Biomedical subjects

R Gallego

Publications and source records attributed to R Gallego.

At least 73 records · Page 4Linked to original sources

PubMed1990

Neuroendocrine cells of the human lung express substance-P-like immunoreactivity.

The occurrence of substance P (SP) in the neuroendocrine population of human lungs was investigated by immunohistochemical methods. All individuals studied (n = 16) had SP-like immunoreactive cells, being more numerous in lungs of fetuses and newborn infants than in adults. These cells, both solitary and forming neuroepithelial bodies, were found at all levels of the respiratory mucosa. Solitary neuroendocrine cells and neuroepithelial bodies were found in the bronchial and bronchiolar mucosa, while at the alveolar level neuroepithelial bodies were also seen. A more intense SP-like immunoreactivity was found in the basal cytoplasm of these cells. Occasionally they show cytoplasmic prolongations which interdigitate with neighboring epithelial cells. These facts suggest that SP-like immunoreactive cells may have a paracrine or local secretion function, acting over surrounding epithelial cells or structures situated in the lamina propria. The evidence of great numbers of SP-like immunoreactive neuroendocrine cells in fetuses and infants might be the expression of a functional role of SP in lung development.

Adult↗

PubMed1989

Localization of serotonin-like immunoreactivity in the Merkel cells of pig snout skin.

The presence of serotonin in the Merkel cells of pig snout epidermis was investigated by the peroxidase-antiperoxidase immunohistochemical technique. Serotonin-like immunoreactive Merkel cells were found in groups located at the base of epidermal rete pegs and in the external root sheath of sinus hair follicles (vibrissae). Immunoreactivity was stronger on the basal side of the Merkel cells, where dense-cored granules are most numerous. Neither the nerve terminal associated with the Merkel cell nor the neighbouring epidermal cells were immunostained. These results are the first evidence of serotonin-like immunoreactivity in mammalian Merkel cells. The fact that immunoreactivity is strongest in those parts of the Merkel cells with the highest granule density suggests that in these cells serotonin is probably localized in the dense-cored granules.

Animals↗

PubMed1989

Calcitonin gene-related peptide (CGRP) immunoreactivity in the neuroendocrine Merkel cells and nerve fibres of pig and human skin.

The presence of calcitonin gene-related peptide (CGRP) in the skin of pig snout and human fingertip was investigated using immunohistochemical techniques. CGRP immunoreactivity was found in Merkel cells and nerve fibres of both species. In pig snout skin, Merkel cells containing CGRP were seen forming clusters at the tips of rete ridge epidermis and in the external root sheath of sinus hair follicles (vibrissae). Human Merkel cells immunostained for CGRP were found isolated or forming small groups in the basal layer of glandular epidermal ridges. In all cases, immunoreactivity was more intense on the side of the Merkel cell facing the associated nerve terminal (which was never positive for CGRP). This part of the Merkel cell has the greatest density of dense-cored granules, suggesting that CGRP must be stored in these granules. Nerve bundles containing CGRP-immunoreactive fibres were found at dermal and hypodermal level, and blood vessels were often surrounded by CGRP nerve fibres. In pig snout skin some nerve fibres containing CGRP penetrated the epidermis and terminated as free endings, and in the human fingertip a small number of CGRP-immunoreactive nerve fibres were seen in Meissner's corpuscles.

Animals↗

PubMed1989

[Justification for subtotal esophagectomy in late spontaneous esophageal rupture].

A patient is presented who was operated for an intestinal obstruction and developed in the immediate postoperative period Boerhaave's syndrome. Subtotal esophagectomy with bipolar exclusion was performed. We discuss the advantages of radical surgery, even in advanced cases, if the size of the lesion justifies it, as compared to more conservative therapeutic attitudes.

Esophageal Diseases↗

PubMed1988

Membrane properties of primary sensory neurones of the cat after peripheral reinnervation.

