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Biomedical subjects

A Holub

Publications and source records attributed to A Holub.

At least 19 recordsLinked to original sources
PubMed2003

Ligand density modulates eosinophil signaling and migration.

Eosinophils are a major component of the inflammatory response in persistent airway inflammation in asthma. The factors that determine the retention of eosinophils in the airway remain poorly understood. Elevated levels of fibronectin have been observed in the airway of patients with asthma, and the levels correlate with eosinophil numbers. To determine if fibronectin density modulates eosinophil function, we investigated the effect of fibronectin and vascular cell adhesion molecule 1 (VCAM-1) density on eosinophil migration and signaling via the p38 and extracellular regulated kinase (ERK)-mitogen-activated protein kinase (MAPK) signaling pathways. There was a dose-dependent inhibition of eosinophil spreading and migration on increasing concentrations of fibronectin but not VCAM-1. In addition, activation of p38 MAPK was inhibited at high fibronectin but not high VCAM-1 concentrations, and ERK activity was slightly reduced at high VCAM-1 and fibronectin concentrations. Together, the results demonstrate that fibronectin but not VCAM-1 inhibits eosinophil migration and signaling.

Adult↗
PubMed1998

The crystal structure of phosphoribulokinase from Rhodobacter sphaeroides reveals a fold similar to that of adenylate kinase.

The essential photosynthetic enzyme phosphoribulokinase (PRK) is responsible for the conversion of ribulose 5-phosphate (Ru5P) to ribulose 1,5-bisphosphate, the substrate for the CO2 fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco). We have determined the structure of the octameric bacterial form of PRK to a resolution of 2.5 A. The protein is folded into a seven-member mixed beta-sheet surrounded by alpha-helices, giving the overall appearance of the nucleotide monophosphate family of kinases. Homology with the nucleotide monophosphate kinases suggests a number of amino acid residues that are likely to be important in catalysis and suggests the roles of some amino acid residues that have been mutated prior to the determination of the structure. Further, sequence identity across eukaryotic and prokaryotic species and a calculation of the buried surface area suggests the identity within the octamer of a dimer conserved throughout evolution. The width of the groove leading to the active site is consistent with an oriented molecule of thioredoxin controlling the oxidation state of two cysteines that regulate activity in the eukaryotic enzymes. Although neither Asp 42 nor Asp 169 can be definitively assigned as the catalytic base, the crystal structure suggests the location of a ribulose 5-phosphate binding site and suggests a role for several of the conserved basic residues.

Adenylate Kinase↗
PubMed1997

[Veterinary medicine in the modern world].

Present veterinary medicine is the result of a global scientific effort. Unknown are ideological or national barriers. However, the conditions for its realization vary from country to country with a changing clientele as well. The number of farm animals is increasing, as well as interest in the health of animals not in the care of man. There are about 600,000 veterinarians in the world, globally unevenly distributed. Relatively speaking, the least are in areas with greater agricultural population, and the most, in societies of the postindustrial age. In recent years many regions of the world have been going through an avalanche of changes. Even though the concepts of these consequence to the health care of animals far from agree, the direction of veterinary responsibility is shifting from public to private sector. In this regard the care of animal health on an international, national or regional level has been repeatedly analyzed and intricately evaluated from the early '80s. A generally accepted policy has been that in the care of animal health both sectors, public and private, play a significant role. However, under discussion are their relative proportions which differ in various parts of the world. The market is increasingly permeating into health care. In our country up to now the critical break in the development of veterinary medicine has not been objectively evaluated. We are still too concerned with the past, passing on disinformation, persisting in old dogmas and moss-grown myths. The way into a world of new priorities and the hierarchy of values in today's turbulent times is uneasy, all the more to be tentaciously sought.

Animal Diseases↗
PubMed1994

[Changes in hydration in chicken and duck eggs during incubation].

Water loss was determined during incubation in 80 eggs of the domestic fowl, White Leghorn-LB and New Hampshire-NH (between the 1st and 20th day), and in 80 eggs of Beijing White ducks (between the 1st and 25th day). Our data have shown that, the lowest actual water content was found in NH eggs, the highest in the duck eggs. Water content decreased absolutely and relatively during incubation; 365 in LB, 500 in NH and 312 mg/d in ducks. Water loss was higher in the first half of hatching. In the second half it was probably partly offset by water originating from fats oxidized for energetic purposes; the offset made a third in LB and NH, and still more in the ducks. Our results are somewhat different from the literature data, the variability of which is considered to be rather high in general. There were large shifts of water among the egg components during incubation. Water totally disappeared from the albumen, although it contained approximately three quarters of water was at the beginning of hatching. Already in the first half of incubation, more than a third of water was transported to the embryo, fetal membranes and fluids. In the subsequent ten days, water accumulation in the body of the developing and growing embryo was especially rapid; the water amount increased eight times in the fowl, seven times in the duck bodies. Water losses and its shifts show not only interspecific differences related to different lengths of incubation, but also intraspecific ones, between BL and NH.

Animals↗
PubMed1994

[Sows and piglets--nutritional interactions].

