Biomedical subjects

A García-Muñoz

Publications and source records attributed to A García-Muñoz.

3 recordsLinked to original sources

PubMed1999

Comparison between MEM and Nott dynamic retinoscopy.

PURPOSE: The aim of this study was to compare MEM dynamic retinoscopy with the Nott method, to discover whether there were different results in the accommodative response and whether a relation exists between the two techniques. METHODS: We performed MEM and Nott dynamic retinoscopy in 50 visually normal university students. Both methods were performed first on the basis of static retinoscopy and second with the result of the subjective refractive exam (binocular balancing). RESULTS: A statistically significant difference existed between the methods. Nott retinoscopy assessed on basis of the subjective refractive exam was the method that obtained the lowest amounts of accommodative lag (+0.42 D), whereas MEM method performed through the static retinoscopy result showed the highest accommodative lag (+0.94 D). Furthermore, correlation analysis showed that a linear relation existed between both methods, so that the Nott value was about one-half the value of the MEM retinoscopy. CONCLUSIONS: MEM dynamic retinoscopy showed greater lag than Nott retinoscopy.

Accommodation, Ocular↗

PubMed1993

Membrane potential oscillations in CA1 hippocampal pyramidal neurons in vitro: intrinsic rhythms and fluctuations entrained by sinusoidal injected current.

The mechanisms mediating intrinsic and entrained CA1 pyramidal neuron rhythmic membrane potential oscillations were investigated in rat hippocampal slices. Intrinsic oscillations (6-14 Hz, < 10 mV) were evoked by long duration (2 s), depolarizing current pulses in 42% of the cells. Oscillations were also evoked by imposing sinusoidal transmembrane currents at 2, 7, and 14 Hz, adjusted at 7 Hz to imitate the synaptically mediated in vivo "intracellular theta". Slow all-or-none events (40 mV, 55 ms)--reminiscent of the rhythmic, high threshold slow spikes observed in vivo--were evoked and entrained by the sine wave current cycles with large, imposed depolarization in 35% of the cells. Intrinsic oscillations were insensitive to Ca(2+)-free, Co2+ (2 mM) and Mn2+ (2 mM) solutions, but were blocked by tetrodotoxin (TTX; 5 microM), illustrating that they were Na(+)-mediated. Tetraethylammonium (TEA; 15 mM) unmasked slow all-or-none events (40-50 mV, 20-55 ms) and plateau potentials (40-60 mV, 100-700 ms). Plateaus were Co2+ and Mn2+ resistant and were abolished by TTX, hence suggesting that the underlying persistent conductance was Na(+)-mediated. Plateaus were entrained one-to-one at all sinusoidal current frequencies in Ca(2+)-free, TEA + Co2+, or TEA + Mn2+ solutions. However, the high threshold Ca2+ spikes uncovered in TEA + TTX could only follow sinusoidal currents of less than 7 Hz. In conclusion, the high threshold Ca2+ and persistent Na+ conductances coexist in CA1 pyramidal cells. The persistent Na+ conductance mediated the intrinsic oscillations, and fluctuated at all the sine wave current frequencies used. The more sluggish high-threshold Ca2+ conductance exclusively oscillated at frequencies of less than 7 Hz and did not support the intrinsic rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

[Thalamic dementia due to infarct of the left thalamus and genum of the right internal capsule].

INTRODUCTION AND OBJECTIVES: Thalamic dementia is the clinical consequence of a disorder of both thalami. It is generally secondary to bilateral paramedial thalamic infarcts due to disorders of small blood vessels or cardioembolism. We report a case of dementia of acute onset involving the left thalamus and the genum of the right internal capsule. CLINICAL CASE: A 33 year old man, HIV positive, category B2, admitted to hospital for tuberculous meningitis presented with the acute onset of somnolence, followed by marked bradypsychism, personality changes, marked disorder of executive explicit memory without associated praxic, gnosic or language disorders. Ocular motility remained normal. There was left central facial paralysis with inverse emotive voluntary dissociation. The other cranial nerves were normal. There was left hemiparesia with extensor plantar reflex. No other alterations. Cerebral MR imaging was compatible with paramedial infarcts of the left thalamus and genum of the right internal capsule. CONCLUSIONS: Thalamic dementia generally occurs in bilateral paramedian thalamic disorders. There are cases of disorders of executive memory secondary to infarcts of the genum of the internal capsule due to interruption of the thalamotemporal pathways and a contralateral paramedial thalamic lesion.

Adult↗