Comparison of capillary earlobe and venous blood monitoring for occupational lead surveillance

Biological monitoring for occupational lead exposure involves routine venous blood draws from exposed employees. This uncomfortable procedure normally yields more blood than what is needed for analysis. Capillary blood sampling is less invasive but introduces the possibility of surface contamination. The objective of this study was to compare venous and capillary (earlobe) blood lead samples obtained from occupationally exposed individuals. Phlebotomists trained specifically in the collection of blood samples for lead determination collected 2 venous blood samples and 2 capillary earlobe samples from each participating employee. Before the capillary draw, the employee's earlobe was cleansed with an alcohol wipe in an effort to remove potential lead contamination. A second alcohol wipe was then used to sanitize the lancing area and was retained for lead analysis. Both the venous and capillary samples were subsequently analyzed with the use of graphite furnace atomic absorption spectrometry (GFAAS). GFAAS of venous blood specimens was considered the reference method of sampling and analysis. We collected and analyzed 126 paired earlobe and venous samples. Earlobe sampling was preferred to venous sampling by 54% of the employees surveyed. The mean difference between the capillary and venous results was 38.8 +/- 48.1 microg/dL. Lead concentrations in earlobe blood were more than twice those found in venous samples in more than half of the samples (64 of 126). Despite simple cleansing with an alcohol wipe and no visible skin contamination, 94% of the wipe samples from earlobes contained more than 1 microg of lead. Even low concentrations of contamination can significantly alter the concentration of lead in the blood; for example, sample contamination of 0.3 microg lead in a 200-microL blood sample would yield an increase of 150 microg/dL in the measured lead concentration. The findings of this study suggest that until satisfactory skin cleansing and decontamination techniques are identified and evaluated, earlobe sampling should be avoided in the surveillance of occupational blood lead levels.     

Effect of Cryopreservation on Semen Sample

There are varied indications of preserving a semen sample for utilization at a later day. However, the freeze-thaw cycle is bound to impart deleterious effect on the fertilizing potential of the sample. 60 semen samples divided into three groups were preserved in this study. On subsequent thawing, after three months it was seen that the yield varied between 66% to 72%. The post thaw percent yield bears a linear relationship with the pre-freeze quality. 5 pregnancies were achieved in the study testifying the preservation of fertilizing ability of the thawed samples. Sub normal semen samples which might be otherwise acceptable in a therapeutic insemination, do not withstand freezing.Key Words: Cryopreservation, Semen     

Management of acute liver failure

Acute liver failure (ALF) is a devastating syndrome that triggersa cascade of events, leading to multiple organ failure and oftendeath. A previously normal liver may fail within days or weeks;and despite recent advances in intensive care and organ support,mortality rates remain high. In those patients with high gradesof encephalopathy, the chances of survival are less than 20%with medical management alone. Early deaths in ALF are oftencaused by cerebral oedema or cardiovascular collapse, whereaslate deaths tend to result from sepsis and multiple organ failure.Liver transplantation is the only current definitive treatmentin those failing supportive medical management. However, hepaticassist devices are currently under investigation to provideliver support as a ‘bridge to transplantation’ orduring recovery of the native liver.     

Helicobacter pylori eradication to prevent gastric cancer in a high-risk region of China: a randomized controlled trial

Context  Although chronic Helicobacter pylori infection is associated with gastric cancer, the effect of H pylori treatment on prevention of gastric cancer development in chronic carriers is unknown. Objective  To determine whether treatment of H pylori infection reduces the incidence of gastric cancer. Design, Setting, and Participants  Prospective, randomized, placebo-controlled, population-based primary prevention study of 1630 healthy carriers of H pylori infection from Fujian Province, China, recruited in July 1994 and followed up until January 2002. A total of 988 participants did not have precancerous lesions (gastric atrophy, intestinal metaplasia, or gastric dysplasia) on study entry. Intervention  Patients were randomly assigned to receive H pylori eradication treatment: a 2-week course of omeprazole, 20 mg, a combination product of amoxicillin and clavulanate potassium, 750 mg, and metronidazole, 400 mg, all twice daily (n = 817); or placebo (n = 813). Main Outcome Measures  The primary outcome measure was incidence of gastric cancer during follow-up, compared between H pylori eradication and placebo groups. The secondary outcome measure was incidence of gastric cancer in patients with or without precancerous lesions, compared between the 2 groups. Results  Among the 18 new cases of gastric cancers that developed, no overall reduction was observed in participants who received H pylori eradication treatment (n = 7) compared with those who did not (n = 11) (P = .33). In a subgroup of patients with no precancerous lesions on presentation, no patient developed gastric cancer during a follow-up of 7.5 years after H pylori eradication treatment compared with those who received placebo (0 vs 6; P = .02). Smoking (hazard ratio [HR], 6.2; 95% confidence interval [CI], 2.3-16.5; P<.001) and older age (HR, 1.10; 95% CI, 1.05-1.15; P<.001) were independent risk factors for the development of gastric cancer in this cohort. Conclusions  We found that the incidence of gastric cancer development at the population level was similar between participants receiving H pylori eradication treatment and those receiving placebo during a period of 7.5 years in a high-risk region of China. In the subgroup of H pylori carriers without precancerous lesions, eradication of H pylori significantly decreased the development of gastric cancer. Further studies to investigate the role of H pylori eradication in participants with precancerous lesions are warranted.      

