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Biomedical subjects

A Fernandes

Publications and source records attributed to A Fernandes.

At least 109 records · Page 6Linked to original sources
PubMed1989

Postnatal development of neuropeptide Y-like immunoreactivity in area 17 of normal and visually deprived rhesus monkeys.

Immunocytochemical methods were used to examine neuropeptide Y (NPY) immunoreactive neurons and fibers in area 17 of rhesus monkeys during the first year of life. NPY-immunoreactive (+) neurons are nonpyramidal cells which are either multipolar, bipolar, or bitufted in shape. They occur most frequently in layer 6 and the subjacent white matter, are sparser in the supragranular layers, and absent from layer 4C. Labeled somata in the supragranular layers are smaller compared to those in layer 6 and the white matter. A typical axon originates from the NPY+ soma or from a primary dendrite and frequently is varicose. Distribution and morphologies of NPY+ neurons in area 17 of infants are similar to those of adult monkeys. Thus, it seems that NPY+ neurons in rhesus monkeys are mature from birth. NPY+ fibers occur in area 17 from birth; however, they differ in density and distribution from those of older infant and adult monkeys. At birth, a prominent fiber plexus is found in the deepest part of layer 1, and another in the white matter. Immunoreactive processes are sparse in the remaining cortical gray, except for some vertical fibers extending from pia to white matter. By 4 months of age, labeled fibers form a coarse network in layers 2, 3, 5, and 6. In addition, a distinct plexus extends through layers 4B, 4A, and the lowest aspect of layer 3. Also, a thin immunoreactive fiber band is found at the bottom of layer 4C. In the remainder of layer 4C, NPY+ fibers are scant. The supragranular layers also exhibit a unique immunoreactive "snarl" of fibers. Increases in density of NPY+ processes in the older infants are gradual so that between 7 and 13 months of age, NPY+ fibers appear to have achieved adultlike densities. These observations indicate that NPY+ fibers in area 17 of newborn rhesus monkeys undergo postnatal maturation which reaches a plateau around 4 months of age. After monocular visual deprivation from birth to 4 months of age, either by eyelid suture or by occlusion with an opaque contact lens, density and distribution of NPY+ neurons and fibers, including snarls, appear similar to those of age-matched undeprived infants. Thus, disruption of the normal binocular input does not seem to arrest the maturation of the NPY system in area 17 of rhesus monkeys during a sensitive period of early postnatal development.

Animals↗
PubMed1989

Dopamine synthesis and metabolism in rhesus monkey retina: development, aging, and the effects of monocular visual deprivation.

The normal postnatal development, the influence of age, and the effects of visual deprivation on the dopamine system in the retina of rhesus monkeys were examined. The lowest level of retinal dopamine was found at birth. By 3-4 weeks of age, the dopamine concentration had more than doubled. This level remained relatively constant in the retinas of older infants and of adult monkeys up to 34 yr of age. The level of the dopamine metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) and the activity of tyrosine hydroxylase did not significantly change as a function of age during the postnatal life span. Monocular occlusion of newborn or infant monkeys for 1-15 months with opaque contact lenses resulted in decreases in the retinal concentrations of dopamine and DOPAC relative to the concentrations in the same animals' unoccluded eyes. Occlusion also resulted in a lower level of tyrosine hydroxylase activity in the retina. Monocular eyelid suture from birth to 15 months of age resulted in less consistent alterations of retinal dopamine and DOPAC levels; tyrosine hydroxylase activity, however, was consistently reduced by lid suture. Thus, dopamine synthesis and metabolism, and the ontogenetic increase of the retinal dopamine level of rhesus monkey are reduced by light deprivation.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1989

[Physiopathology of arterial hypertension. Significance of the renin-angiotensin-aldosterone system and structural changes].

It is presented a review of some recent aspects of the hypertension's physiopathology, namely those related with the renin-angiotensin-aldosterone system and with the cardiovascular structural changes. The large action range of the angiotensin is pointed out, in particular those actions related with the heart's and vessel's adaptation to a chronic load of pressure. In the end, the author stresses some recent references about the genetic's role on the pathogenesis of the structural changes.

Angiotensin II↗
PubMed1989

Corneal biometrics of the rhesus monkey (Macaca mulatta).

Keratometry, retinoscopy, horizontal diameter, and pachymetry were measured in adult and infant rhesus monkeys (Macaca mulatta). The adult monkeys had a mean corneal thickness of 0.47 +/- 0.03 mm (+/- standard deviation), corneal diameters of 10.6 +/- 0.5 mm, keratometry values of 51.90 +/- 1.61 diopters, and subjective refractions of 0.48 +/- 2.36 diopters. Female adult monkeys had smaller corneal diameters by 0.06 mm (P = .02) and steeper corneas by 0.77 diopters (P = .04). Infant female monkeys also had steeper corneas by 2.37 diopters (P = .05). No significant differences were found between right and left eyes in either adult or infant monkeys.

Animals↗
PubMed1989

Development of acuity in a primate model of human infantile unilateral aphakia.

