Analysis of antibiotic residues in milk from healthy dairy cows treated with bovine mastitis ointment using ultra-performance liquid chromatography coupled with electrospray tandem mass spectrometry

This study was conducted to analyze penicillin G (PEG), streptomycin (STR) and neomycin (NEO) residues in milk of healthy lactating cows. Milk samples were collected from all four quarters of 12 dairy cows 2–7 days after intramammary infusions of an ointment containing PEG, STR and NEO once (n = 4; group I) or twice (n = 4, group II) daily. Ultra-performance liquid chromatography coupled with electrospray tandem mass spectrometry was used to determine the antibiotic residues in the samples. The correlation coefficient (r 2) of the calibration curves for all antibiotics was > 0.999 and the limits of detection and quantification were 0.002–0.005 µg/mL and 0.007–0.02 µg/mL, respectively. Recovery rates were ranged from 75.5 to 92.3%. In group I, PEG, STR and NEO residues were detected in milk at 2, 3 and 2 days post-treatment, respectively, which were below the maximum residue limit (MRL). In group II, PEG, STR and NEO residues were detected in milk at 2, 3 and 3 days post-treatment, respectively, which were bellow the MRL. These results suggest that a 3-day for milk withdrawal period after the ointment treatment might be sufficient for reduction of the antibiotic residues below the MRL.

Comparison of blood concentration for oral administration of micronized and non-micronized amoxicillin in Sprague-Dawley rats / 동물의과학연구지

Amoxicillin, a well-known antibiotic, has a broad spectrum against gram-negative and gram-positive bacteria. This experiment was conducted in order to investigate the effect of micronized and non-micronized amoxicillin prepared using different comminution techniques on change in blood concentration of rats. Forty adult male Sprague Dawley rats (6~7 weeks of age, body weight 128.3 +/- 10.7 g) were randomly allocated to two treatment groups: micronized amoxicillin (MA) group treated with micronized amoxicillin trihydrate powder (particle size, over 90% of 10 microm), non-micronized amoxicillin (NMA) group treated with non-micronized amoxicillin trihydrate powder (particle size, over 70% of 100 microm), given 480 mg/kg body weight once daily for four days. The results showed a significant increase in serum concentration in the MA group on days 3 and 4, compared to the NMA group (P<0.05). In particular, serum concentration of the MA group on day 4 was increased almost two times that of the NMA group. The results indicate that due to the increase of the drug's oral bioavailability, higher serum concentration would be achieved with the micronized amoxicillin trihydrate than with the non-micronized drug.

Secondary Trigeminal Neuralgia Caused by Pharyngeal Squamous Cell Carcinoma: A Case Report

Trigeminal neuralgia (TN) is characterized by recurrent paroxysms of unilateral facial pain that typically is severe, lancinating, and activated with cutaneous stimulation. There are two types of TN, classical TN and atypical TN. The pain nature of classical TN are the same as those described above, whereas atypical TN is characterized by constant, burning pain. We describe the case of a 49-year-old male presenting with right-sided facial pain. The patient was diagnosed with temporomandibular joint disorder at a dental clinic and was on medical treatment, but his symptoms worsened gradually. He was referred to our pain clinic for further evaluation. Radiologic evaluation, including MRI, showed a parapharyngeal tumor. For the relief of TN, a right mandibular nerve (V3) root block was performed at our pain clinic, and then he was scheduled for radiation and chemotherapy.