Outgassing behavior and composition of comet C/1999 S4 (LINEAR) during its disruption.

The gas activity of comet C/1999 S4 (LINEAR) was monitored at radio wavelengths during its disruption. A runaway fragmentation of the nucleus may have begun around 18 July 2000 and proceeded until 23 July. The mass in small icy debris (

Treatment of paediatric trigger finger: a systematic review and treatment algorithm.

PURPOSE: Paediatric trigger finger (PTF) is a rare condition as seen by the lack of studies published about paediatric populations. Due to this general lack of information, the steps to employ to correct this disorder, whether surgically or non-surgically, have not yet reached consensus status. The objective of this study is to review the published literature regarding treatment options for PTF in order to develop a proposed step-wise treatment algorithm for children presenting with trigger finger. METHODS: A systematic review of the literature was conducted on PubMed to locate English language studies reporting on treatment interventions of PTF. Data was collected on number of patients/fingers seen in the study, the category of the fingers involved, the number of patients/fingers undergoing each intervention and reported outcomes. RESULTS: Seven articles reporting on 118 trigger fingers were identified. In all, 64 fingers were treated non-surgically, with 57.8% (37/64) resolving. In all, 54 fingers were initially surgically treated, with 87% (47/54) resolving. In total, 34 fingers did not have resolution of symptoms following primary treatment, and 27 fingers received follow-up treatment, with 92.6% (25/27) resolving. Overall, 92.4% (109/118) of fingers achieved resolution of symptoms after all treatments were completed. CONCLUSION: Limitations for this study included few prospective studies and small sample sizes. This is likely due to the rarity of PTF. This review of the literature indicated that a step-wise approach, including non-operative and surgical techniques, should be employed in the management of PTF. LEVEL OF EVIDENCE III: This work meets the requirements of the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses).

Inhibition by alpha-tetrahydrodeoxycorticosterone (THDOC) of pre-sympathetic parvocellular neurones in the paraventricular nucleus of rat hypothalamus.

BACKGROUND AND PURPOSE: alpha-tetrahydrodeoxycorticosterone (THDOC) is an endogenous neuroactive steroid which increases in plasma and brain concentration during stress. It has both positive and negative modulatory effects on GABA activated GABAA currents, dependent upon the dose. We investigated the effects of THDOC on spinally-projecting "pre-sympathetic" neurones in the parvocellular subnucleus of the hypothalamic paraventricular nucleus (PVN), to determine whether it activates or inhibits these neurones, and by what mechanism. EXPERIMENTAL APPROACH: Rat spinally-projecting (parvocellular) PVN neurones were identified by retrograde labelling and the action of THDOC investigated with three modes of patch-clamp: cell-attached action current, whole-cell voltage-clamp and cell-attached single-channel recording. KEY RESULTS: In cell-attached patch mode, parvocellular neurones fired action potentials spontaneously with an average frequency of 3.6 +/- 1.1 Hz. Bath application of THDOC reduced this with an EC50 of 67 nM (95% confidence limits: 54 to 84 nM), Hill coefficient 0.8 +/- 0.04, n = 5. In whole-cell patch-clamp mode, pressure ejection of GABA evoked inward currents. These were clearly GABAA currents, since they were inhibited by the GABAA receptor antagonist bicuculline, and reversed near the chloride equilibrium potential. THDOC significantly potentiated GABAA currents (1 microM THDOC: 148 +/- 15% of control, n = 5, p < or = 0.05, ANOVA). Single-channel analysis showed no differences in conductance or corrected mean open times in the presence of 1 microM THDOC. CONCLUSIONS AND IMPLICATIONS: THDOC inhibited parvocellular neuronal activity without showing any evidence of the bidirectional activity demonstrated previously with cultured hypothalamic neurones. Our data are consistent with the hypothesis that THDOC acts by potentiating the post-synaptic activity of endogenously released GABA.

Detergent effects on enzyme activity and solubilization of lipid bilayer membranes.

