Constitutional symptoms at the onset of rheumatoid arthritis and subsequent arterial stiffness.

The onset of rheumatoid arthritis (RA) can be associated with constitutional symptoms. Systemic inflammation may be a common factor behind such symptoms and the subsequent development of arterial disease. The aim of this study was to determine if a relationship exists between constitutional symptoms and arterial stiffness. We recruited 103 ambulatory RA patients (85 female) without overt arterial disease aged between 40 and 65 years attending hospital clinics. A research nurse measured arterial stiffness (heart rate standardised augmentation index, AIX) using the 'SphygmoCor' device, fasting lipids and erythrocyte sedimentation rate (ESR). Assessment included patient recall of constitutional symptoms at arthritis onset (aching muscles, tiredness, generalised weakness, low mood/depression, fever, loss of weight, loss of appetite) and a detailed medical record review. Regression analysis was used to adjust mean differences in AIX in the presence/absence of constitutional symptoms for current age, sex, arthritis duration, age arthritis onset, study ESR, ever smoked, mean arterial blood pressure (BP), treated hypertension and cholesterol. Mean age was 54 years (age arthritis onset 42 years), brachial BP 125/82 mmHg, cholesterol 5.4 mmol/L, ever smoked 59%, median RA duration 9 years, median ESR 16 mm/h and mean AIX 31.7 (SD 7.8). Unadjusted mean difference in AIX was -0.7 (95%CI -4.5 to 3.1; p = 0.72) in the presence of constitutional symptoms and the adjusted mean difference was -0.1 (-3.2 to 2.9; p = 0.93). No individual symptoms were significantly associated with increased arterial stiffness. In conclusion, we found no convincing association between constitutional symptoms at the onset of arthritis and subsequent arterial stiffness.

Effect of high hydrostatic pressure on the bacterial mechanosensitive channel MscS.

We have investigated the effect of high hydrostatic pressure on MscS, the bacterial mechanosensitive channel of small conductance. Pressure affected channel kinetics but not conductance. At negative pipette voltages (corresponding to membrane depolarization in the inside-out patch configuration used in our experiments) the channel exhibited a reversible reduction in activity with increasing hydrostatic pressure between 0 and 900 atm (90 MPa) at 23 degrees C. The reduced activity was characterized by a significant reduction in the channel opening probability resulting from a shortening of the channel openings with increasing pressure. Thus high hydrostatic pressure generally favoured channel closing. Cooling the patch by approximately 10 degrees C, intended to order the bilayer component of the patch by an amount similar to that caused by 50 MPa at 23 degrees C, had relatively little effect. This implies that pressure does not affect channel kinetics via bilayer order. Accordingly we postulate that lateral compression of the bilayer, under high hydrostatic pressure, is responsible. These observations also have implications for our understanding of the adaptation of mechanosensitive channels in deep-sea bacteria.

Patch-clamp experiments with porins extracted from a marine bacterium (Photobacterium profundum strain SS9) and reconstituted in liposomes.

The reconstitution of bacterial porins in liposome bilayers for patch-clamp recording is well established. However, the solutions used in the dehydration, rehydration, and osmotic swelling of the liposomes have been developed for porins from enteric bacteria. Porins from marine bacteria normally function in contact with seawater whose ionic composition and osmotic pressure would appear to be incompatible with the established methods. Here, we show that, contrary to expectation, an established reconstitution and patch-clamp method works well with porins, mainly OmpH and OmpL, extracted from the deep-sea marine bacterium Photobacterium profundum strain SS9 and that seawater can be introduced at a supplementary stage.

Effect of pregnancy on bone mineral density and biochemical markers of bone turnover in a patient with juvenile idiopathic osteoporosis.

