Evidence that direct binding of G beta gamma to the GIRK1 G protein-gated inwardly rectifying K+ channel is important for channel activation

Activation of G protein-gated K+ channels by G protein-coupled receptors contributes to parasympathetic regulation of heart rate in the atrium and inhibitory postsynaptic potentials in the peripheral and central nervous system. Having found that G beta gamma activates the cloned GIRK1 channel, we now report evidence for direct binding of G beta gamma to both the N-terminal hydrophilic domain and amino acids 273-462 of the C-terminal domain of GIRK1. These direct interactions are physiologically important because synthetic peptides derived from either domain reduce the G beta gamma binding as well as the G beta gamma activation of the channel. Moreover, the N-terminal domain may also bind trimeric G alpha beta gamma, raising the possibility that physical association of G protein-coupled receptors, G proteins, and K+ channels partially accounts for their compartmentalization and hence rapid and specific channel activation by receptors.

The afterdepolarization in Rana temporaria muscle fibres following osmotic shock

Rana temporaria sartorius muscle fibres were exposed to varied sequences of solution and temperature changes that have been employed hitherto in procedures that sought to decouple the transverse tubules from the surface membrane. The incidence of such detubulation was assessed in large numbers of fibres through demonstrating a loss or otherwise of the after-depolarization that normally reflects successful tubular propagation of the surface action potential. This criterion yielded assessments of the existing detubulation techniques in agreement with earlier results. The experiments then developed an improved detubulation procedure that required only brief (15 min) exposures to glycerol, its replacement in a single step by a Ca2+/Mg(2+)-Ringer solution for 30 min, and rapid cooling from room temperature (19-21 degrees C) to 6-10 degrees C prior to final restoration of the normal Ringer solution. This sequence of steps yielded an optimal incidence (98%) of detubulation in viable surface fibres that were amenable to electrophysiological studies. Studies that systematically modified the detubulation procedure demonstrated that the omission of any one step in the protocol significantly reduced the incidence of detubulation with or without accompanying deteriorations in fibre resting potentials. Successful detubulation accordingly required an initial exposure to an optimal glycerol concentration that lasted for a minimal duration and for its abrupt withdrawal. Inclusion of a cooling step within 30 min after glycerol withdrawal was coincident with, and critical to, optimal tubular isolation. Thus, cooling steps that either preceded, or that followed the glycerol withdrawal step by more than 60 min, resulted in a sharp reduction in the incidence of detubulation. Similarly, a critical period of exposure to Ca2+/Mg2+ Ringer solution also promoted detubulation without compromising the recovery of stable and satisfactory resting potentials. The findings reported here remain consistent with a primarily osmotic mechanism for detubulation. However, they demonstrated additional and important influences of temperature and of divalent cation concentration on the extent of tubular detachment when such factors were modified during the time course of the expected volume changes that followed each adjustment in osmotic condition.

The effect of cerebrospinal fluid dilution of isobaric 0.5% bupivacaine used for spinal anaesthesia

A prospective study was conducted to see the effect on spinal anaesthesia of the dilution of isobaric 0.5% bupivacaine with cerebrospinal fluid. Sixty patients were randomly allocated to three groups. In group 1, patients received 3 ml isobaric 0.5% bupivacaine intrathecally without aspirating cerebrospinal fluid. In groups 2 and 3, cerebrospinal fluid 1 ml and 2 ml was aspirated respectively and mixed with 3 ml isobaric 0.5% bupivacaine. A total volume of 4 ml in group 2 and 5 ml in group 3 was administered. Thus, the volume of cerebrospinal fluid remained unchanged. Pinprick analgesia and motor block was evaluated from induction until recovery. No differences in onset time, duration and 'two segments regression' were noticed. The only statistical difference was the time to reach complete motor block, which was shorter in group 1 as compared to groups 2 and 3 (6.9 SD 1.4 min versus 11.3 SD 3.0 and 13.5 SD 3.9 min respectively). The mean value of maximum decrease in systolic blood pressure was small, being less than 15% of the pre-operative value for each group. In conclusion, the effect of diluting isobaric 0.5% bupivacaine with cerebrospinal fluid, 1 ml and 2 ml, is minimal and it is an unnecessary procedure with limited clinical effect.

