Developmental and behavioral effects of postnatal amitraz exposure in rats

The effects of postnatal amitraz exposure on physical and behavioral parameters were studied in Wistar rats, whose lactating dams received the pesticide (10 mg/kg) orally on days 1, 4, 7, 10, 13, 16 and 19 of lactation; control dams received distilled water (1 ml/kg) on the same days. A total of 18 different litters (9 of them control and 9 experimental) born after a 21-day gestation were used. The results showed that the median effective time (ET50) for fur development, eye opening, testis descent and onset of the startle response were increased in rats postnatally exposed to amitraz (2.7, 15.1, 21.6 and 15.3 days, respectively) compared to those of the control pups (1.8, 14.0, 19.9 and 12.9 days, respectively). The ages of incisor eruption, total unfolding of the external ears, vaginal and ear opening and the time taken to perform the grasping hindlimb reflex were not affected by amitraz exposure. Pups from dams treated with amitraz during lactation took more time (in seconds) to perform the surface righting reflex on postnatal days (PND) 3 (25.0 +/- 2.0), 4 (12.3 +/- 1.2) and 5 (8.7 +/- 0.9) in relation to controls (10.6 +/- 1.2; 4.5 +/- 0.6 and 3.4 +/- 0.4, respectively); the climbing response was not changed by amitraz. Postnatal amitraz exposure increased spontaneous motor activity of male and female pups in the open-field on PND 16 (140 +/- 11) and 17 (124 +/- 12), and 16 (104 +/- 9), 17 (137 +/- 9) and 18 (106 +/- 8), respectively. Data on spontaneous motor activity of the control male and female pups were 59 +/- 11 and 69 +/- 10 for days 16 and 17 and 49 +/- 9, 48 +/- 7 and 56 +/- 7 for days 16, 17 and 18, respectively. Some qualitative differences were also observed in spontaneous motor behavior; thus, raising the head, shoulder and pelvis matured one or two days later in the amitraz-treated offspring. Postnatal amitraz exposure did not change locomotion and rearing frequencies or immobility time in the open-field on PND 30, 60 and 90. The present findings indicate that postnatal exposure to amitraz caused transient developmental and behavioral changes in the exposed offspring and suggest that further investigation of the potential health risk of amitraz exposure to developing human and animal offsprings may be warranted.     

Pulmonary complications in toxic epidermal necrolysis: a prospective clinical study

BACKGROUND: Both experimental and clinical studies have shown that the increase in regional blood flow induced by acetylcholine is not completely prevented by inhibitors of the synthesis of endothelium-derived nitric oxide. To establish the role of ATP-sensitive potassium (KATP) channels and prostacyclin in mediating acetylcholine-induced increase in peripheral blood flow in humans, we assessed the effects of acetylcholine on the iliac artery blood flow velocity before and after glibenclamide, an antagonist of KATP channels, or before and after acetylsalicylic acid, an inhibitor of prostacyclin production. MATERIAL AND METHODS: Seventeen patients without evidence of peripheral vascular disease and normal coronary arteries at angiography received intra-iliac incremental bolus injections of acetylcholine (0.2, 2, 20 and 50 micrograms) via a 5F femoral sheath, at the end of routine cardiac catheterization. All injections were repeated 90 minutes after oral administration of glibenclamide (10 mg) in 10 patients of 15 minutes after i.v. infusion of acetylsalicylic acid (1000 mg) in the remaining 7 patients. Right iliac artery blood flow velocity was measured by using an intravascular 0.014-in Doppler guidewire. RESULTS: Before glibenclamide or acetylsalicylic acid administration, acetylcholine infusion increased average peak velocity by 128% (p < 0.001) and by 121% (p < 0.001), respectively. After glibenclamide or acetylsalicylic acid the increases of average peak velocity during acetylcholine infusion (by 121%, p < 0.001, and by 121%, p < 0.001, respectively) were similar (p = ns) to those observed during the control infusion. CONCLUSIONS: In man acetylcholine-induced vasodilatation in the territory supplied by the iliac artery is not prevented by glibenclamide or acetylsalicylic acid, thus suggesting that it is independent of activation of KATP channels and prostacyclin release.     

