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Biomedical subjects

M Jaramillo

Publications and source records attributed to M Jaramillo.

At least 19 recordsLinked to original sources
PubMed2001

Are different kinds of acoustic features processed differently for speech and non-speech sounds?

This study examined how changes in different types of acoustic features are processed in the brain for both speech and non-speech sounds. Event-related potentials (ERPs) were recorded in native Finnish speakers presented with sequences of repetitive vowels (/e/) or complex harmonical tones interspersed with infrequent changes in duration, frequency and either a vowel change (/o/ for vowel sequences) or a double deviant (frequency+duration change for tone sequences). The stimuli were presented monaurally in separate blocks to either the left or right ear. The results showed that speech stimuli were more efficiently processed than harmonical tones as reflected by an enhanced mismatch negativity (MMN) and P3a ERP components. In addition, the duration change in vowels elicited a larger MMN component than the equivalent change in tones. This result might reflect enhanced processing of duration features in the Finnish language in which phoneme duration plays a critical role.

Acoustic Stimulation↗
PubMed2001

Large cholesterol granuloma of the petrous apex treated via subcochlear drainage.

This is a case report of a patient with bilateral cholesterol granuloma of the petrous apex, who presented with unilateral symptoms. Initially suspected as having a dermoid cyst, he underwent posterior fossa exploration, drainage and biopsy. Symptoms recurred one year later and subcochlear drainage of the petrous apex cyst was successfully performed. Follow-up for over 18 months shows no clinical nor imaging signs of recurrence. A MEDLINE literature search was carried out and relevant paper publications reviewed. Case presentation including initial, pre- and post-operative imaging is presented. This is followed by discussion of current concepts on the presentation and management of large cholesterol cysts of the petrous apex.

Adult↗
PubMed2001

Preattentive extraction of abstract feature conjunctions from auditory stimulation as reflected by the mismatch negativity (MMN).

Brain mechanisms extracting invariant information from varying auditory inputs were studied using the mismatch-negativity (MMN) brain response. We wished to determine whether the preattentive sound-analysis mechanisms, reflected by MMN, are capable of extracting invariant relationships based on abstract conjunctions between two sound features. The standard stimuli varied over a large range in frequency and intensity dimensions following the rule that the higher the frequency, the louder the intensity. The occasional deviant stimuli violated this frequency-intensity relationship and elicited an MMN. The results demonstrate that preattentive processing of auditory stimuli extends to unexpectedly complex relationships between the stimulus features.

Acoustic Stimulation↗
PubMed2000

Mismatch negativity and behavioural discrimination in humans as a function of the magnitude of change in sound duration.

This study investigated how duration changes are processed in the human brain as indexed by the mismatch negativity (MMN), a component of the auditory event-related potential (ERP) reflecting sensory memory. Subjects were presented with sequences of repetitive 100-ms white noise bursts interspersed by occasional duration deviants which were 1, 10, or 50 ms (decrements) or 110, 150, or 200 ms (increments) in duration. In a separate task, subjects were asked to detect deviants within the sequence via a button-press. MMN was elicited by both stimulus decrements and increments and increased in amplitude as a function of the amount of deviation from the standard duration except for the shortest, 1-ms deviant. Behavioural detection paralleled the MMN responses, suggesting a link between the processes underlying MMN and behavioural measures.

Acoustic Stimulation↗
PubMed2000

An update on "special stain" histochemistry with emphasis on automation.

For nearly 100 years, pathologists have utilized "special histochemical stains" to assist in tissue-based diagnosis. As illustrated in Figures 1 and 2, histochemical stains have been used to identify infectious microorganisms (e.g., Mycobacterium tuberculosis with acid-fast bacillus (AFB) stain), to detail inflammatory stromal or structural alterations (e.g., fibrosis in liver cirrhosis with Masson trichrome), to identify microanatomic sites of disease (e.g., basement membrane in glomerulonephritis with Jones methenamine silver), to identify abnormal chemical deposits (e.g., iron in hemochromatosis with Prussian blue stain), or abnormal immune deposits (e.g., amyloid via Congo red stain). The current surgical pathology laboratory may employ a repertoire of 20 to 25 "special stains" to ensure the full diagnostic complement. While the diagnostic repertoire and the biochemical recipes for the stains are now a well-established, codified part of surgical pathology, there is an ever-moving, leading edge of new developments including new reagents, applications, and methods. This review seeks to update the reader on some of the new applications including both new reagents and methods. Particular emphasis will be placed on the recent technologic advance of automating special stains in kinetic-mode (1-4). The authors consider in turn: 1. In brief, the "news" (recent literature review) of new staining applications; 2. In greater detail, two new applications for detection of Microsporidia and Helicobacer pylori; 3. The new technologic advancement of kinetic mode automation of special stains.

