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Biomedical subjects

R Ferrer

Publications and source records attributed to R Ferrer.

At least 55 records · Page 3Linked to original sources
PubMed1991

Morphological study of the caecal epithelium of the chicken (Gallus gallus domesticus L.).

1. The structure of the chicken caecal epithelium has been investigated at macroscopic and microscopic levels (scanning and transmission electron microscopy). 2. Morphological data distinguish three regions in the caecum: proximal, with well developed villi, but smaller and less numerous than those present at mid-jejunum; medial, with longitudinal folds and small villi, and distal, with longitudinal and transverse folds and small villi similar to those of the medial region. 3. Microvilli of enterocytes from the tip of the villus of the proximal caecum are shorter and thinner than jejunal microvilli; microvilli of medial and distal regions are poorly developed. 4. There is a decrease in microvillus surface area along the villus axis as a result of the progressive decrease of microvillus length from the tip of the villus to the crypt, both in the proximal caecum and jejunum. In tip of the villus, the amplification of apical surface due to microvilli is 24, 12.7 and 14 times in proximal, medial and distal caecum, respectively, while in the jejunum the amplification factor is 33.1. 5. The higher development of proximal caecal apical surface supports the view that this region is better adapted for the absorption of nutrients that the other caecal regions.

Animals↗
PubMed1991

[Incorporation of transferrin into the erythron in anemic and polycythemic conditions].

A ferrokinetic study was performed in 79 patients, 25 with absolute polycythaemia, 19 with relative polycythaemia and 35 presenting anaemia of different aetiology. The incorporation of transferrin into the erythron (ITE) was estimated on each case. The mean ITE values found in absolute primary and secondary polycythaemia and in secondary polycythaemia were, respectively, 281 +/- 85, 181 +/- 99 and 74 +/- 19 mumol/L tb/d (i.e., micromoles per litre of total blood per day). The mean ITE in iron deficiency anaemia was 110 +/- 43 mumol/L tb/d, in haemolytic anaemia this was 274 +/- 151 mumol/L tb/d, and in patients with myelodysplastic syndromes such values was 116 +/- 49 mumol/L tb/d. Significant differences were found for each group of patients with respect to a normal control group. Such findings are in accordance with the pathophysiology of the different pathologies studied. The values found in haemolytic anaemia and myelodysplastic syndromes are similar to those reported by others. The results of this study stress the advantages of evaluating the erythropoietic activity of the bone marrow by means of the ITE.

Adult↗
PubMed1990

Modulation of the frequency of glucose-dependent bursts of electrical activity by HCO3/CO2 in rodent pancreatic B-cells: experimental and theoretical results.

The burst pattern of electrical activity recorded from pancreatic B-cells in response to 11 mM glucose shows a large islet to islet variability. The relationship between burst frequency and glucose sensing (the threshold for electrical activity and the graded increase in electrical response to glucose, i.e. active phase %) has not been investigated within the same islet. In this work, we show that low HCO3 (5 mM) Hepes buffered solutions reversibly reduce the frequency of bursts compared to control (25 mM) HCO3 buffered solutions in the same islet. There was no change in the threshold or active phase (%). Using the mathematical model of Sherman et al. 1988, we explored mechanisms for a change in frequency independent of a change in active phase (%). Increased exchangeable calcium pool size and increased cell to cell coupling were the two theoretical treatments which could reproduce the experimental data. We conclude that burst frequency can be modulated independent of the active phase and that alteration of a calcium pool size best fits the experimental data.

Animals↗
PubMed1990

[The effect of the day of parturition in the technological cycle of maternity on the morbidity of diarrhea in lactating piglets].

