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Biomedical subjects

M Barón

Publications and source records attributed to M Barón.

At least 19 recordsLinked to original sources
PubMed2005

Duration of attacks of first division trigeminal neuralgia.

Objective measurements of duration of attacks have been performed in 8 (5 female and 3 male) patients suffering from primary first division (V-1) trigeminal neuralgia. The mean age of the patients was 67.5 +/- 11.4 years, and the mean age at onset 64.0 +/- 9.7 years. During the study the patients were off treatment. A total of 192 attacks were witnessed by the authors and exactly timed by a stop-watch. The duration of attacks ranged from 2 to 32 s, with a mean of 6.5 +/- 6.1 s. The unweighted mean was 8.8 +/- 5.7 s, with a range of 2.4-17.5 s. With the present data the duration of attacks of V-1 neuralgia has been exactly determined, and the clinical distinction of V-1 neuralgia from other shortlasting headaches, particularly from SUNCT, has been substantially clarified.

Aged↗
PubMed2004

Cluster headache: interictal asymmetric increment in intraocular pressure elicited by Valsalva manoeuvre.

Changes in intraocular pressure (IOP) elicited by a Valsalva manoeuvre were studied in 11 male patients (mean age 39.8 years) suffering from episodic cluster headache (CH), and 12 healthy male controls (mean age 39.9 years). The tests were performed at rest and while exhaling hard through a mouthpiece connected to a mercury manometer. In the CH group, during symptomatic periods, between attacks, Valsalva manoeuvre elicited an asymmetric increase in IOP with significantly higher values on the symptomatic side (P = 0011), whereas no asymmetric increments in IOP were found during asymptomatic periods. Outside the cluster period the IOP values both baseline and with Valsalva manoeuvre did not differ from controls. The increment in IOP took place within a few seconds, as in spontaneous CH attacks, thus pointing to a rapid increase in intraocular blood volume or vasodilatation. These findings may reflect a latent increased vascular reactivity of the symptomatic orbit during CH period.

Adult↗
PubMed2002

Numular headache: a coin-shaped cephalgia.

Numular headache is a chronic, mild to moderate, pressurelike pain in a circumscribed cranial area of approximately 2 to 6 cm in diameter. Pain usually is limited to the parietal region, although it may appear in any cranial site. It is a benign process of usually unknown origin.

Adult↗
PubMed2002

Objective assessment of autonomic signs during triggered first division trigeminal neuralgia.

A total of 26 episodes of V-1 trigeminal neuralgia attacks have been recorded in two female patients. Autonomic phenomena were assessed according to a semiquantitative scale. Attacks lasted 17 +/- 5 s. Mild lacrimation without conjunctival hyperaemia, rhinorrhea or ptosis was observed, even in relatively long lasting episodes. This is in clear contradiction with SUNCT (shortlasting, unilateral, neuralgiform headache with conjunctival injection, tearing and rhinorrhea) attacks that are always dramatically accompanied by both lacrimation and conjunctival injection of the symptomatic side from the very onset of symptoms. Carbamazepine provided complete and sustained relief of symptoms in both patients. Herein we will show differential autonomic features of V-1 trigeminal neuralgia vs. SUNCT that will both aid the clinician to distinguish both syndromes and stress that both entities are nosologicaly different.

Aged↗
PubMed2000

Clinical-molecular study of a family with essential tremor, late onset seizures and periodic paralysis.

We report the clinical features of, and the molecular study performed on, a Spanish family with essential tremor (ET), late onset epilepsy and autosomal dominant hypokalemic periodic paralysis (hypoPP). The presence of hypoPP in this kindred suggested an ion channel as a candidate gene for ET. Our study identified an Arg528His CACNL1A3 mutation in patients with hypoPP, and excluded this mutation as the cause of tremor or epilepsy in this kindred.

Adult↗
PubMed2000

[Isolated sensory trigeminal neuropathy caused by a lateral pontine infarct]].

Lesion of cranial nerves due to vascular damage at pontine level generally associates affectation of near nerve tracts. Isolated fifth nerve palsy due to vascular pontine lesions has been scarcely reported. We present a hypertense 57 year old woman who suffered from sudden paresthesias and hypoesthesia on the three divisions of trigeminal nerve without motor involvement and with preservation of corneal and masseter reflexes. Cranial magnetic resonance showed small dorsolateral pontine infarct over the right fifth cranial nerve entry. Isolated sensitive trigeminal neuropathy is a rare debut form of pontine infarct.

Cerebral Infarction↗
PubMed1997

Isolated pontine infarctions with prominent ipsilateral midfacial sensory signs.

BACKGROUND: Pontine infarctions may produce combined motor, sensory, cerebellar, and cranial nerve dysfunction. Midline sensory complaints and facial pain are uncommon. CASE DESCRIPTIONS: Three patients are described with hypoesthesia and numbness of the midline facial area associated with dysarthria and contralateral hemiparesis due to pontine strokes. MRI demonstrated isolated ipsilateral ischemic infarctions of the ventral pons. CONCLUSIONS: Pontine infarctions can produce diverse sensory features. Ipsilateral midfacial sensory defect has been rarely reported. The clinicoanatomic basis for the ipsilateral midfacial sensory defect described is unknown. Involvement of the dorsal trigeminothalamic tract or fiber tracts related to central regions of the face, located in the medial part of the midbrain, could help to explain these data. The symptoms could be due to direct damage or to edema resulting from the infarct. In some patients, midfacial sensory complaints, particularly of the ala nasi, could be an early sign of major pontine deficits and may be important to determine appropriate treatment.

