Ingestion and effects of polystyrene nanoparticles in the silkworm Bombyx mori.

Information on the occurrence and effects of nanoplastics in ecosystems worldwide currently represent one of the main challenges from the ecotoxicological point of view. This is particularly true for terrestrial environments, in which nanoplastics are released directly by human activities or derive from the fragmentation of larger plastic items incorrectly disposed. Since insects can represent a target for these emerging contaminants in land-based community, the aim of this study was the evaluation of ingestion of 0.5 µm polystyrene nanoplastics and their effects in silkworm (Bombyx mori) larvae, a useful and well-studied insect model. The ingestion of nanoplastics, the possible infiltration in the tissues and organ accumulation were checked by confocal microscopy, while we evaluated the effects due to the administered nanoplastics through a multi-tier approach based on insect development and behaviour assessment, as endpoints at organism level, and the measurements of some biochemical responses associated with the imbalance of the redox status (superoxide dismutase, catalase, glutathione s-transferase, reactive oxygen species evaluation, lipid peroxidation) to investigate the cellular and molecular effects. We observed the presence of microplastics in the intestinal lumen, but also inside the larvae, specifically into the midgut epithelium, the Malpighian tubules and in the haemocytes. The behavioural observations revealed a significant (p < 0.05) increase of erratic movements and chemotaxis defects, potentially reflecting negative indirect effects on B. mori survival and fitness, while neither effect on insect development nor redox status imbalance were measured, with the exception of the significant (p < 0.05) inhibition of superoxide dismutase activity.

First evidence of protein modulation by polystyrene microplastics in a freshwater biological model.

Microplastics (MPs) are now one of the major environmental problems due to the large amount released in aquatic and terrestrial ecosystems, as well as their diffuse sources and potential impacts on organisms and human health. Still the molecular and cellular targets of microplastics' toxicity have not yet been identified and their mechanism of actions in aquatic organisms are largely unknown. In order to partially fill this gap, we used a mass spectrometry based functional proteomics to evaluate the modulation of protein profiling in zebra mussel (Dreissena polymorpha), one of the most useful freshwater biological model. Mussels were exposed for 6 days in static conditions to two different microplastic mixtures, composed by two types of virgin polystyrene microbeads (size = 1 and 10 µm) each one. The mixture at the lowest concentration contained 5 × 105 MP/L of 1 µm and 5 × 105 MP/L of 10 µm, while the higher one was arranged with 2 × 106 MP/L of 1 µm and 2 × 106 MP/L of 10 µm. Proteomics' analyses of gills showed the complete lack of proteins' modulation after the exposure to the low-concentrated mixture, while even 78 proteins were differentially modulated after the exposure to the high-concentrated one, suggesting the presence of an effect-threshold. The modulated proteins belong to 5 different classes mainly involved in the structure and function of ribosomes, energy metabolism, cellular trafficking, RNA-binding and cytoskeleton, all related to the response against the oxidative stress.

New benzomorphan derivatives of MPCB as MOP and KOP receptor ligands.

There is considerable interest in developing KOP Opioid receptor ligands as clinically useful analgesics. Moreover, compounds with mixed KOP receptor and mu-opioid peptide (MOP) receptor agonist/antagonist properties could have a better therapeutic potential. The benzomorphan-based synthetic ligands MPCB and CCB have been shown to bind KOP receptors with high affinity and selectivity. We report here a series of compounds synthesized to perform structure-affinity relationship (SAR) studies on MPCB. The aim of this study was to optimise KOP receptor-ligand interaction and to modulate MOP receptor selectivity. In the benzylamide analogue of MPCB (compound 9) the presence of a third aromatic nucleus, at an appropriate distance and conformation with respect to aromatic pharmacophoric residues, increased KOP receptor affinity by about 6-fold compared to MPCB (Ki = 35 nM and Ki = 240 nM, respectively). Instead, compound 28 with a tertiary amino group in the nitrogen substituent displayed a comparable KOP receptor affinity (Ki = 179 nM) but also high MOP receptor affinity (Ki = 45 nM). Thus, the present study shows that in benzomorphan-based ligands the presence of different functional groups in the nitrogen substituent, ranging from a positive charged amine to an additional aromatic ring, is able to promote the correct aligment of aromatic pharmacophoric residues with MOP and KOP receptor types. Evaluation of docking simulations of compounds 9 and 28 into the KOP and MOP receptor displayed selective ligand interactions with the important amino acid residues Tyr320 (TMVII) and Trp318 (TMVII), respectively.