Motility related protein 1 (MRP-1/CD9) expression: inverse correlation with metastases in breast cancer

In our previous studies we showed that motility related protein 1 (MRP-1) is a glycoprotein recognized by mAb M31-15, and that the sequence of MRP-1 is identical to that of CD9, a WBC differentiation antigen. Transfection of MRP-1/CD9 cDNA into cultured nonhematopoietic cells suppresses cell motility. The extent of suppression is directly related to the level of MRP-1/CD9 expression. In addition, the metastatic potential of MRP-1/CD9-transfected melanoma BL6 cells is lower than that of control BL6 cells. To determine whether these experimental results are of relevance with respect to actual human tumors, we investigated MRP-1/CD9 expression in 143 invasive ductal carcinomas of the breast. Of 97 patients with MRP-1/CD9-positive tumors, only 36 (37.1%) had lymph node involvement. In contrast, 21 of 39 (53.8%) patients whose tumors had reduced MRP-1/CD9 immunoreactivity and 5 of 7 patients whose primary carcinomas were not stained by the anti-MRP-1/CD9 MAb had lymph node metastases. The comparison of protein expression by 62 primary tumors and their respective metastatic lymph nodes revealed that in almost 50% of the cases, the latter had lower MRP-1/CD9 levels than the former. Moreover, reverse transcriptase-PCR-based analysis disclosed that MRP-1/CD9 gene expression in the metastatic lymph nodes of 17 of 32 patients was strikingly lower than in the primary invasive ductal carcinomas. Gene overexpression was not observed in any of the samples studied. Our data suggest that low MRP-1/CD9 expression may be associated with the metastatic potential of certain human tumors.

Clear cell papulosis: report of three cases of a newly recognized disease

BACKGROUND

Clear cell papulosis is a newly described disease. Since the first report in 1987, no other cases have been reported.

OBJECTIVE

Our purpose was to describe three more newly identified cases that further characterize this disease.

METHODS

Formalin-fixed and paraffin-embedded biopsy specimens were used for histochemical and immunohistochemical studies.

RESULTS

The three patients included two boys and, for the first time, a girl. All three had multiple white papules on the lower part of the abdomen, with or without scattered lesions along the milk lines bilaterally. The main histopathologic finding was the presence of clear cells scattered mainly among the basal cells of the acanthotic epidermis. The clear cells were variably stained by mucicarmine, colloidal iron, alcian blue (pH 2.5), periodic acid-Schiff, the anticytokeratin antibody AE1, carcinoembryonic antigen, epithelial membrane antigen, and gross cystic disease fluid protein-15.

CONCLUSION

Clear cell papulosis is a unique clinicopathologic entity. The clear cells were confirmed to be sweat gland secretory cells by their positive immunostaining with gross cystic disease fluid protein-15. The latter was also present in eccrine sweat gland coil cells. However, whether the clear cells were eccrine or apocrine secretory cells could not be determined.

Systemic artery-to-pulmonary artery shunt after using an omental pedicle flap

A 66-year-old man was hospitalized because of hemoptysis. Four years earlier, he had undergone an operation involving the use of an omental pedicle flap that was supplied by the right gastroepiploic artery for the treatment of empyema. Arteriography revealed that the right gastroepiploic artery communicated with the periphery of the right pulmonary artery. The right gastroepiploic artery was divided surgically.

Caffeine modulates Ca2+ receptor activation in isolated rat osteoclasts and induces intracellular Ca2+ release

A ryanodine-sensitive pathway is involved in intracellular Ca2+ release in response to activation of the osteoclast cell surface Ca2+ receptor. We now report that the ryanodine-receptor modulator, caffeine itself released intracellularly stored Ca2+ and, strongly inhibited Ca2+ release triggered in response to Ca(2+)-receptor activation by Ni2+, a surrogate cation agonist. Caffeine yielded a bell-shaped concentration-response curve (0.005-2 mM) and displayed use-dependent inactivation. Furthermore, responses to caffeine were abolished on prior application of Ni2+ (5 mM). Subthreshold (0.005 mM) caffeine concentrations abolished Ni(2+)-induced elevations in the cytosolic Ca2+ concentration ([Ca2+]). However, in a Ca(2+)-free, ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid-containing solution (extracellular [Ca2+] < 10 nM), caffeine (0.5 mM) neither elevated [Ca2+] nor inhibited the response to Ni2+. Finally, when caffeine was applied to intercept the plateau phase of the cytosolic Ca2+ signal triggered by extracellular Ca2+ elevation (10 mM), a rapid but reversible inactivation followed. These studies strongly indicate the existence of a caffeine-sensitive mechanism for the release of intracellularly stored Ca2+ in the osteoclast.

