The adenosine A1 receptor contributes to the stimulatory, but not the inhibitory effect of caffeine on locomotion: a study in mice lacking adenosine A1 and/or A2A receptors

Caffeine has biphasic effects on locomotion, and blockade of the adenosine A(2A) receptor (A2AR) is necessary for the stimulatory effect of low doses of caffeine, but not for the locomotor depressant effect observed at high doses. We wanted to elucidate the role of the adenosine A(1) receptor (A1R) in mediating the locomotor effects of increasing doses of caffeine using wild-type mice (A1R(WT)), mice heterozygous for (A1R(HET)), and mice lacking the adenosine A(1) receptor (A1R(KO)). Caffeine had the typical biphasic dose-effect relationship in all three genotypes, but the stimulatory action of caffeine was facilitated in the A1R(KO) mice. In order to investigate the interaction between blockade of A1Rs and A2ARs, mice lacking both receptors (A1R(KO)/A2AR(KO)) were tested. Regardless of A1R genotype, animals lacking A2AR were not stimulated by caffeine, whereas animals heterozygous for A2AR were. As expected, the A1R is not crucial for the stimulatory effect of caffeine, but seems to modulate the effect of caffeine exerted via A2AR blockade. Furthermore, these results suggest that the inhibitory effect of high doses of caffeine is due neither to blockade of the A1R, nor of the A2AR, and an effect independent of these adenosine receptors is likely.     

BRAF mutations are detectable in conjunctival but not uveal melanomas

Activating mutations in exon 15 of BRAF have been detected in a high proportion of cutaneous melanomas. To determine whether such mutations are a feature of conjunctival or uveal melanomas, we screened DNA from these tumours. Twenty-one conjunctival and 88 uveal tumours were included in the study. Mutation analysis of BRAF exons 11 and 15 was undertaken using a combination of conformationally sensitive gel electrophoresis and direct sequencing. Mutations in exon 15 were detected in three of the conjunctival tumours (two V599E and one E585 K). None of the uveal tumours possessed a BRAF mutation in either exon 15 or 11. We conclude that uveal melanomas arise independently of oncogenic BRAF mutations, but the development of a proportion of conjunctival tumours involves mutation of this gene.     

The two faces of presbyacusis: hearing impairment and psychosocial consequences

A study of hearing disability and handicap was performed in a sample of elderly persons living in an urban area of G?teborg, Sweden. The aim was to describe the psychosocial consequences of presbyacusis. For this purpose, elderly persons with fairly uncontaminated presbyacusis were chosen. The study group consisted of 154 persons (59 men and 95 women) between the ages of 70 and 91 with a median age of 78 years. The methods used included a self-assessed hearing instrument, pure-tone audiometry, and registration of desired services regarding rehabilitative audiology. The questionnaire included 26 items, 20 of them within four areas: assessment of normality, communication, quality of life and environment/orientation. The results showed that the assessment, whether the hearing was normal or not, was correlated with audiometrically measured hearing. Many of the participants expressed concern that their hearing had deteriorated. Communication situations with background noise were troublesome for many of the participants, but they had only minor problems when performing daily activities like shopping. The quality of life in general was only mildly affected by hearing loss. Items regarding environment and orientation showed varying results. Some everyday aspects of listening were related to hearing ability, but directional hearing was not correlated with measured hearing. In spite of the participants' worry about hearing deterioration, only 8% requested hearing aids as a result of the examination.     

Cytogenetic abnormalities in a hemangiopericytoma of the spleen

To date, only 16 cytogenetically abnormal hemangiopericytomas (HP) have been reported. Despite this low number, some characteristic karyotypic features have already emerged: most HP are near-diploid and breakpoints in 12q13, 12q24, and 19q13 seem to be common, with t(12;19)(q13;q13) being a recurrent translocation. Here, we report the first case of a probably benign splenic HP with chromosomal abnormalities. The abnormal karyotype was 47,XX,t(5;22;11)(q31;q11;q13),+10. None of these abnormalities have previously been reported in HP, suggesting that the karyotypic pattern of splenic HP may differ from soft tissue HP.     

