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Biomedical subjects

A Kowalski

Publications and source records attributed to A Kowalski.

At least 19 recordsLinked to original sources
PubMed2006

Use of MR spectroscopy and functional imaging in the treatment planning of gliomas.

Routine anatomical imaging with CT and MRI does not reliably indicate the true extent or the most malignant areas of gliomas and cannot identify the functionally critical parts of the brain. The aim of the study was to see if the use of MR spectroscopic imaging (MRSI) along with functional MRI (fMRI) can better define both the target and the critical structures to be avoided to improve radiation delivery in gliomas. 12 patients with gliomas underwent multivoxel MRS and functional imaging using GE processing software. The choline to creatine ratio (Cho:Cr), which represents the degree of abnormality for each individual voxel on MRSI, was derived, converted into a grayscale grading system, fused to the MRI images and then transferred to the planning CT images. An intensity-modulated radiation therapy (IMRT) plan was developed using the dose constraints based on both the anatomical and the functionally critical regions. Cho:Cr consistently identified the gross tumour volume (GTV) within the microscopic disease (clinical target volume, CTV) and allowed dose painting using IMRT. No correlation between MRSI based Cho:Cr > or =2 and MR defined CTV nor their location was noted. However, MRSI defined Cho:Cr > or =3 was smaller by 40% compared with post-contrast T1 weighted MRI defined GTV volumes. fMRI helped in optimizing the orientation of the beams. In conclusion, both MRSI and fMRI provide additional information to conventional imaging that may guide dose painting in treatment planning of gliomas. A Phase I IMRT dose intensification trial in gliomas using this information is planned.

Brain↗
PubMed2005

Corticosterone and dexamethasone potentiate cytotoxicity associated with oxygen-glucose deprivation in organotypic cerebellar slice cultures.

Many patients display elevated levels of serum cortisol following acute ischemic stroke. Given that glucocorticoids may potentiate some forms of insult, these studies examined the effects of corticosterone or dexamethasone exposure on cytotoxicity following oxygen-glucose deprivation in the cerebellum, a brain region susceptible to stroke. In organotypic cerebellar slice cultures prepared from neonatal rat pups, 90-min of oxygen-glucose deprivation at 15 days in vitro resulted in significant cytotoxicity at 24-, 48-, and 72-h post-oxygen-glucose deprivation, as measured by uptake of propidium iodide. Exposure of cultures following oxygen-glucose deprivation to the antioxidant trolox (500 microM), but not to the glucocorticoid receptor antagonist RU486 (10 microM), completely blocked oxygen-glucose deprivation-induced cytotoxicity. Corticosterone (1 microM) or dexamethasone (10 microM) exposure alone did not significantly increase propidium iodide uptake above levels observed in control cultures. However, corticosterone or dexamethasone exposure after oxygen-glucose deprivation potentiated oxygen-glucose deprivation-mediated propidium iodide uptake at each time point. Trolox, as well as RU486, co-exposure of cultures to corticosterone or dexamethasone after oxygen-glucose deprivation abolished all cytotoxicity. In conclusion, these data demonstrated that glucocorticoid exposure modulated oxygen-glucose deprivation-mediated propidium iodide uptake, which likely involved glucocorticoid receptor activation and pro-oxidant effects.

Animals↗
PubMed2004

Identification of histone H1.z components in a Muscovy duck (Cairina moschata L.) population.

The general patterns of histone H1 proteins from erythrocyte nuclei of Muscovy duck individuals were similar to those of Pekin type ducks both in acetic acid-urea and 2D polyacrylamide gels. We show here that Muscovy duck histone H1.z in the tested population was represented by three different electromorphs, each presumably encoded by a distinct allelic gene. Accordingly, we have identified six phenotypes consisting of the homodimeric and heterodimeric combinations of the three isoforms. The frequency of the presumptive alleles ranged from 0.506 for the main allele z1 to 0.379 for allele z2 and only 0.113 for the rarest allele z3. In addition to a standard set of somatic H1 variants, an unusual protein X, absent in other avian species, was also revealed.

Alleles↗
PubMed2004

Pregnancy and bovine somatotropin in nonlactating dairy cows: II. Endometrial gene expression related to maintenance of pregnancy.

