Diaphragm replacement. An animal experiment study

OBJECTIVE: The study was designed to test the hypothesis that a dentifrice with fluoride at the same concentration (1000ppm) from two sources, ie NaF and NaMFP, would provide a greater treatment effect than one with NaMFP alone. BASIC RESEARCH DESIGN: A double blind clinical trial with random assignment of children to one of two groups was carried out for three years. The two trial groups were similar at the outset in respect to those variables which might otherwise have affected the outcome, including age and gender, with means per subject of 98.4 sound surfaces and 2.2 decayed and filled surfaces in each group initially. CLINICAL SETTING: Secondary schools in the Isle of Wight, UK, an area of diminished caries experience. PARTICIPANTS: One thousand six hundred and thirty-three children aged initially 10-12 years. INTERVENTIONS: A test dentifrice containing 500ppm NaF plus 500ppm NaMFP, and a standard active control product containing 1000ppm NaMFP. Products were used in the home. OUTCOME MEASURES: Increment of DF teeth and surfaces measured over 36 months. RESULTS: After three years, mean approximal surface increments were 3.6 new DFS in the control group and 3.1 in the test group, a difference 13 per cent (P < 0.05). Thirty-four per cent of the subjects were caries free at the outset. In the 1075 subjects with caries at the outset, the total mean increment on all surfaces was 7.2 new DFS in the control group and 6.4 new DFS in the test group, a difference of 11 per cent (P < 0.05). However, those subjects with initial caries had approximal surface increments of 4.8 new DFS in the control group and 4.0 new DFS in the test group, a difference of 16 per cent (P < 0.01). Included separately along with the conventional rubric were enamel white spots on which no differential treatment effect was observed. CONCLUSIONS: Under the conditions of this study, the regular use of a dentifrice containing 1000ppm fluoride from two sources provided a significantly greater treatment effect than one with fluoride from a single source.     

Influence of metal implants on infection. An experimental study in rabbits

We implanted cylinders of cobalt-chrome or titanium, with smooth or porous surfaces, into rabbit bones which had been inoculated with suspensions of Staphylococcus aureus in various doses. The bacterial concentration required to produce infection of porous-coated titanium implants was 2.5 times smaller than that necessary to infect implants with polished surfaces. Porous-coated cobalt-chromium implants required bacterial concentrations that were 40 times smaller than those needed to infect implants with polished surfaces, and 15 times smaller than those required to infect porous-coated titanium implants. The other advantages and disadvantages of the various implants, such as improved osseointegration, larger ion-release surfaces, surface wear and relative stiffness, must be weighed against the higher infection rates in the porous-coated implants, and particularly in the cobalt-chromium implants.     

Familial resemblances in disgust sensitivity and animal phobias

We present 100 children diagnosed with epilepsy who were seizure-free for more than 1 year and still on monotherapy of antiepileptic drugs (AEDs). We matched each child with a healthy classmate and performed neuropsychological testing and EEG before and after complete withdrawal of the AEDs. The withdrawal phase lasted 3 months, but the dose decrease was individualized for each patient. Three to 4 months after complete withdrawal of the drug all patients were reassessed. Patients with seizure relapse are excluded from the study. Seventeen patients are regarded as dropout, 11 because of seizure relapse and six because of protocol violation. The remaining 83 patients were treated with carbamazepine (n = 56), valproic acid (n = 17), or phenytoin (n = 10). Serum concentrations of the AEDs were measured using peak plasma levels that were taken immediately before or after psychological testing. We used neuropsychological tests to assess psychomotor function and "central" cognitive processing such as information processing or memory function. We found significant improvement attributable to drug withdrawal on only one of the cognitive tests, namely, psychomotor speed, suggesting that the impact of AED treatment on higher-order cognitive function is rather limited. In addition, we found group differences between the epilepsy group and the control group at baseline that persisted after drug withdrawal. Subsequent analysis showed some factors that may have contributed to these group differences. First, patients with a former diagnosis of absence seizures show lower scores both at baseline and after drug withdrawal. We may assume that the seizure propensity has not disappeared completely in these patients. Some evidence is found that phenytoin may have a different cognitive profile than carbamazepine, with more impairment on tests that measure motor and mental speed. Again, this impairment persists after drug withdrawal.     