1. The properties of sensory neurones in the petrosal ganglion of the cat were examined in vitro with intracellular electrodes 2-30 days after cutting the carotid or the glossopharyngeal nerve or 30-120 days after crushing the nerves and allowing time for peripheral reinnervation. Both glossopharyngeal and carotid neurones with conduction velocities faster than 2 m/s and humps on the falling phase of their action potentials were studied. 2. Two days after axotomy, the action potential of glossopharyngeal cells showed increased maximum rate of depolarization and decreased after-hyperpolarization (AHP) amplitude. These cells also showed a decrease in time-dependent inward rectification and conduction velocity. No significant changes were observed in carotid neurones at this stage. 3. Four days after axotomy, these changes were still present in glossopharyngeal cells and the duration of the AHP had also decreased. Among carotid neurones there was an increase in spike duration and a decrease in time-dependent rectification and in the amplitude and duration of the AHP. 4. Eight days after axotomy glossopharyngeal cells additionally showed an increased spike duration and decreased rheobase, while carotid neurones had also decreased in conduction velocity. 5. All the changes described were still present 16 days after cutting the nerves. In addition, the input resistance increased in both types of cells. 6. The effects of axotomy persisted 30 days after cutting the nerve, except for the AHP amplitude in both types of cells and the spike duration in glossopharyngeal neurones which had recovered to near control values. 7. Thirty days after crushing the carotid nerve, some carotid neurones showed chemosensory activity, indicating that reinnervation of the carotid body had taken place. In these cells, the properties altered by axotomy had recovered except for the conduction velocity. 8. Four months after crushing the glossopharyngeal nerve, activity evoked by mechanical and chemical stimulation of the tongue could be recorded from the nerve, indicating that sensory reinnervation had taken place. The electrical properties of the glossopharyngeal cells were normal except for conduction velocity which was still slower than the control value. 9. It is concluded that the electrical membrane properties altered by axotomy revert to normal after peripheral sensory regeneration.

Action Potentials↗

PubMed1987

Membrane properties of glossopharyngeal sensory neurons in the petrosal ganglion of the cat.

The active and passive properties of petrosal ganglion sensory neurons with axons in the glossopharyngeal nerve were examined with intracellular microelectrodes in an in vitro preparation. Glossopharyngeal neurons could be classified into two groups: H-cells showing an inflexion or hump on the falling phase of the spike and F-cells, generating a short action potential without a hump. Most of the neurons found (85%) were H-cells. The axonal conduction velocity of both types of cells fell into the A delta range, although the average value for F-cells (13 m/s) was higher than that found for H-cells (10 m/s). H- and F-cells had similar resting membrane potentials and input resistances, but different action potential characteristics. F-cells showed a smaller action potential with a faster rate of depolarization, followed by a shorter after-hyperpolarization. The response to depolarizing current pulses applied through the microelectrode was also different in both types of cells. About half of the H-cells could not be depolarized to threshold while 85% of F-cells generated spikes. It is concluded that two different populations of petrosal ganglion neurons send axons into the glossopharyngeal nerve.

Action Potentials↗

PubMed1987

Morphometric characterization of the human neuroendocrine Merkel cells.

In this study, the neuroendocrine Merkel cells (NEMCs) from adult human epidermis are defined morphometrically, using the MOP 20 image analyzer to measure 21 parameters of either the cell as a whole, or particular cellular structures. Maximum diameter (8.09 microns), perimeter (26.51 microns), area (36.87 microns2) and form factor (0.626) for the cell as a whole, and maximum diameter (5.08 microns), perimeter (18.74 microns), area (12.54 microns2) and form factor (0.452) for the nucleus were determined. Also measured were nuclear-cytoplasmic ratio (0.5595), filament thickness (10 nm), and granular numerical density (7.02 granules/micron2). Maximum diameter, area, and form factor of neurosecretory granules were 94.23 nm, 5020.05 nm2, and 0.93, respectively. Length of desmosomes linking NEMCs to keratinocytes was determined (286.9 nm) and compared with that of interkeratinocytic desmosomes (385 nm). In addition, length and diameter of cellular processes (spine-like processes (1.58 micron X 0.26 micron), interstitial processes (1.39 micron X 0.25 micron), and microvilli (0.35 micron X 0.25 micron) were measured after separation and classification according to the particular morphologic characteristics of each.

Adult↗

PubMed1987

Staining of neuroendocrine Merkel cells of human epidermis using the uranaffin reaction.

The uranaffin reaction (UR) stains neurosecretory (NS) granules of the neuroendocrine system under certain experimental conditions of staining and rinsing solutions. Human normal neuroendocrine (NE) Merkel cells stained using the UR exhibit a positive reaction in their NS granules, ribosomes, and nuclear chromatin. The average values of maximum granular diameter (GD = 69.1 nm) and area (GA = 3637.8 mm2) of NS granules measured in the adult NE Merkel cells stained with UR are significantly greater than those (GD = 61.4 nm; GA = 2699.8 nm2) seen in the fetal NE Merkel cells also stained with UR. No differences in form factor are found between fetal and adult NS granules. On different samples of human adult and fetal epidermis it is demonstrated that UR is a useful cytochemical marker for the NS granules of normal NE Merkel cells.