(+)-and (-)-Phenazocine enantiomers: Evaluation of their dual opioid agonist/σ1 antagonist properties and antinociceptive effects.

cis-N-Substituted N-normetazocine enantiomers possess peculiar pharmacological profiles. Indeed, dextro enantiomers bind with high affinity σ1 receptor while opposite enantiomers bind opioid receptors. In spite of their stereochemistry, cis-N-2-phenylethyl N-normetazocine (phenazocine) enantiomers showed mixed opioid/σ1 receptor profiles and a significant in vivo analgesia. To the best of our knowledge, there is no information available regarding the evaluation of σ1 pharmacological profile in the antinociceptive effects of (+)- and (-)-phenazocine. Therefore, the present study was designed to ascertain this component by in vitro and in vivo studies. In particular, we tested the σ1 affinity of both enantiomers by a predictive binding assay in absence or presence of phenytoin (DPH). Our results showed that DPH (1 mM) did not increase the σ1 receptor affinity of (+)-and (-)-phenazocine (Ki = 3.8 ± 0.4 nM, Ki = 85 ± 2.0 nM, respectively) suggesting a σ1 antagonist profile of both enantiomers. This σ1 antagonistic component of two phenazocine enantiomers was corroborated by in vivo studies in which the selective σ1 receptor agonist PRE-084, was able to unmask their σ1 antagonistic component associated with the opioid activity. The σ1 antagonistic component of (+)- and (-)-phenazocine may justify their analgesic activity and it suggests that they may constitute useful lead compounds to develop new ligands with this dual activity.

Detection of levodopa, dopamine and its metabolites in rat striatum dialysates following peripheral administration of L-DOPA prodrugs by mean of HPLC-EC.

A high performance liquid chromatography (HPLC) method was developed to detected simultaneously L-dihydroxyphenylalanine (L-DOPA), dopamine (DA), dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in rat striatum dilaysates following oral administration of L-DOPA or its prodrugs. The chromatographic system uses a reversed-phase C18 column with electrochemical detection at +0.30 V. Mobile phase consisted of 0.05 M citric acid, sodium EDTA 50 microM, sodium octylsulphonate 0.4 nM at pH of 2.9 and 8% methanol (v/v) at a flow rate of 1 ml/min. The calibration curves were linear over the concentration range of 10nm to 100 microM and the lower limits of detections were 125 fmol for L-DOPA, 50 fmol for DOPAC, 250 fmol for DA and 150 fmol for HVA at signal noise to ratio of 3. The repeatability (or intra-day precision), expressed by the relative standard deviation, were better than 4%. The construction of microdialysis probes has been described. The in vitro relative recoveries of each microdialysis probe were evaluated and the results show that they are similar and reproducible for all the analytes with CVs from 1 to 4%. The HPLC-EC method was applied to detect the extracellular levels of L-DOPA, DA, DOPAC and HVA in the striatum dialysates of freely moving rats after oral administration of six new potential L-DOPA prodrugs.

Hyperpyrexia associated with intravenous cimetidine therapy. Report of a case.

Fever as a drug reaction is common. It has, however, not been widely recognized as a complication of cimetidine therapy. We observed a patient who, during the administration of intravenous cimetidine, became hyperpyretic and confused. Six hours after cimetidine therapy was discontinued, he became afebrile. The potential for hyperpyrexia to occur with cimetidine should be considered in patients with unexplained fever who are receiving this drug.

