Chloramphenicol 1. Hazards of use and the current regulatory environment

Chloramphenicol is a broad-spectrum antibiotic which has enjoyed extensive use in both medical and veterinary practice. Shortly after its introduction in the late 1940s, the use of chloramphenicol was associated with the induction of an idiosyncratic form of aplastic anaemia in man. This rare and unpredictable adverse effect has since been associated not only with systemic use but with topical applications, as well as occupational exposure. Recognition of the small risk of a potentially fatal adverse reaction, together with the risk of selection of chloramphenicol-resistant pathogens, has led to restrictions on the veterinary uses of chloramphenicol. In Australia at present, the use of chloramphenicol is only permitted in small animals. Its use is specifically prohibited in food-producing animals, including horses.     

Diethylstilboestrol—historical background and current regulatory status

Diethylstilboestrol is a non-steroidal orally active oestrogen that in the past has been widely used in a variety of conditions in both medical and veterinary fields. In recognition of potential systemic availability to man of DES in the tissues of treated food-producing animals, together with an understanding of the potential teratogenic and carcinogenic toxicity of DES in man, the veterinary use of DES has been restricted to oral use in small animals only. Use of DES is prohibited in all food-producing animals.     

Fetal bladder outlet obstruction in a stillborn bovine fetus

A stillborn bovine male fetus with abdominal distention, arthrogryposis and atresia ani was presented for diagnostic evaluation. At necropsy, this fetus had a large amount of ascites, urachal obstruction and marked bladder distention. The ventral surface of the bladder had ruptured and attached to the abdominal wall by fibrinous adhesions. There was bilateral hydronephrosis with moderate pelvic dilatation and cortical attenuation. The rectum was filled with meconium but the anus was imperforate. The right forelimb was contracted. The cause(s) of these abnormalities could not be determined; however, we believe that developmental abnormalities during embryogenesis may be the result of chromosomal abnormalities.     

Personal and household factors involved in recent Rickettsia exposure in a rural population from Yucatán,Mexico

The aim of the study was to describe the epidemiological factors associated with the risks of recent Rickettsia exposure in inhabitants of a rural population from Yucatán, Mexico. The study included 130 inhabitants from Maxcanú, Yucatán. Blood samples were collected to detect IgM and IgG antibodies against Rickettsia typhi and Rickettsia rickettsii by an indirect immunofluorescence antibody test. Additionally, nested polymerase chain reaction was performed to amplify fragments of the 17kDa and sca5 genes. Previously, an epidemiological questionnaire was applied focused on collecting information on personal and housing exposure variables related to the recent infection with Rickettsia to determine epidemiological associations. Results that exhibited a p‐value < .25 were included in a generalized multinomial logistic linear model to determine the variables involved with the risk of contact or Rickettsia infection. In all, 76% (99/130) of the participants presented with immunoglobulin titres against the Rickettsia species evaluated, while rickettsial DNA was detected in 35.4% (46/130) of the participants. The association analysis with the personal exposure variables showed that the productive age group (OR = 0.32; 95% CI = 0.10–1.03) and the elders group (OR = 0.12; 95% CI = 0.01–0.83) were protective factors for recent infection with R. typhi, taking as reference the school group. The presence of a family orchard in the home (OR = 7.56; 95% CI = 1.62–35.29) was a risk factor for recent infection with R. rickettsii. Presumably, the presence of ectoparasites (OR = 2.71; 95% CI = 0.90–8.09) at home was a risk factor for recent infection with both Rickettsia species. Recent infection was demonstrated in inhabitants from Maxcanú, Yucatán. A high seropositive frequency was obtained. The results highlight the importance of the family garden and the presence of ectoparasites in the home as risk factors associated with recent infection with Rickettsia in inhabitants from Maxcanú.     

Time-reversed lasing and interferometric control of absorption

In the time-reversed counterpart to laser emission, incident coherent optical fields are perfectly absorbed within a resonator that contains a loss medium instead of a gain medium. The incident fields and frequency must coincide with those of the corresponding laser with gain. We demonstrated this effect for two counterpropagating incident fields in a silicon cavity, showing that scattering [corrected] can be modulated [corrected] by two orders of magnitude, the maximum predicted by theory for our experimental setup. In addition, we showed that absorption can be reduced substantially by varying the relative phase of the incident fields. The device, termed a "coherent perfect absorber," functions as an absorptive interferometer, with potential practical applications in integrated optics.     

Synergistic effect of ERK inhibition on tetrandrine-induced apoptosis in A549 human lung carcinoma cells

Tetrandrine (TET), a bis-benzylisoquinoline alkaloid from the root of Stephania tetrandra, is known to have anti-tumor activity in various malignant neoplasms. However, the precise mechanism by which TET inhibits tumor cell growth remains to be elucidated. The present studies were performed to characterize the potential effects of TET on phosphoinositide 3-kinase/Akt and extracellular signal-regulated kinase (ERK) pathways since these signaling pathways are known to be responsible for cell growth and survival. TET suppressed cell proliferation and induced apoptosis in A549 human lung carcinoma cells. TET treatment resulted in a down-regulation of Akt and ERK phosphorylation in both time-/concentration-dependent manners. The inhibition of ERK using PD98059 synergistically enhanced the TET-induced apoptosis of A549 cells whereas the inhibition of Akt using {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002 had a less significant effect. Taken together, our results suggest that TET: i) selectively inhibits the proliferation of lung cancer cells by blocking Akt activation and ii) increases apoptosis by inhibiting ERK. The treatment of lung cancers with TET may enhance the efficacy of chemotherapy and radiotherapy and increase the apoptotic potential of lung cancer cells.     

Persistence of passively transferred antibodies in porcine Taenia solium cysticercosis. Cysticercosis Working Group in Peru.

We evaluated the presence and persistence of anticysticercal antibodies in piglets born to Taenia solium infected sows. Infected sows from a disease-endemic area of Peru were transported to a nondisease-endemic area and impregnated. Serum samples were collected from sows and piglets on Day 2 through Week 35 after birth. Using an immunoblot specific for cysticercosis, Ig isotypes to 7 cyst antigens were measured and quantified. Serum samples from the piglets contained detectable antibodies from Week 1 through Week 35 (27 weeks after weaning). The primary Ig isotype present in both sows and piglets was IgG. Antibodies did not appear in piglet serum samples until after suckling, demonstrating that anti-cysticercal antibodies are transferred solely via colostrum. Our data have shown that maternally transferred antibodies to cyst antigens may persist through much of a pig's life. Therefore, the presence of passively transferred antibodies must be considered in studies that examine the prevalence of cysticercosis in pigs. Furthermore, when designing control strategies for cysticercosis, careful evaluation and selection of sentinel pigs becomes a crucial component of sentinel selection.