On the mechanism of thyroid hormone-induced respiratory burst activity in rat polymorphonuclear leukocytes

Administration of single doses of 0.1 mg L-triiodothyronine (T3)/kg for 3 consecutive days to fed rats produced a drastic increase in the respiratory burst activity of isolated polymorphonuclear leukocytes (PMN), stimulated with serum-opsonized zymosan. This effect was evidenced by the 3.8-fold increment in the integrated chemiluminescence, and seems to be primarily related to the enhanced activity of NADPH oxidase elicited by T3 treatment, with the observed higher myeloperoxidase activity playing a contributory role. In these conditions, hyperthyroidism determines a net enhancement in the oxidant capacity of PMN, as the increased rate of O2.- generation found occurs in the absence of changes in the activity of superoxide dismutase.

[Validation of a screening instrument for studying the prevalence of cerebrovascular diseases in the Chilean population]

We assessed a screening instrument, adapted from a model suggested by WHO, aimed to perform population studies on the prevalence of cerebrovascular disease in Chile. Sixty-two subjects, 31 with cerebrovascular diseases and 31 without, were asked about symptoms and requested to do simple movements by trained interviewers. The results of the instrument were compared with a neurological examination performed by two specialists. Global sensitivity and specificity of the instrument, using WHO evaluation criteria, were 100 and 38.7% respectively. When three or more symptoms and one positive sign were considered as cutoff points, global specificity increased to 61% and sensitivity decreased to 93%. It is concluded that the present instrument is highly sensitive but lacks specificity.

Effect of thyroid hormone administration on the depletion of circulating glutathione in the isolated perfused rat liver and its relationship to basolateral gamma-glutamyltransferase activity

The influence of thyroid hormone administration on liver glutathione (GSH) extraction in the isolated perfused liver was studied in fed rats for a period of 1-7 days following a single dose of 0.1 mg 3,5,3'-triiodothyronine (T3)/kg. T3 treatment led to an early and transient calorigenic response, as well as an enhancement in liver GSH removal, reaching a maximal effect at 2 days after hormone administration, which was normalized in the 3- to 7-day period studied. Addition of the gamma-glutamyltransferase (gamma-GT) inhibitor DL-serineborate (4 mM) to the perfusate abolished the increase in the hepatic removal of GSH elicited by T3, and enhanced the sinusoidal concentration of GSH, studied at 2 days after hormone administration. These data support the role of hepatic basolateral gamma-GT ectoactivity in the depletion of portally added and liver-derived GSH as an adaptive response to recover GSH levels after reduction by T3-induced oxidative stress.

Parity and the prevalence of overweight

OBJECTIVE

To assess the association between previous term pregnancies and the prevalence of overweight in a group of urban women, controlling for the influence of age.

METHODS

One thousand twelve women, living in middle and low socioeconomic areas of Mexico City, were interviewed at home and their reproductive histories studied. Height and weight were measured in a clinical setting using controlled procedures. Overweight (BMI > 25) was the dependent variable used to calculate odds ratios and to perform a multiple logistic regression analysis.

RESULTS

Age and parity were significantly associated with the prevalence of overweight. Controlling for age, two or more previous pregnancies significantly increased the magnitude of the association.

CONCLUSION

During the reproductive years parity seems to increase the risk of overweight in low and middle socioeconomic level urban women.

Thyroid calorigenesis and oxidative stress: modification of the respiratory burst activity in polymorphonuclear leukocytes

1. Recent research on experimental animals indicates that thyroid hormone administration is associated with greater electron flow through the microsomal, mitochondrial, and peroxisomal electron transport systems of the liver, as indicated by the enhanced production of superoxide radicals (O2.-) and/or hydrogen peroxide (H2O2). 2. Hyperthyroidism induces an increased respiratory burst activity in rat and human polymorphonuclear leukocytes, an effect that seems to be related to changes in the myeloperoxidase-H2O2 system of the cell, rather than to the direct actions of the hormone or changes in the opsonic capacity of plasma. 3. These findings indicate that thyroid calorigenesis involves an elevated prooxidant activity in target cells, which may be relevant in determining toxic effects within the tissue or in neighboring cells.