Effect of membrane potential on surface Ca2+ receptor activation in rat osteoclasts

Osteoclasts are known to possess a divalent cation-sensitive receptor, the Ca2+ receptor (CaR). The latter monitors changes in the local Ca2+ concentration generated as a result of hydroxyapatite dissolution. CaR activation elevates cytosolic [Ca2+] and thereby inhibits osteoclastic bone resorption. Recent studies have used Ni2+ as a surrogate CaR agonist to elicit changes in cytosolic [Ca2+]. This article examines the effects of membrane potential changes on the kinetics of the cytosolic [Ca2+] signal resulting from such Ni(2+)-induced CaR activation. Membrane potential was altered through variations in the extracellular [K] in combination with applications of the K+ ionophore, valinomycin. Membrane potential changes were confirmed by independent electrophysiological patch clamp studies of whole osteoclasts. The application of valinomycin produced a distinct, sustained elevation of cytosolic [Ca2+] in single fura 2-loaded cells, a "primary" response. This response was independent of valinomycin concentration (between 5 nM to 5 microM) and persisted in Ca(2+)-free, EGTA-containing solutions. It also persisted both in high (105 mM) and low (5 mM) extracellular [K+]. A gradual "secondary" elevation of cytosolic [Ca2+] then followed with the continued application of valinomycin, but this was eliminated by sequestering the extracellular [Ca2+] or by increasing extracellular [K+] from 5 to 105 mM. In a separate set of experiments, the presence of 5 microM [valinomycin]-([K+] = 5 mM) prolonged the cytosolic [Ca2+] signal elicited by 50 microM-[Ni2+] application. These prolonged kinetics persisted in low extracellular [Ca2+] (zero-added Ca2+), but reverted to a rapid time-course in the presence of 105 mM-[K+] or at higher [Ni2+] (500 microM and 5 mM). The experiments thus indicate that membrane voltage modifies the kinetics of CaR activation by Ni2+ and therefore suggests that the CaR is an integral protein in the osteoclast surface membrane.

Kinetic separation of charge movement components in intact frog skeletal muscle

1. Procedures for a complete charge movement separation employed a combination of its steady-state inactivation and activation properties in intact frog skeletal muscle fibres in gluconate-containing solutions. 2. Holding potential shifts from -70 to -50 mV reduced the total charge available between -90 and -20 mV from 16.76 +/- 1.70 nC microF-1 (mean +/- S.E.M.; n = 4 fibres) to 9.25 +/- 1.43 nC microF-1 without significant loss of tetracaine-resistant charge (q beta). 3. The steady-state and kinetic properties of tetracaine-sensitive charge (q gamma) persisted through holding potential changes from -90 to -70 mV in the presence of gluconate and generally resembled activation properties established hitherto in sulphate-containing solutions. 4. Further holding potential displacement to -50 mV abolished q gamma charge movements and depressed the charge-voltage curve. 5. Test voltage steps applied from a -70 mV prepulse level gave rapid monotonic q beta decays and similarly depressed activation functions in 2 mM tetracaine unchanged by holding potential shifts between -70 and -50 mV. 6. The isolated 'on' q gamma charge movements, I(t), always included early transients that preceded any prolonged charging phases and which increased with depolarization. They decayed to stable baselines in the absence of prolonged time-dependent or inward-current phases and yielded integrals, Q(t), that monotonically increased with test voltage. 7. 'Off' steps always elicited rapid monotonic q gamma decays that fully returned the 'on' charge. 8. 'On' and 'off' q gamma currents, I(t), following voltage steps from fixed conditioning to varying test levels mapped onto topologically distinct higher-order phase-plane trajectories, I(Q), that steeply varied with test voltage. 9. In contrast, voltage steps to fixed test potentials of either -70 or -20 mV elicited identical q gamma phase-plane trajectories independent of prepulse history. 10. The q gamma current thus reflects an independent, capacitative process driven uniquely by higher-order dependences upon charge distribution, Q(t), and test voltage, V(t), autonomous of prepulse history or time, t.