Effect of a change in house staff work schedule on resource utilization and patient care.

Concern is frequently expressed by health care providers and consumers that the work environment of physicians-in-training may adversely affect their performance. This article documents the effects of changing from a traditional rotational overnight call schedule for house staff to a schedule designed to reduce sleep deprivation, distribute admissions more evenly throughout the week, and improve continuity of inpatient care on the internal medicine service of a large, university-affiliated Veterans Affairs Medical Center. In a prospective, time-series study, the hypothesis that this change would improve the efficiency and quality of medical care was evaluated by comparing the hospital course of the patients admitted during 4-week periods prior to and following the change in work schedule. The patients in the preintervention group do not differ significantly from those in the postintervention group in any identifiable clinical characteristics. The length of stay was shorter (10.9 vs 9.3 days) and the number of laboratory tests ordered per patient was smaller (24.0 vs 19.0) for patients cared for under the new work schedule compared with those cared for under the traditional work schedule. Resident physicians also committed fewer medication errors under the new work schedule (16.9 vs 12.0 per 100 patients discharged). We conclude that altering the house staff work schedule affects patient care and can lead to a decrease in utilization of health care resources.

Reduction of unnecessary intravenous catheter use. Internal medicine house staff participate in a successful quality improvement project.

BACKGROUND: We had previously observed that a large proportion of peripheral intravenous (i.v.) catheters placed in patients on a regular medical ward at our hospital were unnecessary. We conducted the current study to assess the effect of a quality improvement project led by medicine house staff on the prevalence of unnecessary peripheral i.v. catheters (those without any therapeutic use, referred to as idle). METHODS: All patients on four regular-care medical wards of a large university-affiliated veterans hospital were included in the study. The proportion of i.v. catheter episodes in which catheters were idle 2 or more consecutive days (idle episodes) and the proportion of patients exposed to an idle catheter episode were determined by direct observation, chart review, and patient interview before and after a multidisciplinary quality improvement task force defined guidelines for appropriate i.v. catheter use and made recommendations for hospital policy changes related to i.v. catheter use. RESULTS: The proportion of all i.v. catheter episodes that were idle catheter episodes decreased significantly after the intervention (42% before vs 29% after, P < .01), as did the proportion of patients with an i.v. catheter who had at least one idle i.v. catheter episode (43% vs 27%, P < .001). CONCLUSIONS: This quality improvement effort successfully reduced unnecessary i.v. catheter use. We suspect that house-staff involvement in the intervention was critical. We encourage other academic medical centers to involve house staff in quality improvement activities to improve patient care and to enhance the education of house staff regarding quality improvement processes.

Are things different in the light of day? A time study of internal medicine house staff days.

PURPOSE: To determine how internal medicine house staff spend their days and compare activities during the day with those previously observed during night call. SETTING: University-affiliated Veterans Affairs Medical Center. DESIGN: Two internal medicine house staff teams (one PGY-1 [postgraduate year] and one PGY-2 or PGY-3) observed during 5 short call admitting days. MEASUREMENTS: Time in each activity recorded by trained observers, computed, summed, and compared with that of similar activities of house staff on night call. RESULTS: House staff admitted an average of two patients each day. They spent, on average, 25 minutes per patient performing new patient histories and physical examinations, 29 minutes charting new patient information, and were interrupted after an average of 12 minutes during the new patient evaluation compared with 20, 19, and 7 minutes at night (p > 0.05). The average house officer spent 44 minutes in nonphysician duties and 11 minutes answering pages during the day. On average, house staff spent 3 minutes each day talking in person with patients' families. CONCLUSIONS: A significant amount of time each day was spent performing nonphysician duties. Little time was spent evaluating each patient or in person with patients' families and similar amounts of time were spent in charting and in patient evaluation. House staff appeared to spend more time with new patients during the day than they did at night, although this finding was not statistically significant. As noted during night call, evaluations were frequently interrupted. Future studies should examine why house staff choose to distribute their time in the manner described in this and similar studies.