The objective was to evaluate the effects of pregnancy and bovine somatotropin (bST) on endometrial gene and protein expression related to maintenance of pregnancy in nonlactating dairy cows at d 17. In endometrial tissues, treatment with bST increased the steady state concentration of oxytocin receptor (OTR) mRNA; bST-treated cyclic (bST-C) cows had greater OTR mRNA than bST-treated pregnant (bST-P) cows. Estradiol receptor alpha (ERalpha) mRNA was reduced in bST-P cows compared with control P and C (no bST) cows. Western blotting revealed that pregnancy decreased the abundance of ERalpha protein, and bST stimulated an increase in ERalpha protein in C and P cows. Treatment with bST increased steady state concentrations of progesterone receptor (PR) mRNA. No differences were detected in steady state mRNA concentrations of prostaglandin H synthase-2 (PGHS-2), prostaglandin E synthase, and prostaglandin F synthase due to pregnancy or bST treatment. However, PGHS-2 protein was increased in response to pregnancy and bST treatment. Immunostaining indicated that P decreased ERalpha protein in luminal epithelium and increased PR protein in epithelial cells of the uterine glands. The PR protein response in the glands was less in bST-P cows than in P cows. In the stromal layer of the endometrium, bST decreased PR protein abundance in C and P cows. The PGHS-2 protein was localized exclusively in the luminal epithelium cells of endometrium and was increased in P cows. In conclusion, distinctly different mRNA and protein responses were detected between C and P cows related to prostaglandin biosynthesis, and bST-induced changes may potentially impact mechanisms associated with maintenance of pregnancy in nonlactating cows.

Animals↗
PubMed2002

Comparison of susceptibility to stress in two genetic lines of turkey broilers, BUT-9 and Big-6.

The aim of the study was to compare the level of susceptibility to stress in two broiler turkey lines-BUT-9 and Big-6. The experiment was performed on 120 turkey toms aged ca. 8 weeks. Each of the genetic lines was represented by 60 birds divided into 4 groups--one control and three experimental ones, 15 birds in each. The open field test was conducted in the control groups (not exposed to any stress) in order to determine the motor activity of turkeys. The other groups were subjected to the stress of transport, crowding and overheating. When the experiment was over, following indices were determined in blood plasma obtained from all the birds: the concentration of corticosterone, adrenaline and noradrenaline, the level of glucose, cholesterol, total lipids and triglycerides as well as the activity of creatine kinase. The study revealed that the lighter and slower growing BUT-9 turkeys showed a higher resistance to stress than the Big-6. They were characterised by higher motor activity, a higher initial level of catecholamines in blood and heavier adrenals. The increase in corticosterone was much lower in these birds in response to stress. A lower reactivity was also observed in the biochemical indices (the level of cholesterol, triglycerides and glucose and the activity of creatine kinase). This confirms that BUT-9 turkeys are less sensitive to adverse environmental effects than are the Big-6, an interesting feature for poultry production.

Animal Husbandry↗
PubMed2000

Natural allelic variation of duck erythrocyte histone H1b.

In our previous work (J. Palyga, Genetic polymorphisms of histone H1. b in duck erythrocytes. Hereditas 114, 85-89, 1991) we reported a genetic polymorphism of duck erythrocyte histone H1.b. Here, we screened H1 preparations in a two-dimensional polyacrylamide gel to refine the distribution of allelic forms of H1.b in fifteen duck populations. We have revealed that the frequency of H1.b allelic variants was significantly different among many conservative and breeding duck groups. While b(1) and b(3) were common in all populations screened, the allele b(2), with a slightly lower apparent molecular weight, was confined mainly to brown-feathered ducks (Khaki Campbell and Orpington) and descendent lines. The C- and N-terminal peptides released upon cleavage with N-bromosuccinimide and Staphylococcus aureus protease V8 from duck allelic histones H1. b2 and H1.b3, respectively, migrated differently in the gel, probably as a result of potential amino acid variation in a C-terminal domain.

Alleles↗
PubMed1999

Sudden asystole during craniotomy: unrecognized phenytoin toxicity.

The authors report a case of intraoperative sinus arrest in an otherwise healthy patient undergoing craniotomy for aneurysm clipping after mild subarachnoid hemorrhage. The sinus arrest was precipitated by a rapid infusion of 1500 mg phenytoin and was successfully treated with standard resuscitative measures. The differential diagnosis of intraoperative cardiac arrest and the mechanisms of action of phenytoin are discussed. The authors emphasize the role of phenytoin in cerebral protection.

Anticonvulsants↗
PubMed1998

Measurement of radiation dose delivered to breast tissue during mantle field irradiation for Hodgkin's disease.

