Showing papers by "University of São Paulo published in 1994"

Ethopharmacological analysis of rat behavior on the elevated plus-maze

Abstract: Behavioral categories were measured in rats left on an elevated plus-maze for 5 min, in addition to the traditional measures. Four independent factors emerged from a factor analysis. The variables that loaded highly and positively on Factor 1, seemingly related with anxiety, were: number of entries onto open arms, time spent on open arms, percentage of open/total arm entries, percentage of time on open arms, scanning over the edge of an open arm, and open arm end-exploring. The time spent on enclosed arms loaded highly, but negatively on the same factor. Risk-assessment from an enclosed arm also loaded negatively on Factor 1. Number of enclosed arm entries, total number of arm entries and rearing loaded highly on Factor 2, probably related to motor activity. However, the total number of entries also loaded on Factor 1, being thus a mixed index. Similarly, the number of open arm entries loaded on both Factors 1 and 2. As expected, the variables having high loads on Factor 1 were changed to one direction by administration of two anxiolytics (nitrazepam and midazolam) and to the opposite direction by two anxiogenic drugs (pentylenetetrazol and FG 7142). Such pattern of drug effects was not observed with the remaining variables.

Male pseudohermaphroditism caused by mutations of testicular 17β-hydroxysteroid dehydrogenase 3

Abstract: Defects in the conversion of androstenedione to testosterone in the fetal testes by the enzyme 17β–hydroxysteroid dehydrogenase (17β–HSD) give rise to genetic males with female external genitalia. We have used expression cloning to isolate cDNAs encoding a microsomal 17β–HSD type 3 isozyme that shares 23% sequence identity with other 1 7β–HSD enzymes, uses NADPH as a cofactor, and is expressed predominantly in the testes. The 17βHSD3 gene on chromosome 9q22 contains 11 exons. Four substitution and two splice junction mutations were identified in the 17βHSD3 genes of five unrelated male pseudohermaphrodites. The substitution mutations severely compromised the activity of the 17β–HSD type 3 isozyme.

Sequence and structure of VH domain from naturally occurring camel heavy chain immunoglobulins lacking light chains

Abstract: We cloned 17 different PCR fragments encoding VH genes of camel (Camelus dromedarius). These clones were derived from the camel heavy chain immunoglobulins lacking the light chain counterpart of normal immunoglobulins. Insight into the camel VH sequences and structure may help the development of single domain antibodies. The most remarkable difference in the camel VH, consistent with the absence of the VL interaction, is the substitution of the conserved Leu45 by an Arg or Cys. Another noteworthy substitution is the Leu11 to Ser. This amino acid normally interacts with the CH1 domain, a domain missing in the camel heavy chain immunoglobulins. The nature of these substitutions agrees with the increased solubility behavior of an isolated camel VH domain. The VH domains of the camels are also characterized by a long CDR3, possibly compensating for the absence of the VL contacts with the antigen. The CDR3 lacks the salt bridge between Arg94 and Asp101. However, the frequent occurrence of additional Cys residues in both the CDR1 and CDR3 might lead to the formation of a second internal disulfide bridge, thereby stabilizing the CDR structure as in the DAW antibody. Within CDRs of the camel VH domains we observe a broad size distribution and a different amino acid pattern compared with the mouse or human VH. Therefore the camel hypervariable regions might adopt structures which differ substantially from the known canonical structures, thereby increasing the repertoire of the camel antigen binding sites within a VH.

Point mutation within the tyrosine kinase domain of the RET proto-oncogene in multiple endocrine neoplasia type 2B and related sporadic tumours

Abstract: The susceptibility loci for the three multiple endocrine neoplasia (MEN) type 2 syndromes have been mapped to the region of chromosome 10q11.2 containing the RET proto-oncogene, which codes for a receptor tyrosine kinase. The majority of MEN 2A and familial medullary thyroid carcinoma results from missense mutations within one of five cysteine codons in the extracellular domain of the RET proto-oncogene. We now report a missense mutation, resulting in the substitution of a threonine for a methionine at codon 918 in the tyrosine kinase catalytic domain, in the germline of 26 of 28 apparently distinct families with MEN 2B. DNA from five of 13 apparently sporadic MTC and one of 12 apparently sporadic phaeochromocytomas harboured a similar mutation, but the corresponding germline DNA was wildtype in each case.