[Dissection of vertebral artery: report of a case and review of the literature]

Vertebral artery dissection seems to be a frequent cause of stroke in young adults. We report a 34 years old female that suffered a cardiac arrest while practicing aerobics, with complete recovery and four months later developed an acute Wallenberg's syndrome. Magnetic resonance imaging showed an infarction in the right posterolateral medulla oblongata and in the right cerebellar hemisphere. Angiography revealed an occlusion of the third segment (V3) of the right vertebral artery which was hypoplastic. The patient was anticoagulated with a favorable clinical outcome. A follow up angiography, performed six months later, showed an incomplete recanalization of the vessel. Vertebral artery dissection should be suspected in every patient with ischemic symptoms or signs related to the vertebrobasilar territory, specially in young or middle aged patients with a history of trauma. Magnetic resonance imaging and ultrasound-doppler examinations are the diagnostic test of choice.

[Anuria secondary to perianeurysmal fibrosis]

Presentation of one case of obstructive anuria secondary to perianeurysmal retroperitoneal fibrosis (PRF). Diagnosis was confirmed by abdominal ultrasound and CAT. The condition's initial treatment consisted in bilateral percutaneous nephrostomy. Following clinical stabilization of the patient, surgical resection of aorta aneurysm and ureterolysis with bilateral intraperitonealization was performed. A revision of the specific literature revealed 17 cases similar to ours. Clinical, diagnostic, and pathophysiologic aspects as well as recommended therapeutical procedures are analyzed.

Interhemispheric structural asymmetry induced by a lateralized reaching task in the rat motor cortex

The effects of a lateralized reaching task on the morphological structure of the rat motor cortex were studied during the early postweaning period. Our results show that the consistent use of one forelimb accounts for a significant decrease in the numerical density of cells and an increase in cortical thickness of the contralateral 'forelimb' motor cortex. As a consequence of the early motor training the cell distribution, which is lower rostrally than caudally in nontrained hemispheres, is reversed in the trained hemispheres. This may be interpreted as the specific motor training triggering a higher neuronal branching in the corresponding cortical region. The present findings may further the understanding of the mechanisms involved in the generation of morphological brain asymmetries.

Acquired perforating disease: report of nine cases

BACKGROUND

A study of nine Guatemalan patients with acquired perforating disease associated with chronic renal failure, diagnosed at the Guatemalan Social Security Institute, General Hospital, during the period of January 1990 to March 1993, is presented (Table 1).

METHODS

A dermatological examination and skin biopsy were done on all patients.

RESULTS

Six of the patients were men and three were women; one case was associated with diabetes mellitus. Three of the patients were diagnosed as Kyrle-like acquired perforating disease, and the other six as perforating folliculitis. The lesions were predominantly located in the lower extremities with hyperkeratotic papules and nodules; some of these were accompanied by pruritus and Koebner's phenomenon.

CONCLUSION

The acquired perforating disease is a clinical cutaneous manifestation of chronic renal failure with or without treatment. The lesions can disappear spontaneously with stabilization of the renal damage.

Turnover of hepatic glutathione after acute lindane intoxication

The administration of lindane (60 mg/kg) to fed rats diminished the content of hepatic glutathione (GSH) 4 h after treatment, which was recovered at 24 h. At these experimental times, the activities of glutathione peroxidase, glutathione reductase, glutathione-S-transferases and gamma-glutamyltransferase in the liver of lindane-treated rats and control animals were comparable. Liver GSH turnover, measured after a pulse of [35S]cysteine, was enhanced by 69% (P < 0.05) in lindane-treated rats 24 h after intoxication compared to controls, with a 63% (P < 0.05) increase in the estimated rate of GSH synthesis. It is concluded that lindane enhances GSH synthesis in rat liver 24 h after treatment as a consequence of the decrement in its content observed at early times of intoxication (4 h), thus allowing the recovery of the normal level of hepatic GSH.