Adult↗

PubMed1987

Chronic block of the cervical trunk increases synaptic efficacy in the superior and stellate ganglia of the guinea-pig.

1. The effects of chronic conduction block with tetrodotoxin (TTX) of the cervical sympathetic trunk on synapses in the superior and stellate ganglia were examined in vitro with intracellular recording techniques. 2. The mean maximum amplitude of excitatory post-synaptic potentials (e.p.s.p.s) evoked in superior cervical ganglion neurones by stimulation of the cervical sympathetic trunk was increased significantly after 2 or 4 days of block. The electrical properties of the ganglion cells were not appreciably changed by the period of inactivity. 3. Chronic conduction block for 4 days also resulted in a significant increase in the amplitude of the e.p.s.p.s. evoked in stellate ganglion cells by active collaterals of the blocked fibres. 4. The number of steps in the synaptic response elicited in individual stellate ganglion neurones by graded stimulation of the ansa subclavia and the subclavian trunk (which join to form the cervical sympathetic trunk) was increased after 4 days of conduction block. 5. These results show that elimination of impulse activity in the cervical sympathetic trunk increased synaptic efficacy at the disused synapses in the superior cervical ganglion and at the active synapses in the stellate ganglion. In the latter case, collaterals of the blocked fibres apparently formed new synaptic connexions on stellate ganglion cells.

Animals↗

PubMed1987

Effects of central or peripheral axotomy on membrane properties of sensory neurones in the petrosal ganglion of the cat.

1. The properties of sensory neurones in the petrosal ganglion of the cat were examined in vitro with intracellular electrodes 8 days after section of the central (bulbar roots) or peripheral process. Two types of cells, both with conduction velocities faster than 2 m/s and with humps on the falling phases of their action potentials (H-neurones), were studied: glossopharyngeal neurones arising from the tongue and pharynx, and carotid neurones originating in the carotid body and carotid sinus. 2. Peripheral axotomy produced an increase in action potential duration and a marked decrease in the amplitude and duration of the spike after-hyperpolarization in both glossopharyngeal and carotid neurones. 3. The maximum rate of depolarization of the action potential increased after peripheral axotomy in glossopharyngeal cells but did not change in carotid neurones. 4. The time-dependent inward rectification in response to hyperpolarizing pulses was markedly reduced in both types of cells after peripheral axotomy. 5. Section of the peripheral process produced a decrease of the rheobase of glossopharyngeal cells, but not of carotid neurones. After axotomy the proportion of cells giving tonic discharges in response to long depolarizing pulses increased from 13 to 54% among carotid neurones but did not change in glossopharyngeal cells. 6. No significant changes in membrane potential or input resistance of either group of cells were found after peripheral axotomy. 7. Central axotomy did not produce any changes in the electrophysiological properties of glossopharyngeal or carotid neurones. 8. Peripheral conduction velocity was decreased in both types of cells after peripheral axotomy, but did not change after section of the bulbar roots. 9. It is concluded that the electrical properties of sensory neurones are modified after peripheral axotomy but not after central axotomy. Furthermore, the changes produced by peripheral axotomy are different in neurones innervating different peripheral targets. 10. The possibility that some electrical properties of sensory neurones are maintained by their peripheral targets is discussed.

Action Potentials↗

PubMed1987

EM diversity of neuroendocrine (Merkel) cells of the human skin.

Ultrastructural differences in size of granules of adjacent Merkel cells belonging to normal skin of three patients are demonstrated. The differences, apparent on simple examination of micrographs, were confirmed using morphometric and statistical analysis. Differences are statistically significant (p less than or equal to 0.001) for maximum diameter and granular area. The existence of a NE (Merkel) cells system or population in the skin similar to that observed in diverse epithelial sheets of the human body, is suggested.

Adult↗

PubMed1986

[Intracutaneous skin suture with a resorbable synthetic monofilament suture].

We report about our good experience with a monofile, synthetic, absorbable Polydioxanone thread used for skin suture in an intracutaneous technique, after we performed more than 1,500 sutures of 7 to 30 cm length in patients of any age. We consider the suture to be suitable for children to achieve a cosmetically fine scare without a subsequent necessity to pull out the thread. The breaking strength, the absorbtion rate and the loss of inflammatory reaction is so satisfactory that we could not see any disadvantage by using this absorbable, synthetic thread for skin closure. Especially there was no disturbance in wound healing. In contrast, because of the secure and undisturbed wound-edge adaptation a non-irritant, firm, and hairline-like scar could be achieved. The time to carry out the suture is no longer than for other techniques.