Quantitative studies on the effect of prostacyclin on freshly isolated rat osteoclasts in culture

Prostaglandins exert marked but transient inhibitory effects on bone resorption. The present study examines the effects of prostacyclin (0.15 to 25 microM) on the morphology of freshly disaggregated rat osteoclasts. An area descriptor, rho, represented changes in total cell spread area, and a motility descriptor, mu, represented overall changes in cell motility. The application of prostacyclin intercepted the trend of an increasing cell spread area with time and produced a transient reduction of rho, an R effect. Its magnitude depended upon concentration and was marked at 25 microM prostacyclin. The subsequent recovery (+0.8/min) of rho at this concentration resembled the persistent spreading seen in the absence of the agonist. There was also a sustained decrease in mu to approximately 60% of its pretreatment value (a Q effect) following the application of 25 microM prostacyclin. The extracellular application of 20 mM [Ca2+] produced a similarly transient cell retraction preceded by a rise of cytosolic [Ca2+], but without a corresponding decrease in mu. In contrast, prostacyclin did not elevate cytosolic [Ca2+], suggesting the triggering of an alternative transduction pathway. A fully reversible retraction together with incomplete quiescence may explain the transience characteristic of the antiresorptive action of prostacyclin.

Magnetic resonance imaging planes for the 3-dimensional characterisation of human coronary arteries

We report a magnetic resonance imaging study which developed a consistent hierarchy of imaging planes for examination of the origins, courses and principal branches of the main coronary arteries of prepared human cadaveric hearts. The reference longitudinal axis was chosen between the aortic valve and the apex of the left ventricle. A series of transverse planes then successfully visualised the ostia of the left and right coronary arteries; the left main coronary, its bifurcation, and the left anterior descending artery for a distance 24 mm distal to its origin were clearly distinct in successively posterior sections as was the emergence and course of the right coronary artery. Further sections were derived from an axis that joined the posterior aspects of the left and right coronary artery ostia seen in cross-section, which demonstrated the origins of these arteries. They also traced the circumflex artery 30 mm beyond its point of emergence and demonstrated the course of the right coronary artery between the right ventricle and right atrium. The anatomical identifications were confirmed in selective 3-dimensional reconstructions of the cardiac anatomy around the aortic root and pulmonary artery origin. The orthogonal anatomical arrangements of the left and right coronary artery arterial trees thus permit a consistent set of imaging planes useful for the visualisation of all the major branches in a static heart in vitro. This may offer an approach useful for clinical imaging of human coronary vessels in vivo in the moving heart.

[A case of multifocal eosinophilic granuloma presenting as a rib tumor]

A 19-year-old man was hospitalized because of left chest pain. He had a tumor in the left fifth rib with tenderness. Partial resection of the fifth rib was performed. Pathological examination showed granuloma with infiltration of histiocyte-like cells and eosinophils, and S-100 staining was positive. Therefore, the rib tumor was diagnosed as eosinophilic granuloma. Thereafter, the patient had recurrent bone lesions of the mandible, temporal bone, zygomatic bone, scapula, right eleventh rib, and tibia. Radiation therapy was effective for local treatment of each bone lesion. Moreover, pulmonary lesion was suspected on roentgenographic study. However, he had no respiratory symptoms and there was no significant change on roentgenographic findings over six years. It was considered that follow up for detection of bone and pulmonary lesions should be continued in this case.

IL-10 inhibits HIV-1 replication and is induced by tat

Interleukin 10 (IL-10) is produced by TH2 lymphocytes and regulates both lymphoid and myeloid cells. In the present study we demonstrate that IL-10 is expressed and produced spontaneously in the peripheral blood mononuclear cells (PBMCs) of all HIV-1 infected individuals tested, 3 of 19 cases of HIV-negative lymphoma and none of five healthy controls. IL-10 mRNA was detectable in both monocytes/macrophages and T lymphocytes isolated from PBMCs of HIV infected patients. We have also shown that infection of promonocytic (U937) and T (H9) cell lines with HIV stimulates IL-10 secretion. Furthermore, a T cell line (H9) stably transfected with a HIV tat expression-vector secreted higher levels of IL-10. We have also demonstrated that rhIL-10 inhibited HIV-1 replication in infected monocytes and PBMCs in a dose dependent manner. IL-10 may thus participate in long latency between HIV-1 infection and development of AIDS.