Ruptured abdominal aortic aneurysm: the internist as diagnostician.

PURPOSE: To define the clinical features and assess the frequency and causes of missed diagnoses of ruptured abdominal aortic aneurysm (AAA) in patients initially presenting to internists. PATIENTS: All identified patients with ruptured AAA presenting to internists during a 7 1/2-year period at a large academic medical center. METHOD: Chart review. RESULTS: We identified 23 patients with a ruptured AAA presenting to internists. Most had abdominal pain and tenderness, back or flank pain, and leukocytosis, whereas anemia and profound hypotension (systolic blood pressure below 90 mm Hg) were uncommon at presentation. In 14 cases (61%), the diagnosis of ruptured AAA was initially missed. Nine patients had an interval of 24 hours or more between presentation to the internist and surgery or death. The diagnosis was not made until after shock developed in nine patients who were hemodynamically stable at presentation. Of 17 patients who underwent surgery, 7 of 8 with preoperative shock died, compared with 2 deaths in 9 patients (p < .02) without shock. All six patients who did not have surgery died, yielding an overall mortality of 65% for the series. Ruptured AAAs were most frequently misdiagnosed as urinary tract obstruction or infection, spinal disease, and diverticulitis. Chart review revealed a general lack of physician awareness of the syndromes of contained rupture of AAA and symptomatic unruptured AAA. CONCLUSIONS: In patients with ruptured AAA who present to internists, the diagnosis is often delayed or missed and this appears to adversely effect survival. Internists should familiarize themselves with the presentation and management of ruptured AAA.

Bronchoscopy to evaluate hemoptysis in older men with nonsuspicious chest roentgenograms.

Six of 106 older men with hemoptysis and a nonsuspicious chest roentgenogram who underwent fiberoptic bronchoscopy were found to have cancer. Four of the five bronchogenic carcinomas appeared to be surgically resectable. Cancer patients were significantly older, had smoked within the last five years, and had a significantly higher frequency of central abnormalities on chest roentgenogram. Six additional bronchogenic carcinomas were diagnosed at follow-up. Two of these were probably present but not detected at the time of bronchoscopy. We conclude that (1) hemoptysis with a nonsuspicious chest roentgenogram carries an appreciable risk of cancer in older men with substantial smoking histories, (2) these cancers are often resectable, (3) a chest roentgenogram in which the central lung fields are obscured in any way should not be considered negative in patients with hemoptysis, and (4) a negative bronchoscopic examination does not exclude the possibility of cancer in these patients.

High prevalence of positive antibodies to Legionella pneumophila among outpatients.

A serologic survey of antibodies to Legionella pneumophila serogroups 1 through 6 was performed to assess the prevalence of positive antibody titers among outpatients and to evaluate the association between elevated antibody titers and previously identified risk factors for legionellosis. Subjects were recruited from outpatient clinics at the Minneapolis VA Medical Center. Each participant completed a self-administered questionnaire which asked about their general health and any recent symptoms of illness. Medical records were also audited for all participants to provide additional information on medical history and known risk factors for Legionella infection. Single samples of serum were obtained from each subject, and antibody titers to L pneumophila serogroups 1 through 6 were assayed. Three hundred ninety-six subjects were enrolled in the study. They had a mean age of 67 years, and 98 percent were male subjects. Overall, 36 percent of the subjects had positive antibody titers (greater than or equal to 1:128) to L pneumophila. There were no differences between those with and without elevated titers with respect to recent systemic symptoms or other previously established risk factors for legionellosis. We conclude that positive anti-Legionella antibodies are a frequent occurrence among these outpatients. This has important implications for the interpretation of single or static antibody titers from patients who are acutely ill.

Prevention of stress-induced gastric ulcers by mu- and delta-opioid agonists in the rat.

