Unraveling the role of zinc complexes on indium phosphide nanocrystal chemistry.

The addition of zinc complexes to the syntheses of indium phosphide nanocrystals (InP NCs) has become commonplace, due to their ability to alter and significantly improve observed optical properties. In this paper, the role of zinc complexes on the synthesis and observed properties of InP is carefully examined. Produced InP and InP:Zn2+ NCs are thoroughly characterized from both structural (core and surface) and optical perspectives over a wide range of Zn2+ compositions (0%-43% atomic content). We find no differences in the physical (NC size and polydispersity) and structural properties (crystallographic phase) of InP and InP:Zn2+ NCs. Optically, significant changes are observed when zinc is added to InP syntheses, including blueshifted absorption edges and maxima, increased quantum yields, and the near elimination of surface state emission. These improved optical properties result from surface passivation by zinc carboxylate moieties. Changes to the optical properties begin at zinc concentrations as low as 5%, demonstrating the high sensitivity of InP optical properties to exogenous species.

A Case of Psychosis and Renal Failure Associated with Excessive Energy Drink Consumption.

Energy drinks are nonalcoholic beverages that are widely consumed in the general population, and worldwide usage is increasing. The main stimulant component of energy drinks is typically caffeine. Few case reports exist that link energy drink consumption to psychosis, and similarly few reports exist that associate energy drink consumption with acute renal failure. We present a patient who simultaneously developed psychosis and acute renal failure associated with excessive energy drink consumption. The patient required haemodialysis, and his psychosis resolved on cessation of energy drinks and a brief course of antipsychotic medication. We perform a review of similar cases where excessive caffeinated energy drink consumption has been linked to psychosis or acute renal failure. To our knowledge, this is the first case report describing both renal failure and psychosis occurring simultaneously in a patient. Recognising the spectrum of disorders associated with excessive energy drink consumption is vital for both physicians and psychiatrists, as this has important implications for both prognosis and treatment.

Prolonged exercise induces angiogenesis and increases cerebral blood volume in primary motor cortex of the rat.

Plastic changes in motor cortex capillary structure and function were examined in three separate experiments in adult rats following prolonged exercise. The first two experiments employed T-two-star (T(2)*)-weighted and flow-alternating inversion recovery (FAIR) functional magnetic resonance imaging to assess chronic changes in blood volume and flow as a result of exercise. The third experiment used an antibody against the CD61 integrin expressed on developing capillaries to determine if motor cortex capillaries undergo structural modifications. In experiment 1, T(2)*-weighted images of forelimb regions of motor cortex were obtained following 30 days of either repetitive activity on a running wheel or relative inactivity. The proton signal intensity was markedly reduced in the motor cortex of exercised animals compared with that of controls. This reduction was not attributable to alterations of vascular iron levels. These results are therefore most consistent with increased capillary perfusion or blood volume of forelimb regions of motor cortex. FAIR images acquired during experiment 2 under normocapnic and hypercapnic conditions indicated that resting cerebral blood flow was not altered under normal conditions but was elevated in response to high levels of CO(2), suggesting that prolonged exercise increases the size of a capillary reserve. Finally, the immunohistological data indicated that exercise induces robust growth of capillaries (angiogenesis) within 30 days from the onset of the exercise regimen. Analysis of other regions failed to find any changes in perfusion or capillary structure suggesting that this motor activity-induced plasticity may be specific to motor cortex.These data indicate that capillary growth occurs in motor areas of the cerebral cortex as a robust adaptation to prolonged motor activity. In addition to capillary growth, the vascular system also experiences heightened flow under conditions of activation. These changes are chronic and observable even in the anesthetized animal and are measurable using noninvasive techniques.

Abnormal dendritic spine characteristics in the temporal and visual cortices of patients with fragile-X syndrome: a quantitative examination.