Over 50 detergents were tested to establish which would be most effective in releasing proteins from membrane-bounded compartments without denaturing them. Various concentrations each of detergent were tested for two activities: (1) solubilization of egg phospholipid liposomes as measured by reduction of turbidity and (2) effect of detergent concentration on the activities of soluble, hydrolytic enzymes. Those detergents most effective in solubilizing 0.2% lipid and least detrimental to enzymes were five pure, synthetic compounds recently introduced: CHAPS, CHAPSO, Zwittergents 310 and 312, and octylglucoside. Industrial detergents were generally much inferior, insofar as they solubilized membranes inefficiently and/or inactivated certain hydrolytic enzymes readily. The five detergents were characterized by (a) an unusually high critical micelle concentration and (b) a preference for forming mixed micelles with lipids instead of forming pure micelles, as indicated by an ability to solubilize lipid at concentrations of detergent significantly below the critical micelle concentration. This characteristic permits solubilization of high concentrations of membrane below the critical micelle concentration of the detergent so that protein denaturation is minimized. A generally applicable guideline that emerged from this study is that detergents should be used at approximately their critical micelle concentration which should not be exceeded by the concentration of membrane. Similar considerations should apply to the use of detergents in purifying and reconstituting intrinsic membrane proteins.

Impaired calcium release in cerebellar Purkinje neurons maintained in culture.

Cerebellar Purkinje neurons demonstrate a form of synaptic plasticity that, in acutely prepared brain slices, has been shown to require calcium release from the intracellular calcium stores through inositol trisphosphate (InsP(3)) receptors. Similar studies performed in cultured Purkinje cells, however, find little evidence for the involvement of InsP(3) receptors. To address this discrepancy, the properties of InsP(3)- and caffeine-evoked calcium release in cultured Purkinje cells were directly examined. Photorelease of InsP(3) (up to 100 microM) from its photolabile caged analogue produced no change in calcium levels in 70% of cultured Purkinje cells. In the few cells where a calcium increase was detected, the response was very small and slow to peak. In contrast, the same concentration of InsP(3) resulted in large and rapidly rising calcium responses in all acutely dissociated Purkinje cells tested. Similar to InsP(3), caffeine also had little effect on calcium levels in cultured Purkinje cells, yet evoked large calcium transients in all acutely dissociated Purkinje cells tested. The results demonstrate that calcium release from intracellular calcium stores is severely impaired in Purkinje cells when they are maintained in culture. Our findings suggest that cultured Purkinje cells are an unfaithful experimental model for the study of the role of calcium release in the induction of cerebellar long term depression.

Structural properties of voltage-dependent calcium channels.

Following purification using Ca2+ channel drugs as ligands, the skeletal muscle Ca2+ channel was shown to be a five-subunit structure containing one large (175 kDa) protein that is the pore and four auxiliary subunits. Each subunit has been cloned and expression studies are proceeding rapidly. Particular success has been made in structure-function studies of excitation-contraction coupling using a Ca2+ channel-free mutant muscle. The work confirmed the suggestion made from physiological studies that muscle Ca2+ channels serve dual roles: passing Ca2+ and triggering Ca2+ release from an intracellular organelle. A variety of other predictions about the structure of Ca2+ channels have been reviewed here and these may soon be possible to test. Such concrete predictions along with analogies to studies on other voltage-dependent ion channels should speed progress in structure-function studies of Ca2+ channels.

Plasma free amino acid levels in human subjects after meals containing lactalbumin, heated lactalbumin, or no protein.

Plasma free amino acids were measured in six adult human subjects at four consecutive 1/2 hr intervals following meals containing either 50 g lactalbumin, 50 g heated lactalbumin, or no protein. After the lactalbumin meal, all essential and several nonessential amino acids increased in the plasma. After the heated lactalbumin meal, these increases were either much less or did not appear. Following the no protein meal all measured plasma amino acids fell. The absence of a response to the heated lactalbumin meal was considered to be related to a drop in digestibility of heated lactalbumin as measured in rats.

Obligatory urinary and fecal nitrogen losses in young women, older men, and young men and the factorial estimation of adult human protein requirements.

Obligatory urinary and fecal nitrogen losses and urinary urea nitrogen and creatinine excretion levels were determined in 11 young women (four of whom used oral contraceptives), eight older men, and five young men. Values for obligatory nitrogen losses in the young women who did not use oral contraceptives were similar to those observed previously in young women and lower than those reported for young men. Our values for older men were lower than previously reported values for obligatory losses observed in young and elderly men, but similar to previously reported values for young women and to values for our women who did not use oral contraceptives. The four oral contraceptive users had significantly higher levels of total urinary and fecal obligatory nitrogen losses than the nonusers in our study. When values from our study and values from other recent studies are considered, variations in obligatory nitrogen losses appear to be larger among individuals within an age-sex group than the observed differences between groups. When the intakes of protein recommended as safe by the Food aculated from obligatory nitrogen losses per se, the recommended levels appear to be only marginally adequate.

Pharmacological characterization of the 5-HT receptor-mediated contraction in the mouse isolated ileum.