Calcium influx and release in isolated rat osteoclasts

Intracellular and extracellular sources of cytosolic [Ca2+] elevation in isolated rat osteoclasts were explored by a comparison of fura-2 signals in response to application of the Ca2+ ionophore, ionomycin, in Ca(2+)-containing and in Ca(2+)-free bathing solutions. Cytosolic [Ca2+] transients persisted in osteoclasts bathed in Ca(2+)-free, EGTA-containing solutions. They consisted of a peak cytosolic [Ca2+bd elevation followed by a full decay to baseline and were refractory to manipulations of surface membrane potential through changes in extracellular [K+]. They disappeared upon intracellular Ca2+ store depletion through repeated ionophore applications. They were therefore attributable solely to intracellularly stored Ca2+. In contrast, the fura-2 peaks in osteoclasts exposed to Ca(2+)-containing solutions decayed to sustained levels. Cytosolic [Ca2+] responses then persisted with repeated ionomycin application. These latter phenomena are accordingly attributable to extracellular Ca2+ entry. Finally, restoration of extracellular [Ca2+] to 1.25 mM following the depletion of intracellular Ca2+ stores by treatment with ionomycin elicited a cytosolic [Ca2+] 'overshoot' consistent with capacitative Ca2+ entry via a cytosolic route. These results demonstrate a refillable intracellular source of cytosolic Ca2+ that could function in osteoclastic regulation.

Dimensional analysis of osteoclastic bone resorption and the measurement of biologically active calcitonin

Calcitonin inhibits bone resorption through a direct action on the osteoclast. We report a quantitative analysis of bone resorption by disaggregated rat osteoclasts. We then used our findings to develop a formal bioassay for calcitonin. Osteoclasts were mechanically disaggregated from neonatal rat long bones and dispersed at low densities on slices of devitalized bovine cortical bone. The resulting areas of bone excavation were quantified to micrometric precision by scanning electron microscopy together with computer-assisted image analysis. These findings were correlated with the volumes of bone resorption in the same slices measured by confocal scanning microscopy for the first time. The total planar areas of bone resorption per slice correlated linearly (r = 0.78) with the confocal microscopic measurements of total volume resorbed, provided that volume was expressed to its two-thirds power. The latter transformation resulted in representations of the determined areas ([length]2) and volumes ([length]3) which were dimensionally consistent. These findings thus demonstrate that osteoclastic bone excavations show a consistent relationship between area and volume and that assessments of the area of excavations accordingly provide an empirical representation of the volume of bone resorbed. Furthermore, in view of the skewed nature of the distributions of area measurements, we assessed the effect of transforming the response variable to derive a metameter, (planar area of resorption)1/2. Such transformed data points, which expressed the data in the dimensions of [length], were more normally distributed than the raw data points and had more stable variances over a wider concentration range. We accordingly determined relative potencies using parallel line analyses on the transformed data. The latter offered a consistent correlation to the volume measurements when these were also converted to dimensions of [length] (r = 0.805). It was confirmed that the inhibition of bone resorption by calcitonins from various species, namely, pig, salmon and eel, was quantitatively dependent upon concentration of the respective peptides. The resulting assay was also found to be sufficiently sensitive to measure picomolar peptide concentrations with a precision, lambda (standard deviation/slope), ranging between 0.3 and 0.8. Finally, we identified factors affecting assay precision and sensitivity.

