Zinc and nociception: a pharmacological approach

In the last decade, neurophysiological research regarding nociceptive mediation seems to suggest a possible new approach in pain management--zinc applicability. Immunohistochemical studies prove that zinc can be found in central nervous system, inside structures active in nociception. Zinc stabilizes primary afferent C fibers, nervous fibers involved in nociception. However, this phenomenon is probably only true for extreme zinc concentrations--excess or deficit. Electrophysiological studies indicate that zinc inhibits NMDA receptors, while potentiating the activity of non-NMDA receptors. All these are arguments supporting the existence of a role of endogenous zinc regarding pain transmission.     

Carotid endarterectomy: a new technique replacing internal shunts

Summary  Background. Carotid endarterectomy has been reported to increase the time free from cerebral ischemic events in both symptomatic and asymptomatic patients with a high grade of stenosis of the internal carotid artery. In cases in whom the compensatory circulation during the carotid clamp time is not sufficient, the use of intraluminal shunts has been proposed. However, the use of intraluminal shunts present several problems, such as the tecnical difficulties in positioning the shunt, the variability of time requested for the placement, the inconstancy of the blood flow during surgery, and the need to clamp off the carotid to introduce and remove the shunt.  For these reasons, most operators prefer not to employ intraluminal shunts, while others do use them only in selected cases. The purpose of this work is to present, for the first time, a new type of temporary extraluminal shunt, connecting the femoral to the internal carotid artery with the interposition of a roller pump to regulate the blood flow. This method allows one to perform carotid endarterectomy without interrupting the blood flow to the brain.  Methods. 407 consecutive patients, who underwent carotid endarterectomy between August 1992 and April 2000, were considered. 35 patients presented an absolutely insufficient collateral circulation, demonstrated by important modifications of the electroencephalographic monitoring during the carotid clamp time. In these patients the endorterectomy was performed using a new femoral-carotid extraluminal shunt.  Findings. In all the cases in whom the femoral-carotid extraluminal shunt was positioned, the normalisation of electroencephalographic monitoring was achieved by regulating the blood flow with the interposed roller pump. The use and the placement of the shunt was simple and easy. None of the patients showed postoperative complications, except for one who had a stroke two days after surgery.  Interpretation. The results obtained, although to be confirmed by further studies, seem to demonstrate the effectiveness of our femoral-carotid extraluminal shunt, which was simple to use and safe.     

Parathyroidectomy in chronic renal failure: short- and long-term results on parathyroid function, blood pressure and anemia

To evaluate the long-term results of parathyroidectomy (PTX) on parathyroid function, blood pressure and anemia, data of 45 patients with secondary Hyperparathyroidism in dialysis who had undergone PTX were collected retrospectively from 8 different dialysis units. The patients, 25 M and 20 F, mean age 56 +/- 11 years, who were followed up for an average period of 3.3 +/- 2.3 years, were divided into four groups according to the surgical procedure: 19 patients had had a subtotal PTX; 10 patients had undergone total PTX with autotransplantation (AT); 10 patients had had total PTX without AT, and 6 patients had undergone partial PTX. Taking a reduction in intact PTH > 50% as sign of successful PTX, only 5 patients did not attain this result. Considering values of PTH between 20 and 200 pg/ml at the mid-term observation (1-2 years) as the optimal result, values under 20 pg/ml as an expression of permanent hypoparathyroidism, and those above 200 pg/ml as indicating persistent/recurrent hyperparathyroidism, 65.5% of patients operated with subtotal PTX and total PTX + AT had a therapeutic success, versus 31.2% of patients in the other two groups, due to excess permanent hypoparathyroidism and persistent/recurrent hyperparathyroidism; 20 of 45 patients with preoperative hypertension experienced a statistically and clinically significant decrease in blood pressure levels. An increase in serum hemoglobin was also observed, despite a reduction of administered erythropoietin. In conclusion, the results of PTX obtained from this multicenter study are comparable to those reported by single leading centers. Recommended surgical procedures are subtotal PTX and total PTX with AT. The fall in blood pressure in hypertensive patients is clinically significant, and improvement in anemia is also observed with a reduction in erythropoietin dosage.     

Influenza Vaccination in Orthotopic Liver Transplant Recipients: Absence of Post Administration ALT Elevation

Influenza vaccination has reduced life-threatening complications from influenza virus infection in adult liver transplant recipients. We evaluated changes in aminotransferase level and immunogenicity of influenza vaccination in liver transplant recipients. Fifty-one liver transplant recipients were administered a standard dose of the 2002-2003 inactivated trivalent influenza vaccine. ALT values were measured at baseline, 1 week and 4-6 weeks postvaccination. Antibody responses to each component of the vaccine were measured at baseline and after 4-6 weeks by a hemagglutination inhibition (HAI) assay. Response was defined as an HAI titer > or = 1: 40 and/or a 4-fold increase in antibody titers from baseline. An ALT elevation was defined as a rise of > or = 50% from baseline. There was no difference in the median rise in ALT value between seroconverters and nonseroconverters. A significant number of recipients developed potentially protective antibody titers (p-value < 0.0001). At less than 4 months post transplantation, 1/7 (14%), at 4-12 months, 6/9 (67%), and after 12 months, 30/35 (86%) subjects responded to the H1 strain. Of 51 recipients, one HCV (-) recipients vaccinated within 3 months of transplantation developed acute cellular rejection. Influenza virus vaccination is not associated with allograft rejection or ALT flares in liver transplant recipients.     