The pharmacological characterization of a 5-HT receptor-mediated contractile response in the mouse isolated ileum is described. In the presence of methysergide (1 microM), 5-hydroxytryptamine (5-HT, 0.3 - 100 microM) produced phasic concentration-dependent contractions of segments of the mouse isolated ileum with a pEC(50) value of 5.47+/-0.09. The 5-HT(3) receptor selective agonists m-chlorophenylbiguanide (0.3 - 100 microM, pEC(50) 5.81+/-0.04), 1-phenylbiguanide (3 - 100 microM, pEC(50) 5.05+/-0.06) and 2-methyl-5-HT (3 - 100 microM, pEC(50) 5.00+/-0.07) acted as full agonists to induce contractile responses. 5-methoxytryptamine (0.1 - 100 microM), RS 67506 (0.1 - 100 microM) and alpha-methyl-5-HT (0.1 - 100 microM) failed to mimic the 5-HT responses. The contractile response to 5-HT was not antagonized by either 5-HT(2) receptor antagonists ritanserin (0.1 microM) or ketanserin (1 microM) nor the 5-HT(4) receptor antagonist SB 204070 (0.1 microM). The 5-HT(3) receptor selective antagonists granisetron (0.3 - 1 nM), tropisetron (1 - 10 nM), ondansetron (10 nM - 1 microM) and MDL 72222 (10 nM - 1 microM) caused rightward displacement of the concentration-response curves to 5-HT. The lower concentrations of the antagonists caused approximate parallel rightward shifts of the concentration-response curves to 5-HT with apparent pK(B) values for granisetron (9.70+/-0. 39), tropisetron (9.18+/-0.20), ondansetron (8.84+/-0.24) and MDL 72222 (8.65+/-0.35). But higher concentrations of antagonists resulted in a progressive reduction in the maximum responses. The contractile response to 5-HT was abolished by tetrodotoxin (0.3 microM); atropine (0.1 and 1 microM) decreased the maximum response of the 5-HT concentration-response curve by approximately 65%. It is concluded that a neuronally located 5-HT(3) receptor mediates a contractile response to 5-HT in the mouse ileum. The 5-HT(3) receptor in the mouse ileum has a different pharmacological profile to that reported for the guinea-pig ileum.

Elevated intracellular calcium levels in cerebellar granule neurons of weaver mice.

Weaver mice carry a mutation in the pore domain of the Girk2 (Kcnj6) gene. The mutation causes GIRK2 containing channels to lose ion selectivity and to become constitutively active. It is not known how this alteration in ion channel activity causes in cerebellar granule cells the defects in neurite extension, cell migration and induction of cell death that are characteristic of weaver mice. One possibility is that the mutation causes an inability to regulate intracellular calcium levels properly. We tested this hypothesis by measuring intracellular calcium levels in granule cells and Purkinje cells in slices from the cerebellum of weaver mice. We report here that weaver mice have increases in resting calcium levels in their granule cells, which may account for the multiple effects of the weaver mutation upon these cells.

Detection and Characterization of a Lethal Yellowing (16SrIV) Group Phytoplasma in Canary Island Date Palms Affected by Lethal Decline in Texas.

Polymerase chain reaction (PCR) assays were used to detect phytoplasmas in Canary Island date (Phoenix canariensis) palms displaying symptoms similar to lethal yellowing (LY) disease in Corpus Christi, TX. An rDNA product (1.8 kb) was amplified consistently from 10 of 11 palms by PCR employing phytoplasma universal rRNA primer pair P1/P7. Also, AluI endonu-clease digests and sequencing of P1/P7 products revealed that nontarget Bacillus megaterium-related rDNA sequences of similar size were co-amplified along with phytoplasma rDNA from 10 palms. A 1,402-bp product was obtained from all 11 symptomatic palms when initial P1/P7 products were reamplified by PCR employing nested LY phytoplasma group-specific 16S rRNA primer pair LY16Sf/LY16Sr. Restriction fragment length polymorphism (RFLP) analysis of nested PCR products revealed that palm-infecting phytoplasmas were uniform and most similar to strains composing the coconut lethal yellowing phytoplasma (16SrIV) group. Sequence analysis of 16S rDNA determined the Texas Phoenix palm decline (TPD) phytoplasma to be phylogenetically closest to the Carludovica palmata leaf yellowing (CPY) phytoplasma. rDNA profiles of strains TPD and CPY obtained with AluI were co-identical and distinct from other known 16SrIV group phytoplasmas. On this basis, both strains were classified as members of a new subgroup, 16SrIV-D.

