Development and validation of an acid/alkaline digestion method for efficient microplastic extraction from wastewater treatment plant effluents: Sulfuric acid concentration and contact time do matter

Accurate analysis of microplastic particles (MPs) in environmental samples requires removal of interferences during sample preparation. Wastewater samples are interference-rich and thus particularly challenging, with concentrated sulfuric acid currently deemed impractical as a reagent. Therefore, this study aimed to establish a straightforward, effective, and safe method employing concentrated sulfuric acid and potassium hydroxide to eliminate interferents from effluent samples obtained from wastewater treatment plants (WWTPs). We found that 80 % sulfuric acid at room temperature with a brief contact time of 5 min was viable through a qualitative spot test involving 37 plastics categorized into three types (I, II, and III) based on their polymer structure's oxygen position. A quantitative assessment revealed that treatments involving H2SO4 and KOH (20 %, 24 h, 48 °C), either separately or in combination, had no discernible physical impact on the overall plastics, except for a subtle one for Type III plastics (e.g., nylon and PMMA) known to be labile under harsh pH conditions. This acid/alkaline digestion (AAD) method, incorporating such conditions for H2SO4 and KOH treatments, yielded a high mass removal efficacy (97.8 ± 2.4 %, n = 13) for eliminating natural particle interferents for primary, secondary, and tertiary effluent samples. Furthermore, the AAD method allowed for the determination of MPs in effluents with high surrogate particle recoveries (e.g., 95.1 % for larger than 500 μm size fraction). This method is readily adaptable to create appropriate protocols for different types of environmental matrices.

Gene expression profiling in the developing rat brain exposed to ketamine

Ketamine, a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist, is associated with accelerated neuronal apoptosis in the developing rodent brain. In this study, postnatal day (PND) 7 rats were treated with 20 mg/kg ketamine or saline in six successive doses (s.c.) at 2-h intervals. Brain frontal cortical areas were collected 6 h after the last dose and RNA isolated and hybridized to Illumina Rat Ref-12 Expression BeadChips containing 22,226 probes. Many of the differentially expressed genes were associated with cell death or differentiation and receptor activity. Ingenuity Pathway Analysis software identified perturbations in NMDA-type glutamate, GABA and dopamine receptor signaling. Quantitative polymerase chain reaction (Q-PCR) confirmed that NMDA receptor subunits were significantly up-regulated. Up-regulation of NMDA receptor mRNA signaling was further confirmed by in situ hybridization. These observations support our working hypothesis that prolonged ketamine exposure produces up-regulation of NMDA receptors and subsequent over-stimulation of the glutamatergic system by endogenous glutamate, triggering enhanced apoptosis in developing neurons.

Is over-use of proton pump inhibitors fuelling the current epidemic of Clostridium difficile-associated diarrhoea?

Many developed countries have seen an increase in cases of Clostridium difficile-associated diarrhoea (CDAD) in recent years. This has occurred despite heightened awareness of the risks of broad-spectrum antibiotics, overall reduction in antibiotic use and increased focus on hospital hygiene. Some of the increase is due to the introduction of new hypervirulent strains, but it predates the description of these. The epidemic coincides with increased use of proton pump inhibitors (PPIs), much of which is inappropriate according to UK and other national guidelines. Gastric acid is a key host defence against other gastrointestinal infections and epidemiological and animal studies have demonstrated a positive association between incident CDAD and PPI use. An association with recurrence of CDAD after initially successful treatment has also been found. Vegetative C. difficile cells are rapidly killed at normal gastric pH, but survive at the pH found in patients taking PPI. It has recently been shown that vegetative organisms survive long enough on moist surfaces for transmission between patients to occur. We conclude that restricting PPI use to patients with an appropriate indication would reduce unnecessary expenditure on these agents, and might be an additional means of controlling the current epidemic of CDAD.

Abnormal neuronal metabolism and storage in mucopolysaccharidosis type VI (Maroteaux-Lamy) disease

