Optical polarization from colliding stellar stream shocks in a tidal disruption event.

A tidal disruption event (TDE) occurs when a supermassive black hole rips apart a passing star. Part of the stellar material falls toward the black hole, forming an accretion disk that in some cases launches a relativistic jet. We performed optical polarimetry observations of a TDE, AT 2020mot. We find a peak linear polarization degree of 25 ± 4%, consistent with highly polarized synchrotron radiation, as is typically observed from relativistic jets. However, our radio observations, taken up to 8 months after the optical peak, do not detect the corresponding radio emission expected from a relativistic jet. We suggest that the linearly polarized optical emission instead arises from shocks that occur during accretion disk formation, as the stream of stellar material collides with itself.

Simulation of human exposure to benzylpenicillin residues via pork originating from pigs fed with a dairy by-product.

The use of food industry by-products for feeding is restricted by European Union by-product regulation (1774/2002). However, the actual public health risks involved in the use of such products are poorly recognized. This study focuses on bovine milk rejected at the dairy because of a positive result in antimicrobial drug testing and thereafter used as feed for finisher pigs in Finland. In theory, this current practice could expose pork consumers to antimicrobial drug residues. Raw bulk milk samples originating from rejected lots were analysed with a multiresidue method detecting five beta-lactams, including benzylpenicillin. Based on the probabilistic simulation model developed, concentrations of benzylpenicillin in pork invariably remained below 1% of the maximum residue limit. Therefore, the use of this by-product as feed with the current practice was considered to pose only a negligible risk to consumers of pork products.

Determination of malachite green residues in rainbow trout muscle with liquid chromatography and liquid chromatography coupled with tandem mass spectrometry.

A method for the determination of malachite green and its major metabolite leucomalachite green in rainbow trout muscle is reported with limits of detection of 0.8 and 0.6 microg kg(-1), respectively. Residues were extracted with an acetonitrile-acetate buffer mixture and partitioned into methylene chloride. Clean-up of the extracts was performed on alumina and propylsulfonic acid solid-phase extraction columns using the automated solid-phase extraction system. The chromatographic separation of malachite green and leucomalachite green was achieved on a Chromspher 5B column using an acetonitrile-acetate buffer mobile phase. Leucomalachite green was converted to malachite green by post-column oxidation before spectrophotometric detection at 600 nm. The mean recoveries of malachite green and leucomalachite green from control rainbow trout muscle spiked at 2-50 microg kg(-1) were 65% (range 63.4-65.9%, relative standard deviation 3.9-16.1%) and 74% (range 58.3-82.6%, relative standard deviation 3.3-11.4%), respectively. Qualitative confirmation of the determined residues was performed with liquid chromatography coupled with tandem mass spectrometry detection with limits of detection of 2.5 and 1 microg kg(-1) for malachite green and leucomalachite green, respectively.

Cadmium intake of moose hunters in Finland from consumption of moose meat, liver and kidney.

Although the average cadmium intake in Finland is about 10 microg day(-1), some risk groups can be identified. This study assessed cadmium intake from the consumption of moose meat, liver and kidneys by moose hunters. Consumption data from a postal questionnaire were combined with a representative database on moose cadmium concentrations. Cadmium intakes were calculated as point estimates for all respondents (n = 711), for those consuming moose meat, liver and/or kidneys, and for the highest decile of those. Probabilistic modelling using the Monte Carlo technique was used to simulate the distribution of dietary cadmium exposure. Of the respondents, 69% consumed moose liver and only 23% moose kidneys. The consumption of moose liver or kidneys significantly increased cadmium intake, whereas moose meat (median consumption 17 kg year(-1) person(-1)) contributed only slightly (0.16 microg day(-1) person(-1)) to the daily total cadmium intake. In the simulation, 10% of the moose hunters had an intake of > 8.76 microg day(-1) (14.6% of PTWI for a 60-kg person) from moose. Point estimates provided only a partial understanding of the potential exposure. Simulated distributions of intake were more useful in characterizing exposure. The study revealed that heavy users of moose organs have a relatively narrow safety margin from the levels of cadmium probably causing adverse health effects.

A microbiological six-plate method for the identification of certain antibiotic groups in incurred kidney and muscle samples.