Automation↗
PubMed2000

Base of tongue varices associated with portal hypertension.

A symptomatic case of tongue base varices in a patient with portal hypertension secondary to liver cirrhosis is presented. There are no previously documented cases in the world literature. Oesophageal varices may not be the only source of expectorated blood in a patient with portal hypertension.

Aged↗
PubMed1999

Neuronal populations in the human brain extracting invariant relationships from acoustic variance.

The ability to extract invariant relationships from physically varying stimulation is critical for example to categorical perception of complex auditory information such as speech and music. Human subjects were presented with tone pairs randomly varying over a wide frequency range, there being no physically constant tone pair at all. Instead, the invariant feature was either the direction of the tone pairs (ascending: the second tone was higher in frequency than the first tone) or the frequency ratio (musical interval) of the two tones. The subjects ignored the tone pairs, and instead attended a silent video. Occasional deviant pairs (either descending in direction or having a different frequency ratio) elicited the mismatch negativity (MMN) of the event-related potential, demonstrating the existence of neuronal populations which automatically (independently of attention) extract invariant relationships from acoustical variance.

Acoustic Stimulation↗
PubMed1999

Release of merozoites from Plasmodium falciparum-infected erythrocytes could be mediated by a non-explosive event.

Little is known about the molecular mechanism underlying the release of merozoites from malaria-infected erythrocytes. In the present study, video microscopy was carried out, and images throughout the process of merozoite release from Plasmodium falciparum-infected erythrocytes were digitized and analyzed. Merozoites were shown to escape from the infected host cell in about 1 s through a single site of the infected erythrocyte membrane, whose dimension was estimated to be 2.5 microm. Merozoites were released together with the residual body containing hemozoin, leaving behind a membranous structure that persisted even after an extended period of observation. Densitometric measurements showed that the cytoplasmic content of the infected erythrocyte did not diffuse out as parasites were released, but was gradually lost thereafter. This would indicate that the release of merozoites from infected erythrocytes is not mediated by an explosive event.

Animals↗
PubMed1998

Temporal constraints of auditory event synthesis: evidence from ERPs.

The temporal constraints of auditory event synthesis were investigated using event-related potentials. Standard stimuli consisted of an initial constant-frequency segment followed by a frequency glide. Occasionally, stimuli deviating from this standard both in intensity and within the direction of the glide were presented in the otherwise repetitive sound sequence. Previous results suggested that such 'double' deviants elicit only a single mismatch negativity (MMN) if the two temporally separate deviant elements were integrated within a common unit. Two successive MMNs were elicited by double deviants when the initial constant-frequency segment of the sound was 250 ms long, but only one when this segment was 150 ms in duration. The results support the hypothesis that the auditory input is processed in approximately 200 ms long temporal integration windows.

Acoustic Stimulation↗
PubMed1998

Binaural information can converge in abstract memory traces.

Neural representations for abstract features of auditory stimuli were studied by presenting reading subjects with stimulus blocks composed of pairs of two closely spaced tones. There were frequent ascending standard pairs (i.e., the second tone was higher in frequency than the first tone) and occasional descending deviant pairs. Both types of pairs varied randomly over a wide frequency range. In separate blocks, the tones forming a pair were presented either to the same ear or to opposite ears. The deviant pairs elicited the mismatch negativity (MMN) in all conditions, which indicates that the brain can automatically extract and represent an abstract invariant feature (rise or fall) of stimulation above the point of binaural convergence and detect violations against it. Poor behavioral performance in an active discrimination task suggested that conscious discrimination processes can only partially use the outcome of the preattentive discrimination processes reflected by the MMN.

