Binding kinetics of calbindin-D(28k) determined by flash photolysis of caged Ca(2+).

We have used UV flash photolysis of DM-nitrophen in combination with model-based analysis of Oregon Green 488 BAPTA-5N fluorescence transients to study the kinetics of Ca(2+) binding to calbindin-D(28K). The experiments used saturated DM-nitrophen at a [Ca(2+)] of 1.5 microM.

Sodium/calcium exchange in amphibian skeletal muscle fibers and isolated transverse tubules.

The Na(+)/Ca(2+) exchanger participates in Ca(2+) homeostasis in a variety of cells and has a key role in cardiac muscle physiology. We studied in this work the exchanger of amphibian skeletal muscle, using both isolated inside-out transverse tubule vesicles and single muscle fibers. In vesicles, increasing extravesicular (intracellular) Na(+) concentration cooperatively stimulated Ca(2+) efflux (reverse mode), with the Hill number equal to 2.

[Hantavirus in Chile: review and cases analysis since 1975].

Since the identification of the first case of Hantavirus infection in Chile in 1995, a great advance in the knowledge of the disease natural history has occurred. There is evidence to suppose that the infection by Andes virus in suburban areas of Argentina and Chile, whose natural reservoir is Oligoryzomys longicaudatus, has been present but unidentified for a long time. We describe a serologically proven case occurred in 1975.

Measurement of action potential-induced presynaptic calcium domains at a cultured neuromuscular junction.

Spatially localized Ca(2+) domains are thought to play a key role in action potential (AP)-evoked neurotransmitter release at fast synapses. We used a stage-scan confocal spot-detection method and the low-affinity Ca(2+) indicator Oregon Green 488 BAPTA-5N to study the spatiotemporal profile of presynaptic AP-induced Ca(2+) domains. Families of scanned AP-induced fluorescence transients were detected from spot locations separated by 200-300 nm, within the vicinity of Ca(2+) entry sites.

Inverted double-gap isolation chamber for high-resolution calcium fluorimetry in skeletal muscle fibers.

Here we describe an improved inverted double-grease-gap isolation chamber that allows the formation of grease seals of high mechanical stability and high electrical resistance. We also provide a detailed description of the procedure used to mount the muscle fibers onto the apparatus. The new chamber permits the electrophysiological study of muscle fibers using an inverted microscope and high-resolution objectives, thus complying with the requirements of modern fluorescence confocal detection methods.

[Subjective sleep quality and spectral analysis of electroencephalography during nocturnal sleep].

Introduction: The relation between subjective sleep quality and the stages of polysomnography is unclear. Computerized sleep analysis provides a reliable tool for the study of sleep dynamics.

Objective: To study the relation between subjective sleep quality and spectral EEG parameters during nocturnal sleep.

[Inflammatory pseudotumor of the larynx].

Inflammatory pseudotumors are rare and usually located in lung, although they can develop in any organ. They are unusual in head and neck and very rare in the larynx. A case of laryngeal pseudotumor in a patient with odinophagia and neck pain is reported.

An outbreak of hantavirus pulmonary syndrome, Chile, 1997.

An outbreak of 25 cases of Andes virus-associated hantavirus pulmonary syndrome (HPS) was recognized in southern Chile from July 1997 through January 1998. In addition to the HPS patients, three persons with mild hantaviral disease and one person with asymptomatic acute infection were identified. Epidemiologic studies suggested person-to-person transmission in two of three family clusters.

Mapping and comparison of the B-cell epitopes recognized on the Plasmodium vivax circumsporozoite protein by immune Colombians and immunized Aotus monkeys.

Plasma samples of individuals from two malaria-endemic villages on the Colombian Pacific coast and synthetic peptides representing different fragments of the central and flanking regions of the Plasmodium vivax circumsporozoite protein (CSP) were used to perform a fine mapping of the B-cell epitopes on the whole CSP. In addition, the immunogenicity of long polypeptides corresponding to the amino (N) and carboxyl (C) regions was evaluated in Aotus monkeys. The epitopes recognized after natural infection of humans and after immunization of Aotus with these synthetic peptides were compared.

[Inferior vena cava filters. Indications and results in 111 patients].

Background: Anticoagulation is the treatment of choice for deep vein thrombosis and pulmonary embolism. Occasionally this treatment is contraindicated or fails to prevent pulmonary embolism. In these patients, inferior cava vein interruption is indicated and filter insertion is the procedure commonly performed.

Supercharging accelerates T-tubule membrane potential changes in voltage clamped frog skeletal muscle fibers.

In voltage-clamp studies of single frog skeletal muscle fibers stained with the potentiometric indicator 1-(3-sulfonatopropyl)-4-[beta[2-(di-n-octylamino)-6-naphthyl] vinyl]pyridinium betaine (di-8 ANEPPS), fluorescence transients were recorded in response to both supercharging and step command pulses. Several illumination paradigms were utilized to study global and localized regions of the transverse tubule system (T-system). The rising phases of transients obtained from global illumination regions showed distinct accelerations when supercharging pulses were applied (95% of steady-state fluorescence achieved in 1.

Fast voltage gating of Ca2+ release in frog skeletal muscle revealed by supercharging pulses.

1. In single frog skeletal muscle fibres, we utilized supercharging voltage clamp command pulses to boost the rate of depolarization in the transverse tubular system (T-system) such that 95 % of steady-state potential is achieved in < 2 ms (as indicated by fluorescent potentiometric dye signals detected from a global illumination region). Signals detected near the edge of muscle fibres indicate that peripheral regions of the T-system are not significantly overcompensated under these conditions.