Skin microvascular dilatation response to acetylcholine and sodium nitroprusside in peripheral arterial disease

The relative magnitude of endothelial versus non‐endothelial vasodilatation in the skin of limbs of patients with peripheral arterial occlusive disease (PAOD) is not known. We therefore investigated the effects of iontophoretically administered sodium nitroprusside (SNP) and acetylcholine (Ach) on the skin microvascular blood flow measured by laser‐Doppler fluxmetry. Methods: Blood flow changes in the skin was measured on the dorsal side of the foot in three different groups: (i) 11 patients (mean age 73 years) with PAOD, with a mean ankle‐brachial index of 0·46, (ii) eight age‐matched elderly healthy volunteers (mean age 73 years) and (iii) young healthy group (n=15; mean age 34 years). For drug administration with iontophoretic technique we used a Periont Micropharmacology System. Results: In patients with PAOD, Ach produced a vasodilatation, which was directly correlated to the strength of iontophoretic stimulation. The difference between the patients and the elderly healthy group was significant after the highest stimulation (160 s, P<0·05). The same pattern was found during stimulation with SNP. In comparison with the young healthy group there was a statistically significant difference (P<0·001) with a slower and less pronounced response in patients with PAOD. Conclusion: In patients with PAOD it is possible to achieve local vasodilatation from a baseline level by delivering Ach or SNP through the skin. The two vasodilators, acting by different mechanisms, produced the same vasodilatation response, suggesting that the impaired vasodilatation capacity in patients with peripheral arterial disease may not emanate primarily from local endothelial dysfunction in the skin microcirculation.     

Can the USP paddle method be used to represent in‐vivo hydrodynamics?

Experiments in-vitro and in dogs were conducted to find in-vitro hydrodynamic conditions that can be used to represent gastrointestinal motility patterns. Specifically, the dissolution performance of micronised and coarse-grade felodipine (a poorly soluble, neutral, lipophilic drug) was studied in a biorelevant medium in the USP paddle apparatus at various paddle speeds. Ratios of percentage dissolved (slower:faster rev min(-1)) were calculated pairwise. These ratios were then compared with AUC ratios obtained in a corresponding pharmacokinetic study in Labradors, in which the absorption of both the micronised and coarse-grade felodipine had been compared under two gastrointestinal hydrodynamic conditions. Using a paddle speed combination of 75 and 125 rev min(-1) to represent the motility patterns in response to administration of normal saline and 5% glucose, respectively, the in-vitro ratios (75:125 rev min(-1) dissolution ratio was 91% for the micronised and 46% for the coarse-grade powder) showed good agreement with the pharmacokinetic data (saline-to-glucose absorption ratio was 98% for the micronised and 46% for the coarse-grade powder). It was concluded that, provided an appropriate composition is chosen for the dissolution test, the USP paddle apparatus can be used to reflect variations in hydrodynamic conditions in the upper gastrointestinal tract.     

A longitudinal study of long-term quality of life after ileal pouch-anal anastomosis

BACKGROUND: There is a lack of longitudinal long-term studies of quality of life (QOL) after surgery with ileal pouch-anal anastomosis (IPAA) for ulcerative colitis, where cohorts of patients are used as their own controls. METHODS: Forty ulcerative colitis patients who had undergone IPAA were prospectively assessed while they had a temporary ileostomy, and at a median of 18 months and 7 years after ileostomy closure. QOL was measured with the Psychosocial Adjustment to Illness Scale and the Well-Being Profile. RESULTS: QOL was good at all three time points and, with some exceptions, did not change significantly between the assessments. There was a high degree of stability in the patients' evaluation of their QOL over time. CONCLUSIONS: QOL was already good when the patients had a temporary ileostomy and generally did neither improve nor deteriorate during 7 years after ileostomy closure. QOL was also quite stable in terms of individual differences.     

Dynamics of calcium clearance in mouse pancreatic beta-cells

Pancreatic beta-cells maintain glucose homeostasis by their regulated Ca(2+)-dependent secretion of insulin. Several cellular mechanisms control intracellular Ca(2+) levels, but their relative significance in mouse beta-cells is not fully known. We used photometry to measure the dynamics of cytosolic Ca(2+) ([Ca(2+)](i)) clearance after brief, depolarization-induced Ca(2+) entry. Treatment with thapsigargin or cyclopiazonic acid, inhibitors of the sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA) pumps, nearly doubled the peak and slowed the decay of the depolarization-induced Ca(2+) transients. The remaining thapsigargin-insensitive decay was slowed further by inhibition of the plasma membrane Ca(2+)-ATPase (PMCA) and plasma membrane Na(+)/Ca(2+) exchanger (NCX) via alkalization of the bath solution, by adding lanthanum, or by substitution of Na(+) with Li(+). Mitochondrial Ca(2+) uptake contributed little to clearance in thapsigargin-pretreated cells. Together, the SERCA, PMCA, and NCX transport mechanisms accounted for 89 to 97% of clearance in normal solutions. We developed a quantitative model for the dynamic role of removal mechanisms over a wide range of [Ca(2+)](i). According to our model, 50 to 64% of initial Ca(2+) removal is via the SERCA pump, whereas the NCX contributes 21-30% of the extrusion at high [Ca(2+)](i), and the PMCA contributes 21-27% at low [Ca(2+)](i).