3,3',5-triiodothyronine-induced hepatic respiration: effects of desferrioxamine and allopurinol in the isolated perfused rat liver

The effect of daily doses of 0.1 mg 3,3',5-triiodothyronine (T3)/kg for three consecutive days on hepatic O2 uptake was studied in the isolated perfused rat liver, in the absence and presence of the antioxidants desferrioxamine (DFO) and allopurinol (A). T3 treatment elicited a thermogenic condition in the animals, together with a 25% increase of total O2 consumption by the liver, which is inhibited by 0.5 mM DFO or 1 mM A. The antioxidant-sensitive respiration is enhanced by 62-64% by T3 over control values and represents 16-25% of the net increase in O2 uptake elicited by the hormone treatment. The respiratory components suppressed by the antioxidants are suggested to represent O2 equivalents related to T3-induced oxidative stress, and correlate with elevated rates of fractional lactate dehydrogenase efflux from the perfused livers.

Environmental deprivation delays the maturation of motor pyramids during the early postnatal period

The effects of environmental deterioration upon the development of motor cortex was studied in 30 Sprague-Dawley albino rats during lactation (1st-18th postnatal days). The use of Golgi-Cox-Sholl methodology allowed qualitative and particularly quantitative evaluations since impregnation of neurons take place at random without any selectivity. Morphometric studies were assessed by measuring layers II-III pyramidal neurons, basal dendritic branching, under camera lucida. Early environmental impoverishment results in a highly significant decrease in the number and length of peripherical branches and terminal dendrites. These results extend previous observations made predominantly in non-motor cortices which indicate that during early postnatal life restrictions or enrichments of the environment may be associated with quantitative changes in the differentiation of cerebrocortical neurons. It is of upmost importance to consider that the potential effects of different types of epigenetic cues are highly selective since pyramids of pups subjected to mild nutritional manipulation during the same developmental period remained unaffected.

Early life environmental deterioration, nutrition and ontogenesis of the motor cortex in the rat: a Golgi study

Sprague-Dawley albino rats were subjected to an experimental paradigm in which environmental and nutritional variables were studied from birth to day 18. The use of Golgi-Cox-Sholl methodology allowed quantitative evaluations of neurons which were randomly impregnated with metallic mercury after fixation in a mercury salt. The nutritional treatment employed did not significantly influence the cytoplasmatic differentiation of cortical neurons although it was able to induce gross morphological modifications in body weight and size. By contrast, an impoverished surrounding during a limited period of time had a profound effect on the basal dendritic tree. The evidence presented here suggests the importance of the preweaning environment on the development of neural appendages. Motor pyramids of pups housed in deteriorated conditions underwent a progressive decrement in the length and number of peripheral branches and terminal dendrites. A decreased rate of cortical differentiation was also observed in overnourished pups as a result of reducing the litter size. This regressive event, can probably be attributed to social and sensory-motor limitations of the experimental group. However, to confirm this possibility, further research is required.

Influence of hyperthyroidism on superoxide radical and hydrogen peroxide production by rat liver submitochondrial particles

Administration of daily doses of 0.1 mg of 3,5,3'-triiodothyronine (T3)/kg body weight for 3 consecutive days to fed rats elicited a calorigenic response in the animals, in concomitance with a 36% increase in the rate of 0(2) consumption by the liver. In these conditions, liver submitochondrial particles (SMP) from T3-treated rats exhibited marked increases in the rate of superoxide radical generation, both in the presence of NADH (142%) or succinate (152%). Furthermore, liver SMP from hyperthyroid animals released hydrogen peroxide at higher rates than those of euthyroid rats, either under basal conditions or in the succinate-supported process, both in the absence and presence of antimycin-A. It is concluded that the hyperthyroid state in the rat leads to a drastic enhancement in the capacity of liver mitochondria to produce active oxygen species, which correlates with the elevated respiratory rate observed in the intact organ.

