STJMMABY. A series of experiments has been carried out in order to develop antibiotic preparations which, when infused into the udder at drying-off, eliminate established infection and prevent new infection from occurring in the dry period. It has been shown that the persistence of antibiotic in the dry udder is affected by the solubility of the antibiotic salt, the quantity of antibiotic infused and the base in which it is formulated. Whereas 0-2 g cloxacillin as the sodium salt infused in a 3 % aluminium monostearate in mineral oil base after the last milking of lactation persisted for less than 1 week, 0-5 and 1-0 g cloxacillin in the form of the benzathine salt, in a similar base, usually persisted for 3 weeks.Secretions removed from the udders of dry cows inhibited the growth of Bacillus subtilis and Sarcina lutea but not 2 strains of staphylococci.The dry period between consecutive lactations is particularly important in the control of udder disease. It is a time when many new infections occur and because few old infections spontaneously recover during this period, a higher proportion of cows is found to be infected at calving than at the preceding drying-off. Further, it is only during the dry period that the regeneration of damaged udder secretory issue occurs and when established infection can be eliminated without adding antibiotic to saleable milk. Based on these considerations, Neave, Dodd & Kingwill (1966) have proposed a control of udder disease in which the elimination of infection in the dry period is an essential part.
SummaryPenicillin G at a dose level of 1 and 5 million units infused in a quick release base or an aqueous solution into quarters of cows after the last milking of the lactation persisted in infused quarters for about 4 days. From 1 h after infusion penicillin was detected in the venous blood and from 2 h after infusion in non-infused quarters.
SummaryThe sensitivities of isolates of bovine staphylococci, corynebacteria and streptococci to various antibiotics were determined. The growth of various strains of Staphylococcus aureus was inhibited by the following range of concentrations of antibiotic: cloxacillin, 0·07 to 0·6 μg/ml; penicillin G, 0·018 to > 250 μg/ml; streptomycin, 1·25 to > 250 µg/ml; novobiocin, 0·15 to 25 μg/ml; chlortetracycline, 0·6 to 10 µg/ml. The concentrations of cloxacillin required to inhibit growth were between 0·15 and 1·25 μg/ml for strains of Streptococcus agalactiae; 0·07 to 0·3 μg/ml for strains of Streptococcus dysgalactiae and 0·15 to 0·6 μg/ml for strains of Streptococcus uberis.The corynebacteria were generally sensitive to the penicillins (ampicillin, penicillin G, phenethicillin and cloxacillin), but showed least sensitivity to cloxacillin which had a similar activity to that of chlortetracycline, neomycin and oleandomycin. Chloramphenicol and streptomycin were less active than the penicillins and novobiocin showed little activity against Corynebacterium ulcerans.A clear relationship was confirmed between the sensitivity of staphylococci to cloxacillin and penicillin G. Some indication was found of an association between the sensitivity of staphylococci to cloxacillin and the success of cloxacillin intramammary therapy in the non-lactating udder. There was no evidence of a change in the sensitivity of Staph. aureus following exposure to cloxacillin in the non-lactating udder.
Introduction The COVID-19 pandemic has disrupted the lives of many people. The risk and interpersonal cost of infection as well as the public health measures implemented to mitigate the spread likely have psychological costs. Yet, due to the ever-changing nature of the pandemic, psychological impact has been difficult to capture through research efforts. Here, we leveraged an on-going, geographically representative study to examine the relationship among sleep, stress, and memory function before and during the COVID-19 pandemic. Methods Participants (N=1958, aged=18+) were enrolled in a 21-day ecological momentary assessment study. All participants provided demographic information, including zipcodes, which were used to identify rural vs urban locale. Participants were instructed to complete up to three daily check-ins during set time windows—morning, afternoon, night--via a phone application. At each morning check-in, participants were asked about sleep duration and quality, and at every check-in, participants reported perceived stress ratings. Participants also completed a paired-associates memory task on Day 2 of the study. For the task, participants were instructed to encode a list of 20 unrelated word and picture pairs. Immediately after encoding, participants were tested on five picture-word pairs. Tests 2 and 3 occurred on a unique set of five words from the initial list three and six days after initial encoding, respectively. Pre- and during COVID assessments were defined as March 2019 to March 2020 and April 2020 to October 2021, respectively. Results Mixed effects binomial regressions revealed that pre-COVID, longer sleep durations were associated with better memory performance (ß=.09, p<.05), and counterintuitively, higher subjective sleep quality was associated with worse memory performance (ß=-.35, p<.001). During COVID, longer nighttime awakenings were associated with poorer memory performance (ß=-.01, p<.05) and living in a rural vs urban environment was associated with poorer memory performance (ß=.48, p<.01). Older age was associated with worse memory performance pre- and during COVID (ß=-.01, p<.01). Stress was not related to memory pre- or during COVID in these models. Conclusion Findings support that sleep difficulty before and during the pandemic likely impacts memory function. Additionally, those living in rural U.S. environments may be particularly vulnerable to cognitive changes in the pandemic context. Support (If Any)
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