Dermatologic Surgical Procedures↗

PubMed1986

Staining of Merkel cells of pig snout epidermis using the uranaffin reaction. Morphometric analysis of neuroendocrine granules.

The uranaffin reaction (UR) specifically stains neurosecretory (NS) granules of the neuroendocrine system when performed at pH 3.9 and at a 4% concentration of uranyl acetate. Merkel-cell NS granules stained using the UR were found to have a different appearance than granules observed after routine processing. We therefore compared the average values obtained with both methods, examining the maximum diameter, area, form factor, and numerical density of such NS granules. The maximum diameter and area of NS granules were significantly greater (P less than 0.001) in samples stained using a conventional technique (CT) (93.30 nm, 6,411 nm2) that in those stained with the UR (63.95 nm, 2,148 nm2). The form factor of conventionally stained NS granules (0.9) was significantly greater (P less than 0.001) than that of granules stained with the UR (0.7). No significant difference in numerical density was found for the two techniques (CT: 8.11 +/- 2.51; UR: 6.14 +/- 2.38). It was found that the UR is a useful cytochemical marker for NS granules of Merkel cells, and that the ultrastructural morphology and intracellular arrangement of NS granules stained with the UR are different from those revealed using CT.

Animals↗

PubMed1984

Axonal conduction velocity and input conductance in petrosal ganglion primary sensory neurones of the cat.

Petrosal ganglion chemoreceptor neurones were impaled with glass microelectrodes in an 'in vitro' preparation maintained at 36.5 degrees C. For each cell, the input conductance and the axonal conduction velocity were calculated from the voltage change produced by a hyperpolarizing pulse, and from the latency of the spike evoked by carotid nerve stimulation. In 34 neurones, the average values for these variables were 3.7 X 10(-8) Siemens and 10 m/s. The two parameters were related by a power function with an exponent of 0.9, which is lower than the value of 2 expected on the basis of simple linear relations between soma and axon diameters and between axon diameter and conduction velocity.

Animals↗

PubMed1983

The ionic basis of action potentials in petrosal ganglion cells of the cat.

The ionic conductances underlying the action potential and after-hyperpolarization of the cat petrosal ganglion neurones with myelinated axons in the carotid nerve were studied in vitro. Neurones were divided into two groups based on the presence or absence of an inflexion or hump on the spike falling phase. The application of tetrodotoxin (TTX, 3 X 10(-7)-3 X 10(-6) M) revealed the presence of a TTX-resistant component in spikes with a hump, which was abolished in Na+-free solution. The action potential without a hump was blocked by TTX. The spike hump decreased or was abolished when Ca2+-channel blockers (Mn2+, 3-4 mM or Co2+, 5 mM) or low-Ca2+ solutions (0.1-0.2 mM) were applied to the preparation. In neurones with a hump on the spike, regenerative responses were obtained in Na+-free, high-Ca2+ (8.8 mM) solution; these responses were antagonized by Mn2+, and their amplitude was proportional to the external Ca2+ concentration. It is concluded that the action potential with a hump was produced by an Na+ current, a part of which was TTX-resistant, and by a Ca2+ current which is responsible for the hump. Neurones without a hump had a TTX-sensitive Na+ spike. The spike with a hump was followed by a long-lasting after-hyperpolarization which reversed polarity at about -82 mV. During the hyperpolarization an increase in membrane conductance was observed. The amplitude and duration of the long hyperpolarizing potential decreased when Ca2+-channel blockers or low-Ca2+ solutions were applied. In Na+-free solution, regenerative responses were followed by a long hyperpolarization associated with an increase in membrane conductance. It is concluded that the long after-hyperpolarization is produced by activation of the Ca2+-dependent K+ conductance.

Action Potentials↗

PubMed1983

Membrane properties of cat sensory neurones with chemoreceptor and baroreceptor endings.