Differential Willingness to Undergo Smallpox Vaccination Among African-American and White Individuals

OBJECTIVE:  To examine potential disparities in willingness to be vaccinated against smallpox among different U.S. racial/ethnic groups.
DESIGN:  Cross-sectional survey using an experimental design to assess willingness to be vaccinated among African Americans compared to whites according to 2 strategies: a post-exposure "ring vaccination" method and a pre-exposure national vaccination program.
SETTING:  Philadelphia County district courthouse.
PARTICIPANTS:  Individuals awaiting jury duty.
MEASUREMENTS:  We included 2 scenarios representing these strategies in 2 otherwise identical questionnaires and randomly assigned them to participants. We compared responses by African Americans and whites.
MAIN RESULTS:  In the pre-exposure scenario, 66% of 190 participants were willing to get vaccinated against smallpox. In contrast, 84% of 200 participants were willing to get vaccinated in the post-exposure scenario ( P  = .0001). African Americans were less willing than whites to get vaccinated in the pre-exposure scenario (54% vs 77%; P  = .004), but not in the post-exposure scenario (84% vs 88%; P  = .56). In multivariate analyses, overall willingness to undergo vaccination was associated with vaccination strategy (odds ratio, 3.29; 95% confidence interval, 1.8 to 6.1).
CONCLUSIONS:  Racial disparity in willingness to get vaccinated varies by the characteristics of the vaccination program. Overall willingness was highest in the context of a post-exposure scenario. These results highlight the importance of considering social issues when constructing bioterror attack response plans that adequately address the needs of all of society's members.     

Cassava cyanogens and fish mercury are high but safely consumed in the diet of native Amazonians

The two most important staple foods (cassava and fish) in the diet of native Amazonians contain neurotoxins (linamarin and monomethyl mercury, MMHg). These same neurotoxins are public health issues in other parts of the world. Factors such as chemistry, environment, and human ecology determine the endemism of neuropathies caused by consumption of cassava (Manihot esculenta Crantz) and fish. Linamarin is a natural component of cassava tubers that can be destroyed before consumption by proper processing. Furthermore, small amounts of the toxin absorbed by people consuming cassava can be effectively metabolized if the diet contains adequate protein-containing sulfur amino acids. Naturally occurring Hg in the waters of the Amazonian rain forest is methylated to MMHg by microorganisms and bioconcentrated in the aquatic food chain. There is no effective method for MMHg removal from fish. Despite high concentrations of naturally occurring neurotoxins in cassava (linamarin) and fish (MMHg), daily consumption of these foods in large amounts over the course of a lifetime poses no health hazards for Amazonians.     

Mercury Biomagnification in a Tropical Black Water,Rio Negro,Brazil

The population living along the riverbanks of the Amazon basin depends heavily on fish for nutritional support. Mono-methyl-mercury (MMHg) concentrates in fish, which can contaminate humans, the risk depending not only on fish MMHg concentration but also on the amount of fish consumed. We sampled nine locations of the Rio Negro basin, differing in water pH, Hg concentrations, and dissolved organic carbon (DOC), and determined total Hg from 951 fish samples of species representative of the food web: herbivorous, detritivorous, omnivorous, and piscivorous. Mercury concentrations varied widely in all species but showed a trend that depended on fish feeding strategies. The highest mean concentration was found in the piscivorous species (688.90 ng/g^–1), followed by omnivorous (190.30 ng/g^–1), detritivorous (136.04 ng/g^–1), and herbivorous (70.39 ng/g^–1). Fish Hg concentrations exceeding current safe limits (500 ng/g^–1) for human consumption were found mainly in the piscivorous species (60%). Significant positive correlation between fish weight and Hg concentration was seen for the piscivorous Serrasalmus spp. (n = 326; r = 0.3977; p < 0.0001), Cichla spp. (n = 125; r = 0.4600; p < 0.0001), and Pimelodus spp. (n = 12; r = 0.8299; p = 0.0008), known locally as Piranha, Tucunaré, and Mandi, respectively. However, a negative correlation was seen for nonpiscivorous Potamorhina latior (n = 30; r –0.3763; p = 0.0404) and Leporinus spp. (n = 44; r = –3987; p = 0.0073), known as Branquinha (detritivorous) and Aracu (omnivorous). Fish-Hg concentrations in the acidic waters (pH range, 4.09–6.31) of the Rio Negro habitat, with its wide gradient of Hg concentrations (3.4–11.9 g/L^–1) and DOC (1.85–15.3 mg/L^–1)—but no history of gold mining activity—are comparable to other Amazonian rivers. Opportunity fish catches in the Rio Negro habitat show high muscle-Hg derived from natural sources, but no systematic association with site-dependent geochemistry.     

Development and reproducibility of a tool to assess school food-purchasing practices and lifestyle habits of Australian primary school-aged children

Objective: To describe the development and reproducibility of a self‐report instrument, for use with children in years 4–6, to identify sources of food eaten during the day, and type and frequency of food purchases at school. Design: Tool development stages included formulation of content and format, expert review, piloting and a test–retest study. Subjects/setting: The pilot study included school students (n = 20) in years 4 and 5 (seven girls, mean age 9.7 ± 0.7 years) attending an Australian public primary school. The test–retest study was performed in a large metropolitan public primary school (n = 245 children, 52% female, mean age 10.7 ± 0.91 years) including children from years 4 (n = 88), 5 (n = 84) and 6 (n = 73). Statistical analysis: A Kappa statistic was used to assess level of agreement between the two time periods separated by 1 week. The results were analysed using SAS version 8.2 with each question compared at time 1 and 2. Results: The mean kappa was 0.529 using pairings from 17 questions. Values ranged from 0.18 to 0.71 (CI 0.46–0.60). Conclusions and applications: The School Eating Habits and Lifestyle Survey has been developed and pilot‐tested in primary school‐aged children and shown to have moderate stability over time. The results show that each phase of development, particularly those spent in consultation and testing, led to progressive improvement of this instrument. This process improved the quality of information produced and gave insights to self‐report of dietary intake and behaviours among children.