Magnetic resonance imaging and computed tomography of transitional cell carcinoma of renal pelvis and ureter

Fourteen patients with clinically suspicious transitional cell carcinoma of renal pelvis or ureter were preoperatively examined with magnetic resonance imaging (MRI) and computed tomography (CT). All of the cases had surgical approval. In eleven of these patients, the tumor was correctly detected by MRI. Two cases were falsely positive including one squamous cell carcinoma (SCC) and one Wilms' tumor of the kidney. The final case was falsely negative. The positive predictive value of MRI was 92.9%. The sensitivity was 91.7%. In seven of the fourteen patients, the CT findings were truly positive. There were five falsely negative findings and two falsely positive cases. The positive predictive value by CT was 64.3%. The sensitivity was 59.3%. Tumor stagings were done for all patients. The accuracy rate of staging was 7/7 by CT and 10/11 by MRI. MRI showed better identification of distant metastasis in the liver, vertebrae and vascular structure because of its high tissue contrast and larger field of view. MRI had a higher positive predictive rate and sensitivity for identification of uroepithelial tumor than CT.

Modulation of the osteoclast Ca2+ receptor by extracellular protons: possible linkage between Ca2+ sensing and extracellular acidification

We report a sensitivity of the osteoclast cell surface Ca2+ receptor to extracellular protons. Freshly isolated rat osteoclasts were exposed to the known agonists of the Ca2+ receptor, Ca2+ and Ni2+, in extracellular solutions set at different pH values. Decreasing the extracellular pH from 7.8 to 4.0 units markedly potentiated the cytosolic Ca2+ signals elicited in response to Ca2+ receptor activation by either Ni2+ (50 microM, 500 microM or 5 mM) or Ca2+ (5 mM). Each response consisted of a rapid and usually transient elevation of cytosolic [Ca2+]. Maximal cytosolic [Ca2+] responses were obtained at pH values of 6.6 (for 5 mM-[Ni2+]) and 4.0 units (for 5 mM-[Ca2+]). Finally, the effects of extracellular pH persisted in Ca(2+)-free, EGTA-containing solutions, suggesting a modulation of intracellular Ca2+ release.

[Comparison of double-lumen endobnonchial versus single-lumen endotracheal tube anesthesia in bilateral thoracoscopic sympathectomy]

Since the development of video endoscopic surgery, the number of transthoracic endoscopic sympathectomy has been increasing. The use of double-lumen endobronchial tube or single-lumen endobronchial tube during anesthesia for these surgeries has been a controversial. 385 palmar hyperhidrosis patients divided into three groups: group I, under alterative one lung ventilation anesthesia with double-lumen endobronchial tube; group II, under alterative one lung ventilation anesthesia with single-lumen endobronchial tube; group III, under two lung ventilation anesthesia with single-lumen endobronchial tube were studied. All had received bilateral thoracoscopic sympathectomy. The age of patients ranged from 8 to 64 years old. There were 154 male and 231 female. The average anesthesia durations for group I, II and III were 38.56 +/- 10.28, 34.14 +/- 5.21, 31.83 +/- 3.34 min respectively. The variables considered in the study were: physique of the patients; duration of anesthesia; airway pressure changes; SaO2 changes during the operation and post-anesthesia complaints. We found that upon using double-lumen endobronchial tube, SaO2 levels was better maintained especially in the obese patients and the patients who had received a traditional surgical operation before.

Elevated cytosolic calcium levels in human lymphocytes during surface virus infections

Generalised metabolic and electrolyte disturbances are known to accompany both plasma and surface virus infections. We have investigated whether these infections could impair the transport of Ca2+ from cells under conditions of controlled concentrations of the energy substrate glucose. Thus, cytosolic calcium levels ([Ca2+]i) were measured in single isolated lymphocytes obtained from healthy volunteers or those suffering from coryza. Before making measurements using a Ca(2+)-sensitive fluorescent dye indo 1, we incubated lymphocytes in buffers containing 0 mM-, 5.6 mM- or 11.2 mM-[glucose]. We found that [Ca2+]i of lymphocytes obtained from the sick were significantly higher than those from healthy controls both at 0 mM and 5.6 mM-[glucose], and that [Ca2+]i was inversely related to the media glucose concentration for both groups. These results suggest a diminished capacity of cation pumping in viral infections, such as coryza, in relationship to the available glucose as energy substrate.

