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M F Moraes

Publications and source records attributed to M F Moraes.

18 recordsLinked to original sources
PubMed2001

Real time mapping of rat midbrain neural circuitry using auditory evoked potentials.

Auditory evoked potentials were recorded in 360 homogeneously spaced sites, in a volume encapsulating the lateral lemniscus-inferior colliculus transition of anaesthetized rats, in order to calculate the electric field vector distribution with each moment in time referenced to the onset of sound presentation. Software, to conduct calculations and graphical representation, and hardware, to minimize neural damage upon recording, were developed in our laboratory. Our results indicate a smooth transition of both amplitude and direction of vectors, suggestive of sequentially activated sites with outward and inward ionic currents coherent with what is known of this part of the primary auditory pathway. That is, anatomical sites (neural generators) and latency for activation matches previous research of the auditory pathway, while adding a real time perspective to the anatomical substrates recruited during the auditory evoked response. An algorithm for calculating the divergent of the vector field, an estimate of the current source density inside the three-dimensional control volume, was used to infer the possible current sinks and sources generating the field potentials. This technique allowed a clear visualization of two distinct discharges arising from the lateral lemniscus towards the inferior colliculus, thus recording signal propagation, as a movie file, with 0.06 ms time resolution.

Algorithms↗
PubMed2001

Effects of low-protein diet on the baroreflex and Bezold-Jarisch reflex in conscious rats.

The present study evaluated the effects of a low-protein diet (LP, 6% protein) on cardiovascular reflexes of Male Fisher rats. Three experimental groups, and their respective controls (15% protein), were used: (1) Baroreceptor reflex (BAR); (2) Bezold-Jarisch reflex (BJR); and (3) Prazosin treated. Dietary restriction began after weaning (three weeks) and lasted for a period of five weeks, after which animals were subjected to the experimental protocols. The BAR group was evaluated through injections of phenylephrine (0.5-5.0 microgram/Kg, i.v.) and sodium nitroprusside (0.7-7.0 microgram/Kg, i.v.) while the BJR was evaluated through injections of serotonin (2.5-10 microgram/Kg, i.v.). Our results showed an increased baroreflex gain bradycardia for the LP group (-0.96+/-0.34 vs. -2.12+/-1.06 bpm/mmHg) and a larger bradycardia for the BJR the LP group (160+/-18% greater than controls). Basal cardiovascular parameters were not different between LP and control rats, however LP animals treated with prazosin resulted in a larger fall of blood pressure (-19+/-3 vs. -28+/-5 mmHg). In conclusion, LP rats present an increased responsiveness of BAR and BJR, which could contribute to their normal levels of cardiovascular parameters, in spite of the possible increase in the sympathetic vasomotor tonus observed with the prazosin protocol.

Afferent Pathways↗
PubMed2000

Time evolution of acoustic 'information' processing in the mesencephalon of Wistar rats.

A traditional analysis of intra-encephalic auditory evoked potentials does not highlight the dynamical evolution of the auditory 'information' processing in neither time nor space. This work presents a method for tracing such signal evolution throughout the primary auditory pathway in the mesencephalon of adult anesthetized Wistar rats, using a unilateral 3 kHz tone burst stimulus. The results of the acoustic evoked potentials mapping are presented as conventional 20 ms recordings and re-analyzed in intervals of 1 ms-time windows. The parameter used, as an 'activity' correlate, was the maximum/minimum voltage difference obtained from each time window. The methodology used clearly indicates sequential signal propagation from the dorsal and ventral nuclei of the lateral lemniscus up to the inferior colliculus.

Acoustic Stimulation↗
PubMed1999

Cellular immune responses to Mycobacterium tuberculosis in a patient with Takayasu's arteritis.