The properties of chemoreceptor and baroreceptor neurones in the petrosal ganglion of the cat were examined in vitro with intracellular micro-electrodes. Chemoreceptor neurones with myelinated axons (average conduction velocity, 11 m/s) showed action potentials with a hump on the falling phase, followed by a prolonged after-hyperpolarization (average duration, 260 ms). The duration of the hump present in the action potential of chemoreceptor neurones was positively correlated with the duration of the after-hyperpolarization. In response to prolonged depolarization, chemoreceptor neurones showed only one or a few action potentials at the beginning of the depolarization. Two types of baroreceptors neurones with myelinated axons were found: fast (F) baroreceptors (average conduction velocity, 33 m/s) and slow (S) baroreceptors (average conduction velocity, 10 m/s). F baroreceptors had action potentials without a hump followed by a short after-hyperpolarization (average duration, 43 ms), while S baroreceptors had spikes similar to those found in chemoreceptors except for a shorter hyperpolarization (average duration, 145 ms). Both types of baroreceptor neurones fired repetitively throughout prolonged depolarization. It is concluded that, in the petrosal ganglion, primary sensory neurones originating a given type of sensory terminal share a particular set of electrophysiological properties.

Action Potentials↗

PubMed1980

Enhancement of synaptic function in cat motoneurones during peripheral sensory regeneration.

1. Monosynaptic excitatory post-synaptic potentials (e.p.s.p.s) were recorded from medial (m.g.) and lateral gastrocnemius (l.g.) motoneurones in the cat 2-30 weeks after crushing the m.g. nerve.2. The mean amplitudes of homonymous and heteronymous e.p.s.p.s evoked from the m.g. nerve were initially depressed (2-3 weeks after injury) and subsequently reached levels greater than normal for a period (8-12 weeks) before slowly declining to about 70% of the normal values (by week 30).3. Monosynaptic e.p.s.p.s evoked in m.g. motoneurones from the intact l.g. nerve showed neither initial depression nor subsequent alterations following crush of the m.g. nerve.4. By the eighth week after nerve crush, about 70% of Group I and Group II sensory fibres in the m.g. nerve responded to muscle stretch, about 15% had regenerated into the muscle but did not respond to muscle stretch, and the remainder failed to regenerate across the neuroma formed by the nerve crush.5. Homonymous, monosynaptic e.p.s.p.s produced by impulses in single sensory fibres responding to stretch of the m.g. muscle were recorded 8 weeks after crush of the m.g. nerve. Their amplitude distribution was indistinguishable from that obtained in normal, unoperated cats. Thus, there was no evidence that functionally reinnervated sensory fibres are responsible for the enhanced phase of composite e.p.s.p.s observed during peripheral regeneration.6. When the m.g. nerve had been sectioned and prevented from regenerating into the muscle for 8 weeks, the amplitudes of homonymous and heteronymous e.p.s.p.s evoked from the m.g. nerve were significantly smaller than those observed in control animals. Thus, there was no evidence that non-regenerating sensory fibres are responsible for the enhanced phase of composite e.p.s.p.s after nerve crush.7. It is suggested that the sensory fibres responsible for abnormally large composite e.p.s.p.s following nerve crush are those that regenerate into the muscle but do not achieve functional reinnervation. This possibility is discussed in relation to the increase in central synaptic efficacy observed after prolonged disuse of the sensory pathway.

Animals↗

PubMed1979

The effects of blood osmolality changes on cat carotid body chemoreceptors in vivo.

The possibility that carotid chemoreceptors respond to changes in plasma osmolality was investigated in the cat, perfusing the carotid artery with blood made hyper- or hypo-osmotic and recording chemoreceptor activity from carotid nerve fibers. Blood made hyperosmotic with sucrose or NaCl reduced the chemoreceptor discharge, while hypoosmotic blood increased chemoreceptor activity. The minimal osmolality variation necessary to obtain a detectable frequency change was 3--8% of the control. Frequency changes of 30% of the control were obtained with a 20% variation in osmolality. The frequency variations produced by the osmotic changes lasted as long as the infusion was maintained (up to 15 min). In some instances a rebound was observed when iso-osmotic saline was perfused again. A transient change in frequency and a clear rebound were obtained when blood made hypersomotic with glycerol was perfused. These effects probably reflect a rapid change in intracellular osmolality due to the free passage of glycerol across cellular membranes. The modifications in chemoreceptor activity consecutive to osmolality variations are the opposite of those observed in isolated and superfused carotid bodies. As it is known that osmolality values affect the smooth muscle of the blood vessels, we conclude that our results are mainly produced by changes in carotid body blood flow due to a direct effect of hyper- and hypo-osmotic solutions on vascular muscle tone. Chemoreceptor excitation during a decrease in blood osmolality may contribute reflexly to the increased vascular resistance observed during acute osmolality reductions in man.

Animals↗