Catecholamines in paraganglia associated with the hepatic branch of the vagus nerve: effects of 6-hydroxydopamine and reserpine

Paraganglia are clusters of cells containing catecholamines (CA), mainly norepinephrine (NE) and dopamine (DA). The presence of epinephrine (E), on the other hand, has only been determined by indirect methods in retroperitoneal paraganglia of newborn and aged rats. Because their location, paraganglia associated with the hepatic branch of the vagus nerve may be a possible source of CA for the liver. The main purposes of the present study were to determine CA levels and whether E can be found in the omentum minus which includes paraganglia associated with the hepatic branch of the vagus nerve, and then to study the effects of 6-hydroxydopamine and reserpine on their CA content. Twenty-four female Wistar rats were randomly ascribed to three groups receiving two intraperitoneal injections of either 6-hydroxydopamine, reserpine or saline. Twenty-four hours after the last administration the rats were anesthetized and a portion of the omentum minus was obtained. Left adrenal medulla and a liver fragment were also collected as controls. The samples were processed to be analyzed by high performance liquid chromatography and catecholamine histofluorescence. The results confirm previous reports about the presence of considerable amounts of norepinephrine and dopamine in paraganglia. Norepinephrine and dopamine in the omentum like the adrenal medulla were significantly depleted by reserpine but not by 6-hydroxydopamine treatment, suggesting that some other sources in addition to sympathetic terminals are responsible for CA in the omentum. On the contrary, both drugs reduced liver NE, consistent with the localization of this amine mainly to hepatic sympathetic terminals. Histofluorescence of the omentum revealed 2-4 paraganglia per tissue fragment. Paraganglia associated with the hepatic branch of the vagus nerve contain also E. The presence of perihepatic sources of extra-adrenal CA, and more specifically E, could be of physiological significance.     

Aluminum is a weak agonist for the calcium-sensing receptor

BACKGROUND: Aluminum (Al3+) has diverse biological effects mediated through activation of a putative extracellular cation-sensing receptor. A recently identified calcium-sensing receptor (CaSR), which has been identified in target tissues for Al3+, may transduce some of the biological effects of Al3+. METHODS: To test this possibility, we transfected human embryonic kidney 293 (HEK 293) cells with a cDNA encoding the rat CaSR and evaluated CaSR expression by Western blot analysis and function by measurement of intracellular calcium ([Ca2+]i) levels and inositol monophosphate (IP1) generation following stimulation with Al3+ and a panel of CaSR agonists. RESULTS: The CaSR protein was detected by immunoblot analysis in cells transfected with the CaSR cDNA but not in nontransfected HEK 293 cells. In addition, [Ca2+]i levels and IP1 generation were enhanced in a dose-dependent fashion by additions of the CaSR agonists calcium (Ca2+), magnesium (Mg2+), gadolinium (Gd3+), and neomycin only in cells transfected with CaSR. To determine if Al3+ activated CaSR, we stimulated cells transfected with rat CaSR with 10 microM to 1 mM concentrations of Al3+. Concentrations of Al3+ in the range of 10 microM to 100 microM had no effect on [Ca2+]i levels or IP1 generation. In contrast, 1 mM Al3+ induced small but significant increases in both parameters. Whereas Gd3+ antagonized calcium-mediated activation of CaSR, pretreatment with Al3+ failed to block subsequent activation of rat CaSR by Ca2+, suggesting a distinct mechanism of Al3+ action. CONCLUSION: Al3+ is not a potent agonist for CaSR. Because Al3+ affects a variety of target tissues at micromolar concentrations, it seems unlikely that CaSR mediates these cellular actions of Al3+.     

Lipoprotein(a) and other lipoproteins in hypothyroid patients before and after thyroid replacement therapy

AIMS: To analyse the influence of thyroid hormones on serum lipoprotein(a) (Lp(a)) concentration and other lipid parameters, and hence potentially on coronary artery disease (CAD) risk. METHODS: Thirty-six patients with hypothyroidism and 165 age-matched control euthyroid subjects were evaluated in a cross- sectional study, determining thyroid function tests and fasting serum lipids and lipoproteins. In a follow-up study for those hypothyroid patients the same determinations were repeated after normalization of thyroid state by levothyroxine (L-T(4)) replacement therapy. Patients needing other treatments were excluded. At baseline, patients with hypothyroidism had significantly higher levels of Lp(a), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), apolipoprotein (apo) A-I and apo B, and a higher TC/high-density lipoprotein cholesterol (HDL-C) ratio than control subjects. RESULTS: Severity of the hypothyroid state, expressed by serum thyroid-stimulating hormone, was correlated with serum levels of Lp(a), LDL-C, and TC (r= 0.64, 0.52, 0.49, P= 0.005, P= 0.033, P= 0. 048, respectively). The pretreatment Lp(a) levels were also correlated with those of posttreatment Lp(a)(r= 0.68, P= 0.002). All patients, who presented basal Lp(a) levels higher than 30 mg/dl, showed a decrease in Lp(a) concentrations by L-T(4)therapy, and these normalized in eight cases (22.2%). Euthyroid state gave rise to a significant reduction of serum Lp(a) by 32.3%, of LDL-C by 22. 8%, of TC by 17%, of apo A-I by 9.6%, and of apo B by 9.3%. After L-T(4)therapy, CAD risk, expressed as TC/HDL-C ratio, decreased by 19.9%. CONCLUSIONS: These results show that hypothyroidism is associated not only with elevated serum levels of LDL-C but also with elevated serum Lp(a) concentrations. Lp(a) levels may be at least partially modulated by thyroid hormone-dependent mechanisms, thus increasing the risk of developing premature atherosclerosis in hypothyroid state, that might be reduced by L-T(4)therapy.     