High melatonin solubility in aqueous medium.

Abstract: The pineal hormone melatonin (5-methoxy-N-acetyl-tryptamine) has been reported to participate in important physiological processes. Although some of its biological actions seem to depend on a protein receptor at the membrane surface, melatonin is known to interact with a large variety of tissues and cells, suggesting that the molecule may not necessarily interact through a specific membrane receptor at a specific cell. Most discussions of melatonin activity have assumed that the molecule is highly hydrophobic. Contrary to belief, the present work shows that melatonin is soluble in a purely aqueous medium up to 5 x 10(-3) M and describes a new method of melatonin preparation which shows the high hydrophilicity of the molecule. The results presented will affect the current biological hypothesis on the need of a melatonin carrier in the blood stream or the mechanisms which allow the hormone to cross the cell membrane and interact at the level of the nucleus.

Human papillomavirus and invasive cervical cancer in Brazil

Abstract: A hospital-based case-control study was undertaken to examine the role of human papillomavirus (HPV) in the development of invasive cervical cancer in Brazil. The study included 199 histologically confirmed incident cases and 225 age-frequency-matched controls selected from a wide range of diagnostic categories. A polymerase chain reaction technique was used to detect HPV DNA in cervical specimens collected with spatula and brush. HPV DNA was detected in 84% of the cases compared with 17% of controls. Grouping HPV types 16, 18, 31 and 33, 66% of the cases were positive compared with only 6% of the controls. In addition to HPV, number of sexual partners, early age at first intercourse, parity and duration of oral contraceptive use were significantly associated with an increased risk of cervical cancer. A history of previous Papanicolaou smears was significantly associated with a decreased risk. After adjustment, only presence of HPV DNA, parity and history of previous smears remained as independent risk factors. The adjusted odds ratios of cervical cancer associated with HPV 16, 18, 31, and 33 was 69.7 (95% confidence interval 28.7-169.6) and with unidentified types was 12.0 (5.1-28.5). The very high risks found in this study further implicate this virus in the aetiology of cervical cancer.

The elevated T-maze: a new animal model of anxiety and memory.

Abstract: In an attempt to analyze different types of anxiety, and at the same time assess memory, a new experimental model was developed. The apparatus, named the elevated T-maze, consisted of three arms of equal dimensions (50 × 10 cm) elevated 50 cm from the ground. One arm, enclosed by 40-cm high walls, was perpendicular to two open arms. The first experimental session was conducted 25 min after IP injection of either drug or saline. To assess inhibitory (passive) avoidance, the rat was placed at the end of the enclosed arm and the time taken to withdraw from this arm was recorded three times in succession. Soon afterwards, the rat was placed at the end of one of the open arms and the time taken to withdraw from this arm was measured, thus estimating one-way escape. To assess memory, inhibitory avoidance and escape were measured again 3 days later, without drug. Dose-response curves were determined for the benzodiazepine anxiolytic and amnestic agent diazepam (DZP, 0.5–4 mg/kg), as well as for ipsapirone (IPS, 0.25–2 mg/kg), an azapirone anxiolytic that is devoid of clinically significant amnestic effects. The doses of 1, 2, and 4 mg/kg DZP and of 1 and 2 mg/kg IPS impaired inhibitory avoidance, an effect that may be viewed as anxiolytic. Inhibitory avoidance remained impaired 3 days later in the rats treated with 1–4 mg/kg DZP, indicating anterograde amnesia. This effect was not due to state-dependent learning, because rats injected both at pretraining and pretesting with 2 mg/kg DZP still showed complete amnesia. In contrast, the doses of 1 and 2 mg/kg IPS did not significantly affect memory, indicating a dissociation between the drug effects on anxiety and memory. Neither the performance of escape nor its memory was affected by DZP or IPS. Therefore, the two aversive tasks studied are likely to generate distinct types of fear/anxiety and memory, which may correlate with different classes of psychiatric disorders. The present results also warrant further exploration of the elevated T-maze as a potential model for the combined study of anxiety and memory.