Reduction of cataract by plasma etching of intraocular lenses. An animal experiment study

BACKGROUND: We studied if a modification of the silicon intraocular lens (IOL) by plasma etching is able to promote a bonding of the IOL surface and the capsular bag which might inhibit proliferation and migration of lens epithelial cells. METHODS: Silicon-disc lenses (90D, Adatomed), as disposable for regular cataract surgery, were used. Their haptic surface was etched via the use of a SO2 plasma, leaving the optic unmodified. The experiments were done on dwarf rabbits to allow for tight apposition of IOL and bag. Nine rabbits underwent extracapsular lensectomy using propofol anaesthesia and phaco/clear cornea surgical technique. Six eyes each received either no, a regular or a modified IOL. After 11 weeks the eyes were enucleated. Capsular bag and IOL were digitized using a flatbed scanner with transparency adapter. The data obtained were calibrated against a densitometric standard. The densities of the various specimen were analyzed quantitatively using self designed software. RESULTS: In aphacic eyes no significant posterior capsule opacification (PCO) was detectable. In the same time-span the regular IOL had developed a dense, heterogenous PCO. The plasma-treated IOL showed, especially in the central areas, a significant reduction of PCO as compared to untreated IOL. CONCLUSION: The reduction of PCO could not be explained by adhesion of the IOL surface and the capsular bag, which would impair migration of lens epithelial cells and thereby PCO. Likewise, lower PCO may be related to improved hydrophilic properties of the surface-modified IOL.     

A study of the metal sulfide-sulfur dioxide reaction in aqueous media by reaction pressure characterization and ultraviolet spectrophotometry

The metal sulfide-sulfur dioxide reaction has been characterized for seven different sulfide ores by using the changes in sulfur dioxide pressure during the reaction and by ultraviolet spectrophotometric analysis of the reaction products. The UV analysis, which showed that thiosulfuric acid is a major product of the metal sulfide-sulfur dioxide reaction, was used to monitor the r rate of formation of thiosulfuric acid during the reaction. Results from a series of base-line experiments using ferrous sulfide showed a high correlation between the rate of change of sulfur dioxide pressure, the rate of appearance of ferrous ion, and the rate of formation of thiosulfuric acid. These results were compared with those obtained in similar experiments with six naturally-occurring sulfide ores. Finally, the UV method was employed to monitor the kinetics of the decomposition of thiosulfuric acid into elemental sulfur. Using these results, in conjunction with the mechanisms previously developed for the Wackenroder reaction and the acid decomposition of thiosulfate, a mechanism is proposed for the acid oxidative dissolution of sulfide ores which accounts for the formation of elemental sulfur.     

Tissue distribution and subcellular localization of a G-protein activated phosphoinositide 3-kinase. An immunohistochemical study

Hereditary spastic paraplegia (HSP) is characterized by progressive weakness and spasticity of the lower limbs due to degeneration of corticospinal axons. We found that patients from a chromosome 16q24.3-linked HSP family are homozygous for a 9.5 kb deletion involving a gene encoding a novel protein, named Paraplegin. Two additional Paraplegin mutations, both resulting in a frameshift, were found in a complicated and in a pure form of HSP. Paraplegin is highly homologous to the yeast mitochondrial ATPases, AFG3, RCA1, and YME1, which have both proteolytic and chaperon-like activities at the inner mitochondrial membrane. Immunofluorescence analysis and import experiments showed that Paraplegin localizes to mitochondria. Analysis of muscle biopsies from two patients carrying Paraplegin mutations showed typical signs of mitochondrial OXPHOS defects, thus suggesting a mechanism for neurodegeneration in HSP-type disorders.     

Dynamic interstitial laser application for therapy of secondary liver tumors. An animal experiment study

Laser-induced interstitial thermotherapy (LITT) is a promising method of treating different types of tumors. To increase the effectiveness of LITT, a new thermo-controlled application system for minimal invasive intervention was designed. This laser system consists of a laser applicator 3 mm in diameter, insertion equipment and an Nd:YAG laser source. The power of the laser source is controlled dynamically by thermosensors in a water-cooling system of the laser applicator. In in vivo experiments in five pigs, within 10 min we found homogeneous coagulation regions in the liver that were of 3 cm and 5 cm in diameter. Via ultrasound we observed in real time the increasing coagulation zone that appeared as a hyperechogenic halo. However, due to perifocal edema, the real coagulation area was smaller than detected by ultrasound. Macroscopically and microscopically, the coagulation zones showed well-demarcated borders of the coagulation lesions, and the surrounding tissue appeared vital. The reparative reaction after irradiation was early fibrosis. In the course of 4 weeks, the surrounding scar capsule, containing fibrocytes, biliary ductules and collagen fibers enlarged. As a result, the coagulation necrosis became more and more fragmented between collagen fibers and was largely resorbed. The absence of complications in our animal experiments suggest that the technique of thermo-controlled laser light application is safe and useful in therapy for metastases that are not resectable.     

