Dextran-related complications in head and neck microsurgery: do the benefits outweigh the risks? A prospective randomized analysis

Increased experience with free-tissue transfer has minimized flap loss secondary to microvascular thrombosis, yet pharmacologic antithrombotic prophylaxis continues to be used routinely. Currently there is no consensus on the ideal pharmacologic agent, dosing, or efficacy. Low-molecular-weight dextran has been widely used for prophylaxis due to its properties of volume expansion and enhanced microrheology. Significant systemic morbidity (pulmonary morbidity, cardiac morbidity, anaphylaxis) is known to occur with use of low-molecular-weight dextran. The purpose of this study was to evaluate morbidity associated with postoperative low-molecular-weight dextran and aspirin prophylaxis in head and neck microsurgery patients. This study was a randomized prospective analysis of 100 consecutive patients undergoing microvascular reconstruction for head and neck malignancy during a 2-year period. Patients were randomized into one of three postoperative antithrombotic prophylaxis treatment groups: low-molecular-weight dextran 20 cc/hour for 48 hours (n = 35), low-molecular-weight dextran 20 cc/hour for 120 hours (n = 32), or aspirin 325 mg/day for 120 hours (n = 27). Six patients were excluded intraoperatively due to the need for systemic heparin therapy. Treatment groups were compared for age, sex, prior medical problems, duration of anesthesia, and intraoperative fluid intake. Flap outcome and the incidence of local and systemic complications were evaluated in the treatment groups. Patient ages ranged from 12 to 84 years (mean age, 58 years). No significant difference was found among the treatment groups with respect to age, sex, prior medical problems, duration of anesthesia, intraoperative fluid intake, and the distribution of donor and recipient sites. There were no total flap losses and two partial flap losses in this series. Three flaps were reexplored and all were salvaged. The incidence of systemic complications (congestive heart failure, myocardial infarction, pulmonary edema, pleural effusion, and pneumonia) was as follows: low-molecular-weight dextran 120 hours, 51 percent; low-molecular-weight dextran 48 hours, 29 percent; and aspirin, 7 percent. Analysis of these data suggests that the method of prophylaxis had no effect on overall flap survival. However, the incidence of systemic complications was significantly related to the method of prophylaxis, with patients receiving low-molecular-weight dextran 120 hours and 48 hours at a 7.2 and 3.9 times greater relative risk, respectively, of developing a systemic complication compared with patients receiving aspirin. The results of this study have eliminated the routine use of low-molecular-weight dextran prophylaxis at our institution in an effort to reduce morbidity in head and neck microsurgical reconstruction.     

Coexistence of antibodies to tick-borne agents of babesiosis and Lyme borreliosis in patients from Cotia county,State of São Paulo,Brazil

This paper reports a case of coinfection caused by pathogens of Lyme disease and babesiosis in brothers. This was the first case of borreliosis in Brazil, acquired in Cotia County, State of S o Paulo, Brazil. Both children had tick bite history, presented erythema migrans, fever, arthralgia, mialgia, and developed positive serology (ELISA and Western-blotting) directed to Borrelia burgdorferi G 39/40 and Babesia bovis antigens, mainly of IgM class antibodies, suggestive of acute disease. Also, high frequencies of antibodies to B. bovis was observed in a group of 59 Brazilian patients with Lyme borreliosis (25.4%), when compared with that obtained in a normal control group (10.2%) (chi-square = 5.6; p < 0.05). Interestingly, both children presented the highest titers for IgM antibodies directed to both infective diseases, among all patients with Lyme borreliosis.     

Acute schistosomiasis outbreak in the metropolitan area of Belo Horizonte, Minas Gerais: alert about the risk of unnoticed transmission increased by growing rural tourism

The present article describes the occurrence of 17 cases of acute schistosomiasis in the metropolitan area of Belo Horizonte, state of Minas Gerais, Brazil. All individuals affected took a bath in a swimming pool of a holiday resort that was provided with water from a nearby brook. The apparently clean water and the absence of snails in the pool gave the wrong impression that there was no risk for infection. During a malacological survey at the site snails of the species Biomphalaria glabrata were found and tested positive for Schistosoma mansoni. All the patients live in the middle-class area of Barreiro, metropolitan area of Belo Horizonte and have medium grade school education. The difficulties in establishing the right diagnosis is expressed by the search for medical attention in 17 different medical facilities, the wide range of laboratory test and the inadequate treatment administration. A lack of knowledge about the disease was found in all groups studied. The booming rural tourism in endemic areas is identified as a probable risk factor for infection, especially for individuals of the non-immune middle and upper class parts of the society in urban centers. Special attention is given to a multidisciplinary approach to the complex issue of disease control and prevention.     

Technicolour transgenics: imaging tools for functional genomics in the mouse

Over the past decade, a battery of powerful tools that encompass forward and reverse genetic approaches have been developed to dissect the molecular and cellular processes that regulate development and disease. The advent of genetically-encoded fluorescent proteins that are expressed in wild type and mutant mice, together with advances in imaging technology, make it possible to study these biological processes in many dimensions. Importantly, these technologies allow direct visual access to complex events as they happen in their native environment, which provides greater insights into mammalian biology than ever before.     

Role of endothelium-derived relaxing factors in the renal response to vasoactive agents in hypothyroid rats

This study analyzed the role of nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF) in the abnormal renal vascular reactivity of hypothyroid rats. Renal responses to vasoconstrictors [VC: phenylephrine (PHE) and ANG II] and vasodilators [VD: ACh, sodium nitroprusside (SNP), and papaverine (PV)] were studied in kidneys from control and hypothyroid rats under normal conditions and after NO or EDHF blockade. NO was blocked by the administration of Nomega-nitro-l-arginine methyl ester (l-NAME) and EDHF by the administration of tetraethylammonium (TEA) or by an increased extracellular K+. The response to VC was also evaluated after endothelium removal. Hypothyroid kidneys showed reduced responsiveness to PHE and a normal response to ANG II. l-NAME and TEA administration produced an increased sensitivity to PHE and to ANG II in control preparations. l-NAME also increased the response to PHE in hypothyroid kidneys, but the differences between control and hypothyroid kidneys were maintained. TEA administration did not change the response to either VC in hypothyroid preparations. In endothelium-removed preparations, TEA was unable to increase pressor responsiveness to VC. Hypothyroid kidneys showed reduced responsiveness to ACh and SNP and normal response to PV. The differences between hypothyroid and control preparations in the responses to ACh and SNP were maintained after l-NAME or increased K+. In conclusion, this study shows that 1) the attenuated response to PHE in hypothyroidism is not related to an increased production of endothelium-derived relaxing factors NO and EDHF; 2) the response to VC in hypothyroid preparations is insensitive to EDHF blockade; and 3) hypothyroid preparations have a reduced reactivity to the NO donor, and NO-independent vasodilatation remains unaffected.