Fish consumption, mercury exposure, and heart diseases

There is increasing concern regarding methylmercury exposure in populations that consume large amounts of fish. This situation poses a dilemma for those who choose to consume fish for its beneficial effects on heart disease risk. Recent evidence suggests that high mercury content in fish may diminish the cardioprotective effect of fish intake. We explore the current knowledge of Hg toxicity on the heart and evaluate the epidemiologic evidence to date.     

Breastfeeding and the risk of childhood leukemia: a meta-analysis

OBJECTIVE: The authors used a meta-analytic technique to (1) quantify the evidence of an association between duration of breastfeeding and risk of childhood acute lymphoblastic leukemia (ALL) or acute myeloblastic leukemia (AML), (2) assess the influence of socioeconomic status (SES) on any such associations, and (3) discuss the implications of these findings for the evaluation of whether breastfeeding reduces the risk of childhood leukemia. METHODS: A fixed effects model was employed to systematically combine the results of 14 case-control studies addressing the effect of short-term (< or = 6 months) and long-term (>6 months) breastfeeding on the risk of childhood ALL and/or AML. Subgroup analyses of studies that did and did not adjust for SES were also performed. RESULTS: A significant, negative association was observed between long-term breastfeeding and both ALL risk (odds ratio [OR]=0.76; 95% confidence interval [CI] 0.68, 0.84) and AML risk (OR=0.85; 95% CI 0.73, 0.98). Short-term breastfeeding was similarly protective for ALL and AML. Results for studies that adjusted and did not adjust for SES were not significantly different from the results for the 14 studies combined. CONCLUSIONS: This meta-analysis showed that both short-term and long-term breastfeeding reduced the risk of childhood ALL and AML, suggesting that the protective effect of breastfeeding might not be limited to ALL as earlier hypothesized. Potential bias introduced by different participation rates for case and control samples that differed in SES can be minimized by implementing larger case-control studies with SES-matched, population-based controls.     

Sargaquinoic acid supports the survival of neuronal PC12D cells in a nerve growth factor-independent manner

Sargaquinoic acid (designated previously as MC14) was isolated from a marine brown alga Sargassum macrocarpum, and has been found to possess a novel nerve growth factor (NGF)-dependent neurite outgrowth promoting activity in PC12D cells. In this study, we explored the neuroprotective effects of MC14 in terms of its survival supporting, antioxidant and neurite-regenerating activities under NGF deficient or deprived conditions. Intriguingly, MC14 did not only promote the NGF-induced survival support on neuronal PC12D cells, but also significantly abated neuronal PC12D cell death even in the absence of NGF. The pharmacological inhibition of phosphatidylinositol-3 kinase (PI3K) by wortmannin significantly suppressed the survival supporting activity of MC14, whereas the NGF receptor (tyrosine kinase A or TrkA) inhibitor K252a showed no detectable effect on MC14 activity. These results demonstrate that MC14 supports survival of neuronal PC12D cells in an NGF-independent manner, and that PI3K may be required for the neuroprotective activity of MC14. In addition, we have shown that MC14 markedly enhanced neurite-regeneration and protected PC12D cells from hydrogen peroxide (H(2)O(2))-induced oxidative stress. These pharmacological features suggest that MC14 may be a potentially important neuroprotective agent.     

Substance P induces inward current and regulates pacemaker currents through tachykinin NK1 receptor in cultured interstitial cells of Cajal of murine small intestine

We investigated whether substance P modulates pacemaker currents generated in cultured interstitial cells of Cajal of murine small intestine using whole cell patch-clamp techniques at 30 degrees C. Interstitial cells of Cajal generated spontaneous inward currents (pacemaker currents) at a holding potential of -70 mV. Tetrodotoxin, nifedipine, tetraethylammonium, 4-aminopyridine, or glibenclamide did not change the frequency and amplitude of pacemaker currents. However, divalent cations (Ni2+, Mn2+, Cd2+, and Co2+), nonselective cationic channel blockers (gadolinium and flufenamic acid), and a reduction of external Na+ from normal to 1 mM inhibited pacemaker currents indicating that nonselective cation channels are involved in their generation. Substance P depolarized the membrane potential in current clamp mode and produced tonic inward pacemaker currents with reduced frequency and amplitude in voltage clamp mode. [D-Arg1, D-Trp7,9, Leu11] substance P, a tachykinin NK1 receptor antagonist, blocked these substance P-induced responses. Furthermore, [Sar9, Met(O2)11] substance P, a specific tachykinin NK1 receptor agonist, depolarized the membrane and tonic inward currents mimicked those of substance P. Substance P continued to produce tonic inward currents in external Ca2+-free solution or in the presence of chelerythrine, a protein kinase C inhibitor. However, substance P-induced tonic inward currents were blocked by thapsigargin, a Ca2+-ATPase inhibitor in the endoplasmic reticulum or by an external 1 mM Na+ solution. Our results demonstrate that substance P may modulate intestinal motility by acting on the interstitial cells of Cajal by activating nonselective cation channels via the release of intracellular Ca2+ induced by tachykinin NK1 receptor stimulation.