Uptake and release of calcium by rat brain synaptosomes

Rat brain synaptosomes, prepared by discontinuous Ficoll density gradient centrifugation, accumulated ⁴⁵Ca during brief incubations in modified Krebs-Ringer media. Uptake of ⁴⁵Ca was increased by 5 mM glutamate and 50 mM KCl, conditions that depolarize nerve cells; uptake of ²²Na was also increased by these agents. With 0.2 mM diphenylhydantoin, the increased ⁴⁵Ca uptake due to KCl was diminished, whereas that due to glutamate was less affected; conversely, with 0.15 μM tetrodotoxin the increased ⁴⁵Ca uptake due to glutamate was diminished, whereas that due to KCl was less affected. Both diphenylhydantoin and tetrodotoxin diminished the augmented uptake of ²²Na due to KCl and glutamate; thus the increased uptake of ⁴⁵Ca under depolarizing conditions may be dissociated from the increased influx of sodium. Ruthenium red decreased the uptake of ⁴⁵Ca under all conditions, as did procaine and the lanthanide Pr³⁺. Neither 5 mM lutamate nor 50 mM KCl increased ⁴⁵Ca uptake by brain mitochondria under comparable experimental conditions, whereas ATP increased the uptake by mitochondria but not that by these synaptosomes. Altering the sodium gradient by equimolar substitution of lithium or choline for sodium in the medium increased ⁴⁵Ca uptake, whereas ²²Na uptake was decreased. Inhibiting the sodium pump by ouabain or strophanthidin also increased ⁴⁵Ca uptake, and increased ²²Na uptake as well. The increased uptake of ⁴⁵Ca induced by ouabain was inhibited by diphenylhydantoin and tetrodotoxin. Measurements of the total calcium content showed that conditions producing an increased uptake of ⁴⁵Ca also produced a net uptake of calcium, rather than merely accelerating a ⁴⁵Ca⁴⁰Ca exchange. Experiments measuring the loss of previously accumulated ⁴⁵Ca showed that directly decreasing the sodium gradient or inhibiting the sodium pump slowed the loss of ⁴⁵Ca. These data are considered in terms of calcium influx through ‘leak’ pathways and gated channels (sensitive to membrane depolarization) and of net efflux dependent on a coupled sodium-calcium exchange mechanism.     

Transformation of cultured rat adrenocortical cells by Kirsten murine sarcoma virus (Ki-MSV).

Two-week-old primary cultures of normal adult rat adrenal cortex were exposed to Kirsten murine sarcoma virus (KiMSV). Within a week, the adrenal cells, which are normally fusiform and aligned in parallel, became pleomorphic and piled up extensively. Saturation density increased from 5-10 x 10(4) to 5-10 x 10(5) cells/cm2, population doubling time during exponential growth decreased from 36-40 to 16h, acid production increased and the growth rate became independent of a reduction in serum concentration from 10% to 1%. Inoculation of 2 x 10(6) of these transformed cells into immuno-depressed rats produced rapidly growing tumors within 1 week. Histologically, the tumors were pleomorphic carcinomas with areas ranging from anaplasia to near-normal, highly differentiated adrenocortical tissue. In addition to histologic evidence of differentiation, metabolic studies using 14C-prognenolone showed that the transformed cells were capable of 20alpha reduction and delta5,3beta dehydrogenation, both characteristic of normal steroid-secreting tissues. The transformed adrenocortical cells produced infectious C-type virus as indicated by electron microscopy, 3H-uridine incorporation, and focus formation in NRK (normal rat kidney) cultures. The neutralization pattern of this virus resembled that of authentic Ki-MSV. The transformation of adrenocortical cells by K-MSV demonstrates the capacity of this agent to induce carcinomas in differentiated cells after short-term culture, and widens the range of tissues known to be susceptible to K-MSV to include a secretory epithelium of mesodermal origin.     

Imaging of testicular tumours

This article reviews the diagnosis, pathology and imaging of testicular tumours, predominantly germ cell tumours. It will discuss the imaging techniques used in their diagnosis, staging and surveillance.     

Newborn screening for medium chain acyl-CoA dehydrogenase deficiency (MCADD) in the UK

The Department of Health and the National Screening Committee are funding a new newborn screening service for the rare inherited disorder medium chain acyl-CoA dehydrogenase deficiency, otherwise known as MCADD. Screening commenced as a pilot programme on 1 March 2004 from six laboratories in England. An evaluation study following all positive cases of MCADD from this first two-year pilot period will continue for a further three years to measure the overall effectiveness of screening for MCADD in the UK. This article reviews the background to the introduction of the pilot programme and describes the features and complications of MCADD, including the diagnosis and management.     