Acoustic Stimulation↗
PubMed1998

[Comparative evaluation of triamcinolone in coccidiosis control in fattening chickens].

The effectiveness of Triancinolone as a protector against coccidiosis in broilers was tested in a random design experiment. Cobb x Cobb one-day old chicken were assigned to the treatments: T1: no medication-no inoculation; T2: no medication-inoculation; T3: Triancinolone-inoculation; T4: Sodic Monensin-inoculation; and T5: Sodic Salinomycin-inoculation. The inoculation was accomplished with 10,000 oocysts of Eimeria tenella and 40,000 of intestinal Eimerias. The results of the intestinal damage degree showed that T3 (60.6%) and T4 (63.6%) were better to control coccidias in relation to T5 (96.9%) and T2 (100%). The oocysts number in feces (number/g) showed the best effectiveness for T3 (4,300) comparing with T4 (126,900), T5 (98,100), and T2 (382,000). These results emphasize the effective action mechanism of Triancinolone to interfere with the biological cycle of coccidias. The feed conversion was better (P < 0.05) in the groups that received the drugs (T3, T4, and T5) comparing with T2. This fact showed the adverse effect that coccidiosis cause on the broiler performance behavior. Triancinolone showed the best action effectiveness on the control of coccidiosis.

Animals↗
PubMed1994

Otitis media (silent): a potential cause of childhood meningitis.

Sixteen temporal bones from 8 infants with otitis media, who died of meningitis, and 6 controls from infants with only otitis media, were studied histologically. All bones contained middle ear effusion and residual mesenchyme, but, unlike the controls, the meningitic cases showed considerable histopathological tissue changes of chronic and acute otitis media and chronic inflammatory cells in the round window membrane and within the perilymph, the modiolus, and the cochlear aqueduct, suggesting the latter as likely portals from the inner ear to the meninges. Since all tympanic membranes were intact and 3 were histologically normal, this silent route of infection warrants medical vigilance.

Acute Disease↗
PubMed1991

Multiple mRNAs encode the murine translation initiation factor eIF-4E.

All eukaryotic cellular mRNAs (except organellar) possess at their 5' end the structure m7GpppX (where X is any nucleotide) termed the "cap." The cap structure facilitates the melting of mRNA 5' secondary structure through the action of initiation factor-4F (eIF-4F) in conjunction with eIF-4B. eIF-4F consists of three subunits of which one, eIF-4E (eIF-4E has recently been designated eIF-4 alpha according to the Nomenclature Committee of the International Union of Biochemistry (NC-IUB) (Safer, B. (1989) Eur. J. Biochem. 186, 1-3)), contains the cap binding site. Several lines of evidence suggest that eIF-4E regulates the rate of translation initiation. Consequently, changes in cellular eIF-4E levels could control growth and differentiation. To investigate the possibility that eIF-4E expression is regulated, we studied the pattern of eIF-4E expression in several cell lines. Here, we show the existence of multiple mRNAs for eIF-4E that are generated by differential polyadenylation. In addition, we show tissue-specific differences in eIF-4E mRNA expression and utilization of polyadenylation sites.

Animals↗
PubMed1991

RNA unwinding in translation: assembly of helicase complex intermediates comprising eukaryotic initiation factors eIF-4F and eIF-4B.

Ribosome binding to mRNA requires the concerted action of three initiation factors, eIF-4A, eIF-4B, and eIF-4F, and the hydrolysis of ATP in a mechanism that is not well understood. Several lines of evidence support a model by which these factors bind to the 5' end of mRNA and unwind proximal secondary structure, thus allowing 40S ribosomal subunits to bind. We have previously used an unwinding assay to demonstrate that eIF-4A or eIF-4F in combination with eIF-4B functions as an RNA helicase. To elucidate the molecular mechanism of RNA unwinding, we used a mobility shift electrophoresis assay which allows the simultaneous analysis of unwinding and complex formation between these factors and RNA. eIF-4F forms a stable complex (complex A) with duplex RNA in the absence of ATP. Addition of eIF-4B results in the formation of a second complex (complex B) of slower mobility in the gel. In the presence of ATP, both complexes dissociate, concomitant with the unwinding of the duplex RNA. We present evidence to suggest that unwinding occurs in a processive as opposed to distributive manner. Thus, we conclude that helicase complexes that are formed in the absence of ATP on duplex RNA translocate processively along the RNA in an ATP-dependent reaction and melt secondary structure. These helicase complexes therefore represent intermediates in the unwinding process of mRNA that could precede ribosome binding.

