Membrane-localized β-subunits alter the PIP2 regulation of high-voltage activated Ca2+ channels

The β-subunits of voltage-gated Ca(2+) (Ca(V)) channels regulate the functional expression and several biophysical properties of high-voltage-activated Ca(V) channels. We find that Ca(V) β-subunits also determine channel regulation by the membrane phospholipid phosphatidylinositol 4,5-bisphosphate (PIP(2)). When Ca(V)1.3, -2.1, or -2.2 channels are cotransfected with the β3-subunit, a cytosolic protein, they can be inhibited by activating a voltage-sensitive lipid phosphatase to deplete PIP(2). When these channels are coexpressed with a β2a-subunit, a palmitoylated peripheral membrane protein, the inhibition is much smaller. PIP(2) sensitivity could be increased by disabling the two palmitoylation sites in the β2a-subunit. To further test effects of membrane targeting of Ca(V) β-subunits on PIP(2) regulation, the N terminus of Lyn was ligated onto the cytosolic β3-subunit to confer lipidation. This chimera, like the Ca(V) β2a-subunit, displayed plasma membrane localization, slowed the inactivation of Ca(V)2.2 channels, and increased the current density. In addition, the Lyn-β3 subunit significantly decreased Ca(V) channel inhibition by PIP(2) depletion. Evidently lipidation and membrane anchoring of Ca(V) β-subunits compete with the PIP(2) regulation of high-voltage-activated Ca(V) channels. Compared with expression with Ca(V) β3-subunits alone, inhibition of Ca(V)2.2 channels by PIP(2) depletion could be significantly attenuated when β2a was coexpressed with β3. Our data suggest that the Ca(V) currents in neurons would be regulated by membrane PIP(2) to a degree that depends on their endogenous β-subunit combinations.     

First Clinical Experience with Intranasal Cooling for Hyperthermia in Brain-Injured Patients

Introduction

Hyperthermia is common in brain-injured patients and associated with a worse outcome. As brain rather than body temperature reduction, theoretically, is the most important in cerebral protection, there is logic in targeting cooling at the brain. Selective brain cooling can, in theory, be obtained by cooling the skull or by heat loss from the upper airways. In this preliminary safety and efficacy study, we report clinical data from brain-injured patients who because of hyperthermia were treated with intranasal cooling.

Methods

Nine intubated brain-injured patients with hyperthermia were treated using a prototype intranasal balloon system perfused with cold saline. Temperature in the cerebrum, esophagus, and bladder was monitored together with intracranial pressure.

Results

In only two of nine patients, normothermia was reached in the esophagus and in only four of nine patients it was reached in the bladder. When normothermia was reached, the time to normothermia was delayed. In the brain, normothermia was reached in two of five patients after approximately 72 h. Median temperature curves from the first 72 h of cooling showed that normothermia was not reached in any of the three compartments. The temperature in the brain and bladder were on average 0.6 and 0.5 °C higher than in the esophagus. ICP increased with increasing brain temperature. We found no signs of clinical important injury to the nasal mucosa from the cold saline or pressure in the balloons.

Conclusion

In brain-injured patients with hyperthermia, cooling with a prototype intranasal balloon system was clinically inadequate as the effect was delayed and not brain selective.     

Stable Fixation but Unpredictable Bone Remodelling Around the Lord Stem : Minimum 23-Year Follow-Up of 66 Total Hip Arthroplasties

Early designs of uncemented hip implants turned out to be failures mainly because the prerequisites for durable implant fixation were unknown. One exception was the chrome–cobalt stem of the Madreporic Lord prosthesis. We prospectively studied this prosthetic design in 107 hips that underwent surgery in 1979–1986. At the last follow-up, five stems and 54 cups had been revised, corresponding to stem and cup survival rates of 92% ± 3% and 45% ± 5% at 26 years. In all, 66 hips with remaining Lord stems were available for clinical follow-up 26 years (24–29) after the index operation. The mean total Harris hip and pain scores were 81 (SD 14) and 41 (SD 5).     

Gender Differences in the Electrophysiological Characteristics of Atrioventricular Conduction System and their Clinical Implications

Objective - The underlying mechanisms of the differences in sex distribution of patients with atrioventricular (AV) nodal re-entrant tachycardia and Wolff-Parkinson-White syndrome are poorly understood. The objective of this study was to determine potential gender differences in the electrophysiological properties of the normal AV conduction system that may be attributable to differences in sex distribution. Design - The AV conduction properties were studied in 96 patients (52 men and 44 women) who underwent electrophysiological testing, 32 patients with atrial tachycardia, 39 with idiopathic ventricular tachycardia and 25 with unexplained palpitations or syncope. Results - The AH (83 &#45 15 ms) and His-ventricular intervals in men (42 &#45 6 ms) were significantly longer than in women (78 &#45 14, 38 &#45 6 ms, p < 0.05, respectively), as was the PR interval (160 &#45 17 vs 152 &#45 13 ms, p = 0.02). The effective refractory period of AV node in men (349 &#45 75 ms) was longer than in women (297 &#45 45 ms, p = 0.03). However, no significant difference was observed between men and women with respect to the incidence of AV nodal dual pathway and the maximum AH interval achieved during premature stimulation or incremental pacing. The AV block cycle length was significantly longer in men (371 &#45 76 ms) than in women (330 &#45 52 ms, p = 0.02). A longer ventriculoatrial block cycle length was also found in men than in women although not at a significant level (436 &#45 107 vs 384 &#45 90 ms, p = 0.08). In addition, men (23%) were twice as likely to have ventriculoatrial dissociation during ventricular pacing as women were (11%, p = 0.2). Conclusion - The data show that gender-related differences in AV conduction properties may be responsible for the differences in sex distribution observed in patients with AV nodal re-entrant tachycardia and those with ventricular pre-excitation.     

