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Biomedical subjects

D Soares

Publications and source records attributed to D Soares.

At least 19 recordsLinked to original sources
PubMed2002

Amphibious auditory responses of the American alligator (Alligator mississipiensis).

Animals that thrive both on land and underwater are faced with the task of interpreting stimuli in different media. This becomes a challenge to the sensory receptors in that stimuli (e.g., sound, motion) may convey the same type of information but are transmitted with different physical characteristics. We used auditory brainstem responses to examine hearing abilities of a species that makes full use of these two environments, the American alligator (Alligator mississipiensis). In water, alligators responded to tones from 100 Hz to 2,000 Hz, with peak sensitivity at 800 Hz. In air, they responded to tones from 100 Hz to 8,000 Hz, with peak sensitivity around 1,000 Hz. We also examined the contribution to hearing of an air bubble that becomes trapped in the middle ear as the animal submerges. This bubble has been previously implicated in underwater hearing. Our studies show that the trapped air bubble has no affect on auditory thresholds, suggesting the bubble is not an important adaptation for underwater hearing in this species.

Air↗
PubMed2002

Evolutionary convergence and shared computational principles in the auditory system.

Precise temporal coding is a hallmark of the auditory system. Selective pressures to improve accuracy or encode more rapid changes have produced a suite of convergent physiological and morphological features that contribute to temporal coding. Comparative studies of temporal coding also point to shared computational strategies, and suggest how selection acts to improve coding. Both the avian cochlear nucleus angularis and the mammalian cochlear nuclei have heterogeneous cell populations, and similar responses to sound. These shared characteristics may represent convergent responses to similar selective pressures to encode features of airborne sound.

Animals↗
PubMed2001

The cytoarchitecture of the nucleus angularis of the barn owl (Tyto alba).

The cochlear nucleus angularis (NA) of the barn owl (Tyto alba) was analyzed using Golgi, Nissl, and tract tracing techniques. NA forms a column of cells in the dorsolateral brainstem that partly overlaps with, and is rostral and lateral to, the cochlear nucleus magnocellularis (NM). Highest best frequencies are mapped in lateral NA (NAl), intermediate in medial NA (NAm), and lowest in the foot region (NAf). Cell density followed the tonotopic axis and decreased with decreasing best frequency. NA contained four major cell classes: planar, radiate, vertical, and stubby. Planar and radiate classes were further subdivided into bipolar and multipolar types according to their number of primary dendrites. Planar neurons were confined to an isofrequency band, whereas radiate neurons had dendrites that could extend across an isofrequency band. Vertical cells had long dendrites oriented perpendicularly to isofrequency bands. Stubby cells were the most numerous and were confined to an isofrequency band because of their short dendrites. Neurons in each of these four classes projected to the inferior colliculus and dorsal nucleus of the lateral lemniscus.

Animals↗
PubMed2001

Molecular components of the archaeal nucleosome.

Here we describe the organization of the archaeal nucleosome, in which four archaeal histones are circumscribed by approximately 80 bp of DNA. Through a combination of sequence comparisons, 3D structural studies, site-directed mutagenesis and assays for DNA binding, we have assigned functions to most of the individual residues in the histone fold of the representative archaeal histone rHMfB. By SELEX selection, the sequences of DNA molecules that are most readily bound and wrapped by rHMfB into archaeal nucleosomes in vitro have been identified, and these define DNA structures that position archaeal nucleosome assembly.

Archaea↗
PubMed2001

Evolution and development of time coding systems.

Precise temporal coding is a hallmark of both the electrosensory and auditory systems. Selective pressures to improve accuracy or encode more rapid changes have produced a suite of convergent physiological and morphological features that contribute to temporal coding. Comparative studies of temporal coding can also point to shared computational strategies, and suggest how selection might act to improve coding.

Animals↗
PubMed2001

Geographical distribution of Biomphalaria snails in the State of Minas Gerais, Brazil.