We are studying infant rhesus monkeys that have been reared under various conditions of deprivation to model infantile unilateral aphakia. Grating acuity was assessed in these monkeys from birth to approximately 1 year of age using the quick acuity card procedure. We found that an uncorrected aphakic eye develops little or no pattern vision. Undercorrection or near point optical correction of an aphakic eye with an extended-wear contact lens coupled with continuous occlusion of the opposite eye sometimes results in normal development of acuity in the aphakic eye but does so only at the cost of loss of vision in the occluded eye. Fifty percent partial occlusion coupled with near-point correction of the aphakic eye results in similar development of acuity for both eyes during the time tested. Monkeys wearing near-point correction in the aphakic eye and without any occlusion of the other eye show surprisingly good residual acuities in their aphakic eyes. Based on these results we conclude that aphakic eyes should be treated by providing them with an optical correction, and that occlusion of the opposite eye should be used cautiously.

Animals↗
PubMed1988

The correction of aphakia in infants with hydrogel extended-wear contact lenses. Corneal studies.

Although hydrogel extended-wear contact lenses (EWCLs) have been used extensively in the correction of aphakia in neonates, little is known about the effects of these lenses on infant corneas. Recent studies have demonstrated that long-term contact lenses can induce endothelial morphometric changes, including an increased coefficient of variation (CV) of mean endothelial cell area. Using wide-field specular microscopy, the authors studied 11 eyes of 10 patients, 1 to 3 years of age who, after lensectomy for congenital cataracts, wore EWCLs for the correction of aphakia. Except for two corneas in which increased pachometric readings and CV developed after repeated episodes of lens loss and inflammation, the EWCL were well tolerated and associated with few complications in this study.

Aphakia, Postcataract↗
PubMed1988

Mechanisms of hemolysis induced by copper.

An excess of copper is the cause of hemolysis in a number of clinical conditions. Incubation of human erythrocyte (RBC) suspensions with copper (II) causes the formation of methemoglobin, lipid peroxidation and hemolysis. A new variant of the thiobarbituric acid (TBA) method, which minimizes the formation of interfering chromophores, was used to detect lipid peroxidation. Lipid peroxidation precedes hemolysis and the antioxidant vitamins C and E, which inhibit lipid peroxidation, also inhibit hemolysis. Consequently lipid peroxidation appears to be the cause of RBC destruction. Lipid peroxidation arises mostly from the oxidation of oxyhemoglobin by copper as it is inhibited in RBCs with carbon monoxyhemoglobin or methemoglobin. A direct interaction of copper with the red cell membrane seems to play only a minor role. Copper effects depend on the presence of free SH groups. Lipid peroxidation is probably initiated by activated forms of oxygen as it is increased by an inhibitor of catalase and reduced by hydroxyl radical scavengers. With higher copper concentrations hemolysis is greater: its mechanism appears different as lipid peroxidation is smaller but hemoglobin alterations, namely precipitation, are more pronounced.

Ascorbic Acid↗
PubMed1987

Alcohol interactions with lipids: a carbon-13 nuclear magnetic resonance study using butanol labeled at C-1.

The interactions of carbon-13 enriched butanol with dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine (DMPC) were studied using C-13 nuclear magnetic resonance. It was found that above the gel to liquid crystal phase transition the resonance from the butanol could be resolved into two signals with similar chemical shifts but different T1 values and line widths. In contrast, only one narrow resonance was observed for ethanol, which has considerably less solubility in the lipids than butanol. Thermodynamic analyses of the effects of butanol on the phase transition temperature predict much greater solubility or butanol when the lipid is above the phase transition temperature than when it is below. It was concluded that the two butanol resonances represent two slowly exchanging populations, the free butanol in the aqueous phase and butanol dissolved in the liquid crystalline region of the lipid. No bound butanol was detected below the gel to liquid crystal phase transition. Relaxation studies were performed on the resonance of the bound butanol in DPPC and DMPC, including measurements of T1, line width, and nuclear Overhauser enhancement. Theoretical analysis of the relaxation parameters indicates that the lipid-bound alcohol has very high mobility within the fluid lipid bilayer. The data are consistent with butanol being present at the aqueous boundary or head group region of the lipid.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1987

Intrathecal administration of morphine for the relief of pains in labour and estimation of maternal and fetal plasma concentration of morphine.

Thirteen healthy women in active labour received an intrathecal injection of morphine 1.0 mg. Eighty-five percent (11 patients) experienced acceptable or good pain relief. Analgesia set in 15-45 min after injection and reached a maximum after 15-120 min and lasted until delivery. Eighty-five percent (11 patients) of the patients developed mild side-effects i.e., pruritus, nausea and emesis. The intrathecal injection of morphine did not adversely affect the condition of the infant. Venous blood samples from the patients and umbilical cords for estimation of plasma morphine showed extremely low concentrations. No patients experienced any discomfort during the injection of morphine. These results indicate that morphine 1.0 mg administered intrathecally decreases labour pains to an acceptable level.

Anesthesia, Obstetrical↗
PubMed1987

Abnormal development of the axial length of aphakic monkey eyes.