Validation and improvement of a predictive model for treatment outcome in patients with temporomandibular disorders

OBJECTIVE: To examine whether it was possible to improve individual prediction of treatment outcome in patients with temporomandibular disorders (TMD) through continuous quality improvement registrations and implementation of changes in clinical routines. MATERIAL AND METHODS: All 5777 patients referred to a specialist clinic for stomatognathic physiology; 2187 TMD patients started treatment. The patients were divided into Muscle or Mainly TMJ symptom groups. Actual treatment outcome was predicted as Good or Dubious based on patient history and clinical findings. The degree of improvement of initial symptoms was graded using a numeric rating scale 0-100. Improvement in initial complaints of 50% or more was judged as a clinically important difference (CID); 989 patients (76%) completed treatment 1992-1998 (Sample 1) and 769 (86%) treatment 1999-2004 (Sample 2). RESULTS: For patients with Muscle symptoms in Sample 1, CID was reached by 90% of those predicted Good and by 56% of those predicted Dubious. In Sample 2, the figures were Good 93% and Dubious 57%. In subgroup Mainly TMJ symptoms, CID was reached by 94% of those predicted Good and by 88% if predicted Dubious in Sample 1. In Sample 2, the figures were the same for those predicted Good, i.e. 94%, and Dubious, 73%. CONCLUSION: Continuous quality improvement registrations and implementation of changes in clinical routines improved the ability to predict individually the actual treatment outcome between patients predicted Good or Dubious, respectively. Rheumatic disease turned out not to be a negative predictor for treatment outcome.     

Detection of molecular variants of prolactin in human serum, evaluation of a method based on ultrafiltration

BACKGROUND: In human blood, there are several molecular variants of prolactin with different biological effects. There is a need for new methods to detect and quantify these variants in order to fully understand the pathophysiological role of prolactin. METHODS: A method based on ultrafiltration was optimized, validated and compared to PEG precipitation. Serum samples from 84 patients were analyzed before and after pre treatment on two immunoassays, Elecsys (Roche) and Access (Beckman). Protein G precipitation was used to confirm presence of macroprolactin. RESULTS: The recovery of prolactin after ultrafiltration was lower than after PEG precipitation. A limit of 40% recovery after PEG precipitation corresponded to 27% recovery after ultrafiltration. Using these limits there were total agreement regarding detection of macroprolactin (r(s)=0.96). In contrast, recovery of prolactin in samples without macroprolactin showed a considerable disagreement between ultrafiltration and PEG precipitation (r(s)=0.48). Within-run CV was 4% for the ultrafiltration method. The correlation coefficient (r) between the immunoassays was 0.96 after ultrafiltration. CONCLUSIONS: Ultrafiltration can be used to compare different prolactin immunoassays and to detect macroprolactin in assays with interference from PEG. For samples without macroprolactin ultrafiltration may give additional information reflecting individual variations of other molecular variants of prolactin.     

Heart rate recovery after exercise is related to the insulin resistance syndrome and heart rate variability in elderly men

Objective We investigated the associations between heart rate recovery after exercise (as a suggested measure of vagal activity), heart rate variability, and measurements of the insulin resistance syndrome. Material and Methods Seventy men aged 70 years were examined with a symptom-limited bicycle exercise test, a 24-hour heart rate variability test, and different measurements of different components of the insulin resistance syndrome. Results Heart rate recovery after exercise (mean ± SD 20 ± 9 beats during the first minute) was related to both the SD of the R-R interval and the low frequency power at the heart rate variability analyses (r = 0.39, P < .002 for both). Furthermore, heart rate recovery after exercise was related to insulin sensitivity at the hyperinsulinemic eugleucemic clamp (r = 0.28, P < .03), and to high-density lipoprotein cholesterol and exercise capacity, and inversely to obesity and insulin and glucose levels 2 hours after an oral glucose load (P < .05 for all). Heart rate recovery after exercise was not related to left ventricular mass measured by means of echocardiography or to the number of ventricular premature complexes at a 24-hour Holter recording. Conclusion Heart rate recovery 1 minute after exercise was related to measurements of 24-hour heart rate variability. Furthermore, heart rate recovery after exercise was related to several of the major components of the insulin resistance syndrome, thereby establishing a link between this syndrome and cardiac autonomic nervous activity. (Am Heart J 2002;144:666-72.)