Distribution, abundance and bionomics of Aedes albopictus in southern Texas.

A survey was conducted for Aedes albopictus in southern Texas during the summer of 1992. Thirty-five new country records were added to the distribution of this imported mosquito in Texas. Aedes albopictus was widely distributed throughout the ecological regions in the survey area, but its abundance decreased in counties adjacent to the Rio Grande River. However, these counties had high densities of Aedes aegypti.

Colonization of rock holes by Aedes albopictus in the southeastern United States.

Aedes albopictus was collected from water-holding rock holes along 3 streams in Georgia and 1 in South Carolina. To compare the occurrence of Ae. albopictus and Aedes atropalpus, rock holes were sampled for immature Aedes at 2 sites where there were numerous rock holes harboring mosquitoes. At 1 of these sites, tree holes and various types of artificial containers were also sampled for immature Aedes. At both sites, immature Ae. albopictus occurred in rock holes much less frequently than the rock-pool specialist, Aedes atropalpus. Moreover, the distribution of Ae. albopictus was limited to rock holes in less flood prone locations, whereas Ae. atropalpus was often a common mosquito even in rock holes that were among the most susceptible to flooding by rising stream levels. By contrast. Ae. albopictus was frequently found in the samples from tree holes and artificial containers. Thus, it appears that riverine rock holes that are flooded frequently may be, at best, marginal habitats for Ae. albopictus.

Distribution of Aedes albopictus in Georgia, USA.

A statewide survey was conducted for Aedes albopictus in Georgia during the summers of 1991-94. All 159 counties in Georgia were determined to be infested. Aedes albopictus was widely distributed throughout all ecological regions in the survey area.

Polyurethane scaffold in lateral meniscus segmental defects: clinical outcomes at 24 months follow-up.

BACKGROUND: Segmental tissue loss in the lateral meniscus is associated with pain and increased risk of osteoarthritis even when indications have been carefully considered. HYPOTHESIS: Repairing the defect using a novel biodegradable scaffold will reduce pain and restore the knee function. METHODS: In this prospective multicenter study, a total of 54 patients (37 males/17 females; mean age: 28 years [16-50]) were enrolled. All patients presented with postmeniscectomy syndrome and segmental lateral meniscus loss, and were treated with a polyurethane biodegradable scaffold (Actifit(®), Orteq) implanted arthroscopically. Clinical outcomes were assessed at 6, 12 and 24 months using Visual Analogue Scale (VAS), International Knee Documentation Committee Score (IKDC) and Knee Injury and Osteoarthritis Outcome Score (KOOS). RESULTS: VAS decreased from 5.5 at baseline to 3.6 at 6 months, 3.4 at 12 months and 2.9 at 24 months. IKDC improved from 47.0 at baseline to 60.2, 67.0 and 67.0 at 6, 12 and 24 months. All KOOS subscores improved between baseline and 24 months. DISCUSSION: Clinical results of this study demonstrate clinically and statistically significant improvements of pain and function scores (VAS, IKDC, and all KOOS subscales except sport), at the 6 months follow-up and on all clinical outcomes at the 2-year follow-up. The Actifit(®) scaffold is safe and effective in treating lateral meniscus defects. LEVEL OF EVIDENCE IV: continuous prospective multicenter study.

Large conductance calcium-activated potassium channels affect both spontaneous firing and intracellular calcium concentration in cerebellar Purkinje neurons.

We investigated the contribution of large conductance calcium-activated potassium (BK) channels to spontaneous activity of cerebellar Purkinje neurons in mice and rats. In Purkinje neurons which fire tonically, block of BK channels increased the firing rate and caused the neurons to fire irregularly. In Purkinje neurons which exhibited a trimodal pattern of activity, present primarily in mature animals, block of BK channels had little effect on firing rate or regularity but shortened the single cycle duration of the trimodal pattern. The contribution of BK channels to the action potential waveform was also examined. BK channels contributed a brief afterhyperpolarization (AHP) of approximately 3 mV which followed each action potential, but made little contribution to action potential repolarization. The amplitude of the BK-dependent AHP did not change with age although there was an increase in the total AHP. The difference in the contribution of BK channels to the firing rate among the two populations of Purkinje neurons was the consequence of the decrease in the fractional contribution of BK channels to the AHP. We also found that block of BK channels increases intracellular calcium concentration during spontaneous firing. Thus, although BK channels do not affect action potential repolarization, they nevertheless control calcium entry with each action potential by contributing to the AHP.