INTRODUCTION: Takayasu's arteritis (TA) is a disease of unknown aetiology, characterized histologically by an inflammatory cell infiltrate that affects all layers of the arterial wall. Its association with tuberculosis (TB) was described 50 years ago, based on the presence of Langhan's giant cells and granulomas similar to those found in tuberculous lesions. The presence of TB in patients with TA well as been reported in several studies as well as a positive tuberculous response, but these associations could be fortuitous in countries where TB is endemic. Recent studies have shown that patients with TA have a heightened humoral response to mycobacterial antigens including the 65 kDa fraction, a heat shock protein (HSP) that has also been found to be expressed in the arterial wall of patients with TA. The purpose of this study was to determine lymphoproliferative response and interferon-gamma (IFN-gamma) production by peripheral blood mononuclear cells (PBMC) stimulated by live Mycobacterium tuberculosis (Mtb) H37Rv and a panel of mycobacterial antigens, in the hope of contributing to a better understanding of the cellular immune responses to Tuberculosis in Takayasu's arteritis. MATERIAL AND METHODS: Standard lymphoproliferation tests and IFN-gamma determination (ELISA) were performed in a 47-year old black man who fulfilled criteria for TA and 10 healthy controls, BCG vaccinated, Mantoux positive. The following were used: Mtb H37Rv, Purified Protein Derivative (PPD), purified 30 kDa, recombinant M. bovis BCG 10 kDa, 38 kDa, 65 kDa, 70 kDa, Short Term-Culture Filtrate Proteins (ST-CFP), Mid Term-Culture Filtrate Proteins (MT-CFP) obtained from H37Rv and phytohemaglutinin (PHA) as mitogen for positive control. RESULTS: PBMC from the patient with TA when compared to the mean values of the 10 healthy donors showed decreased proliferation in response to all antigens, with the exception of 65 kDa. The TA patient showed a similar pattern of IFN-gamma production to that obtained with control donors, with the exception of higher IFN-gamma production in response to ST-CFP and MT-CFP. CONCLUSIONS: We have shown reactivity of peripheral lymphocytes to HSP 65 kDa and a trend towards higher production of IFN-gamma in response to ST-CFP and MT-CFP in a patient with TA. These facts, together with the already established heightened humoral response, strengthens the association between TB and TA. However, HSP 65 kDa is not specific to TB and we conclude that similar studies using lymphocytes obtained from the arterial wall of TA patients may help to clarify the role of mycobacterial infection in Takayasu's arteritis.

Antigens, Bacterial↗
PubMed1998

Lithogenic risk factors in the urine of black and white subjects.

OBJECTIVE: To identify biochemical and dietary factors which may play a role in the low incidence of stone formation in the black South African population. SUBJECTS AND METHODS: The study included 31 semiurbanized black and 29 urbanized white subjects. The protocol and modern laboratory techniques used to assess recurrent stone formers were followed. Urinary sodium, potassium, creatinine, calcium, phosphate and urate levels were measured, and urinary citrate, oxalate and cystine assessed. RESULTS: Black subjects ate a diet significantly higher in sodium (P < 0.04); there was no difference in serum levels but urinary sodium was significantly higher (P < 0.001) in black than in white subjects. Urinary potassium, calcium, citrate, phosphate and cystine were all significantly lower in black than in white subjects (P < 0.001 for the first four and P < 0.03 for cystine). CONCLUSION: Certain intrinsic factors in South African black subjects may account for their lower frequency of stone formation than in white subjects. Of these, the very low urinary calcium, decreased urinary cystine and different interactions between sodium and calcium/cystine are probably important.

Adult↗
PubMed1998

[Cellular immune response to mycobacterial antigens].

The authors studied the immunological response before and after beginning anti-tuberculous therapy, of a previously health, HIV negative, 22 year old black male, from the Republic of Cape Verde. The patient had multiple vertebral bony lesions associated to subcutaneous abscesses. As immunological markers of antigen recognition, we measured blastogenic and cytotoxic responses and gamma-IFN secretion towards 30 kD, 65 kD, filtrate proteins of M. tuberculosis, M. tuberculosis (H37Rv) and PPD cultures. To characterise the role of cytokines during infection, expression of mRNA for gamma-IFN, IL-4 and IL-10 was also analysed. A slight increase of lymphocyte proliferation and gamma-IFN production was seen in response to purified protein derivative (PPD) and short term culture filtrate proteins (ST-CFP), after one month of therapy. More significant, was the increase in M. tuberculosis and PPD-specific cytolytic T lymphocyte response after one one month of treatment. After 6 months of treatment, blastogenic and cytotoxic responses and gamma-IFN production were considerably higher toward the antigen panel. The CD4/CD8 ratio increased from 0.7 to 1.4 after treatment. We observed that ST-CFP and MT-CFP induced increasingly higher lymphoproliferation and gamma-IFN production, confirming their role in the protective immune responses to M. tuberculosis. The reduced immune responses in the peripheral blood of this patient probably reflect a high activity in the local sites of infection. This case of disseminated tuberculosis infection maybe related to nutritional or social factors or may represent an example of reduced in ate resistance against tuberculosis infection.

Adult↗
PubMed1997

Heart rate variability and baroreceptor function in chronic diabetic rats.