Juvenile idiopathic osteoporosis (JIO) is rare, presenting with vertebral fractures in the immediate prepubertal years; however, recovery is normally observed. We report the case of a 19-year-old pregnant woman previously diagnosed with JIO. She experienced three vertebral fractures in the third trimester of pregnancy. She delivered by caesarean section at 38 weeks gestation. Spinal bone mineral density decreased by 25%, hip bone mineral density by 10%, and forearm bone mineral density by 3% during pregnancy. Bone resorption markers, free pyridinoline and deoxypyridinoline (fPYD and fDPD), were elevated at baseline and markedly increased during pregnancy (fPYD/fDPD at 0, 10, 15, 20, and 28 weeks and immediately postpartum: 36.2/11.5, 52.9/15.8, 54.3/13.3, 51.1/13.3, 90/21.8, and 95.6/22.7 nmol/mmol creatinine, respectively) The bone formation marker, bone-specific alkaline phosphatase (BSAP), was within the reference range at baseline and increased in the third trimester. (BSAP at 0, 10, 15, 20, and 28 weeks and immediately postpartum: 20.5, 18.3, 17.7, 19.8, 26.9, and 30.0 U/liter, respectively). Parathyroid hormone (PTH) was measured by two methods to assess the possible effect of PTH fragments. PTH(1-84) (Roche) showed little change during the pregnancy, whereas the Nichols assay [(1-84) and(7-84) PTH fragment], revealed increases paralleling the changes in bone resorption. This young woman's bone turnover showed an exaggerated response to pregnancy, with bone resorption predominating over formation. PTH fragments may have partially mediated this effect.

Ion channels under high pressure.

Hydrostatic pressure (<100 MPa) affects the kinetics of ion channels but not their conductance. In voltage-gated channels, pressure acts on the movement of the charge sensor and on the conformational change involved in opening the channel pore. It has also been shown to act on N-type inactivation ball-binding, C-type inactivation and to activate BK channels. There is little doubt that these are sites of adaptation to high pressure in the channels of deep-sea animals. Pressure studies should not be regarded in isolation; they relate well to experiments using other variables such as osmotic pressure, solvent viscosity and temperature. Furthermore ion channels could transduce pressure in the sensory system of aquatic animals, providing information about the animals' depth, a prediction supported by our knowledge of heat-activated channels in mammals.

A method of patch clamp recording in hyperbaric oxygen.

A method of patch clamp recording in hyperbaric oxygen is described which is derived from a method for patch clamping at high hydrostatic pressure. Excised patches equilibrate with hyperbaric oxygen within 10 minutes. Experiments with BK channels expressed in HEK 293 cells showed that 1 MPa O2 caused an increase in the ionic permeability of the patch, an effect accelerated in the presence of ferrous ions. Seal resistance was unaffected. Small negative currents, (VH - 40 to - 65 mV, symmetrical KCl solutions), apparent in skewed all-points amplitude histograms, reduced the signal to noise ratio. In some patches the BK channel activity was inhibited and in others it persisted with the currents becoming irresolvable in the increased noise.

Avascular necrosis of the femoral head in patients with prostate cancer treated with cyproterone acetate and radiotherapy.

We report the case histories of two patients with histologically confirmed adenocarcinoma of the prostate, both of whom had been treated with steroidal anti-androgen therapy in the form of cyproterone acetate prior to radical or palliative pelvic irradiation, and who subsequently developed femoral head avascular necrosis. This is a diagnosis that should be considered in patients with prostate cancer who present with hip pain in the absence of biochemical evidence of disease progression.

Effect of high hydrostatic pressure on the porin OmpC from Escherichia coli.

Porin OmpC from Escherichia coli was reconstituted in liposomes and its gating kinetics were recorded at high hydrostatic pressure, up to 90 MPa, using a development of the patch clamp technique. The composition of the recording solution influenced the results but generally high hydrostatic pressure favoured channel opening.

The transduction of very small hydrostatic pressures.

This paper reviews experiments in which cells, subjected to hydrostatic pressures of 20 kPa or less, (micro-pressures), demonstrate a perturbation in growth and or metabolism. Similarly, the behavioural responses of aquatic animals (lacking an obvious compressible gas phase) to comparable pressures are reviewed. It may be shown that in both cases the effect of such very low hydrostatic pressures cannot be mediated through the thermodynamic mechanisms which are invoked for the effects of high hydrostatic pressure. The general conclusion is that cells probably respond to micro-pressures through a mechanical process. Differential compression of cellular structures is likely to cause shear and strain, leading to changes in enzyme and/or ion channel activity. If this conclusion is true then it raises a novel question about the involvement of 'micro-mechanical' effects in cells subjected to high hydrostatic pressure. The responses of aquatic animals to micro-pressures may be accounted for, using the model case of the crab, by the mechanical, bulk, compression of hair cells in the statocysts, the organ of balance. If this is true, it raises the interesting question of why the putative cellular mechanisms of micro-pressure transduction appear to have been superseded by the statocyst.