The study investigated the frequency of piglet diarrhoea from birth to weaning (33rd day) in a farrowing pigsty with 3 rows of boxes during 7 rearing cycles with 240 piglets each, always related to the day of birth in connection with the onset of the cycle. 3 groups were differentiated according to the day of birth: 3 and 4, 5, 6 and 7, based on the disposition of the sow. Also investigated was the position of the litters in the middle or one of the marginal rows of boxes of the pigsty. The germ density of the air during 2 cycles each of the rainy and dry seasons was investigated in the empty pigsty as well as after the 6th day of occupation by means of sedimentation in endo agar. A significant influence was found of the day birth (p less than 0.05) and of the interaction of row of boxes and day of birth (p less than 0.05) as well as the row of boxes and season (p less than 0.05) on the morbidity and mortality due to piglet diarrhoea. The higher levels occurred in the groups of animals born later and housed in the central row of boxes. The number of units forming colonies increased significantly (p less than 0.05) in 10 cm2/min samples on endo agar from the 0th to the 6th day of the cycle and reached 100% of the samples from which also E. coli K 88 was isolated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Mortality by crushing in domestic pigs: study of the causes and their relationship to the time and the month of the year in the climatic conditions of Cuba].

In the course of 3 years a complex of 25,000 pigs were investigated once per week for the dead among the 398 sucking piglets, and in the case of losses due to crushing to death the type of lesions and the connection with diseases was investigated. Of the piglets investigated, 88 were crushed to death (21.2%), among them 65 (73.8%) diseased--mainly infected by coli bacilli (60 = 68.2%)--and 23 (5.8%) healthy animals. The losses due to crushing to death were highest in January and differed from all other months of the year (p less than 0.05). Another peak of losses in July was only significant (p less than 0.05) as compared with the values of April and November. January and July also exhibited the highest proportion of coli-infected piglets. The most frequent lesions were edema and cyanosis of the skin, of the mucous membrane, and the hypodermic tissue, haemothorax and haemoperitonaeum, liver cracks, lung cracks, kidney cracks, stomach cracks, large intestine cracks, and multiple fractures of the ribs and of the skull. It is concluded that the losses due to crushing to death can be related to the decrease in vitality of the piglets due to diseases, caused in winter by decreased vitality and in summer by pressure caused by coli infection.

Animals↗
PubMed1988

External auditory canal temperature and reaction time relationship during long performances.

In order to study the relationship between body temperature and reaction time (RT), and check the hypothesis proposed by Kleitman (Sleep and Wakefulness, University Press, Chicago, 1963) about a 'Basic Rest-Activity Cycle' (BRAC), RT tasks were delivered to 24 subjects at 10-min intervals for 320 min, while simultaneously registering bilateral ear canal temperatures. Time series analyses in frequency and time domains were applied to the data. Our results did not show a 90-100 min ultradian rhythmicity in the performance of RT tasks, but 6 of the 24 subjects presented significant periods within limits of BRAC in temperature.

Adult↗
PubMed1988

Ultradian cyclicity in auditory and visual reaction time during long performance.

24 subjects were tested to check the hypothesis proposed by Kleitman about a "basic rest-activity cycle". Reaction time tasks were delivered at 10-min. intervals for 320 min. Spectral density function analyses showed no significant periods within the limits of the cycle. Discussion concerns fulfilling assumptions of spectral analysis and Fisher's test.

Adult↗
PubMed1987

Relation between alpha-methyl-D-glucoside influx and brush border surface area in enterocytes from chicken cecum and jejunum.

We have investigated the possible relation between the phloridzin-sensitive influx of alpha-methyl-D-glucoside (concentration 5 mmol/l) and the brush border surface area, in chicken isolated enterocytes. The intestinal regions studied were: jejunum and proximal cecum (both with high affinity sugar transport sites), medial cecum (with a low affinity transport system) and distal cecum (which lacks any transport ability). Cell apical surface measured by electron microscopy gave the following results; jejunal cells (0.41 micron 2) greater than proximal cecal cells (0.23 micron 2) greater than medial cecal cells (0.15 micron 2) = distal cecal cells (0.14 micron 2). This parameter is mainly determined by the length of microvilli. Sugar influx studies showed that the concentration of the substrate in cell water (in mmol/l) was jejunum (7.1) greater than proximal cecum (2.9) greater than medial cecum (1.7) greater than distal cecum (not different from zero). The decline in influx rate from proximal to distal cecum may be explained both by changes in surface and by the different carriers involved (different Km). Results of sugar concentration in the distal cecal cells do not correlate with the other segments studied since the substrate enters in these cells by a passive process. It is concluded that the degree of development of microvilli should be taken into account when estimating nutrient transport rates in different intestinal segments.