Published and unpublished observations on geographical distribution of Biomphalaria snails in the State of Minas Gerais, Brazil, were compiled. This work is aimed at knowing the present occurrence of Biomphalaria species in this region, and at contributing to the elaboration of the planorbid chart of Minas Gerais. In malacological surveys, performed by several researchers, the presence of seven species of this genus was recorded. Those planorbids were found in 12 mesoregions, in 283 (33.1%) municipalities out of 853 with the following distribution: B. glabrata (185 municipalities), B. straminea (125), B. tenagophila (58), B. peregrina (57), B. schrammi (26), B. intermedia (20) and B. occidentalis (2). B. glabrata and B. tenagophila are found naturally infected by Schistosoma mansoni in Minas Gerais. In 24 municipalities the three snail hosts of S. mansoni in Brazil, B. glabrata, B. tenagophila and B. straminea, are present.

Animals↗
PubMed2001

Computed Tomography in the evaluation of seizures at the University Hospital of the West Indies.

A retrospective evaluation of the Computed Tomography (CT) findings in three hundred and forty-four patients with seizures, presenting over a one-year period, was carried out to determine the value of this examination in the assessment of these patients. Eighty-four per cent of patients had non-contrast studies only. Of the remaining patients, two had contrast studies only and the rest had both non-contrast and contrast studies. All cerebral abnormalities detected on contrast studies were evident on non-contrast scans. Forty-two per cent of all patients presenting with seizures were found to have a demonstrable abnormality on CT. There was a greater detection rate in patients with seizures secondary to trauma, cerebrovascular incidents, infection, metabolic causes and suspected tumours. Computed tomography continues to have a place in the evaluation of certain types of seizure patients. The routine use of intravenous contrast does not appear to be justifiable.

Adolescent↗
PubMed2000

Malignant meningioma with extension into the neck.

One per cent of all brain tumours and twenty per cent of meningiomas eventually develop an extracranial extension. The least common site is the neck. We report a case of malignant meningioma with extension into the neck of a 39-year-old male.

Adult↗
PubMed1999

A morphological study of the cochlear nuclei of the pigeon (Columba livia).

The pigeon cochlear nucleus angularis (NA) and nucleus magnocellularis (NM) were analyzed with Golgi and Nissl techniques. NA was divided into a medial NAm and NA proper, which could be subdivided further into an intermediate NAi and lateral NAl. NAm contained a mostly homogeneous population of a unique multipolar cell type with very short dendrites and large somatic spines. NA proper contained four cell types: large, medium, and small multipolars, and medium bipolar. The medium multipolar cells were most common, and resembled the multipolar cells of the mammalian ventral cochlear nucleus. NM presented a homogenous appearance with a mediolateral gradient of cell size and shape. Medially located higher best frequency NM principal cells had round cell bodies with small somatic spines and few dendrites. By comparison, laterally located low best frequency NM stellate cells had more dendrites and spindle shaped cell bodies. The similarities between the cell types of NA and the cell types in the cochlear nuclei of other amniote vertebrates may be due to homology or convergent evolution.

Animals↗
PubMed1998

Archaeal histone stability, DNA binding, and transcription inhibition above 90 degrees C.

The DNA binding and compacting activities of the recombinant (r) archaeal histones rHMfA and rHMfB from Methanothermus fervidus, and rHPyA1 from Pyrococcus species GB-3a, synthesized in Escherichia coli, have been shown to be completely resistant to incubation for 4h at 95 degrees C in the presence of 1M KCl. Continued incubation of rHMfA and rHMfB at 95 degrees C resulted in a gradual loss of these activities, and rHMfA and rHMfB lost activity more rapidly at 95 degrees C when the salt environment was reduced to 200 mM K Cl. rHPyA1, in contrast, retained full activity even after a 60-h incubation at 95 degrees C in 1 M KCl, and reducing the salt concentration did not affect the heat resistance of rHPyA1. rHPya1-DNA complexes remained intact at 100 degrees C, and rHPyA1 bound to the template DNA in in vitro transcription reaction mixtures assembled using Pyrococcus furiosus components at 90 degrees C. Transcription in vitro from the P. furiosus gdh promoter was reduced by rHPyA1 binding, in a manner that was dependent on the histone-to-DNA ratio and on the topology of the DNA template. Transcription from circular templates was more sensitive to rHPyA1 binding than transcription from a linear template, consistent with rHPyA1 binding introducing physical barriers to transcription and causing changes in the topology of circular templates that also reduced transcription.