Comparative psychology and the study of animal learning.

Comparative psychology and the study of animal learning have been closely related since the start of both areas of study. At its inception, comparative psychology addressed questions about the evolution of consciousness and intelligence. The scope of comparative psychology then increased to include a wide range of issues related to behavioral evolution and adaptation. Both of these aspects of comparative psychology are reflected in contemporary research on animal learning. Contemporary investigations of animal learning and cognition reflect the roots of comparative psychology in questions about animal intelligence. Contemporary studies of adaptive specializations and functions of learning are related to the contemporary emphasis in comparative psychology on the role of behavior in evolution and adaptation. In addition, the comparative method remains important in the study of both specialized and general learning processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dysbaric osteonecrosis in divers and caisson workers. An animal model

Dysbaric osteonecrosis was induced successfully in adult sheep after 12 to 13, 24-hour exposures to compressed air (2.6-2.9 atmospheres absolute) during a 2-month period. All exposed sheep had decompression sickness and extensive bone and marrow necrosis in their long bones. Radiographic analysis of these progressive lesions showed mottled to distinct medullary opacities and endosteal thickening characteristic of dysbaric osteonecrosis. Six months after the last hyperbaric exposure, neovascularization of once ischemic fatty marrow was centripetal from the diaphyseal cortex. Proliferating endosteal new bone, fatty marrow calcification, and appositional new bone formation were widespread. Juxtaarticular osteonecrosis involved marrow fibrosis and loss of osteocytes in subchondral cortical bone. Tidemark reduplication in juxtaarticular bone and cartilage thinning suggested possible early osteoarthritis induction by recurrent episodes of transient ischemia after multiple hyperbaric exposures. Dysbaric osteonecrosis appears to involve a bone compartment syndrome of elevated intramedullary pressure initiated by decompression induced N2 bubble formation in the fatty marrow of the long bones. An animal model that can be used to investigate the pathogenesis, diagnosis, and treatment of dysbaric osteonecrosis is discussed.     

An HVEM study of an unusual ordering reaction in platinum-carbon

In platinum containing carbon in solid solution an ordered phase with twice the lattice parameter of the matrix has been found in regions near grain boundaries and inclusions. The ordering was observed after quench-aging treatments as well as during electron irradiation above 300 kV in the temperature range of 250 to 650 °C. Outside this temperature range disordering took place thermally at high temperatures (>650 °C) and athermally by irradiation at low temperatures (<250 °C). The threshold voltage for athermal disordering was ~380 kV, well below the 1300 kV threshold for displacement damage in Pt. The simplest ordered structure consistent with the diffraction evidence is face-centered cubic Pt₇C, similar to Pt₇Cu. An important implication of these observations is that substantial amounts of carbon can be effectively transferred from interstitial to pseudo-substitutional sites under certain conditions. This is linked to the earlier observation of a large binding energy between interstitial carbon and platinum vacancies (~0.6 eV).     

Uncontrollability and unpredictability in post-traumatic stress disorder: An animal model.

The disturbances observed in animals subjected to unpredictable and uncontrollable aversive events resemble posttraumatic stress disorder (PTSD) symptoms and thus may constitute an animal model of this disorder. It is argued that the similarity between animals' symptoms and those of trauma victims may reflect common etiological factors. Relevant experiments in which animals exhibit generalized fear and arousal, discrete fear of a CS, analgesia, and avoidance are reviewed with the view that these manifestations may be analogous to the PTSD symptom clusters of persistent arousal, reexperiencing, numbing, and avoidance, respectively. Finally, animal paradigms are suggested to test the validity of the model, and specific hypotheses are derived from the animal literature regarding trauma variables that are predictive of particular PTSD symptom clusters. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An assessment of long-term reaction to rape.