Mitochondrial aldehyde dehydrogenase polymorphism in Asian and American Indian populations: detection of new ALDH2 alleles

Genetic deficiency of the mitochondrial aldehyde dehydrogenase (ALDH2) is frequent in Asian peoples where it is an important factor negatively regulating drinking behavior. To obtain additional information on gene geography of known ALDH2 alleles, and look for new variants, ALDH2 genes were evaluated in a Chinese population from Taiwan, a Yakut population of Siberia, and in five North American Indian populations. A novel approach based on a single-strand conformation polymorphism assay, and polymerase chain reaction-directed mutagenesis was developed for genotyping. In the Taiwan Chinese population, the ALDH2(2) allele frequency was 0.319 +/- 0.025, and this allele was not detected in the Yakut population nor in the five North American Indian populations. However, a new allele, ALDH2(3), was detected in Pima Indians at a frequency of 0.044 +/- 0.022, and this allele was also observed in 1 of 49 Pueblo samples. ALDH2(3) is a silent transition 1464 G-->A, and it possibly has a wide distribution among North American Indians. A new subtype of the ALDH2(2) allele, designated as ALDH2(2Taiwan), was found in 1 of 174 Chinese from Taiwan. ALDH2(2Taiwan) is characterized by two G-->A transitions at bases 1486 and 1510, resulting in Glu-->Lys substitutions at both the 479 and 487 positions. Thus, this second nonconservative ALDH2 substitution occurs within the sequence of the already inactive ALDH2(2) allele.     

A novel dialysis procedure measuring free Zn2+ in bovine milk and plasma

A dialysis method was developed for measuring free Zn2+ concentration in plasma and milk for determination of the electrochemical gradient for Zn2+ across the mammary gland. This method used the zinc content of casein after dialysis as the metal ion indicator because zinc in the calcium phosphate-citrate complex inside casein micelles is dependent on the free Zn2+ concentration of an associated aqueous phase. Zinc, calcium and magnesium distribution in milk confirmed the high zinc binding by bovine casein. Zinc in the casein, dialyzed against standards or unknowns, was measured by atomic absorption spectrophotometry. Average free Zn2+ concentrations measured by the dialysis method in plasma and milk of five cows were 0.141 and 0.331 nmol/L, respectively. The equilibrium potential of Zn2+ ions across the mammary epithelium, calculated from free Zn2+ concentrations in blood and milk measured by the dialysis method, was -11.4 mV, consistent with the mammary electrical potentials noted in previous studies. Therefore, no electrochemical gradient for zinc between the two compartments was apparent, and it is not necessary to invoke an active transport mechanism in the mammary gland to explain the higher zinc concentration in milk than in plasma of most species.     

Evidence for an efflux pump in multidrug-resistant Campylobacter jejuni

Mechanisms of drug resistance in Campylobacter jejuni were investigated. Mutant strains 34PEFr, which was resistant to pefloxacin (128-fold increase in the MIC), and 34CTXr, which was resistant to cefotaxime (32-fold increase in the MIC) and which was derived from the susceptible parent 34s, were obtained by serial passages on pefloxacin and cefotaxime gradient plates, respectively. Both mutants showed cross-resistance to erythromycin, chloramphenicol, tetracycline, beta-lactams, and quinolones. While the quinolone resistance of strain PEFr could be explained by a mutation at codon 86 of the gyrA gene, the multidrug resistance phenotype of both strains was further investigated. Accumulation of pefloxacin, ciprofloxacin, and minocycline was measured by fluorometry and was found to be lower in the mutant strains than in the parent strain. Preincubation of the cells with carbonyl cyanide m-chlorophenylhydrazone, however, completely abolished this difference. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of outer membrane preparations from both mutant strains showed overexpression of two proteins of 55 and 39 kDa which were absent from the outer membranes of the wild-type strain. These results indicate that in C. jejuni 34PEFr and 34CTXr, multidrug resistance is associated with an efflux system with a broad specificity.     