Neonatal cataract surgery is becoming more common because irreversible amblyopia occurs if an eye receives inadequate inputs during an early sensitive period of visual development. To model conditions for treating congenital monocular cataracts in humans, we have reared rhesus monkeys which underwent unilateral lensectomy as neonates. Post-surgical A-scan ultrasonography at 8-26 months revealed that the axial length of the aphakic eye in these monkeys was shorter when compared to that of the unoperated eye. This finding has important implications for the long-term clinical management of lensectomized infants in order to achieve good vision in the aphakic eye.

Animals↗
PubMed1986

Indirect monitoring and analysis of truncal stress over extended time periods.

Low back pain is a common ailment encountered in clinical practice, yet there has hitherto been no completely satisfactory method for the measurement of truncal stress, which is a major factor in low back pain. Truncal stress has been difficult to record during the course of a working day because subjects were constrained by trailing cables attached to the monitoring equipment. We have used a pressure sensitive transmitter (radio pill) to record intra-abdominal pressure, which has been shown previously to be an indirect measure of truncal stress. The system makes possible multichannel recordings on magnetic tape throughout the working day by using a portable, battery powered recorder strapped to the subject's waist. A novel ferrite rod contributes materially to minimizing artefacts due to signal loss. The recorded data are replayed, at 60 times real time, into a microcomputer programmed to analyse this data.

Abdomen↗
PubMed1986

Extended-wear contact lens correction of aphakia in infant primates. Corneal studies.

Extended-wear contact lenses (EWCL) are being used increasingly for the correction of aphakia in infants, but there is a lack of data documenting their effects on the corneas of young children. Therefore, corneal studies were performed on infant monkeys wearing EWCL for the correction of surgical aphakia. Nine newborn monkeys underwent unilateral lensectomy and anterior vitrectomy. Seven eyes were fitted with aphakic EWCL postoperatively and two wore no lenses. After at least six months, corneas were studied with slit-lamp and specular microscopy, and with light microscopy (LM) and electron microscopy (EM). Small central corneal opacities developed in two aphakic eyes corrected with EWCL after episodes of keratoconjunctivitis. One of these corneas was found to have a mildly increased coefficient of variation (CV) of endothelial cell size (polymegathism). Although EWCL are well tolerated by the corneas of aphakic infant primates, their association with endothelial polymegathism, which may indicate physiologic compromise, mandates careful long-term follow-up.

Animals↗
PubMed1986

Liver trauma.

A series of 97 patients has been studied who were treated for liver injury at Westmead Hospital between January 1979 and January 1985. Patients were noted to be younger than those reported in previous series from Sydney, and to have suffered more frequent, significant, head injuries. Paramedical roadside intervention probably allowed more patients to reach hospital alive than was the case before the advent of the Intensive Care Ambulance system. Improved organ imaging has allowed more confident non-operative management of 13% of patients. Hepatic resection has been used infrequently (10%). Packing has been used in six patients as part of the definitive treatment of severe injuries and coagulopathy, and to allow the transfer of a further seven patients from peripheral hospitals. Ten of these 13 patients survived. Head injury continues to be a major cause of death in these patients. Death from the liver injury itself is usually associated with high grade damage to the liver and the associated hepatic veins and vena cava. It is speculated that improvement in the management of these lethal injuries will come about only from the early identification of patients likely to have suffered such trauma, and the pre-operative control of bleeding. Balloon catheter placement under radiological control, to tamponade the inferior vena cava and abdominal aorta, is suggested as one means by which this goal might be achieved.

Adolescent↗
PubMed1984

Subarachnoid anaesthesia with 0.5% bupivacaine: effects of density.

The effects of subarachnoid administration of 0.5% bupivacaine 4 ml in 8%, 5% or 0% glucose were investigated in a double-blind study in 30 women undergoing laparotomy through a lower abdominal incision. The onset time for maximum segmental spread of analgesia was 10-15 min for all solutions. Cephalad segmental spread of analgesia was three to four segments higher with the hyperbaric solutions (T4-5 v. T7-8). Time of onset of complete motor blockade of the lower limbs was 5-10 min for all solutions. The glucose-free solution did not produce sufficient surgical anaesthesia because of too low cephalad spread. Duration of motor blockade generally decreased with increasing glucose concentration, only the hyperbaric solutions providing useful for abdominal surgery, with a duration of 1-1.5 h. Anaesthesia (halothane) was required in seven of 10 patients in the glucose-free group and in five of 20 in the hyperbaric groups. No occurrence of "post-spinal headache" was recorded in the study.

Adult↗
PubMed1983

[Double heterozygote hemoglobin D/B0 thalassemia. Report of 3 cases in a Portuguese family].

The first Portuguese cases of a combination of Hb D and B0 thalassaemia are reported. The structure of the Hb variant was identified as Hb D Los Angeles, Punjab, Chicago, Portugal. The cases reported belong to one family living in the south of the country: a woman and her two sons. Twice, in two different generations, women with a Hb D gene, married men with B0 thalassaemia trait. The hypochromic and microcytic red cell morphology in the propositi have been the first abnormalities for subsequent investigations.

Adult↗