Examined reactions to rape by interviewing 27 female rape victims at least 1 yr after the assault and assessing their current functioning through such measures as the Beck Depression Inventory and Profile of Mood States. Victims were significantly more depressed and reported less pleasure in daily activities than 26 matched nonvictim controls. Ss who had been victims of sudden violent attacks by complete strangers showed the most severe reactions, being even more depressed, fatigued, and fearful and getting less satisfaction from activities than victims of other types of assaults. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An animal model for the behavioral effects of interferon.

Interferon, which is produced during viral infections, has cognitive and neurological effects in humans. A dose of 1600 U/g of mouse interferon-alpha significantly depressed horizontal activity, head pokes into a food chamber, and food intake in mice 10 hr and 24 hr after injection. An 800 U/g dose had only slight effects on horizontal activity and food intake, whereas a 400 U/g dose had no effect. There was no evidence of sensitization to interferon when a second 400 U/g dose was given after the 1600 U/g dose. The results imply that mouse interferon-alpha can be used in mice as a model for studying the fatigue and anorexia produced by interferon. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A study of the reaction kinetics for the formation of rare earth-transition metal laves compounds

The kinetics of the reaction A_(s) + 2B (s) =AB _2(s) was studied by differential thermal analy sis. TheA component was Pr, Gd, Dy or Er, theB was Fe, Co, or Ni and the resultingAB ₂ compound was a MgCu₂ Laves intermetallic compound. A generalized search method to de termine the reaction mechanism was developed and applied to the above reactions. The re actions were found to be diffusion controlled and the kinetics best described by the Valensi-Carter equation.     

A study of the reaction kinetics for the formation of rare earth-transition metal laves compounds

The kinetics of the reaction A_(s) + 2B (s) =AB _2(s) was studied by differential thermal analy sis. TheA component was Pr, Gd, Dy or Er, theB was Fe, Co, or Ni and the resultingAB ₂ compound was a MgCu₂ Laves intermetallic compound. A generalized search method to de termine the reaction mechanism was developed and applied to the above reactions. The re actions were found to be diffusion controlled and the kinetics best described by the Valensi-Carter equation.     

An event-related potential study of age-related changes in sensitivity to stimulus deviance

The mismatch negativity (MMN) of the event-related (brain) potential (ERP) has been shown to reflect the storage of information in sensory memory and is thought to reflect the operation of a mechanism that compares frequently occurring standard with infrequently occurring deviant acoustic events. The MMN was recorded from young (mean = 23 years) and elderly (mean = 72 years) adults to small (50 Hz) and large (300 Hz) frequency deviants and to a variety of novel, environmental sounds. At each level of deviance, MMN amplitude was smaller in the ERPs of older relative to younger adults. Young, but not older adults showed robust MMNs at the smallest level of deviance. Moreover, a P3 component was observed in the ERPs of the young to both large tonal and novel deviants, whereas a robust P3 component was evident only to the novel deviants in the ERPs of the old. The data suggest that older adults demonstrate less sensitivity to stimulus deviance and that only highly deviant events are likely to involuntarily capture their attention.     

Reward sensitivity in depression: A biobehavioral study.

The approach-withdrawal model posits 2 neural systems of motivation and emotion and hypothesizes that these systems are responsible for individual differences in emotional reactivity, or affective styles. The model also proposes that depression is characterized by a deficit in reward-seeking behavior (i.e., approach motivation) and is associated with a relative decrease in left frontal brain activity. The authors tested aspects of this model by comparing the electroencephalogram alpha power of depressed and nondepressed individuals during a task that manipulated approach motivation. The study found that control participants and individuals with late-onset depression exhibited the hypothesized increase in left frontal activity during the approach task but individuals with early-onset depression did not. This suggests that early-onset depression may be associated with a deficit in the hypothesized approach motivation system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schizophrenia, infection and temperature. An animal model for investigating their interrelationships

Cell-free supernatants of 40 Salmonella strains of different serovars were tested for the existence of enterotoxic substances in the rabbit skin permeability factor test, rabbit ileal loop test, tissue culture assays (CHO K1, RTG-2), and baby mouse test. There were differences in the test results between the strains even within the same serovar. Correlation coefficients between the results of different toxin tests were low. It is therefore improbable that the "enterotoxic activity" of Salmonella is caused by only one toxic substance. The activities revealed in the different test systems could not be related to virulence or the epizootiological behaviour of the strains. The in vitro occurrence of the virulence factor "enterotoxin production" is lower for Salmonella than for E. coli and V. cholerae.