Animals↗
PubMed1986

Hexose transport by chicken cecum during development.

Hexose accumulation during development has been studied in tissue slices from chicken cecum. The age of birds ranged from 0 to 7 weeks after hatch. Ceca were divided into six portions according to their situation either proximal (PC), medial (MC) or distal (DC) to the ileocecal junction. In 0-day-old chicks all segments can accumulate 3-O-methyl-D-glucose (0.5 mmol/l) against a concentration gradient through a phloridzin-sensitive mechanism. Cumulative capacity is lower in DC than in PC and declines with development. Distal segments lose sugar transport ability 1-2 days after hatch whereas the medial region retains some concentrative ability in older birds. In 7-week chickens, PC slices have a similar cumulative ability to that of jejunum (yolk sac region). Kinetic studies showed that in PC the apparent Km for phloridzin-sensitive transport was half that in 1-day- than in 7-week-old birds; apparent Vm increased by 50% in this time range. The ability to transport sugars by the cecum was further confirmed in isolated enterocytes from 5- to 7-week-old chickens using alpha-methyl-D-glucoside (0.1 mmol/l) as substrate. Cell sugar concentration was greater in PC than in jejunal cells and jejunal greater than MC enterocytes. Sugar present in cells from DC was the same as in phloridzin-treated cells. It is concluded that cecal epithelium may play a significant role in the absorption of sugars during development.

3-O-Methylglucose↗
PubMed1986

Characteristics of the chicken proximal cecum hexose transport system.

The properties of the sugar transport system present in chicken proximal cecum have been studied and compared to the jejunal transport system. Experiments were carried out in isolated enterocytes from 5- to 7-weak-old birds. Results show that: (1) Cecal cells are capable of high sugar transport rates by a phloridzin-sensitive mechanism. After 60 min incubation, the accumulation ratio (control/phloridzin-incubated cells) for 0.1 mmol/l alpha-methyl-D-glucoside (alpha-MG) was 43 and that of 3-oxy-methyl-D-glucose (3-OMG) was 25. In jejunal cells, ratios were 37 for alpha-MG and 13 for 3-OMG. The differences found in cumulative capacity of 3-OMG between cecal and jejunal cells suggest that the sodium-independent pathway offers a very small contribution to sugar efflux in the steady-state in the former cells. (2) Lowering external Na+ concentration reduces the steady-state alpha-MG accumulation in cecal cells (as in jejunal cells), indicating that the transport system is Na+-dependent. (3) The process depends on the electrochemical Na+ gradient across the cell membrane since both 2,4-dinitrophenol (0.2 mmol/l) and ouabain (0.25 mmol/l) abolish sugar accumulation. (4) Addition of 10 mmol/l) 3-OMG to the incubation medium markedly reduces the uptake of alpha-MG (concentration: 0.1 mmol/l), indicating that the cecal transport system can be inhibited by analogues of the transported substrate. (5) The specific sugar transport process is a saturable function of alpha-MG concentration, the apparent Km being 1.02 mmol/l and Vm 10.7 mmol/mg cell protein X min.(ABSTRACT TRUNCATED AT 250 WORDS)

3-O-Methylglucose↗
PubMed1986

Preparation and properties of isolated epithelial intestinal cells from chicken cecum and jejunum.

The isolating agents, one enzymatic (hyaluronidase) and two chemical (sodium citrate and EDTA) have been used to search for the best technique to prepare suspensions of viable cells from chicken cecum and jejunum. Viability of enterocytes was assessed in terms of cell membrane integrity (trypan blue exclusion test), metabolic activity (oxygen uptake, lactate production and ATP content) and monosaccharide cumulative capacity. Results show that: In both cecum and jejunum, membrane integrity is better in cells harvested with citrate than those isolated with hyaluronidase or EDTA; The best metabolic status was found in cecal cells isolated with citrate and in jejunal cells obtained with hyaluronidase; The capacity to support alpha-methyl-D-glucoside gradients is highest in the cells harvested with citrate. The citrate-containing isolation medium is thus considered to yield epithelial cell suspensions with the best functional conditions.

Adenosine Triphosphate↗