[Age as source of variation in various parameters of 'delta sleep'].

Introduction: The clinic usefulness of a diagnostic test is in relationship to the precision with which measures the studied phenomenon. The lack of precision involve the reliability upon causing confounded results of the normal and diseased populations.

Objective: Since the sleep varies in function of the age, to find sleep parameters that fit better to the changes that the aging produces in the sleep.

[Immune-mediated inner ear disease: report of clinical cases].

Many clinical and experimental studies have obtained evidence of immune-mediated inner ear disease. Discrepancies between theories of the mechanisms of injury to the inner ear and the laboratory tests that identify it mean that the diagnosis is based on clinical symptoms and a positive response to treatment. We report four cases of immune-mediated inner ear disease characterized by endolymphatic hydrops, fluctuating hearing loss, sudden deafness (first symptom of primary Sjögren's syndrome), and rapidly progressive sensorineural hearing loss.

Localized detection of action potential-induced presynaptic calcium transients at a Xenopus neuromuscular junction.

1. Action potential (AP)-induced fluorescence transients were measured, using Ca2+ indicators and a spot-detection method, at single nerve terminals of a cultured Xenopus neuromuscular junction preparation with simultaneous measurement of neurotransmitter release. 2.

Kinetic properties of DM-nitrophen and calcium indicators: rapid transient response to flash photolysis.

We describe a high temporal resolution confocal spot microfluorimetry setup which makes possible the detection of fluorescence transients elicited by Ca2+ indicators in response to large (50-200 microM), short duration (< 100 ns), free [Ca2+] transients generated by laser flash photolysis of DM-nitrophen (DM-n; caged Ca2+). The equilibrium and kinetic properties of the commercially available indicators Fluo-3, Rhod-2, CalciumOrange-5N (COr-5N) and CalciumGreen-2 (CGr-2) were determined experimentally. The data reveal that COr-5N displays simple, fast response kinetics while, in contrast, Fluo-3, Rhod-2 and CGr-2 are characterized by significantly slower kinetic properties.

Deficiency of naive T cells in patients with sudden deafness.

Background: Although there are a number of reports concerned with the role of immunity in the sudden onset of progressive sensorineural hearing loss, there are few references dealing with the involvement of immune-mediated mechanisms in sudden deafness.

Objectives: To study the phenotype of peripheral blood lymphocytes in a group of patients with sudden deafness by use of 3-color flow cytometry.

Design: The study was carried out prior to the start of steroid therapy.

Unstable, low-level transmission of malaria on the Colombian Pacific Coast.

The development of immune responses to malarial infection in inhabitants of endemic areas differs according to the level of exposure to the parasite. Adults living in a region where the level of malaria transmission is low (Colombia) have been shown to exhibit a similar response to each of the three regions of the circumsporozoite protein (the central repeated NANP region, and the flanking N- and C-termini). Conversely, donors exposed to a frequent sporozoite challenge in areas of high malaria transmission (Mali) exhibit antibodies predominantly to the NANP repeated domain.

Direct measurements of presynaptic calcium and calcium-activated potassium currents regulating neurotransmitter release at cultured Xenopus nerve-muscle synapses.

The understanding of neurotransmitter release at vertebrate synapses has been hampered by the paucity of preparations in which presynaptic ionic currents and postsynaptic responses can be monitored directly. We used cultured embryonic Xenopus neuromuscular junctions and simultaneous pre- and postsynaptic patch-clamp current-recording procedures to identify the major presynaptic conductances underlying the initiation of neurotransmitter release. Step depolarizations and action potential waveforms elicited Na and K currents along with Ca and Ca-activated K (KCa) currents.

[Abdominal aortic aneurysm: course of morbimortality of elective surgery in 20 years].

Abdominal aortic aneurysms (AAA) usually undergo progressive dilatation and eventually may rupture, complication that carries a high mortality rate. If certain clinical conditions, like operative risk and aortic diameter are met, all patients should be considered for surgical repair. Analysis of our results with the surgical treatment of asymptomatic AAA prompted this study.

[Protocol for the endoscopic sinus surgery: comparative analysis of 200 cases].

A preliminary analysis was published in 1993 of 100 cases of endoscopic sinus surgery (ESS) carried out in our service following a protocol that included sinusitis, nasal polyps, and other endoscopic nasal procedures. Another 100 cases of ESS were analyzed for the present study and compared with the 1993 group. Comparative analysis showed improved results in the second series, with fewer minor complications and no major complications.

Vascular response to guided tissue regeneration procedures using nonresorbable and bioabsorbable membranes in dogs.

Revascularization of the periodontal tissues was studied following guided tissue regeneration (GTR) procedures using both nonresorbable and bioabsorbable membranes. The procedures were performed in 8 female beagle dogs, 4 to 6 years old. Second, third, and fourth mandibular premolars were involved; experimental periods covered from 3 days to 49 days.

Adaptation of single cardiac ryanodine receptor channels.

Single cardiac ryanodine receptor (RyR) channel adaptation was previously defined with Ca2+ stimuli produced by flash photolysis of DM-nitrophen (caged-Ca+2). Photolysis of DM-nitrophen induced a very fast Ca+2 overshoot (Ca+2 spike) at the leading edge of the Ca+2 stimuli. It has been suggested that adaptation (tau approximately 1.