In conscious chronic (12 to 18 weeks) streptozotocin diabetic rats, we examined the changes in basal heart rate, with particular attention to heart rate variability assessed by evaluating the standard deviation (bpm) of the lengths of adjacent pulse pressure. We also investigated in anesthetized rats the ability of the aortic baroreceptors to acutely (30 minutes) reset to hypertensive levels. For this purpose, pressure-nerve activity curves for the baroreceptors were obtained, and gain (slope of the curve) and mean arterial pressure at 50% of maximal baroreceptor activity were calculated. The shift of the pressure-nerve activity curve was used as an index of resetting. Conscious diabetic rats (n=6) exhibited lower mean arterial pressure (93+/-6 versus 109+/-4 mm Hg), heart rate (272+/-25 versus 359+/-11 bpm), and heart rate variability (18+/-7 versus 36+/-6 bpm) than control rats (n=7). Under anesthesia, diabetic rats (n=7) and control rats (n=8) exhibited similar mean arterial pressure (113+/-6 versus 109+/-7 mm Hg in control rats ), mean arterial pressure at 50% of maximal baroreceptor activity (117+/-5 versus 107+/-6 bpm), gain (1.66+/-0.08 versus 1.81+/-0.05%/mm Hg), and extent of resetting (44+/-12 versus 49+/-9%) to hypertensive levels. The present study demonstrated that conscious chronic diabetic rats presented lower heart rate variability than control rats. On the other hand, chronic diabetes was not associated with alterations in baroreceptor function or its ability to rapidly reset to hypertensive levels.

Animals↗
PubMed1997

Low-cost automatic activity data recording system.

We describe a low-cost, high quality device capable of monitoring indirect activity by detecting touch-release events on a conducting surface, i.e., the animal's cage cover. In addition to the detecting sensor itself, the system includes an IBM PC interface for prompt data storage. The hardware/software design, while serving for other purposes, is used to record the circadian activity rhythm pattern of rats with time in an automated computerized fashion using minimal cost computer equipment (IBM PC XT). Once the sensor detects a touch-release action of the rat in the upper portion of the cage, the interface sends a command to the PC which records the time (hours-minutes-seconds) when the activity occurred. As a result, the computer builds up several files (one per detector/sensor) containing a time list of all recorded events. Data can be visualized in terms of actograms, indicating the number of detections per hour, and analyzed by mathematical tools such as Fast Fourier Transform (FFT) or cosinor. In order to demonstrate method validation, an experiment was conducted on 8 Wistar rats under 12/12-h light/dark cycle conditions (lights on at 7:00 a.m.). Results show a biological validation of the method since it detected the presence of circadian activity rhythm patterns in the behavior of the rats.

Animals↗
PubMed1997

Glass pipette-carbon fiber microelectrodes for evoked potential recordings.

Current methods for recording field potentials with tungsten electrodes make it virtually impossible to use the same recording electrode also as a lesioning electrode, for example for histological confirmation of the recorded site, because the lesioning procedure usually wears off the tungsten tip. Therefore, the electrode would have to be replaced after each lesioning procedure, which is a very high cost solution to the problem. We present here a low cost, easy to make, high quality glass pipette-carbon fiber microelectrode that shows resistive, signal/noise and electrochemical coupling advantages over tungsten electrodes. Also, currently used carbon fiber microelectrodes often show problems with electrical continuity, especially regarding electrochemical applications using a carbon-powder/resin mixture, with consequent low performance, besides the inconvenience of handling such a mixture. We propose here a new method for manufacturing glass pipette-carbon fiber microelectrodes with several advantages when recording intracerebral field potentials.

Animals↗
PubMed1997

[Kikuchi's disease. A rare cause of fever, lymphadenopathies and polyarthritis].

This is a case report of a 29-year-old white female patient with Kikuchi's disease, presenting fever, polyarthritis, lymph gland enlargement, anemia, leucopenia with a relative lymphocytosis, altered liver function tests and circulating immune complexes. A literature review is made with emphasis on the etiology, clinical course and pathogenesis of this illness.

Adult↗
PubMed1997

[Hepatopulmonary syndrome].

Hepatopulmonary Syndrome is an uncommon clinical situation of unknown cause. It remains the focus of intense investigation and ongoing debate. The authors present a case of a 77 year old man with chronic liver disease known for 5 years, who developed central cyanoses, digital clubbing and hypoxemia. On searching for the cause of these clinical features, the diagnosis of Hepatopulmonary Syndrome was admitted and confirmed by contrast enhanced echocardiography using agitated saline, and also by technetium 99m-labelled macroaggregated albumin scanning.

Aged↗
PubMed1989

Comparison of aztreonam plus clindamycin with tobramycin plus clindamycin in the treatment of intra-abdominal infections.