Base Sequence↗
PubMed1991

Modulation of the mitogenic activity of eukaryotic translation initiation factor-4E by protein kinase C.

Eukaryotic initiation factor-4E (eIF-4E) binds to the cap structure of eukaryotic mRNAs and is a component of the cap-binding protein complex eIF-4F. eIF-4E is present in cells in limiting concentrations and is phosphorylated both in vivo and in vitro by protein kinase C (PKC). Recently, eIF-4E has been implicated as an intracellular transducer of extracellular growth signals; microinjection of recombinant eIF-4E into quiescent NIH 3T3 cells induced DNA synthesis. In the present report, the mitogenic activity of eIF-4E was examined after coinjection with PKC. Recombinant eIF-4E was phosphorylated by PKC at the same amino acid that is phosphorylated in cultured cells and reticulocytes in response to phorbol ester. At limiting concentrations of eIF-4E, coinjection with PKC induced a fivefold increase in the mitogenic activity of eIF-4E. Injection of PKC alone or coinjection of eIF-4E with cAMP-dependent protein kinase (PKA) or the Raf protein had no effect. These results suggest that the mitogenic activity of eIF-4E is enhanced by PKC-specific phosphorylation and that phosphate addition is a rate-limiting step in eIF-4E activity.

Animals↗
PubMed1990

Translation initiation factors that function as RNA helicases from mammals, plants and yeast.

Ribosome binding to eukaryotic mRNAs requires the concerted action of three eukaryotic initiation factors: eIF-4A, eIF-4B and eIF-4F as well as the hydrolysis of ATP. These initiation factors are implicated in the unwinding of mRNA 5' secondary structure and have been isolated from mammals, yeast and wheat germ. We used an RNA unwinding assay to compare the activities of these factors from the different species. We also measured the inter-species interchangeability of these factors in the unwinding reaction. In mammals, it has been previously shown that a combination of rabbit reticulocyte eIF-4F and -4B or eIF-4A and -4B were active in the RNA unwinding assay. In wheat germ, the combination of eIF-4A and eIF-4F resulted in RNA unwinding in a reaction that was stimulated by eIF-4B. Mammalian eIF-4A was able to substitute in this system. We also show that yeast eIF-4A is able to effectively substitute for mammalian eIF-4A in duplex RNA unwinding in combination with mammalian eIF-4B, while wheat-germ eIF-4A was only partially able to substitute. Taken together, these results suggest that initiation factor requirements for RNA unwinding are largely similar in mammals, yeast and plants.

Animals↗
PubMed1990

Translation initiation factors induce DNA synthesis and transform NIH 3T3 cells.

Several polypeptide factors that are essential for the initiation of protein synthesis bind to eukaryotic mRNAs and facilitate the formation of ribosome initiation complexes. Purified mRNA-binding translation initiation factors were microinjected into quiescent NIH 3T3 cells to study the possible growth-promoting role of these factors in living cells. We report that recombinant eIF-4E and rabbit reticulocyte eIF-4F induce a dose-dependent increase of DNA synthesis and morphologically transform NIH 3T3 cells. These results suggest that polypeptides involved in activating the rate-limiting step of protein synthesis (initiation complex formation) can be mitogenic and oncogenic when overexpressed in a cell by direct injection. Thus, eIF-4E and eIF-4F represent a class of proto-oncogenic proteins that is cytoplasmic, is involved in protein synthesis initiation, and is distinct from the proto-oncogenes that have been identified previously.

Animals↗