Linear minimum mean square error estimation for discrete-time Markovian jump linear systems

Abstract: The linear minimum mean square error estimator (LMMSE) for discrete-time linear systems subject to abrupt changes in the parameters modeled by a Markov chain /spl theta/(k)/spl epsiv/{1...,N} is considered. The filter equations are derived from geometric arguments in a recursive form, resulting in an on-line algorithm suitable for computer implementation. The author's approach is based on estimating x(k)1/sub {/spl theta/(k/=i}) instead of estimating directly x(k). The uncertainty introduced by the Markovian jumps increases the dimension of the filter to N(n+1), where n is the dimension of the state variable. An example where the dimension of the filter can be reduced to n is presented, as well as a numerical comparison with the IMM filter. >

Vascular free radical release. Ex vivo and in vivo evidence for a flow-dependent endothelial mechanism.

Abstract: Mechanisms underlying production of vascular free radicals are unclear. We hypothesized that changes in blood flow might serve as a physiological stimulus for endothelial free radical release. Intact isolated aortas from 45 rabbits were perfused with the spin trap alpha-phenyl-N-tert-butylnitrone (PBN, 20 mmol/L) and formed radical adducts detected by electron paramagnetic resonance spectroscopy (EPR). Sequential perfusion at 2, 7.5, and 12 mL/min changed cumulative vascular PBN radical adduct yields, respectively, from 3.2 +/- 0.9 to 4.1 +/- 0.7 (P < .05) and 7.0 +/- 1.5 (P < .005) pmol/mg with endothelium and from 3.6 +/- 1.6 to 3.8 +/- 1.4 and 2.2 +/- 0.8 pmol/mg without endothelium (P = NS). In endothelialized aortas, superoxide dismutase (SOD) completely blocked flow-induced free radical production, whereas inactivated SOD, indomethacin, and the nitric oxide synthetase antagonist nitro-L-arginine methyl ester (L-NAME) had no effect; relaxations to acetylcholine remained unchanged with higher flows. To assess the role of flow on in vivo radical production, femoral arterial plasma levels of the ascorbyl radical, a stable ascorbate oxidation product, were measured by direct EPR in 56 other rabbits. Ascorbyl levels were assessed at baseline (30.2 +/- 0.7 nmol/L) and at peak-induced iliac flow changes. Flow increases from 25% to 100% due to saline injections through an extracorporeal aortic loop induced significant dose-dependent increases in ascorbyl levels (n = 5). In addition, after papaverine bolus injections, flow increased by 114 +/- 8% versus baseline, and ascorbyl levels increased by 5.4 +/- 0.7 nmol/L (n = 31, P < .001); similar results occurred with adenosine, isoproterenol, or hyperemia after 30-second occlusions (P < .05, n = 4 or 5 in each group). Active SOD completely blocked papaverine-induced ascorbyl radical increase, despite preserved flow response (delta ascorbyl = 0.02 +/- 1.6 nmol/L, P = NS); inactivated SOD, catalase, indomethacin, and L-NAME had no effect. Blood flow decreases of 65% to 100% due to phenylephrine or 60-second balloon occlusions were accompanied by an average decrease of 4.4 nmol/L (P < .05) in ascorbyl levels. No change in ascorbyl signal was observed when rabbit blood alone was submitted to in vitro flow increases through a tubing circuit. Thus, increases in blood flow trigger vascular free radical generation; such a response seems to involve endothelium-derived superoxide radicals unrelated to cyclooxygenase or nitric oxide synthetase activities. This mechanism may contribute to explain vascular free radical generation in physiological or pathological circumstances.