A microbiological method was developed for group level identification of antibiotics in incurred kidney and muscle samples from cattle and pigs. The method was composed of six test bacterium-plate growth medium combinations and the result was recorded as a profile of growth inhibition zones. The sample profiles were compared to two sets of references: one constructed with standard antibiotic solution profiles, and the other with these combined with profiles of microbiologically and chemically identified residues from incurred samples. The algorithm employed in profile comparison located the minimal sum of absolute pairwise differences over the tests, with the addition of a number of experimentally observed intra-test criteria. Chemical identification and quantitation of incurred residues was based on liquid chromatography. The method identified penicillin G as a penicillinase sensitive penicillin, enrofloxacin and ciprofloxacin belonging to fluoroquinolone group, and oxytetracycline belonging to tetracycline group. Each of these residues was microbiologically identified below the Maximum Residue Limit (MRL) for kidney tissue. Combining sample profiles with the standard reference data set did not enhance the resolution. Microbiological and chemical identification test results were in good agreement. The results of this study show that a microbiological identification method is a useful tool in preliminary characterisation of antibiotic residues in animal tissues.

Microbiological and chemical detection of incurred penicillin G, oxytetracycline, enrofloxacin and ciprofloxacin residues in bovine and porcine tissues.

Incurred penicillin G, oxytetracycline, enrofloxacin and ciprofloxacin residues in bovine and porcine muscle and kidney samples were analysed by microbiological and chemical methods, the former using Bacillus subtilis BGA as a test organism on agar media of pH 6, pH 7.2 and pH 8 and the latter using liquid chromatography. Least squares fits between the logarithms of the chemically obtained concentrations of the antimicrobials and the widths of the inhibition zones were used to estimate the inhibition zone widths corresponding to the maximum residue limit concentrations. In vitro sensitivities were determined with standard antimicrobial solutions. The results indicate that if B. subtilis BGA is used as a test organism, muscle tissue cannot be used as test material for screening oxytetracycline, enrofloxacin and ciprofloxacin residues on the plates used in this study, while penicillin G can be screened from muscle tissue. Because of the numerous factors causing or increasing variation in the analysis, the inhibition zone caused by a given antibiotic concentration cannot be predicted precisely. Therefore, a positive agar diffusion test needs to be confirmed chemically. If a kidney sample gives a positive agar diffusion test result, the antimicrobial concentration in a muscle sample from the same carcass should be checked chemically.

Detection of canine parvovirus antigens with antibodies to synthetic peptides.

Antibodies produced in rabbits against an 18-amino acid peptide (peptide 1, NSLPQSEGATNFGDIGVP) of capsid protein VP2/residues 292-309 of canine parvovirus (CPV) or against an 18-amino acid peptide (peptide 2, GKRNTVLFHGPASTKGKS) of nonstructural protein NS1/residues 391-409 of CPV identified, in immunofluorescence analysis, viral antigens in canine A 72 cells infected with CPV. Antibodies to peptide 2 also identified viral antigens in bovine cells infected with bovine parvovirus. In western blot analysis, antibodies to peptide 1 and peptide 2 also detected viral antigens derived from blue fox parvovirus, feline parvovirus, mink enteritis virus and raccoon dog parvovirus. The peptide antibodies could be used as convenient tools in diagnosis of infections caused by CPV or closely related viruses affecting cats, minks, blue foxes and raccoon dogs.

Liquid chromatographic determination of biogenic amines in dry sausages.

A liquid chromatographic method is described for the determination of biogenic amines found in dry sausages: tryptamine, phenylethylamine, putrescine, cadaverine, histamine, serotonin, tyramine, spermidine, and spermine. Amines were extracted with perchloric acid solution and derivatized with dansyl chloride. After derivatization, ammonia was added to remove an interfering peak near cadaverine. Liquid chromatographic separations were performed by using a Spherisorb ODS2 column and an ammonium acetate-acetonitrile gradient elution program. The limits of determination of the individual amines were 1-5 mg/kg. This method is also applicable to detection of amines in other food samples.

Open lung biopsy in children with diffuse pulmonary lesions.

During the period 1973-81, open lung biopsy was performed in 33 consecutive children, aged 1 month to 13 years, to exclude or diagnose Pneumocystis carinii pneumonia and to differentiate other interstitial pulmonary lesions. Twenty-one of the patients were undergoing immunosuppressive treatment because of their malignant disease. The clinical diagnosis was correct only in 55% of the patients, but open lung biopsy and histological examination gave the final answer in every patient. Pneumocystis carinii was the causative organism in 67% of the immunosuppressed patients. Nine patients had postoperative complications, 5 of which were mild in nature and resolved spontaneously. Three patients had to be reoperated on for postoperative sequelae. There was one death possibly caused by surgical intervention--tension pneumothorax 10 days after surgery. It is concluded that open lung biopsy is the most reliable method in the diagnosis of diffuse interstitial pneumonitis in children. The need of anaesthesia is no contra-indication and the benefits of the biopsy far outweight the risks of its complications.