The emergence of resistance to amikacin in Serratia marcescens isolates from patients with nosocomial infection

Administration of either amikacin (1985) or gentamicin (1984, 1986-1991) as first-choice aminoglycoside did not decrease the high incidence of amikacin-resistant Serratia marcescens (ARSm) isolates responsible for nosocomial infections at the J.A. Fernández Hospital of Buenos Aires (42% in 1984, 31% in 1985 and 41% in 1987, differences not significant). In addition, a significant peak (P = 0.003) was detected in 1986, with an ARSm incidence of 70%. The incidence of ARSm decreased by 1988-1991 for reasons not related to aminoglycoside use. In the period 1984-1987 all S. marcescens isolates carried the 6'-aminoglycoside-acetyltransferase-Ic [aac(6')-Ic] gene, while in addition 20% of the isolates contained the plasmid-encoded 3'-aminoglycoside-phosphotransferase-VIa[aph(3')-VIa] and 2% the 6'-aminoglycoside-acetyltransferase-Ib [aac(6')-Ib] genes. From 1988 to 1992 resistance to amikacin was associated with only 4 ARSm isolates and correlated with the appearance of Tn1331-related sequences in these isolates. This transposon or related sequences, however, was not widely spread in the S. marcescens population under investigation. Combined use of restriction fragment length polymorphism (RFLP), ribotyping and plasmid profile analysis revealed that S. marcescens strains of the same genotype, including isolates either expressing or not the aac(6')-Ic gene, were involved in outbreaks occurring in May 1984, May 1985 and May 1986. Furthermore, these epidemiological tools permitted discrimination of different S. marcescens clones, each bearing a particular amikacin-resistance marker.     

不同浓度乙醇对内皮细胞分泌作用的影响

目的 研究不同浓度乙醇对内皮细胞的保护作用。方法 应用过氧化氢损伤培养的人脐静脉内皮细胞,并与不同浓度乙醇进行孵育,检测内皮细胞产生的内皮素及一氧化氮。结果低、中浓度乙醇明显减少损伤的内皮细胞产生的内皮素。同时实验还提示长时间高浓度乙醇对内皮细胞有明显损伤作用;不同浓度的乙醇均抑制内皮细胞产生一氧化氮。结论低、中浓度乙醇使内皮细胞在受损时生成的内皮素明显减少。     

Necrotizing histiocytic lymphadenitis (Kikuchi-Fujimoto disease) in a 7-year-old girl

Kikuchi-Fujimoto's disease is a rare self-limited condition of young adults that usually involves the cervical lymph nodes and is associated with fever, rash and some haematological alterations. Diagnosis is based on characteristic pathologic findings that permit differentiation of this disease from lymphoma, systemic lupus erythematous and infectious lymphadenopathies. We describe a case of 7 year-old female presenting with cervical localization of Kikuchi-Fujimoto's disease. To our knowledge, this case results the earliest affection of this disease. Our proposal with this article is to remind the pediatricians and pediatric surgeons of this poorly recognized entity when children ask for cervical masses and fever.     

Hamartoma mamario: un tumor infrecuente

We present a case of hamartoma of the breast. This is an infrequent tumour that requires the correct diagnosis to distinguish it from other histopathology types because it has a better prognosis. The characteristic image from a mammogram is useful in its diagnosis.     

电动全人工心脏原型样机的初步研制

研究了基于电能源的全人工心脏原型样机及其体外循环测试的情况。研制的该原型机采用直流无刷电机驱动推板结构往复水平运动，循环吸入和排出血液。     

Nerve growth factor and striatal glutathione metabolism in a rat model of Huntington's disease

Purpose: To test the influence of nerve growth factor (NGF) on striatal glutathione (GSH) content and the activities of GSH-related enzymes from quinolinic acid-lesioned rats. Methods: Rats were intrastriatally injected with QA and NGF. Enzymatic and GSH assays were performed one week later. Results: NGF prevented the QA-induced decline in glutathione reductase activity and GSH content. Conclusions: NGF is able to prevent some of the disturbances induced by the excitotoxic insult in the striatal GSH metabolism.