Aged↗
PubMed1995

Copper(II) inhibition of electron transfer through photosystem II studied by EPR spectroscopy.

EPR spectroscopy was applied to investigate the inhibition of electron transport in photosystem II by Cu2+ ions. Our results show that Cu2+ has inhibitory effects on both the donor and the acceptor side of photosystem II. In the presence of Cu2+, neither EPR signal IIvery fast nor signal IIfast, which both reflect oxidation of tyrosinez, could be induced by illumination. This shows that Cu2+ inhibits electron transfer from tyrosinez to the oxidized primary donor P680+. Instead of tyrosinez oxidation, illumination results in the formation of a new radical with g = 2.0028 +/- 0.0002 and a spectral width of 9.5 +/- 0.3 G. At room temperature, this radical amounts to one spin per PS II reaction center. Incubation of photosystem II membranes with cupric ions also results in release of the 16 kDa extrinsic subunit and conversion of cytochrome b559 to the low-potential form. On the acceptor side, QA can still be reduced by illumination or chemical reduction with dithionite. However, incubation with Cu2+ results in loss of the normal EPR signal from QA- which is coupled to the non-heme Fe2+ on the acceptor side (the QA(-)-Fe2+ EPR signal). Instead, reduction of QA results in the formation of a free radical spectrum which is 9.5 G wide and centered at g = 2.0044. This signal is attributed to QA- which is magnetically decoupled from the non-heme iron. This suggests that Cu2+ displaces the Fe2+ or severely alters its binding properties. The inhibition of tyrosinez is reversible upon removal of the copper ions with EDTA while the modification of QA was found to be irreversible.

Copper↗
PubMed1994

Flash-induced absorption spectroscopy studies of copper interaction with photosystem II in higher plants.

Measurements of flash-induced absorption changes at 325, 436, and 830 nm and of oxygen evolution were performed in order to analyze in detail the inhibition of photosystem II (PS II) by Cu(II) in PS II membrane fragments from spinach. (a) The kinetics of P680+ reduction become markedly slower in the presence of 100 microM CuSO4. (b) The CuSO4-induced kinetics of P680+ reduction are dominated by a 140-160-microsecond decay. (c) The extent of these 140-160-microsecond kinetics, normalized to the overall decay, remains virtually unaffected by addition of the exogenous PS II donor, NH2OH. (d) In thoroughly dark-adapted samples the CuSO4-induced 140-160-microsecond kinetics are already observed after the first flash and remain unchanged by a train of excitation flashes. (e) The extent of P680+ and QA- formation under repetitive flash excitation is not diminished by addition of 100 microM CuSO4. (f) The induction of microsecond kinetics of P680+ reduction at the expense of ns kinetics and the inhibition of the saturation rate of oxygen evolution exhibit the same dependence on CuSO4 concentration. (g) CuSO4 also transforms the 10-20-microsecond reduction of P680+ by TyrZ in Tris-washed PS II membrane fragments into 140-160-microsecond kinetics without any effect on the extent of flash-induced P680+ formation. These results unambiguously show that Cu(II) does not affect the charge separation (P680+QA-), but instead specifically modifies TyrZ and/or its micro environment so that the electron transfer to P680+ becomes blocked.

Copper↗
PubMed1991

Studies on rod horizontal cell S-potential in dependence of the dark/light adapted state: a comparative study in Cyprinus carpio and Scyliorhinus canicula retinas.

Changes in light sensitivity, response time-course and electrical coupling of rod driven horizontal cells (RHC) were examined in the dark and light adapted states by intracellular recording. Comparative analyses were made of two fishes from different photic environments. RHC of Cyprinus carpio and external horizontal cells (EHC) of Scyliorhinus canicula retinas showed similar changes of their electrical responses to light stimuli when the dark-adapted retina was light-adapted: a decrease in sensitivity, an acceleration in the response time-course and an increase in the coupling strength.

Adaptation, Ocular↗
PubMed1982

[In vivo and in vitro actions of biscarbamates on the photosynthetic activity of chloroplasts].

The "photosynthetic inhibition" component in the whole context of plant toxicity, when different concentrations of the bis-carbamate phenmedipham are supplied through the roots or foliar application to spinach plants grown in hydroponic media have been determined. Chloroplasts were isolated after eight days of the herbicide addition, and then determined: electron transport H2O leads to NADP+, H2O leads to ferrycyanide and ascorbate/DPIP leads to NADP+, cyclic and non cyclic photophosphorilation, CO2 assimilation rate and intermediate patterns of CO2 fixation. We have also determined in foliar disks the O2 evolving and the CO2 assimilation capabilities. Type A and type B chloroplasts showed increased inhibition, respectively, of the Phot. II dependent electron transport chains H2O leads to NADP+ and H2O leads to ferricyanide, to the extent that the phenmedipham concentration increased in the hydroponic media and the spraying solution, so that a 50% inhibition of both processes was obtained at 100 microM and 10 microM, respectively, against 0.2 microM in the in vitro experiments. Non cyclic photophosphorylation showed a stronger inhibition than the cyclic one. Concerning the Phot. I dependent electron transport ascorbate/DPIP leads to NADP+, the chloroplast preparations showed a negligible inhibition. We have found a synergistic effect of the above two factors on the CO2 assimilation. The intermediate patterns of CO2 assimilation showed a decrease of the 3C-compounds P-glycerate and trioses-P, with a parallel increase of the sugar mono and diphosphates as well as disaccharides and amino acids.

Carbamates↗