Acquired perforating disease associated with chronic renal failure

A 48-year-old man, in a chronic hemodialysis program, had numerous skin lesions develop that consisted of follicular papules and small hyperkeratotic nodules, located on the trunk, hips, and upper and lower extremities (where the lesions were more numerous). The nodules measured 3 to 5 mm and had a dark discoloration (Figs 1 and 2). Four months previously, the patient noticed the appearance of disseminated papular and pruritic lesions. The lesions did not improve with the prescribed local nonspecific treatment. The patient had chronic renal failure during the previous 10 years, secondary to renal vein thrombosis. As a result, he has had periodic hemodialysis for 18 months. The clinical diagnosis of the skin lesion was Kyrle disease, and a skin biopsy was performed on a nodular lesion from the thigh. The histologic sections showed skin with hyperkeratosis, an invagination of the epithelium filled with keratin and amorphous material. In some sections, the invagination appeared to be a cyst, which in serial sections, showed partial rupture of the lateral wall. No evidence of hair was found inside the invagination.

Effects of hyperthyroidism on rat liver glutathione metabolism: related enzymes' activities, efflux, and turnover

The effect of hyperthyroidism on liver glutathione (GSH) metabolism was studied in fed rats after the administration of 0.1 mg T3/kg body wt, for 1-3 consecutive days. T3-calorigenesis resulted in elevated rates of O2 consumption by the liver, together with higher lipid peroxidative processes and GSH depletion, compared to the euthyroid state. The study of the enzymes related to GSH metabolism revealed no significant changes in the activity of glutathione peroxidase and glutathione reductase, with decreases (27-41%) in the activity of glutathione-S-transferases and marked elevation (133%) in that of gamma-glutamyl transferase, 3 days after T3 treatment. At this experimental time, the activity of the NADPH generating enzyme glucose-6-phosphate dehydrogenase was enhanced by 84% in the liver of T3-treated rats, compared to that in the controls. In these conditions, the canalicular efflux of GSH was not altered by T3, whereas net and fractional rates of sinusoidal GSH efflux were enhanced by 86% and 288%, respectively. The latter effect of hyperthyroidism was found in parallel with an enhancement in sinusoidal lactate dehydrogenase and protein release, suggesting that loss of GSH might be related to a permeabilization of the hepatocyte plasma membrane. Liver GSH turnover assessed after a pulse of [35S]cysteine resulted in a 209% increase in the fractional turnover rate in hyperthyroid rats over controls, under steady state conditions for both hepatic GSH pools, leading to a 62% enhancement in the respective turnover flux. Data suggest that the elevation in the sinusoidal GSH efflux from the liver and in the hepatic capacity to degrade the tripeptide are major mechanisms leading to GSH depletion in the liver of T3-treated rats. As the increased GSH use is not balanced by the elevation in GSH synthesis, a lower steady state level of GSH is attained in the liver.

Effects of preweaning environmental enrichment on basilar dendrites of pyramidal neurons in occipital cortex: a Golgi study

The effects of postnatal environmental stimulation on the branching patterns of cortical dendrites were measured in rats. Pups were exposed to 4 daily multisensory enrichment sessions from days 10-24, while littermates were maintained in standard conditions. At 25 days of age, the brains were stained using the Golgi-Cox-Sholl method. Camera lucida drawings were made of the basilar dendritic trees from a total of 528 layer-III occipital cortex pyramidal neurons. A highly significant increase was found in number and length of segments from order 1-5 in the neurons from the enriched subjects.

Effect of a simultaneous potassium and carbohydrate load on extrarenal K homeostasis in end-stage renal failure

Patients with chronic renal failure (CRF) are continuously exposed to hyperkalemia. In these patients the extrarenal disposal of a potassium load may be very important to determine the plasma potassium levels. We studied the effect of a combined oral load of potassium (0.5 mEq/kg body weight) and carbohydrate (0.5 g/kg body weight) to mimic normal ingestion of potassium. Eight CRF patients and 5 control subjects were studied. The maximal increase in plasma potassium levels achieved was significantly higher in the patients (1.07 +/- 0.1 mEq/l) than in controls (0.39 +/- 0.05 mEq/l). Basal insulin levels were higher in the CRF patients and increased with the oral potassium and carbohydrate load in both controls and patients. In the CRF patients only 58.9 +/- 3% of the potassium load was translocated to the intracellular space compared to 81 +/- 6% in the controls. No correlation was found between the acid base status and maximal potassium increase. We conclude that patients with CRF exhibit an impaired extrarenal handling of potassium and that this abnormality does not appear to be related to insulin secretion or acid base status.