Charge conservation in intact frog skeletal muscle fibres in gluconate-containing solutions

1. The conservation of intramembrane charge was investigated in intact voltage-clamped frog skeletal muscle fibres under conditions that minimized time-dependent ionic currents and so facilitated precise determination of capacitative charge. 2. Prolonged (q gamma) transients were demonstrated in 3,4-diaminopyridine and tetraethyl-ammonium gluconate-containing low [Ca2+] solutions in response to 125 ms pulses that explored the voltage range -90 to -20 mV. The tetracaine-sensitive, q gamma, component then accounted for a significant proportion (over 50%) of available charge. 3. Both delayed 'on' q gamma currents and 'off' current tails decayed to steady direct current (DC) baselines without significant residual ionic current slopes in the chosen extracellular solutions. This suggested that the current transients represented capacitative decays. It was also compatible with the precise determination of effective charge by integration. 4. The advent of 'on' q gamma current was accompanied by increased 'off' charge. Thus, charge was conserved through all 'on' and 'off' steps and through test voltages that extended from the threshold appearance of q gamma as a slow transient to its full merger with the earlier q beta decay at stronger depolarizations. 5. Charge conservation persisted through a wide range of 'on' pulse durations between 60 and 370 ms and was therefore independent of the interval following the q gamma decay. 6. The quantity of q gamma charge remained a monotonic single-valued function of test voltage, whether this potential was reached directly from the -90 mV holding potential or following a prepulse to -10 mV. 7. These findings suggest that the q gamma charge movement represents the electrical signature of an intramembrane entity whose transitions are primarily driven by, and therefore conserved with, the steady-state potential.

[Postoperative lung function in patients with funnel chest]

We evaluated the postoperative lung function determined by spirometry in 54 patients with funnel chest (48 males and 6 females: age range, 4-18 years). Thirty-one patients had sternal turnover as corrective surgery, while 23 had sternal elevation with absorbable PLA (polylactic acid) strut. The mean value of vital capacity as a percentage of predicted (%VC) was 97.3% before operation. %VC was decreased at 3 months (80.5%), 6 months (87.4%), 12 months (82.8%), 24 months (85.9%), and 36 months (77.7%) after the operation (p < 0.01). In patients who had sternal elevation, %VC was decreased at 3 months but not at 6 months, 12 months, 24 months, or 36 months after the operation, while %VC was decreased at any point after the operation in patients who had sternal turnover. No significant changes were seen in forced expiratory volume in one second as a percentage of predicted (FEV1.0%), nor in the ratio of residual volume to total lung capacity (RV/TLC). In conclusion, sternal elevation with PLA strut is a better corrective surgery for funnel chest than sternal turnover, because of its less lung function loss after the operation.

Osteoclast function and its control

Bone resorption appears to be dependent on a range of processes. It requires an adequate number of osteoclasts to access bone mineral. These osteoclasts must be activated by a mechanism which is dependent upon prior osteoblastic stimulation. A range of factors then contribute to the formation of a functionally effective resorptive hemivacuole. These entail osteoclast adhesion to the bone surface leading to the formation of a sealing zone. Only then can subsequent processes such as H+ ion transport, enzyme secretion and matrix digestion become effective. Thus, any one process is potentially limiting to resorption and is a potential target for regulation. Long-range regulation takes place through the action of hormones, of which the mode of action of calcitonin has been the subject of recent investigations in isolated osteoclasts. Such studies have shown a possible involvement of distinguishable receptor subtypes, the occupancy of which may activate at least two types of triggering mechanism. It is likely that an eventual influence on motility properties through G protein mediation accounts for the actions of this hormone and of related peptides such as amylin and CGRP at the cellular level. Similar pathways may contribute to shorter range modulation of osteoclast activity by increases in ambient Ca2+. Finally, there is recent evidence for a contribution of endothelial cell-derived product to osteoclast regulation.

Amylin in bone conservation current evidence and hypothetical Considerations

Amylin, a 37-amino-acid long single-chain polypeptide, is structurally homologous to calcitonin and calcitonin gene-related peptide (CGRP). The peptide is secreted from pancreatic beta cells and is thought to have an anti-insulin action. Here, we review the recently described effects of amylin on calcium homeostasis and discuss its possible role in bone conservation. Amylin is a potent hypocalcemic and antiresorptive peptide. Studies using isolated osteoclasts have revealed that amylin inhibits cell motility (Q effect), without affecting cell spread area or elevating cytosolic [Ca(2+)]. Thus, amylin action is similar to that of calcitonin, but lower in potency. Lower circulating concentrations of amylin in type-1 diabetes may cause the bone loss associated with this condition.