A rat model of otitis media with effusion caused by eustachian tube obstruction with and without Streptococcus pneumoniae infection: methods and disease course.

OBJECTIVE: To describe the clinical and histopathologic progression of a rat model of otitis media with effusion caused by eustachian tube obstruction (ETO) with and without Streptococcus pneumoniae infection. METHODS: In 164 rats, the left, bony eustachian tube was approached via a ventral incision and obstructed with dental material. Then 108 rats were infected via an intrabullar injection with S pneumoniae. At 48 hours, the infected rats were treated for 5 days with ampicillin. All ears were evaluated by weekly otomicroscopy. On each of days 1, 2, 7, 21, 35, 56, and 112, four rats were killed for histologic study. All effusions were cultured for bacteria. RESULTS: Fourteen rats died of surgical complications; effusion resolved by 2 weeks in 9 rats. During the first few days, infected ears with ETO had bulging tympanic membranes, followed by tympanic membrane retraction, purulent effusion, and otorrhea (50%) over the next few weeks, whereas uninfected ears with ETO developed retraction and serous effusion during the same time frame. At later times, all ears with ETO presented with retraction and serous or serous-mucoid effusion. S pneumoniae was recovered only from the infected ears with ETO (days 1 and 2), with some colonization by nonpathogenic microorganisms observed equally in both groups of ears. Histology showed a typical acute inflammatory reaction in the challenged ears with ETO through day 14 and then a chronic inflammation for all ears with ETO. CONCLUSION: The experimental methods provoked reproducible pathologic signs similar to those for otitis media with effusion. Given the availability of rat-specific reagents, this model is well suited for studies of cytokine elaboration during disease pathogenesis.     

Neurons labeled from locomotor-related ventrolateral funiculus stimulus sites in the neonatal rat spinal cord.

Spinal cord/brainstem preparations from 5- to 8-day-old rats, maintained in vitro, were used to determine the cells of origin and regions of termination of fibers in the superficial ventrolateral funiculus (VLF) at a site from which rhythmic locomotor-like activity can be induced. Rhythmic locomotor-like activity was recorded from lumbar ventral roots after short trains of stimuli (50 Hz for 0.5-2 seconds) delivered to the VLF. Field potential mapping revealed that single VLF stimuli elicited responses in the ipsilateral ventrolateral medulla. Tract-tracing experiments by using biocytin, pressure-injected into the VLF, showed that only a small number of brainstem neurons were labeled and these were scattered bilaterally in the ventrolateral and lateral medulla. Dense concentrations of nerve terminals were found in the lateral reticular nucleus ipsilateral to the stimulation site. Labeled spinal cord neurons included a primary population of large cells distributed bilaterally in lamina VII from T13 to L4, with peak numbers in L2 ipsilaterally and in L3 contralaterally. Intracellular recordings revealed that some L2 and L3 neurons with rhythmic responses to VLF stimulation could be activated antidromically from the VLF, with latencies of less than 1.0 msec. These observations led us to speculate that the superficial VLF carries a locomotor-related tract originating bilaterally in lumbar lamina VII and terminating in the ipsilateral medulla, including the lateral reticular nucleus. This pathway may be part of the spinoreticular or spinoreticulotectal pathway that has been described in many species, the function of which has only loosely been ascribed.     

Targeted disruption of hepatic frataxin expression causes impaired mitochondrial function, decreased life span and tumor growth in mice

We have disrupted expression of the mitochondrial Friedreich ataxia protein frataxin specifically in murine hepatocytes to generate mice with impaired mitochondrial function and decreased oxidative phosphorylation. These animals have a reduced life span and develop multiple hepatic tumors. Livers also show increased oxidative stress, impaired respiration and reduced ATP levels paralleled by reduced activity of iron-sulfur cluster (Fe/S) containing proteins (ISP), which all leads to increased hepatocyte turnover by promoting both apoptosis and proliferation. Accordingly, phosphorylation of the stress-inducible p38 MAP kinase was found to be specifically impaired following disruption of frataxin. Taken together, these findings indicate that frataxin may act as a mitochondrial tumor suppressor protein in mammals.     

Psychoactive drug use among practicing physicians and medical students

We surveyed random samples of 500 practicing physicians and 504 medical students in a New England state during 1984-1985; 70 percent of the physicians and 79 percent of the students responded. Fifty-nine percent of the physicians and 78 percent of the students reported that they had used psychoactive drugs at some time in their lives. In both groups, recreational use most often involved marijuana and cocaine, and self-treatment most often involved tranquilizers and opiates. In the previous year, 25 percent of the physicians had treated themselves with a psychoactive drug, and 10 percent had used one recreationally. Although most of the use was experimental or infrequent, 10 percent of the physicians reported current regular drug use (once a month or more often) and 3 percent had histories of drug dependence. More physicians and medical students had used psychoactive drugs at some time than had comparable samples of pharmacists and pharmacy students. The results suggest a need for renewed professional education about the risks of drug misuse.     