Microsatellite instability in gynecological sarcomas and in hMSH2 mutant uterine sarcoma cell lines defective in mismatch repair activity

We have examined a panel of gynecological sarcomas for microsatellite instability. The genomic DNA from 11 of 44 sarcomas contained somatic alterations in the lengths of one or more di-, tri-, tetra-, or pentanucleotide microsatellite sequence markers, and 6 of these cases had alterations in two or more markers. In addition, di-, tri-, and tetranucleotide microsatellites were found to be highly unstable in single cell clones of two cell lines derived from a uterine mixed mesodermal tumor. Since such instability is characteristic of cells defective in postreplication mismatch repair, we examined mismatch repair activity in extracts made from these lines. Both extracts were repair deficient, while an extract of another gynecological sarcoma cell line not exhibiting microsatellite instability was repair proficient. The repair deficiency was complemented by a colon tumor cell extract that was defective in the hMLH1 protein but not by an extract defective in hMSH2 protein. This suggested that the defect in the uterine sarcoma line could be in hMSH2. Subsequent analysis of the gene revealed a 2-bp deletion in exon 14, leading to premature truncation of the hMSH2 protein at codon 796 and no detectable wild-type gene present. These data suggest that the microsatellite instability observed in these cell lines, and possibly in a significant number of gynecological sarcomas, is due to defective postreplication mismatch repair. There was no apparent correlation with microsatellite instability and clinical outcome.     

Polymerase chain reaction determination of RhD blood type: an evaluation of accuracy

OBJECTIVE: To evaluate the accuracy of polymerase chain reaction (PCR) amplification of a portion of the RhD gene by testing a large number of DNA samples derived from individuals whose RhD status was established by the standard serologic method. METHODS: Seven hundred sixty-five samples were obtained from two sources: subjects taking part in studies at the University of Iowa Hospitals and Clinics (n = 107), and Centre d'Etude du Polymorphisme Humain (CEPH) families used for studies of genetic variation (n = 658). Deoxyribonucleic acid was extracted from blood samples of University of Iowa volunteers and from CEPH families by standard techniques. With few modifications, published primers, reaction and electrophoresis conditions, which yield a 1200-bp fragment in all individuals and a 600-bp fragment in RhD-positive individuals, were used. RESULTS: By standard serologic techniques, we identified samples from 632 RhD-positive and 133 RhD-negative individuals. Two (both from CEPH) of the 632 RhD-positive individuals were characterized as RhD-negative by PCR. Seven of the 133 RhD-negative samples were judged to be RhD-positive by PCR because of the presence of a light 600-bp band. Despite repeated attempts, no bands or DNA were identified in one RhD-negative sample. Thus, the sensitivity of RhD typing by PCR was 99.7%, the specificity 94.0%. CONCLUSION: Based on our data, it would appear that the use of PCR to establish RhD type can be introduced cautiously into current management schemes in the evaluation of RhD sensitization.     

Signal transduction by T- and B-cell antigen receptors: converging structures and concepts

Recent evidence demonstrates that the antigen receptor complexes of T and B lymphocytes are very similar in general architecture and primary and secondary structure of component polypeptides, and that they use common mechanisms for transmembrane signal transduction. Most importantly, multiple subunits of each receptor (Ig-alpha, Ig-beta and Ig-gamma, CD3 gamma, CD3 delta and CD3 epsilon, and T-cell receptor zeta and eta) possess a motif of approximately 26 amino-acids, denoted ARH1, which appears to carry sufficient structural information for receptor-mediated lymphocyte activation.