Monte Carlo simulations of weak polyampholyte microgels: pH-dependence of conformation and ionization

We performed Metropolis Monte Carlo simulations to investigate the impact of varying acid and base dissociation constants on the pH-dependent ionization and conformation of weak polyampholyte microgels under salt-free conditions and under explicit consideration of the chemical ionization equilibria of the acidic and basic groups and their electrostatic interaction. Irrespective of their relative acid and base dissociation constant, all of the microgels undergo a pH-dependent charge reversal from positive to negative with a neutral charge at the isoelectric point. This charge reversal is accompanied by a U-shaped swelling transition of the microgels with a minimum of their size at the point of charge neutrality. The width of the U-shaped swelling transition, however, is found to depend on the chosen relative acid and base dissociation constants through which the extent of the favorable electrostatic intramolecular interaction of the ionized acidic and basic groups is altered. The pH-dependent swelling transition of the microgels is found to become broader, the stronger the intramolecular electrostatic interaction of the oppositely charged ionized species is. In addition, the intramolecular charge compensation of the acidic and basic groups of the microgels allows their counterions to abandon the microgel and the associated gain in translational entropy further amplifies the broadening of the pH-dependent swelling transition. The analysis of the radial ionization profiles of the acidic and basic groups of the differently composed microgels reveals a variety of radial ionization patterns with a dependence on the overall charge of the microgels.

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

[Virus detection, clinical signs, and laboratory findings in dogs with acute hemorrhagic diarrhea: a retrospective study of 935 cases]

OBJECTIVE

The study evaluated which viruses can be detected in dogs with acute hemorrhagic diarrhea and compared signalment, clinical signs, and laboratory abnormalities among groups of dogs infected with different viruses and those that tested virus-negative.

MATERIAL AND METHODS

Fecal samples from 935 dogs with acute hemorrhagic diarrhea were examined by electron microscopy. The medical records of these patients were retrospectively evaluated for clinical and laboratory parameters.

RESULTS

Virus was detected in 44.2% of the dogs presented with acute bloody diarrhea. The highest prevalence for a virus infection was demonstrated for canine parvovirus (19.9%), followed by coronavirus (17.3%), and paramyxovirus (13.9%). More than one virus species was detected in 6.5% of all fecal samples. Dogs with a virus-positive fecal sample were significantly younger than dogs that tested negative on electron microscopy. Among virus-positive dogs, dogs with parvovirus infection were significantly younger when compared to dogs infected with other enteric viruses. Parvovirus-infected patients also showed significantly lower leukocyte and erythrocyte counts as well as hematocrit, total protein, and albumin levels compared to all other groups. No significant differences were seen when evaluating sex, clinical parameters, character of diarrhea or vomiting among all groups.

CONCLUSION

Young dogs are more likely to suffer from viral enteritis.

CLINICAL RELEVANCE

Based on clinical parameters it is not possible to differentiate a virus-positive from a virus-negative dog or to diagnose a certain virus species. Besides the young age, parvovirus infection is associated with typical changes in laboratory parameters, but not with specific clinical signs. A virologic fecal examination is always indicated.

Comparison of the prevalence of enteric viruses in healthy dogs and those with acute haemorrhagic diarrhoea by electron microscopy

Objectives: To evaluate prevalence of enteric viruses in healthy dogs and to compare it with prevalences in dogs with acute haemorrhagic diarrhoea.

Methods: Faecal samples were collected from 200 healthy dogs and examined by electron microscopy for presence of viral particles. Data were compared with viral prevalences that had been determined retrospectively by electron microscopy for 936 dogs with acute haemorrhagic diarrhoea.

Results: There were significantly more negative faecal samples among the healthy dogs (82·0 per cent) compared with 55·8 per cent in dogs with acute haemorrhagic diarrhoea (P<0·001). With a prevalence of 17·5 per cent, significantly more healthy dogs were shedding coronavirus compared with 11·6 per cent in dogs with acute haemorrhagic diarrhoea (P=0·034). Parvovirus was only detected in one healthy dog (0·5 per cent), thus with a prevalence that was significantly lower than 16·0 per cent detected in the dogs with acute haemorrhagic diarrhoea (P<0·001). Paramyxovirus was not found in any of the healthy dogs but was found in 9·3 per cent of dogs with acute haemorrhagic diarrhoea (P<0·001).

Clinical Significance: Results suggest that shedding of parvovirus and paramyxovirus is strongly associated with acute haemorrhagic diarrhoea. However, coronavirus seems to be even more prevalent among healthy dogs, raising the need for further studies to investigate the strain‐associated pathogenicity of this virus.

Implementation of a quiet hour: effect on noise levels and infant sleep states

It is necessary to decrease environmental stimuli in order to provide developmentally supportive care to the very low birthweight (VLBW) infant, thereby enhancing the sleep/wake cycle and possibly physiologic stability. The purpose of this study was to determine if it was possible to decrease the noise level in the Developmental Unit, and promote sleep states in infants on the unit. After determining control noise levels and infant state, the last hour of each shift was designated a Quiet Hour. During this time, noise levels were monitored in the room in five locations. Infant sleep states were also noted. The results indicate that noise levels decreased significantly on two of the three shifts. Fewer infants were crying during the Quiet Hour than the control period (2.4 vs 14.3 percent), and more were in deep or light sleep (84.5 vs 33.9 percent). This study demonstrates that noise levels in Developmental Units can be significantly decreased, and that the decreased noise levels positively impact infant state. By enhancing sleep states, nurses can enhance the long term developmental outcome of the VLBW infant. However, the reduction of noise is highly dependent on the collaborative efforts of all health care providers within the unit.

Pediatric occupational therapy in the home

This article discusses the challenges and implications for pediatric practice in the home. Pediatric occupational therapists are moving the treatment setting from the clinic to the home. Working within the home environment requires occupational therapists to adapt their roles, functions, and treatment styles. Intervention frequently involves practical and relevant treatment, using activities and objects from the child's world. Thus, functional goals may be more realistically achieved in the child's living environment. Involvement with family members also offers opportunities to develop collaborative relationships with parents and, therefore, to integrate the intervention program into the child's home life.

Integrating play in neurodevelopmental treatment

This article presents one perspective on the integration of play activities within a neurodevelopmental frame of reference. Based on the premise that activities are characteristic of occupational therapy intervention, issues related to combining play activities with neurodevelopmental principles are discussed. Clinical examples are also provided to illustrate the value of integrating play activities within the occupational therapy treatment of the child with cerebral palsy.