Fragile-X syndrome is a common form of mental retardation resulting from the inability to produce the fragile-X mental retardation protein. Qualitative examination of human brain autopsy material has shown that fragile-X patients exhibit abnormal dendritic spine lengths and shapes on parieto-occipital neocortical pyramidal cells. Similar quantitative results have been obtained in fragile-X knockout mice, that have been engineered to lack the fragile-X mental retardation protein. Dendritic spines on layer V pyramidal cells of human temporal and visual cortices stained using the Golgi-Kopsch method were investigated. Quantitative analysis of dendritic spine length, morphology, and number was carried out on patients with fragile-X syndrome and normal age-matched controls. Fragile-X patients exhibited significantly more long dendritic spines and fewer short dendritic spines than did control subjects in both temporal and visual cortical areas. Similarly, fragile-X patients exhibited significantly more dendritic spines with an immature morphology and fewer with a more mature type morphology in both cortical areas. In addition, fragile-X patients had a higher density of dendritic spines than did controls on distal segments of apical and basilar dendrites in both cortical areas. Long dendritic spines with immature morphologies and elevated spine numbers are characteristic of early development or a lack of sensory experience. The fact that these characteristics are found in fragile-X patients throughout multiple cortical areas may suggest a global failure of normal dendritic spine maturation and or pruning during development that persists throughout adulthood.

Localization of protein Ser/Thr phosphatase 5 in rat brain.

Protein phosphatase 5 is a recently discovered Ser/Thr phosphatase that is structurally related to calcineurin and protein phosphatases 1 and 2. Northern blot and in situ hybridization studies have shown that protein phosphatase 5 mRNA is present at high levels in brain and is localized to discrete regions. In the present study, we used immunocytochemistry and immunoblot analyses to examine the regional and subcellular distribution of this enzyme in brain. Our work demonstrates that protein phosphatase 5 is widely expressed throughout brain, but is not uniformly distributed. The most intense staining occurred in neurons of the cerebellum, cerebral cortex, and the supraoptic nucleus of the hypothalamus. Other areas also contained immunoreactive cell bodies, including the globus pallidus, hippocampus, thalamus, lateral preoptic area of the hypothalamus, substantia nigra and other brainstem nuclei. Staining in these cells was observed primarily in perikarya and proximal processes.

Water deprivation optimizes hippocampal activity and facilitates nictitating membrane conditioning.

The effects of water deprivation on hippocampal responsiveness and behavior during nictitating membrane (NM) conditioning were assessed in 12 New Zealand White rabbits (Oryctolagus cuniculus). The results showed that water deprivation produced a significant shift in electroencephalographic (EEG) frequencies such that deprived rabbits had a higher proportion of 2-8 Hz activity than did ad-lib controls. In subsequent NM training, the rabbits took significantly fewer trials to reach criterion (M = 66 vs. M = 117). A correlation coefficient quantitatively describing the relation between pretraining EEG patterns and subsequent learning rate was highly significant (r = .84). Multiple-unit analyses indicated that deprivation enhanced hippocampal responsiveness to the conditioning stimuli, especially early in training. It was concluded that the hippocampus is responsive to motivational level and that one role of the hippocampus is in the nonassociative, modulatory processes that affect the rate of conditioning.

Classical conditioning with electrical stimulation of cerebellum as both conditioned and unconditioned stimulus.

Stimulating electrodes were implanted in rabbit cerebellum, providing an electrical conditioned stimulus (CS) activating cortical parallel fibers and thence Purkinje and other cells, and an electrical unconditioned stimulus (US) activating underlying white matter and eliciting unconditioned responses. Paired CS-US presentations led to the development of conditioned responses, which showed extinction following CS-alone trials and reacquisition with significant savings on reinstatement of paired trials. Increased local excitability as a result of paired training (but not following unpaired stimulus presentations) was observed in cerebellar cortex, as manifested in substantial decreases in CS threshold for response elicitation in all subjects. This preparation offers a model for the study of plastic neuronal interactions within cerebellar networks critically involved in associative learning.

Cerebellar stimulation as an unconditioned stimulus in classical conditioning.