Mucopolysaccharidosis (MPS) type VI, also known as Maroteaux-Lamy disease, is an inherited disorder of glycosaminoglycan catabolism caused by deficient activity of the lysosomal hydrolase, N-acetylgalactosamine 4-sulphatase (4S). A variety of prominent visceral and skeletal defects are characteristic, but primary neurological involvement has generally been considered absent. We report here that the feline model of MPS VI exhibits abnormal lysosomal storage in occasional neurones and glia distributed throughout the cerebral cortex. Abnormal lysosomal inclusions were pleiomorphic with some resembling zebra bodies and dense core inclusions typical of other MPS diseases or the membranous storage bodies characteristic of the gangliosidoses. Pyramidal neurones were shown to contain abnormal amounts of GM2 and GM3 gangliosides by immunocytochemical staining and unesterified cholesterol by histochemical (filipin) staining. Further, Golgi staining of pyramidal neurones revealed that some possessed ectopic axon hillock neurites and meganeurites similar to those described in Tay-Sachs and other neuronal storage diseases with ganglioside storage. Some animals evaluated in this study also received allogeneic bone marrow transplants, but no significant differences in neuronal storage were noted between treated and untreated individuals. These studies demonstrate that deficiency of 4S activity can lead to metabolic abnormalities in the neurones of central nervous system in cats, and that these changes may not be readily amenable to correction by bone marrow transplantation. Given the close pathological and biochemical similarities between feline and human MPS VI, it is conceivable that children with this disease have similar neuronal involvement.

Pediatric sedation for procedures titrated to a desired degree of immobility results in unpredictable depth of sedation

OBJECTIVE

To test the hypothesis that the need to attain immobility during pediatric sedation for procedures determines the depth of sedation, which cannot always be predicted.

DESIGN

A retrospective review of sedation documents of 301 consecutive sedations of pediatric patients undergoing various procedures

SETTING

Division of Critical Care sedation service within a children's hospital.

MEASUREMENTS AND MAIN RESULTS

The medical records and sedation forms of our most recent 301 consecutive sedations were retrospectively reviewed. Based on the data gathered, the patients were categorized according to their achieved level of immobility, their level of consciousness according to the definitions of the American Academy of Pediatrics, the procedures for which sedation was administered, and the sedatives used. A total of 125 males and 89 females received 301 sedations. Their ages ranged from 22 days to 29 years (mean 7 y + 6 y). We recognized four categories of immobility for procedures. In category 1, some motion was allowed during painless and noninvasive procedures to the extent that it did not risk the patient nor hinder the successful performance of the procedures. In category 2, the patients were kept motionless during painless and noninvasive procedures. In category 3, the patients were kept motionless during painful and invasive procedures with the addition of local anesthetic. In category 4, the patients remained motionless throughout their painful or invasive procedure without the use of local anesthetics. There were 32, 10, 156 and 103 sedations in each category, respectively. Conscious sedation (CS) was observed in six sedations (19%) in category 1 of immobility; it was observed in none (0%) in category 2, in 4 sedations (2.6%) in category 3, and in 1 sedation (1%) in category 4. Deep sedation (DS) was noted in 26 category 1 sedations (81%), in 10 category 2 sedations (100%), in 136 category 3 sedations (87%), and in 63 category 4 sedations (61%). General anesthesia (GA) was only observed in categories 3 and 4 in 16 sedations (10%) and 39 sedations (38%), respectively. Intravenous (IV) ketamine, as a single agent or in combination with other agents, was the most frequently used sedative (88%) followed by IV benzodiazepines (64%), propofol (39%), opiates (15%), and barbiturates (5%). A total of 59 (19%) adverse events were encountered during the 301 sedations. In categories 1 and 2, no adverse event (0%) was encountered. In category 3, 19 adverse events took place (32%), and 40 adverse events (68%) (P< 0.05) occurred in category 4.

CONCLUSIONS

Pediatric sedation results in 4 categories of immobility. Complete immobility during painful and invasive procedures is associated with a higher incidence of adverse events. The depth of sedation (ie, CS, DS, or GA) required to achieve each category of immobility is unpredictable and varies from patient to patient. Thus, granting a limited sedation authority (conscious sedation only) to physicians may be of limited practical value.

Delirium in an intensive care unit: a study of risk factors

OBJECTIVES

(1) To establish risk factors for the development of delirium in an intensive care unit (ICU) and (2) to determine the effect of delirium on morbidity, mortality and length of stay.

DESIGN

Prospective study.

SETTING

Sixteen-bed medical/surgical ICU in a university hospital.

PATIENTS

Two hundred and sixteen consecutive patients admitted to the ICU for more than 24 h during 5 months were included in the study.

INTERVENTIONS

Medical history, selected laboratory values, drugs received and factors that may influence patient psychological and emotional well-being were noted. All patients were screened with a delirium scale. A psychiatrist confirmed the diagnosis of delirium. Major complications such as self-extubation and removal of catheters, as well as mortality and length of stay were recorded.

