineal gland and the commissural areas. Conclusions: These results reveal that SP and CGRP are involved in the innervation of pineal gland in carnivores. In turn we suggest that these peptides can regulate/ /modulate melatonin secretion. (Folia Morphol 2019; 78, 4: 695–702)
9

Pięćdziesiąt lat Wydziału Medycyny Weterynaryjnej Uniwersytetu Warmińsko-Mazurskiego w Olsztynie

63%
Koncicki A., Lewczuk B.
Medycyna Weterynaryjna
|
2017
|
tom 73
|
nr 09
10

Szanse rozwoju agroturystyki na obszarach chronionych

63%
Lewczuk B., Szarek s.
Zeszyty Naukowe. Seria: Ekonomika i Organizacja Rolnictwa. Akademia Podlaska
|
2004
|
nr 64
69-76
11

Budowa szyszynki ptakow

63%
Prusik M., Lewczuk B.
Medycyna Weterynaryjna
|
2008
|
tom 64
|
nr 06
764-769
The morphology of the avian pineal glands shows large interspecies variability. Considering the anatomic structure, six types of the pineal organs (I-VI) are distinguished in birds. They differ in the proportion between the distal and proximal parts of the gland as well as in the attachment to the intercommisural region. According to the histological structure, the avian pineal glands are classified into three types: the saccular, tubulo-follicular and solid type. The pineal parenchyma consists of pinealocytes, supporting cells and neurons. Among pinealocytes there are receptor pinealocytes (predominant in the saccular pineals), rudimentary-receptor pinealocytes (predominant in the tubulo-follicular organs) and secretory pinealocytes (most numerous in pineals of the solid type). The population of supporting cells consists of ependymal-like and astrocyte-like cells. Neurons are represented by afferent ganglion cells, present mainly in the saccular pineals. The pineals of tubulo-follicular and solid types possess well developed sympathetic innervation.
12
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Innowacyjność jako czynnik konkurencyjności gospodarstw rolniczych

63%
Lewczuk B., Jablonka R.
Roczniki Naukowe Stowarzyszenia Ekonomistów Rolnictwa i Agrobiznesu
|
2011
|
tom 13
|
nr 2
Innowacje w gospodarstwach rolnych są wymogiem współczesnych czasów. Innowacja to wytwarzanie i dostarczanie na rynek nowych produktów. Dalszy rozwój oraz kontynuowanie przemian w polskim rolnictwie wymaga otwartości rolników na nowe inicjatywy.
13

Sezonowosc cen zywca wieprzowego w Polsce w latach 1991-1997

63%
Lewczuk B., Szarek S.
Trzoda Chlewna
|
1999
|
tom 37
|
nr 05
68-69
14

Zastosowanie rachunku kosztow marginalnych w produkcji zywca wolowego i wieprzowego

63%
Szarek S., Lewczuk B.
Zagadnienia Ekonomiki Rolnej
|
1999
|
nr 4-5
51-59
15

Leu-enkephalin immunoreactivity in the pig pineal gland

63%
Przybylska-Gornowicz B., Lewczuk B.
Folia Histochemica et Cytobiologica
|
2002
|
tom 40
|
nr 2
16

The effect of exogenous melatonin on the pinealocyte ultrastructure in the domestic pig [Sus domesticus] depends on the time of its administration

63%
Lewczuk B., Przybylska-Gornowicz B.
Polish Journal of Veterinary Sciences
|
2000
|
tom 03
|
nr 1
Melatonin secretion is not regulated via simple negative feedback inhibition. However some results show that melatonin may influence its own synthesis and secretion as well as other processes in the pineal gland. The present study was undertaken to check the effects of melatonin administered at different times of day on the ultrastructure of pig pinealocytes. The study was performed in summer under natural photoperiod. Gilts, aged 4 months, received lmg or 3 x lmg melatonin (i.m.) daily for four consecutive days, at different times of day. Point count analysis was used in quantitative studies of pinealocyte substructures. The administration of melatonin caused clear changes in the pinealocyte ultrastructure and the effects were closely dependent on the time of hormone injection. The most visible changes were observed in pinealocytes of pigs which received one injection of melatonin per 24 hr, at the end of the light phase. This schedule of melatonin administration resulted in a decrease in the relative volume of mitochondria and dense bodies of type MBB-1 (specific structures of the pig pinealocytes) as well as an increase in the relative volume of Golgi apparatus and numerical density of multivesicular bodies. The melatonin administration three times per 24 hr (in the morning, in the early afternoon and in the evening) caused a decrease in the relative volume of mitochondria and Golgi apparatus as well as an increase in the relative volume of MBB-1. Treatment with melatonin once per 24 hr in the morning resulted in a decrease in the relative volume of mitochondria.
17

Cytoplasmic dense bodies in pig pinealocyte during postnatal development. Quantitative, ultrastructural study

63%
Przybylska-Gornowicz B., Lewczuk B.
Folia Morphologica
|
1997
|
tom 56
|
nr 1
18

Indole metabolism in the embryonic pineal gland of the domestic turkey - a preliminary study

51%
Prusik M., Kwiecinska K., Lewczuk B.
Acta Biologica Cracoviensia. Series Botanica. Supplement
|
2016
|
tom 58
|
nr 1
19

The study of melatonin release from pineal gland of the domestic pig using a perfusion culture technique

51%
Lewczuk B., Przybylska-Gornowicz B., Wyrzykowski Z.
Acta Neurobiologiae Experimentalis
|
1997
|
tom 57
|
nr 5
20

Dobowe zmiany stezenia melatoniny w osoczu krwi niedojrzalych plciowo loszek podczas dlugiego dnia swietlnego

51%
Lewczuk B., Bulc M., Przybylska-Gornowicz B.
Medycyna Weterynaryjna
|
2006
|
tom 62
|
nr 10
1171-1175
The level of melatonin in plasma was investigated in gilts reared during long summer days (sunrise 430, sunset 2030). Lighting in the animal's rooms was provided by windows and fluorescent lamps, which were automatically turned on at 545 and turned off at 1945. The light intensity during photophase was 500 lux at the level of the animal's eyes. Blood samples were taken from twelve gilts over a 24 hour period and further sampling was continued in six pigs over the following 3 days. The effect of exposure to a 500 lux light during the night on plasma melatonin levels was studied in the remaining six gilts. The concentration of melatonin in the plasma was measured by direct radioimmunoassay employing an R/R/19540-16876 antibody and iodinated tracer. Concentrations of the investigated hormone were low during day and rapidly increased at the onset of night during which the plasma melatonin level remained at an elevated plateau and then declined at the onset of day. The mean concentration of plasma melatonin was about three times higher during the night compared to daytime. Monitoring of the pineal hormone level in blood plasma over four consecutive days indicated regular melatonin rhythms in 5 of the 6 investigated pigs. A 500 lux light (turned on for one night) did not prevent a nocturnal increase in plasma melatonin levels.
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