Intracellular signaling transduction in the differentiation of Trypanosoma cruzi: role of cAMP

We have studied the cell differentiation of Trypanosoma cruzi in an vitro system that allows the transformation of epimastigotes into metacyclic trypomastigotes. Intracellular cAMP levels of epimastigotes increased 3 fold prior to their differentiation into metacyclics where cAMP remained elevated 3.7 fold with respect to epimastigotes. We also observed a 3 fold increase in the specific activity of cAMP-binding of metacyclics crude homogenates. This activity resided in a cAMP-binding receptor protein (CARPT) which was different from the typical cAMP-binding subunits (RI and RII) of cAMP-dependent protein kinases, as shown by the use of polyclonal antibodies prepared against these two types of proteins. Anti-RI antibodies did not react with CARPT, and anti-RII antibodies gave a cross reaction with CARPT which was at least 1,000 fold less sensitive than the one shown by the homologous antigen. On Western blots CARPT displayed a major band with Mr = 87,000 instead of Mr = 56,000 for RII. These studies implicate that cAMP may act as a mediator of the cell differentiation of T. cruzi by a mechanism involving a novel type of cAMP-binding receptor.

Cyclic AMP as an inducer of the cell differentiation of Trypanosoma cruzi

The addition to epimastigotes cultures of T. cruzi, of either cAMP, monobutyryl-cAMP, dibutyryl-cAMP, 8-Br-cAMP (at 2 mM each), or the cAMP-phosphodiesterase inhibitor, papaverine (0.2 mM), promoted the in vitro differentiation of these parasite forms into metacyclics. This effect of cAMP may also be exerted in vivo in the insect vector, since cAMP was detected in the urine and in the Malpighi secretion fluids of Rodnius prolixus.

Biochemical aspects of cellular oxidative stress

Oxidative stress, as proposed by H. Sies, indicates a change in the prooxidant/antioxidant balance of a biologic system in favour of the former. It is related to oxidative reactions that occur in aerobic metabolism which can damage biomolecules through generation of reactive oxygen species. The oxidative deterioration of polyunsaturated fatty acids of membrane phospholipids (lipid peroxidation) is one of the consequences of oxidative stress, and has been observed in the liver cell under the influence of ethanol or lindane intoxication, associated with the calorigenic action of thyroid hormones, induced by the rupture of t-butyl hydroperoxide by cellular hemoproteins, or in the autoxidation of a disrupted tissue. Apart from noxious challenges, oxidative free-radical processes are important in numerous physiological reactions, such as NADPH oxidase in the function of macrophages, ribonucleotide reduction in DNA metabolism, or in eicosanoids production.

Gradients of histogenesis in the ependymal lining of the third ventricle in the rabbit

Tritiated thymidine autoradiography was used to analyze the site, time of origin, and developmental gradients of the specialized lining of the ependymal surface of the third ventricle. Cells destined to form the ependyma are generated between days 15 and 22 of embryogenesis (gestation: 30 +/- 2 days), the majority of the cells undergoing final division on the 18th day of gestation. Ependymal cells originate in an orderly fashion according to 3 gradients. Two gradients of opposite direction (ventrodorsal and dorsoventral) are found in the parasaggital plane. Both gradients start at the level of the hypothalamic sulcus, progressively departing from this anatomical landmark as histogenesis progresses. A third gradient occurs in the caudorostral axis, such that cells located in caudal regions originate earlier than those located in rostral sectors. Thus, an orderly relationship exists between the time of origin of ependymal cells and their final location within the lining of the ventricular wall. These findings indicate, once again, the topographic nature of the gradients of histogenesis. The histogenic gradients displayed by the ependymal lining of the third ventricle appear strongly related to those exhibited by other diencephalic derivatives. The latter suggests that common factors govern the developmental sequence of all diencephalic derivatives as a function of their relative topographic location, independently of their functional role in the adult.