RESULTS

Forty patients (19%) developed delirium; of these, one-third were not agitated. In the multivariate analysis hypertension, smoking history, abnormal bilirubin level, epidural use and morphine were statistically significantly associated with delirium. Traditional factors associated with the development of delirium on general ward patients were not significant in our study. Morbidity (self-extubation and removal of catheters), but not mortality, was clearly increased.

CONCLUSION

Predictive risk factors for the development of delirium in studies outside the ICU may not be applicable to critically ill patients. Delirium is associated with increased morbidity. Awareness of patients at risk may lead to better recognition and earlier intervention.

Intensive Care Delirium Screening Checklist: evaluation of a new screening tool

OBJECTIVE

Delirium in the intensive care unit is poorly defined. Clinical evaluation is difficult in the setting of unstable, often intubated patients. A screening tool may improve the detection of delirium.

METHOD

We created a screening checklist of eight items based on DSM criteria and features of delirium: altered level of consciousness, inattention, disorientation, hallucination or delusion, psychomotor agitation or retardation, inappropriate mood or speech, sleep/wake cycle disturbance, and symptom fluctuation. During 3 months, all patients admitted to a busy medical/surgical intensive care unit were evaluated, and the scale score was compared to a psychiatric evaluation.

RESULTS

In 93 patients studied, 15 developed delirium. Fourteen (93%) of them had a score of 4 points or more. This score was also present in 15 (19%) of patients without delirium, 14 of whom had a known psychiatric illness, dementia, a structural neurological abnormality or encephalopathy. A ROC analysis was used to determine the sensitivity and specificity of the screening tool. The area under the ROC curve is 0.9017. Predicted sensitivity is 99% and specificity is 64%.

CONCLUSION

This study suggests that the Intensive Care Delirium Screening Checklist can easily be applied by a clinician or a nurse in a busy critical care setting to screen all patients even when communication is compromised. The tool can be utilized quickly and helps to identify delirious patients. Earlier diagnosis may lead to earlier intervention and better patient care.

Ocular Onchocerca infections in two dogs in western United States

Two dogs, one from California and one from Arizona, were found to have aberrant infections caused by filarial nematodes of the genus Onchocerca. In both cases, the parasites are localized in or near the eye. In one case the worm was located in the cornea and was surgically removed. In the second case, a very marked granulomatous reaction was induced in the retrobulbar space, mimicking an abscess. This eye was enucleated. The worms in both instances were female, and were gravid, i.e. contained microfilariae in utero, indicating that a male worm(s) had been present and mating had occurred. The exact identity of the species of Onchocerca responsible cannot be determined, although the features observed are most like Onchocerca lienalis of cattle. These cases represent the fourth and fifth such cases reported from the US, and are especially interesting because of the unusual location of the worms, the small number of recognized cases, and the similarity to a recent zoonotic human infection.

Automatic control of pressure support mechanical ventilation using fuzzy logic

There is currently no universally accepted approach to weaning patients from mechanical ventilation, but there is clearly a feeling within the medical community that it may be possible to formulate the weaning process algorithmically in some manner. Fuzzy logic seems suited this task because of the way it so naturally represents the subjective human notions employed in much of medical decision-making. The purpose of the present study was to develop a fuzzy logic algorithm for controlling pressure support ventilation in patients in the intensive care unit, utilizing measurements of heart rate, tidal volume, breathing frequency, and arterial oxygen saturation. In this report we describe the fuzzy logic algorithm, and demonstrate its use retrospectively in 13 patients with severe chronic obstructive pulmonary disease, by comparing the decisions made by the algorithm with what actually transpired. The fuzzy logic recommendations agreed with the status quo to within 2 cm H(2)O an average of 76% of the time, and to within 4 cm H(2)O an average of 88% of the time (although in most of these instances no medical decisions were taken as to whether or not to change the level of ventilatory support). We also compared the predictions of our algorithm with those cases in which changes in pressure support level were actually made by an attending physician, and found that the physicians tended to reduce the support level somewhat more aggressively than the algorithm did. We conclude that our fuzzy algorithm has the potential to control the level of pressure support ventilation from ongoing measurements of a patient's vital signs.

Ceftriaxone-related fatal hemolysis in an adolescent with perinatally acquired human immunodeficiency virus infection

A 14-year-old girl with perinatally acquired human immunodeficiency virus infection had fatal intravascular hemolysis after intravenous administration of ceftriaxone. Laboratory studies confirmed the presence of an antibody against ceftriaxone in the serum and on the patient's red blood cells. No evidence of sepsis, glucose-6-phosphate dehydrogenase deficiency or anaphylaxis was found.