The activity of aztreonam (a beta-lactam antibiotic with specific activity against gram-negative bacteria) was evaluated and compared with that of tobramycin in hospitalized patients with severe intra-abdominal infections due to gram-negative pathogens, either alone or in association with other bacteria. Of a total study population of 156 patients, 76 were assigned to treatment with aztreonam + clindamycin, and the remaining 80 were treated with tobramycin + clindamycin. Patients underwent a variety of surgical procedures involving the peritoneal cavity. The final clinical evaluation revealed similar percentages of satisfactory results: 86.8% for the patients in the aztreonam-treated group and 86.2% for the tobramycin-treated patients. Among the patients who had a poor therapeutic result, gram-negative bacteria, either alone or associated with gram-positive pathogens, were considered responsible for 50% of the infections in the aztreonam group; the percentage increased to 82% among those treated with tobramycin. The incidence of side effects and laboratory alterations was not significant and was similar in both groups. The results of this study suggest that aztreonam may be an effective and safe drug for the treatment of bacterial infections due to gram-negative pathogens.

Abdomen↗
PubMed1984

Bacterial meningitis in Johannesburg--1980-1982.

A 2-year retrospective study of aetiology, age distribution, seasonal variation and antimicrobial sensitivity patterns of bacteria isolated from patients with meningitis in five Johannesburg hospitals for White, Black, Coloured and Asian patients was performed. Neisseria meningitidis was isolated most frequently, followed by Streptococcus pneumoniae, Haemophilus influenzae, Escherichia coli and Streptococcus group B. In the Black population 73% of the meningococcal infections occurred in patients over 3 years of age, and the majority of these infections were caused by serogroup A organisms. Virtually all (93%) of the H. influenzae infections occurred in children of less than 3 years of age. Of the isolates tested, 16% of the meningococci, 4,5% of the H. influenzae and 47% of the pneumococci were resistant to sulphadiazine, ampicillin and penicillin respectively.

Adolescent↗
PubMed1978

Role of the sympathetic nervous system in peptic ulcer production in rats.

The role of the sympathetic nervous system in gastric acid secretion and in experimental duodenal ulceration (cysteamine induced) was studied in rats. The animals were divided randomly into seven groups: (1) control, (2) sham-operated, (3) surgical sympathectomy, (4) chemical sympathectomy (6-HODA), (5) vagotomy, (6) surgical sympathectomy plus vagotomy, and (7) chemical sympathectomy plus vagotomy. Results on gastric acid secretion were expressed as gastric acid output (GAO = micronEq of acid secretion in 1 hour). The means in the control and sham groups were 447.83 +/- 26.67 GAO and 399 +/- 36.4 GAO, respectively. The means in the sympathectomized rats (surgically = 562 +/- 27.21 GAO and chemically = 648.66 +/- 46.53 GAO) were higher (P less than 0.01) than those of the control and sham groups. In the vagotomized group the mean was 156.6 +/- 17.64 GAO, lower than those of the control and sham groups (P less than 0.001). The incidence of ulceration was 47.5% and 46% in the control and sham groups, respectively. Both the sympathectomized groups (surgically, 73%; chemically, 77%), had a significantly elevated incidence of ulceration as compared with the controls (P less than 0.01). The vagotomized group had a 14% incidence of ulceration. These results clearly indicate that sympathectomy has a definite effect on gastric acid secretion and on the incidence of experimental peptic ulceration in rats.

Adrenergic Fibers↗
PubMedDate not supplied

Aztreonam plus clindamycin vs. tobramycin plus clindamycin for the treatment of intraabdominal infections.

Sixty-six patients with acute intraabdominal infections due to gram-negative aerobic organisms were treated with aztreonam plus clindamycin or with tobramycin plus clindamycin in a multicenter, comparative, randomized study. The patients had undergone a variety of surgical procedures; most of them had peritonitis. Thirty-three of the 36 patients in the aztreonam group and 26 of the 30 patients in the tobramycin group had satisfactory clinical responses. Only one gram-negative aerobic pathogen, a strain of Pseudomonas aeruginosa, persisted after treatment; the patient involved was in the tobramycin group. The incidences of adverse reactions, superinfections, and abnormal laboratory values were low in each treatment group. The difference between the efficacies of the two regimens was not statistically significant. This study suggests that aztreonam may be a useful alternative to the aminoglycosides in the treatment of gram-negative intraabdominal infections.

Abdomen↗
PubMedDate not supplied

[Broncho-splenic fistula caused by hydatidosis].

To our knowledge, this is the first case report of a broncho-splenic fistula of hydatid origin. We discuss the clinical, radiological and therapeutic aspects of this rare complication of hydatid disease.

Aged↗