Nutrition energy transfer from sows to piglets is unusually intensive in the suckling period. Due to this transfer, the sows increase their relative standard energy metabolism up to four times, that means to the boundary of the long-term sustainable maximum. They cannot cover these large energy outputs by feed intake, therefore they are catabolizing their own body tissues during suckling and lose about 15% of their live weight. Through milk, which is an energy-rich high-fat diet, up to 1.76 MJ/kg and day of energy (in the first week) are transferred to piglets, and/or up to 2.26 MJ/kg0.75 and day of energy (in the second week), which enables them to double their live weight at birth within the first 7 to 10 days. Milk transfer is of behavioral character in the system dam and litter. In a short time, it assumes a form of cyclic, collective synchronized suckling which is repeated more than twenty times a day and consists of several phases. But the piglets are able to feed not only on genuine milk but also from other sources from the second week of life. Then their weaning begins. They enter from the suckling period to a long, several-week period of weaning, in which some of their functional characteristics are changed fluently, others in a cascade manner. Proper, and to all participants adequate development of this transfer is depending on numerous circumstance which need not always be real. One of the reasons is that birth is such a large load for piglets that they cannot be competitive partners to their less loaded mates in the competition for sources of nutrition. Their participation in the unusually intensive, episodic, delicate transfer of nutrients conditioned by many factors is insufficient, full of failures. Hence they do not sufficiently utilize their growth potential, and do not often survive. Nevertheless, they are so functionally adaptable so that they can live without mothers, in isolation, being able to drink a liquid diet.

Animal Nutritional Physiological Phenomena↗
PubMed1993

The effects of diarrhoea on food intake in piglets weaned on the day of birth.

Large White x Landrace piglets (23 animals) weaned on the first day after birth were reared individually in a thermoneutral environment on a liquid diet having a macronutrient content similar to that of sow's milk. They were offered the diet from sucking bottles nine times a day at 2-h intervals. According to the appearance of the faeces the animals were divided into two groups: diarrhoeic piglets and clinically healthy animals. Their consumption of the diet, energy (GE) and macronutrients was assessed from the 3rd to the 10th day after birth; a total of 514 and 441 measurements were made in diarrhoeic piglets and healthy controls, respectively. With advancing age the intake of the diet by animals of the two groups changed in the same way as we described in previous studies. In diarrhoeic piglets, however, both the actual and the relative food intake, expressed in relation to live body mass and metabolic mass, was lower on days 3, 5 and 6 than in the healthy controls. In the period of the earlier described transient decrease in food consumption this difference disappeared and was observed again in piglets 9 (actual diet intake) and 10 (both actual and relative diet intake) days of age. Impairment of their enteral functions manifested by decreased ingestion of the liquid diet, GE, N substances and lipids was also observed after ontogenic shift of regulatory mechanisms of food intake control to a higher integrative level.

Animals↗
PubMed1991

[Water consumption in piglets weaned early at various ages and fed a liquid diet].

Water consumption was recorded in 72 piglets of the Lorge White breed, weaned either on the second, sixth, tenth day or on the fourteenth day of age, this parameter was followed till the age of four weeks. The piglets were kept individually in a thermoneutral zone and they received a milk diet with macronutrient content, similar to sow's milk and water content of from 78.47%. The diet was offered to suck nine times a day in two-hour intervals. The piglet age at weaning was found to influence significantly water intake. Daily water ingestion is higher in piglets separated from the sows at a younger age than in piglets weaned later on; it reaches as much as 29% in the first group, 26% in the second group, 28% and 20% of live weight in the third and fourth groups, respectively. If converted to the metabolic weight, the percentage is still higher: more than 40% in the first group at the end of the fourth week. Although the spans of weaning beginnings were always identical in particular groups of piglets (four days), the differences in the water consumption were not the same. The differences were smaller between the first and second group, and the third and fourth group, in comparison with those between the second and third group. This fact confirms previous general statements about the periodization of early postnatal life of piglets. The beginning of weaning of the first two groups belongs to the "suckling" period, while the beginning of weaning of the other groups is within the "weaning" period.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1989

Effect of intraperitoneal administration of amino acids on the food intake of piglets on a liquid diet during the first month after birth.

The effect of single intraperitoneal 1 g.kg-1 doses of a solution of 20 amino acids (AA) on food intake was investigated in 20 piglets examined repeatedly between 2 and 26 days of age. The animals were reared individually from day 1 after birth in cages and bottle-fed a liquid diet nine times per day at two-hour intervals from 6 to 22 h. Although amino acid administration did not significantly affect plasma concentrations of total free AA throughout the experiment (as measured just before and 2 and 5 h after AA administration in blood withdrawn from the external jugular vein) it did produce a downward trend in food intake of piglets at 9-10 d of age. In older animals, the depressive effect on food intake was significantly greater and lasted longer. It is suggested that the aminostatic component of food intake regulation in piglets does not begin to operate until the weaning period.

Aging↗
PubMed1979

[An electricodynamic cathethermometer and heat conditions in pens for piglets].

In the farrowing houses the electric dynamic katathermometer (EDK) was used to determine the thermal conditions in boxes for piglets heated by electric infraradiators (EIZ) with an input of 525 W. The density of heat flow of the EDK sensor in the boxes which characterizes the cooling properties of this environment was zero or only very low if the infraradiators were installed 60 to 70 cm above the floor of the boxes, i. e. so as to temper the air to a temperature recommended by the standard. This is apparently caused by the relatively great radiation from the infraradiator which is not registered by the mercury thermometer but is absorbed by the body surface of the piglets and may lead to their overheating. A desirable increase in the cooling properties of the box environment and of the other spaces of the farrowing house was achieved by decreasing the infraradiator input to 260 W and suspending them 50 cm above the floor of the boxes. Their fixation at a greater height allowed the further effective regulation of the heat conditions in the boxes while at the same time cutting down electric energy consumption by a half.

Animal Husbandry↗