Rabbits were implanted with chronic stimulating electrodes in white matter underlying lobule HVI of the cerebellar cortex. Stimulation elicited movements of the face or neck and, when paired with a tone conditioned stimulus (CS), produced learning comparable to that seen with peripheral unconditioned stimuli (USs). CS-alone trials produced extinction. Reinstatement of paired trials produced reacquisition with savings. Additional groups received either explicitly or randomly unpaired CS-US trials before paired conditioning. Low-frequency responding during these sessions indicated that the paired training results were associative and not due to pseudoconditioning or sensitization. Explicitly unpaired sessions retarded learning on subsequent paired trials compared with groups that received either randomly unpaired or no CS-US preexposure. These results are interpreted in terms of the role of the cerebellum and associated pathways in classical conditioning of motor responses.

Parallel augmentation of hippocampal long-term potentiation, theta rhythm, and contextual fear conditioning in water-deprived rats.

The influence of water deprivation on hippocampal long-term potentiation (LTP), theta rhythm, and contextual fear conditioning in rats was examined. In Experiment 1, hippocampal EEG activity and perforant path LTP were assessed in pentobarbital-anesthetized rats. Water deprivation did not affect baseline cell excitability or low-frequency synaptic transmission in the dentate gyrus, but it increased the magnitude of perforant path LTP and elevated the proportion of theta rhythm in the EEG. In Experiment 2, rats were classically conditioned to fear a novel context through the use of aversive footshocks. Water deprivation facilitated the rate of contextual fear conditioning but did not alter the asymptote of learning. Experiment 3 demonstrated that the facilitation of contextual fear conditioning was not due to a change in unconditional shock sensitivity. These results suggest that water deprivation exerts an influence on contextual fear conditioning by modulating hippocampal LTP and theta rhythm and that these processes serve to encode contextual information during learning.

In search of engrams.

The body of literature presented in this paper indicate, as Marr and Albus hypothesized, that the cerebellum is involved in the regulation of classical conditioning. At present, the most parsimonious hypothesis is that the essential memory traces for classical conditioning of eyelid closure, limb flexion, and other discrete responses learned with an aversive US are formed in cerebellar cortex and interpositus nucleus. Both sites contain neuronal elements which encode both conditioned and unconditioned stimuli. Recordings from both cerebellar cortex and the deep nuclei model the topography of the conditioned response and precede the response in time. Lesions of the cortex massively impair conditioning and lesions of the interpositus nucleus completely and permanently abolish the conditioned response without affecting reflex performance.

Hippocampal plasticity during jaw movement conditioning in the rabbit.

Hippocampal CA1 unit responses were recorded during classical conditioning of rhythmic jaw movements in New Zealand White rabbits. Training was accomplished using a 1 kHz tone as the conditioned stimulus (CS) and 1 ml of sweetened water as the unconditioned stimulus (US). The interstimulus interval was 250 ms. Daily sessions consisted of 48 paired trials and six tone alone test trials, with an intertrial interval averaging 60 s. Controls were given explicitly unpaired stimuli. Unit and behavioral conditioned responses developed very rapidly in the trained group, but did not occur in controls. Averaged unit poststimulus histograms showed a correspondence between rhythmic cell discharges and the periodicity of the behavioral conditioned response after training. The results are discussed in relation to a hippocampal role in the modulation of learned movement patterns.

Therapeutic effects of complex motor training on motor performance deficits induced by neonatal binge-like alcohol exposure in rats . I. Behavioral results.