Inhaled nitric oxide leading to pulmonary edema in stable severe heart failure.

Abstract: The mechanism of increased pulmonary wedge pressure and cardiac output after nitric oxide inhalation is not clear. Nitric oxide is rapidly inactivated by hemoglobin before it can produce systemic effects. 3 Thus, selective nitric oxide pulmonary vasodilator effects led to these preliminary results. The hypothesis is that acute reduction in right ventricular afterload caused an acute increment of right ventricular cardiac output. The acute increment of blood return to the impaired left ventricle not associated with reduction in afterload caused the increase in wedge pressure and consequently pulmonary edema. In addition, acute reduction in right ventricular afterload could lead to redistribution of blood volume to pulmonary circulation. The absence of pulmonary edema in these patients in the nitroprusside study reinforces the importance of selective nitric oxide effects in pulmonary circulation.

Survival and predictors of survival in patients with congestive heart failure due to Chagas' cardiomyopathy.

Abstract: BACKGROUNDThe fundamental determinant of the natural history of Chagas' disease is cardiac involvementMETHODS AND RESULTSWe studied 104 male patients with congestive heart failure due to Chagas' disease to estimate the survival distribution function and to evaluate age, functional class (FC), maximal oxygen consumption (VO2max), and ejection fraction (EF) as predictors of survival Statistical evaluation was performed through univariate (Student's t test and chi 2 test) and multivariate analyses (Cox's regression model) Overall survival was 66% at 1 year, 56% at 3 years, and 48% at 5 years Ages were not statistically different (P = 9811) between survivor (403 +/- 87) and nonsurvivor (403 +/- 94) groups The ejection fraction(s) were statistically different (P = 0001) between survival (436 +/- 99) and nonsurvival (306 +/- 81) groups, as was VO2max (P = 0001) (210 +/- 47 and 150 +/- 49, respectively) Most of the surviving patients were in FC II and most of the nonsurvivors were in FC IV (

Mudanças no padrão de alimentação da população urbana brasileira (1962-1988)

Abstract: Contemporary changes in food consumption patterns in urban areas of Brazil are described. The main data sources are two national food expenditure surveys undertaken in the early 60's and late 80's (1961-62 and 1987-88) and one national food intake survey undertaken in the mid-70' s (1974-75). The analysis is restricted to the seven metropolitan areas represented in the three surveys. Food patterns are described on the basis of the relative consumption of different food groups, proportion of energy from carbohydrates, protein and lipids, proportion of animal and vegetable protein and fats, proportion of complex and simple carbohydrates, ratio between poly-unsaturated and saturated fatty acids and relative consumption of cholesterol. Main food changes were similar in the Northeastern and Southeastern cities and involved: 1) reduction in the relative consumption of cereals, beans, roots and tubercles; 2) replacement of lard, bacon and butter by vegetable oils and margarine: and 3) increase in the relative consumption of eggs, milk and dairy products. As a net result of these changes there was, simultaneously, a decrease in the carbohydrate content of the Brazilian diet and an increase in its fat content. Total protein content of the diet remained at around 12% in the three surveys but animal protein increased. Changes in the fat content of the diet involved an increased proportion of vegetable fat, an increased ratio of poly-unsaturated/saturated fatty acids and a reduction in cholesterol intake. Health implications of dietary changes are discussed based on the World Health Organization's dietary guidelines.

Footprint analysis during the growth period.

Abstract: Static footprints were obtained from 672 healthy white subjects ranging in age from newborn to 15 years. The length of the footprint was measured and the medial longitudinal arch was evaluated. The findings showed that the feet grew most rapidly up to 3 years of age. From age 3 onward, the feet maintained an almost constant growth rate, which was the same for both sexes until age 12 years, when girls' feet stopped growing, but boys' feet exhibited further growth. From birth up to 2 years of age, there was a higher incidence of flat feet. Rapid progression of plantar arch development was observed between 2 and 6 years of age.