Cloning of cDNA for the bovine IL-2 receptor (bovine Tac antigen).

We have cloned the Tac analog of the bovine IL-2 receptor (IL-2R) cDNA. Using mouse and human cDNA probes, we isolated five bovine IL-2R clones from a lambda gt11 bovine long-term lymphocyte cDNA library. Three of the clones had inserts of 2600 base pairs (bp), the same size as the bovine IL-2R mRNA visualized on Northern blots. The full-length cDNA contain a 190-bp 5' untranslated region, followed by a 825-bp coding region, and a 3' untranslated region that contain 1600 bp. Comparison of the bovine and human IL-2R-coding sequences revealed 71% homology at the nucleotide level. The 3' and 5' non-coding regions were not as homologous, apart from a specific site in the 5'-untranslated region that contained a 5'-upstream start codon. In this region, 24 of 26 nucleotides were identical for the human and bovine cDNAs. Further analysis of the bovine IL-2R sequence also revealed the following: (i) the hydrophobic domains of the IL-2R protein were more conserved between species than the hydrophilic domains, (ii) the predominant site of intracellular IL-2R phosphorylation in mouse and human was a conserved Ser which was not conserved in the bovine sequence, and (iii) there exists a statistically significant amino acid homology with the AIDS gag protein.     

Time‐dependent effects of isoflurane and dexmedetomidine on functional connectivity,spectral characteristics,and spatial distribution of spontaneous BOLD fluctuations

Anesthesia is often necessary to perform fMRI experiments in the rodent model; however, commonly used anesthetic protocols may manifest changing brain conditions over the duration of the study. This possibility was explored in the current work. Eleven rats were anesthetized with 2% isoflurane anesthesia; four rats were anesthetized for a short period (30 min, simulating induction and fMRI setup) and seven rats were anesthetized for a long period (3 h, simulating surgical preparation). Following the initial anesthetic period, isoflurane was discontinued, and a dexmedetomidine bolus (0.025 mg/kg) and continuous subcutaneous infusion (0.05 mg/kg/h) were administered. Blood‐oxygen‐level dependent resting state imaging was performed every 30 min from 0.75 h post dexmedetomidine bolus until 5.75 h post‐bolus. Evaluation of power spectra obtained from time courses in the primary somatosensory cortex revealed, in general, a monotonic increase in low‐frequency power (0.05–0.3 Hz) in both groups over the duration of resting state imaging. Greater low‐band spectral power (0.05–0.15 Hz) is present in the short isoflurane group for the first 2.75 h, but the spectra become highly uniform at 3.25 h. The emergence of a ~0.18 Hz peak, beginning at the 3.75 h time point, exists in both groups and evolves similarly, increasing in strength as the duration of dexmedetomidine sedation (and time since isoflurane cessation) extends. In the long isoflurane group only, bilateral functional connectivity strengthens with anesthetic duration, and correlation is linearly linked to low‐band spectral power. Convergence of connectivity and spectral metrics between the short and long isoflurane groups occurs at ~3.25 h, suggesting the effects of isoflurane have subsided. Researchers using dexmedetomidine following isoflurane for functional studies should be aware of the duration specific effects of the pre‐scan isoflurane durations as well as the continuing influences of long‐term imaging under dexmedetomidine. Copyright © 2014 John Wiley & Sons, Ltd.     

Clinical Response to COVID-19 and Utilization of an Emergency Dental Clinic in an Academic Institution

IntroductionThe spread of coronavirus disease 2019 (COVID-19) in the spring of 2020 resulted in the temporary suspension of elective dental procedures and clinical dental education in academic institutions. This study describes the use of the Tufts University School of Dental Medicine emergency dental clinic during the peak surge in COVID-19 cases in Massachusetts, highlighting the number of endodontic emergencies.MethodsAggregate data from clinical encounters and call records to an emergency triage phone line from March 30 through May 8, 2020, were used to describe the characteristics of dental emergencies, clinical encounters, and procedures performed.ResultsA total of 466 patient interactions occurred during this period, resulting in 199 patients advised by phone and 267 clinical encounters. The most common dental emergencies were severe dental pain from pulpal inflammation (27.7% of clinical encounters) followed by a surgical postoperative visit (13.1%). The most frequent procedures were extractions (13.9% of clinical encounters) and surgical follow-up (13.5%); 50.2% of the clinical encounters were categorized as aerosol generating, and 86.1% of encounters would have required treatment in a hospital emergency department if dental care was not available. There were no known transmissions of severe acute respiratory syndrome coronavirus-2 among clinic providers, patients, or staff during this period.ConclusionsThese results highlight the importance of endodontic diagnosis and treatment in the provision of emergency dental care during a pandemic and demonstrate that dental treatment can be provided in a manner that minimizes the risk of viral transmission, maintaining continuity of care for a large patient population.