The effects of complex motor task learning on subsequent motor performance of adult rats exposed to alcohol on postnatal days 4 through 9 were studied. Male and female Long-Evans rats were assigned to one of three treatments: (1) alcohol exposure (AE) via artificial rearing to 4.5.g kg-1 day-1 of ethanol in a binge-like manner (two consecutive feedings), (2) gastrostomy control (GC) fed isocaloric milk formula via artificial rearing, and (3) suckling control (SC), where pups remained with lactating dams. After completion of the treatments, the pups were fostered back to lactating dams, and after weaning they were raised in standard cages (two-three animals per cage) until they were 6 months old. Rats from each of the postnatal treatments then spent 20 days in one of three conditions: (1) inactive condition (IC), (2) motor control condition (MC) (running on a flat oval track), or (3) rehabilitation condition (RC) (learning to traverse a set of 10 elevated obstacles). After that all the animals were tested on three tasks, sensitive to balance and coordination deficits (parallel bars, rope climbing and traversing a rotating rod). On parallel bars, both male and female rats demonstrated the same pattern of outcomes: AE-IC rats made significantly more mistakes (slips and falls) than IC rats from both control groups. After 20 days of training in the RC condition, there were no differences between AE and both SC and GC animals in their ability to perform on the parallel bars test. On rope climbing, female animals showed a similar pattern of abilities: AE-IC rats were the worst group; exercising did not significantly improve the AE rats' ability to climb, whereas the RC groups (SC, GC and AE) all performed near asymptote and there were no significant differences among three neonatal treatment groups. There was a substantial effect of the male rats' heavier body weight on climbing ability, and this may have prevented the deficits in AE rats behavior from being detected. Nevertheless, male animals from all three postnatal treatments (SC, GC and AE) were significantly better on this task after RC. Female and male rats from all three postnatal groups demonstrated significantly better performance on the rotarod task after 20 days of 'rehabilitation'. These results suggest that complex motor skill learning improves some of the motor performance deficits produced by postnatal exposure to alcohol and can potentially serve as a model for rehabilitative intervention.

Exercise-induced diarrhea: when to wonder.

Exercise-associated lower gastrointestinal symptoms seem to be a fairly common clinical finding occurring in anywhere from 10-50% of runners. However, it is unclear what percentage of those affected may have discrete medical conditions that are exacerbated by strenuous physical exertion. Perhaps, difficult physical training sessions function as a "stress test" for the colon. A case report of exercise induced diarrhea is presented with a discussion of the current medical literature and proposed management for the primary care sports physician.

The os acromiale: another cause of impingement.

Impingement of the shoulder is a relatively common clinical entity. The os acromiale anomaly is an uncommon one (1-8%) but can be an important cause of the impingement syndrome. The most common place of nonfusion is between the meso- and meta-acromion. The key to diagnosis is a history and physical examination compatible with the impingement syndrome and appropriate radiologic studies (i.e., an axillary view or profile view or computed tomographic scan if necessary). After diagnosis, the initial treatment is conservative with rest, ice, nonsteroidal anti-inflammatory drugs (NSAIDs), injections of corticosteroids in the subacromial space, and most importantly, an appropriate rehabilitation program. If unsuccessful, treatment should be planned based on the size of the unfused fragments. Small fragments (< 4 cm) may be removed by either arthroscopic or open means. Larger fragments may require an attempt at bone grafting and fixation since their removal may result in loss of strength of the deltoid.

Therapeutic uses of vitamin E in prevention of atherosclerosis.

UNLABELLED: The purpose of this review is to present the evidence-based pharmacotherapeutic properties of vitamin E and provide clinical recommendations for use in the arena of atherosclerosis. METHODS: A literature search was conducted from 1966 through March 1999. All usable papers were retrieved, with large, randomized, double-blinded, clinical trials and epidemiological trials receiving emphasis. RESULTS: Vitamin E, a lipid soluble vitamin, is a potent antioxidant. Several epidemiological studies have demonstrated positive relationships between vitamin E intake and the prevention of atherosclerotic heart disease; however, only one, large randomized clinical trial (The CHAOS Trial) has been conducted using more than 400 IU per day of vitamin E. Positive outcomes included a 77-percent reduction in nonfatal myocardial infarction (MI), but no corresponding reduction in mortality. Several large clinical trials are ongoing, investigating vitamin E for the prevention of atherosclerosis. Much less work has been undertaken studying vitamin E for prevention of cerebro- and peripheral vascular disease, but there appears to be promise in these areas as well. CONCLUSIONS: On the basis of the literature search, the authors recommend 400 IU or more per day of vitamin E to patients at high risk or already diagnosed with coronary artery disease. Vitamin E supplementation may also be beneficial in the prevention of cerebro- and peripheral vascular diseases.