Testes neuropsicológicos de aplicação simples para o diagnóstico de demência

Abstract: Thirty patients with dementia defined by DSM-III-R criteria (Alzheimer's disease (22), vascular dementia (3), Parkinson's disease, frontal lobe dementia, possible diffuse Lewy body dementia, normal pressure hydrocephalus and uncertain diagnosis), with scores below 24 points in the Mini-Mental Status Examination and more than 4 years of education were submitted to a neuropsychological evaluation. The scores in the neuropsychological tests were compared to those obtained by thirty normal volunteers paired for age, sex and education. Sensivity, specificity and accuracy of the tests in the distinction of demented and normal volunteers were determined. The accuracies were calculated using ROC curves. Blessed's information-memory-concentration test showed greatest accuracy, followed by copy of simple figures, delayed memory of 10 figures (after 5 minutes), recognition of 10 figures and verbal fluency test (animals). A linear discriminant function, composed by 6 tests: visual perception, incidental memory, delayed memory (after 5 minutes), drawing of a clock, verbal fluency (animals) and calculation tests, was able to discriminate all controls from patients and only one patient was wrongly classified as normal control. These tests were chosen because they can be applied in less than 10 minutes and are very easy to interpret. This discriminant function must be applied in another group of patients and controls in order to demonstrate its value. When associated to the MMSE it may be useful to discriminate patients with dementia from normal people in epidemiological studies.

Natural mutagenesis study of the human steroid 5α-reductase 2 isozyme

Abstract: The enzyme steroid 5 alpha-reductase utilizes NADPH to reduce the double bonds of a variety of steroid substrates with generalized 3-oxo, delta 4,5 structures. One substrate for this membrane-bound enzyme is testosterone, whose reduction to dihydrotestosterone is required for the embryonic differentiation of the external male genitalia and prostate. There are two 5 alpha-reductase isozymes, designated types 1 and 2, which have different biochemical and pharmacological properties. Inherited deficiencies of 5 alpha-reductase type 2 result in a form of male pseudohermaphroditism in which the external genitalia fail to develop normally. Here, nine additional mutations in the 5 alpha-reductase 2 gene in subjects with 5 alpha-reductase deficiency are described. The biochemical consequences of these mutations, as well as 13 previously identified missense mutations, were characterized by recreating the mutations in an expressible cDNA and transfecting into mammalian cells. Twelve of the 22 mutations inactivated the enzyme. The remaining 10 mutations impaired enzyme function by affecting either substrate or cofactor binding. Almost all mutations decreased the half-life of the protein, and all but one of the impaired enzymes had an altered pH optimum. The mutations provide insight into functional domains in the protein as well as an unusual acidic pH optimum characteristic of the 5 alpha-reductase type 2 isozyme.

Stochastic lattice gas model for a predator-prey system.

Abstract: We propose a stochastic lattice gas model to describe the dynamics of two animal species populations, one being a predator and the other a prey. This model comprehends the mechanisms of the Lotka-Volterra model. Our analysis was performed by using a dynamical mean-field approximation and computer simulations. Our results show that the system exhibits an oscillatory behavior of the population densities of prey and predators. For the sets of parameters used in our computer simulations, these oscillations occur at a local level. Mean-field results predict synchronized collective oscillations.

Severe and fatal mass attacks by 'killer' bees (Africanized honey bees--Apis mellifera scutellata) in Brazil: clinicopathological studies with measurement of serum venom concentrations.