The effects of intraperitoneal and intracerebroventricular administration of mu- and delta- selective opioid receptor agonists (DAGO and DPDPE, respectively) on gastric lesions, were investigated in cold-restraint-stressed rats. DAGO and DPDPE, peripherally and centrally administered, induced a significant gastric protection. Naloxone prevented the effects of both opioids whereas naltrindole prevented the gastric protection induced by DPDPE but not that by DAGO. The results suggest that mu- and delta-opioid agonists prevent gastric damage induced by stress through an involvement of both central and peripheral mu- and delta-opioid receptor subtypes.

The kaleidoscope of general internist careers: a challenge for internal medicine training.

As internal medicine residency programs struggle to produce general internists in greater numbers and assure that they are adequately prepared for practice, it is imperative that the graduate medical education system have a clear picture of what competencies will be expected of those entering general internist careers. Feedback from the practicing community and large managed care organizations in Minnesota has made it clear that general internists in that state are functioning in a variety of positions requiring a wide range of skills depending on the practice description, choice of practice setting, and the complement of other primary care providers. General internists functioning in nontraditional careers have special curricular needs. It is imperative that training programs constantly monitor the changing practice environment and stay current on the variety of new generalist career choices to adequately prepare their residents for generalist careers. The graduate medical education enterprise needs to be involved in determining the best teaching strategies for the broad range of ambulatory general medicine competencies and in determining how best to preserve the richness of the medical subspecialty experience critical to the training of excellent general internists.

A process for identifying marginal performers among students in a clerkship.

PURPOSE: To evaluate a review process for identifying marginal performers among students in a clerkship. METHOD: To better identify the marginal performers among the students participating in the medicine clerkship at the University of Minnesota Medical School--Minneapolis, the Medicine Clerkship Committee reviewed in 1990-91 and 1991-92 all students rated by faculty or housestaff as below expectations for any of nine areas of clinical performance (27 students of 890, 3%). (In the past, a student was considered to be a marginal performer only if he or she was assigned an unsatisfactory numerical grade, calculated from the nine ratings, or if written comments by housestaff and faculty and the opinions of the attending faculty and clerkship site coordinator indicated that the student should fail.) Chi-square analysis was used to compare the number of students judged to be marginal performers under the review process with the number of marginal performers in 1988-89 and 1989-90. The two groups were also compared based on their preclerkship performances on standardized examinations. RESULTS: Ten of those reviewed (37%) were judged to have performed marginally. Although the study group's performance on standardized examinations was not different from that of students during the previous two years, significantly fewer students were identified as marginal performers before the review process began than afterwards (2 of 867, 0.2%, versus 10 of 890, 1.1%, p < .05). CONCLUSION: Without changing the way in which faculty and housestaff evaluated students, the review process improved the medicine clerkship evaluation system by identifying significantly more students who were marginal performers.

Training internal medicine residents in the community: the Minnesota experience.

The University of Minnesota Internal Medicine Residency Program has developed ambulatory general medicine rotations in rural community settings and urban managed care settings in Minnesota. Based on what had been learned from community focus groups, from discussions with residents about what they perceived to be training holes in the traditional curriculum, and from resident evaluations of pilot rotations, an educational framework for the rotations was established. The authors describe the process of developing these rotations, their educational rationale and objectives, the structure of the rotations, teaching strategies, faculty development, and the evaluation system, and outline the important elements of the successful implementation of these new rotations. The community practice setting has offered a unique, important, and previously untapped resource for residency training, and the community rotations have been highly valued both by housestaff and by community preceptors. As residency programs begin to offer more community-based ambulatory care opportunities for their trainees, the impact of this trend on quality of training, residents' career choices, and patient outcomes will need to be evaluated.

Effect of indomethacin on opioid-induced gastric protection in cold-restrained stress.

Morphine and the synthetic opioid met-enkephalin analog [D-Ala2, MePhe4, Met(0)5ol] enkephalin (FK 33-824) injected intraperitoneally to rats at doses of 5-20 and 0.5-2 mg/kg respectively showed a protective effect on gastric lesion induced by cold-restraint stress. This protective effect was abolished by pretreatment with indomethacin. This suggests a role for prostaglandins in the protection, induced by opioids of the gastric mucosa against the development of stress-induced ulcers.