Opiate-like effects of sugar on gene expression in reward areas of the rat brain

Drugs abused by humans are thought to activate areas in the ventral striatum of the brain that engage the organism in important adaptive behaviors, such as eating. In support of this, we report here that striatal regions of sugar-dependent rats show alterations in dopamine and opioid mRNA levels similar to morphine-dependent rats. Specifically, after a chronic schedule of intermittent bingeing on a sucrose solution, mRNA levels for the D2 dopamine receptor, and the preproenkephalin and preprotachykinin genes were decreased in dopamine-receptive regions of the forebrain, while D3 dopamine receptor mRNA was increased. While morphine affects gene expression across the entire dopamine-receptive striatum, significant differences were detected in the effects of sugar on the nucleus accumbens and adjacent caudate-putamen. The effects of sugar on mRNA levels were of greater magnitude in the nucleus accumbens than in the caudate-putamen. These areas also showed clear differences in the interactions among the genes, especially between D3R and the other genes. This was revealed by a novel multivariate analysis method that identified cooperative interactions among genes, specifically in the nucleus accumbens but not the caudate-putamen. Finally, a role for these cooperative interactions in a load-sharing response to perturbations caused by sugar was supported by the finding of a different pattern of correlations between the genes in the two striatal regions. These findings support a major role for the nucleus accumbens in mediating the effects of naturally rewarding substances and extend an animal model for studying the common substrates of drug addiction and eating disorders.     

Parental reporting of smelly urine and urinary tract infection

Background: Parents often report that young children have "smelly urine" or a particular urinary odour. There is little evidence that these observations are relevant to the diagnosis of urinary tract infection (UTI). Aims: To determine whether parental reporting of smelly urine is of any relevance to the diagnosis of UTI in children less than 6 years of age. Methods: Parents whose children were having urine collected as part of their admission to a large district hospital were given a simple questionnaire to complete regarding the current smell of their child‘s urine. Parents were asked whether their child‘s urine smelled different from usual or had a particular smell. Microscopy and culture results of the child‘s urine were compared to their parent‘s questionnaire answers to see if there was a association between parental reporting of a different or particular urine smell and a diagnosis of UTI. Results: One hundred and ten questionnaires and urine samples were obtained. Fifty two per cent of parents thought that their child‘s urine smelled different from usual or had a particular smell. Only 6.4% of children were diagnosed as having a UTI. There was no statistically significant association between parental reporting of abnormal urine smell and diagnosis of UTI. Conclusion: In determining whether a young child has a UTI, asking parents about urine smell is unlikely to be of benefit.     

Parental reporting of smelly urine and urinary tract infection.

BACKGROUND: Parents often report that young children have "smelly urine" or a particular urinary odour. There is little evidence that these observations are relevant to the diagnosis of urinary tract infection (UTI). AIMS: To determine whether parental reporting of smelly urine is of any relevance to the diagnosis of UTI in children less than 6 years of age. METHODS: Parents whose children were having urine collected as part of their admission to a large district hospital were given a simple questionnaire to complete regarding the current smell of their child's urine. Parents were asked whether their child's urine smelled different from usual or had a particular smell. Microscopy and culture results of the child's urine were compared to their parent's questionnaire answers to see if there was a association between parental reporting of a different or particular urine smell and a diagnosis of UTI. RESULTS: One hundred and ten questionnaires and urine samples were obtained. Fifty two per cent of parents thought that their child's urine smelled different from usual or had a particular smell. Only 6.4% of children were diagnosed as having a UTI. There was no statistically significant association between parental reporting of abnormal urine smell and diagnosis of UTI. CONCLUSION: In determining whether a young child has a UTI, asking parents about urine smell is unlikely to be of benefit.     

Recommendations for prevention and management of fire ant infestation of health care facilities

The range of imported fire ants now includes most of the southeastern United States, parts of the Southwest, portions of the East and West Coasts, and Puerto Rico. Increasingly, fire ant attacks on patients in health care facilities have been reported. In this paper, we provide recommendations for fire ant control in and around health care facilities that should help prevent building infestation and further attacks. In addition, we provide algorithms detailing fire ant prevention strategies (indoors and outdoors) and patient management after fire ant stings. Physicians in areas endemic for fire ants should be aware of the possibility that patients may be harmed by these insects, and also should be generally familiar with measures used to control fire ants.     

Novel multilocus measure of linkage disequilibrium to estimate past effective population size

Linkage disequilibrium (LD) between densely spaced, polymorphic genetic markers in humans and other species contains information about historical population size. Inferring past population size is of interest both from an evolutionary perspective (e.g., testing the "out of Africa" hypothesis of human evolution) and to improve models for mapping of disease and quantitative trait genes. We propose a novel multilocus measure of LD, the chromosome segment homozygosity (CSH). CSH is defined for a specific chromosome segment, up to the full length of the chromosome. In computer simulations CSH was generally less variable than the r(2) measure of LD, and variability of CSH decreased as the number of markers in the chromosome segment was increased. The essence and utility of our novel measure is that CSH over long distances reflects recent effective population size (N), whereas CSH over small distances reflects the effective size in the more distant past. We illustrate the utility of CSH by calculating CSH from human and dairy cattle SNP and microsatellite marker data, and predicting N at various times in the past for each species. Results indicated an exponentially increasing N in humans and a declining N in dairy cattle. CSH is a valuable statistic for inferring population histories from haplotype data, and has implications for mapping of disease loci.