Amino Acid Sequence↗
PubMed1998

Orbital psuedotumour with intracranial extension. A case report.

Inflammatory pseudotumour of the orbit is an unusual condition of unknown aetiology which rarely extends beyond the orbit. To our knowledge 19 cases with intracranial extension have been reported, none of which involved the pituitary fossa or sphenoid sinus. Most required cytotoxic agents, surgery or radiotherapy in addition to corticosteroids. We present a case of orbital pseudotumour with extension into the pituitary fossa, sphenoid sinus and cavernous sinuses with vascular compression. Marked clinical improvement occurred on steroid therapy alone.

Adult↗
PubMed1997

Temporalis muscle transfer in the correction of lagophthalmos due to leprosy.

In the correction of lagophthalmos due to leprosy neuritis temporalis muscle transfer (TMT) is used to provide a motor to assist in lid closure. This study of TMT in 51 eyes was carried out to assess the effectiveness of TMT in achieving lid closure and corneal protection. The average lid gap preoperatively on light closure was 7.3 mm which was reduced to 3.2 mm on final follow-up. The average lid gap pre-operatively on tight closure was 5.3 mm which was reduced to 0.4 mm at final follow-up. It is possible to train patients with partial or total anesthesia of the cornea in a visual THINK-BLINK reflex. The common complications encountered were ectropion in 6 eyes (12%) and ptosis in 3 eyes (6%).

Adolescent↗
PubMed1997

A simple and inexpensive pinch meter to detect subclinical weakness among leprosy patients.

This paper describes the use of a neonatal sphygmomanometer cuff as a simple, inexpensive pinch meter. Normal values for key pinch, pulp pinch and side pinch in the dominant hand of healthy Nepali people are provided. The pinch meter was also used to test pinch strength in hands affected by leprosy and normal hands. Some patients with leprosy who have no objective weakness on voluntary muscle testing (VMT) have less pinch strength than people without leprosy. The pinch meter is a useful tool for the early detection of motor function loss.

Adolescent↗
PubMed1997

IgM anti-phenolic glycolipid-I antibody measurements from skin-smear sites: correlation with venous antibody levels and the bacterial index.

Measurements of anti-phenolic glycolipid-I antibodies were made in 200 matched samples of capillary blood from the skin-smear site, venous blood collected on filter paper, and sera. A close correlation among the three samples was observed and a weaker correlation among the antibody levels and the average and skin-smear bacterial index. Capillary blood from the skin-smear site had a consistently higher level of antibodies in each sample than did the sera. The collection of capillary blood from skin-smear sites is a convenient and economical method of obtaining samples for serology and for measuring local antibody levels, and it may be more sensitive than measurements of antibodies in sera.

Adolescent↗
PubMed1996

Squamous cell carcinoma of the foot arising in chronic ulcers in leprosy patients.

Squamous cell carcinoma (SCC) of the foot is a rare sequelae of chronic ulceration secondary to leprosy neuropathy. Most of the tumours are relatively slow growing and tend to metastasize late. Survival after local excision is generally good. In this series of 17 patients so far there have been 3 deaths attributable to SCC, all of whom presented with locally advanced tumours and lymph node metastasis.

Adult↗
PubMed1996

Tibialis posterior transfer for the correction of foot drop in leprosy. Long-term outcome.

A comparison was made of the results produced by the circumtibial and interosseous routes of transfer of tibialis posterior for the correction of foot drop due to leprosy neuritis. The findings in 69 feet, of which 63 also had elongation of tendo Achillis, showed that the interosseous route gave a much lower incidence of recurrent inversion deformity of the foot. The results, in terms of improvement in gait and prevention of trophic changes, were satisfactory.

Achilles Tendon↗
PubMed1995

Tibialis posterior transfer in the correction of footdrop due to leprosy.

In the correction of footdrop due to leprosy neuritis the tibialis posterior muscle is re-routed and used to provide dorsiflexion of the foot. This study of tibialis posterior transfer was carried out to compare the results of the circumtibial and interosseous routes. There is no significant difference in the range of motion between either route through the range of the interosseous route is more functional (better dorsiflexion). The interosseous route is preferable as this results in a significantly lower incidence of recurrent inversion deformity of the foot at long-term follow-up when compared with the circumtibial route.

Adolescent↗