Evidence that exposure to methyl mercury during gestation induces behavioral and neurochemical changes in offspring of rats.

On day 15 of gestation, pregnant Sprague-Dawley rats were orally treated by gavage with 8 mg/kg of methyl mercury (MMC). At day 1 of postnatal life the levels of MMC in whole brain of exposed pups were found to be about 100 times higher than those of saline-exposed rats, while they were near to the control values at 21 days and practically normal at 60 days of age. Behavioral experiments showed that exposure to MMC in late gestation did not affect at any tested time (14, 21 and 60 days) locomotor activity or development of ultrasonic vocalization. An increased response to a challenge dose of amphetamine was, however, detected in MMC-exposed pups at day 14. This phenomenon was no longer evident at day 21 and 60 of age. In parallel, an increased density of dopamine receptors was found in the striatum at 14, but not at 21 and 60, days of age. From these data, we tentatively suggest that a high level of MMC induces a transient phenomenon of disuse-supersensitivity of the dopaminergic system. Moreover, further evidence that acute MMC exposure during prenatal life might induce permanent disturbances in learning and memory which could be partially related to a reduced functional activity of the glutamatergic system is provided.

Chiral resolution of the enantiomers of 7-chloro-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide using high-performance liquid chromatography on cellulose-based chiral stationary phases.

Analytical high-performance liquid chromatography (HPLC) methods using derivatized cellulose chiral stationary phases (CSPs) were developed for the separation of the enantiomers of 7-chloro-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxide ((+/-) IDRA21). In previous studies, (+/-) IDRA21 has been found to have an interesting inhibitory effect on the desensitization of alpha-amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazolepropanoic acid (AMPA) receptor and improve cognition in animals. This compound possess one chiral carbon atom, but very little information has been reported on the stereoselectivity of his activity. Therefore resolution of the enantiomers of this compound and subsequent identification of stereospecificity in his pharmacological actions are clearly matters of interest. The resolution were made under normal- and reversed-phase conditions using a mobile phase consisting of n-hexane:2-propanol (70/30, v/v) and water:acetonitrile (60/40, v/v) respectively, and a CSP of silica-based cellulose tris-3,5-dimethyl-phenylcarbamate (Chiralcel OD and Chiracel OD-R). The enantiomeric nature of eluates was confirmed by circular dichroism (CD) spectra. A baseline separation (R(S) > 1.5) was obtained in both cases. Furthermore the isolation of optical isomers of (+/-) IDRA21 was performed using a semipreparative column packed with the same cellulose OD CSP.

High-performance liquid chromatographic method for the quantification of anthranilic and 3-hydroxyanthranilic acid in rat brain dialysate.

Anthranilic acid (ANA) and 3-hydroxyanthranilic acid (3-HANA) have attracted considerable attention as two of the L-tryptophan kynurenine pathway metabolites in the central nervous system. In this study, a highly sensitive and accurate method for the quantification of ANA and 3-HANA has been developed using reversed-phase high performance liquid chromatography (HPLC) with fluorimetric detection. The HPLC assay was carried out using a C(18) column (5 microm, 250 x 4.6 mm i.d.). The mobile phase consisted of a mixture of 25 mM sodium/acetic acid buffer (pH 5.5) and methanol (90:10 v/v). Fluorimetric detection at lambda(ex)=316 nm and lambda(em)=420 nm was used. The assay was applied to the measurement of ANA and 3-HANA acid in rat brain dialysate following administration of L-tryptophan or L-kynurenine. 3-HANA and ANA levels were progressively increased during 90 min following administration of L-tryptophan, then decreased progressively to basal levels. 3-HANA levels were significantly higher than ANA levels after L-kynurenine administration. These findings suggest that the assay developed should provide an improved means for investigation of neurobiology of kynurenine pathway.