Topographical analysis of cortical evoked activity during a variable demand spatial processing task.

This experiment studied changes in brain activity as subjects performed a variable demand spatial rotation task. The task involved the sequential presentation of a template histogram and a spatially rotated comparison histogram. Task difficulty was manipulated by varying the number of bars and the degree of rotation. Topographical analysis of the brain event-related activity data indicated the presence of negative components that were maximal at the vertex within 80 ms and bilaterally in the temporal lobes within 140 ms of stimulus onset and that appeared to be insensitive to changes in task difficulty. Demand-sensitive potentials were recorded, however. Positive components corresponding to P200 and P300 activity were recorded symmetrically around site PZ. The P200 component declined in amplitude, but showed no changes in latency as task demand increased. P300 activity declined in both amplitude and latency as the task became more difficult. Finally, a positive component was recorded over right central cortex approximately 490 ms after stimulus onset. This component declined in amplitude but increased in latency as task difficulty increased.

Ankle injuries. Tips from sports medicine physicians.

In dealing with an ankle sprain, worrisome features are few but important to recognize. A "pop" heard or felt at the time of injury, a prolonged course, or a history of several previous injuries are all of concern. Medial tenderness on palpation, positive results on a squeeze test, or markedly positive results on stress testing are also indicators of severe injuries, which may require referral for treatment. Stress testing by an experienced clinician is appropriate for chronic or severe cases. Otherwise, treatment of the acute, uncomplicated ankle injury is straightforward, focusing on early mobilization, rehabilitation, and protection.

Iron deficiency anemia. When is parenteral therapy warranted?

Iron deficiency anemia is a common problem encountered in primary care practice. Once the diagnosis is confirmed and the possible causes are identified, replacement of iron stores is indicated. Most patients respond favorably to oral iron preparations. However, therapy with intravenous iron dextran (InFeD) may be warranted in some cases. Side effects, which are usually mild, occur in 25% of patients. Test doses of undiluted iron dextran occasionally elicit anaphylactic reactions. However, affected patients still may be successfully treated intravenously with the use of prophylactic antihistamines, corticosteroids, and histamine2 blockers. Treatment of iron deficiency anemia almost always brings symptomatic improvement.

Brucellosis contracted during foreign travel.

Brucellosis, a bacterial infection, is rarely seen in the United States. It occurs mostly in people who work with domestic animals and animal products. However, this patient became infected while in Yugoslavia, and diagnosis was delayed by the gap between appearance of symptoms and positive results of serologic tests. Brucellosis should be suspected in a patient with unexplained fever, especially if he or she has traveled to a country where unpasteurized dairy products are common.

The role of folic acid in deficiency states and prevention of disease.

Folic acid, a water-soluble vitamin, has been used since the 1940s to treat some cases of macrocytic anemia without neurologic disease. Folate deficiency is best diagnosed with red blood cell folate levels along with macrocytosis and/or megaloblastic anemia. In addition to reversing overt deficiency, the vitamin may reduce the incidence of neural tube defects by 45% in women who receive 400 micrograms per day. It is recommended that all women of childbearing age take 400 micrograms of folate per day. Elevations in homocysteine levels, a metabolite intimately associated with folate, are also being found with increasing regularity in those with cardiovascular diseases. Homocysteine levels are reduced by folic acid administration. Therefore, there is some biologic plausibility, but not currently direct proof, for the assumption that folate supplements may prevent heart disease, stroke, and peripheral arterial disease. Controlled trials should take place before widespread food supplementation with folate is carried out on a large scale because of the possibility of outbreaks of permanent B12-related neurologic damage in those with undiagnosed pernicious anemia. However, if a patient has a premature cardiovascular event and has minimal risk factors, ordering a test to determine homocysteine level may be advisable, and if elevated, treating with folic acid supplement as long as B12 deficiency does not coexist.