Abstract: In Sao Paulo State, Brazil, five males, aged between 8 and 64 years, were attacked by 'Africanized' honey bees (Apis mellifera scutellata). The estimated number of stings received by each patient ranged from > 200 to > 1000. All five were transferred to intensive care units in Sao Paulo City. Clinical features included intravascular haemolysis, respiratory distress with ARDS, hepatic dysfunction, rhabdomyolysis (with myoglobinaemia and myoglobinuria), hypertension and myocardial damage (perhaps explained by release of endogenous catecholamines by venom phospholipase A2 and mellitin), shock, coma, acute renal failure and bleeding. Laboratory findings included gross neutrophil leucocytosis, elevated serum enzymes [AST, ALT, LDH, CPK (predominantly CPK-MM)] and creatinine. Clotting times were slightly prolonged. Despite treatment with antihistamines, corticosteroids, bronchodilators, vasodilators, bicarbonate, mannitol and mechanical ventilation, three of the patients died between 22 and 71 h after the attacks, with histopathological features of ARDS, hepatocellular necrosis, acute tubular necrosis, focal subendocardial necrosis and disseminated intravascular coagulation. Whole bee venom and phospholipase A2 (PLA2) antigen concentrations were measured in serum and urine for the first time, using enzyme immunoassay. High venom and PLA2 concentrations were detected in serum and urine for more than 50 h after the stings in two fatal cases, in one of which the total circulating unbound whole venom was estimated at 27 mg, one hour after the attack. An antivenom should be developed to treat the increasing numbers of victims of mass attacks by Africanized 'killer' bees in USA, Middle and South America.

Net nitrogen mineralization and net nitrification along a tropical forest-to-pasture chronosequence

Abstract: Soil inorganic nitrogen pools, net mineralization and net nitrification rates were compared during the dry season along a chronosequence of upland (terra firme) forest, 3-, 9- and 20-year-old pastures in the western Brazilian Amazon Basin state of Rondonia to investigate the influence of forest conversion to pasture on soil nitrogen cycles. Surface soil (0 to 10 cm) from forest had larger extractable inorganic nitrogen pools than pasture soils. In the forest, NO 3 − pools equaled or exceeded NH 4 + pools, while pasture inorganic N pools consisted almost exclusively of NH 4 + . Rates of net N mineralization and net nitrification in seven -day laboratory incubations were higher in the seven - day forest than in the pastures. Net N mineralization rates did not differ significantly among different-aged pastures, but net nitrification rates were significantly lower in the 20-year-old pasture. Higher net N mineralization and net nitrification rates were measured in laboratory and in situ incubations of sieved soil, compared with in situ incubations of intact soil cores. Rates calculated in seven-day incubations were higher than determined by longer incubations. Sieving may increase N mineralization and/or decrease N immobilization compared with intact cores. We concluded that 7-day laboratory incubation of sieved soil was the most useful index for comparing N availability across the chronosequence of forest and pasture sites. High net nitrification rates in forest soils suggest a potential for NO 3 − losses either through leaching or gaseous emissions.

Tellurium in Organic Synthesis

Abstract: This chapter focuses on the application of tellurium (Te) compounds as reducing reagents of organic substrates Inorganic species—such as hydrogen telluride, sodium hydrogen telluride, sodium telluride—and organic derivatives—such as aryltellurols (and tellurolates) and diorganyl tellurides—are widely employed in several reduction processes—such as reduction of carbonyl compounds, nitro derivatives, epoxides, aryl alkenes, and arylalkynes—as well as in the reductive cleavage of several types of carbon–heteroatom bonds In several cases, the use of Te reagents is clearly advantageous compared to the usual methods because of the mildness of the experimental conditions and the great selectivity The first reported radical reaction promoted by Te reagent was probably the conversion of allylic halides into coupled 1,5-dienes by treatment with telluride anions The reaction, which gives the best results when employing the reagent prepared in situ from elemental Te and lithium triethylborohydride, proceeds through the intermediacy of the thermally unstable bis-allylic telluride, followed by the extrusion of Te and coupling of the formed allylic radicals Additional advantages are the possibility of generating the reducing agents in situ as well in catalytic amounts in the presence of an inexpensive coreductant and the recovery of the Te material