The treatment of Hodgkin's disease involves mantle field irradiation. Patients with early stage (I-II) Hodgkin's are often in their 20's or 30's and can expect to live for many decades after the successful management of their disease; however, complications, including second cancers in the treatment area, occur in some survivors. Breast cancer is among the leading second solid cancers that develop in patients who have undergone mantle field irradiation. This paper attempts to determine the dose that may be delivered to breast tissue from mantle field irradiation to treat Hodgkin's disease. Utilizing an anthropomorphic phantom, thermoluminescent dosimeters (TLDs) were placed into a breast phantom constructed of Superflab and TX-150, and were irradiated with 6 MV photons. Readings from 170 TLDs in five layers of breast phantom were analyzed. The results show considerable doses reaching portions of breast tissue. In measured points under the blocks, 8-15% of the prescribed isocenter dose was delivered. For points in the primary beam, readings of up to 91% of the isocentric dose were obtained. Points in the breast near block or collimator edges also received substantial doses; upwards of 70% of the prescribed dose. Several points in the breast outside the treatment field were also measured and readings ranged from 2 to 29% of the prescribed dose. Similar patterns of dose distribution were found on computer plans; however, point-by-point comparisons were not performed. These results are compared with published reports.

Breast↗
PubMed1998

Genetic variants of chicken erythrocyte histone H5.

Two allelic electromorphs a and b of chicken erythrocyte histone H5 have been detected in a sodium dodecyl sulfate polyacrylamide gel. In an acid-urea gel, however, each of the allelic variants was found to be accompanied by a slower migrating form. A comparison of alpha-chymotrypsin-digested products of H5.a and H5.b revealed that they differed in N-terminal domains. The H5 variants were distributed differently not only in various chicken races but also in distinct lines within a breed. Allele H5b was about 2.6-4.6 as abundant as its counterpart H5a in most chicken populations examined. These proportions were distorted in two Leghorn lines: the ratio of H5b to H5a was only 1.6 in line H22 and increased up to 32 in line G99.

Alleles↗
PubMed1998

Temporal analysis of feeding behavior in miniature pigs.

The feeding behavior of four Munich miniature pigs (29-43 kg) housed in pairs of two, was observed for two consecutive weeks. Pigs were conditioned to operate a computer-controlled recording system equipped with feeders delivering a precise food release per response and were then fed ad libitum. In addition to the descriptive analysis of feeding behavior, Walsh-Fourier Spectral Analysis was utilized to investigate the temporal patterns of food ingestion and the synchronisation of feeding patterns between the animals housed together. The pigs had up to 48% of their daily energy intake during the dark cycle and there was a substantial reduction of food intake from the first to the second week. Furthermore, pigs housed together synchronized feeding behavior from week 1 to week 2. The recording system has been shown to be highly reliable and valid and provides an excellent tool for the investigation of ingestive behaviors in miniature pigs.

Animals↗
PubMed1993

Genetic polymorphism of histone H1.z in duck erythrocytes.

Three different phenotypes of erythrocyte histone H1.z were detected in several lines of duck by using two-dimensional PAGE. Electrophoresis and inheritance data have shown that two co-dominant alleles, z1 and z2, encode two proteins which differ slightly in their apparent molecular masses. Allele z1 was very abundant and was found at a frequency at least 0.94, while allele z2 was very rare and was present at a frequency of less than 0.06. Limited chemical and enzymic cleavages appeared to indicate that the allelic forms of histone H1.z differed in the C-terminal regions of their molecules.

Alleles↗
PubMed1993

[Evaluation of semen quality after freezing at the temperature of liquid nitrogen using a modification of two different methods].

Spermatozoon survival rate was analysed after freezing at the temperature of liquid nitrogen (-196 degrees C) with the application of three different cryoprotector substances, vitelline and non-vitelline. A modified method, based on the use of sperm cells of small diameter, was introduced in freezing semen. The best results were achieved while using non-vitelline, multi-ionic cryoprotector. It was found out that glycerol alone does not protect semen from the effects of low temperature.

Cell Survival↗
PubMed1992

Effect of different diurnal lighting conditions on serotonin content in the pig pineal gland. Subcellular fractions of the tissue.

Serotonin content in the pineal glands and in their subcellular fractions of the pig housed under natural and limited to circa 2.5 hours per day lighting conditions has been examined spectrofluorometrically. The shortened circadian light phase caused dramatically high drop of serotonin content in the evening (1900-2000). Correlation between presence of dense bodies in subcellular fractions and content of serotonin has been not observed.

Animals↗