Effect of high hydrostatic pressure on the BK channel in bovine chromaffin cells.

The activity of the BK channel of bovine chromaffin cells was studied at high hydrostatic pressure, using inside-out patches in symmetrical KCl solution, Ca2+-free and at V(H) = -60 to -40 mV. Pressure increased the probability of channels being open (900 atm increasing the probability 30-fold), and it increased the minimum number of channels apparent in the patches. The pressure activation of the channel was reversed on decompression. Channel conductance was unaffected. It was shown that pressure did not act by raising the temperature, or by affecting [Ca] or pH, or the order of the membrane bilayer, and it was concluded that pressure most likely acted directly on the channel proteins and/or their modulating reactions.

Biochemical markers of bone turnover in seronegative spondylarthropathy: relationship to disease activity.

To investigate bone turnover in patients with seronegative spondylarthropathy, a bone formation marker, type 1 procollagen carboxy-terminal propeptide (P1CP), and resorption markers, the pyridinium cross-links of collagen [urinary free (f) PYR and DPYR], were measured. The median f-PYR, f-DPYR and P1CP (+/-interquartile range) were 15.8 (6.00) nmol/mmol creatinine, 3.8 (2.2) nmol/mmol creatinine and 101.5 (38) micrograms/1, respectively. There was a positive correlation between resorption markers and acute-phase reactants such as C-reactive protein (r = 0.42 for PYR, r = 0.42 for DPYR, P < 0.05), and a negative correlation observed between P1CP and the erythrocyte sedimentation rate (r = -0.64, P < 0.05). In the subgroup of patients with an elevated CRP concentration, the concentration of PYR and DPYR was significantly increased (f-PYR 25.7 vs 15.8 and f-DPYR 6.6 vs 3.8, P < 0.01 for f-PYR, P < 0.05 for f-DPYR). This study suggests than an elevation in acute-phase response in patients with seronegative spondylarthropathy is associated with increased concentration of bone resorption markers with a tendency for reduction in bone formation markers. This may represent uncoupling of bone formation and resorption, leading to bone loss in such patients.

The effects of nitrous oxide on a glutamate-gated ion channel and their reversal by high pressure; a single channel analysis.

Nitrous oxide reversibly affects the kinetics, but not the conductance, of the qGluR channel of locust muscle. 0.5 atm N2O at 20.5 degrees C was without effect but both 1.5 and 2.7 atm significantly reduced the probability of the channel opening, the frequency of opening and the mean open time, and prolonged the mean closed time. 100 atm helium was without effect on these parameters, but when 98.5 atm He was combined with 1.5 atm N2O they, and the associated dwell time distributions, were restored to normal. 100 atm similarly combined with 2.7 atm N2O exerted a comparable trend which fell short of significance. The results are consistent with nitrous oxide binding to the channel with a significant molar volume increase, which pressure opposes. This suggests that nitrous oxide may cause conformational changes in the channel, and that the pressure reversal of nitrous oxide anaesthesia in animals could be caused by molecular antagonism.

Microwave thermography as a noninvasive assessment of disease activity in inflammatory arthritis.

Microwave thermography is the technique of measuring natural thermal radiation from body tissues of clinical interest. It is safe, requires no control of environmental conditions and exposes the patient to no ionising radiation. In this study, we found that microwave thermography of the knee joints showed weak correlation with some global parameters of disease activity. Bed rest alone for three days had no significant effect on microwave thermographic index (MTI). Intra-articular steroid injection, however, was associated with a marked fall in MTI both in the injected knee and the contra-lateral knee. We conclude that microwave thermography can measure inflammatory activity in the knee joints of patients with inflammatory arthritis and can respond to clinical change brought about by major treatment intervention.

A brief historical review of non-anaesthetic causes of fires and explosions in the operating room.

Fires and explosions have occurred in the operating theatre for many years. Flammable inhalation anaesthetic agents were responsible for many incidents in the past, but these are no longer available in many countries. Other causes of fires and explosions still exist in the operating theatre and, from time to time, result in serious and occasionally fatal injury. Flammable gastrointestinal gases have been the cause of injury to patients during gastric surgery, laparoscopy and during examination of the large bowel with electrical instrumentation. Gases formed in the bladder during urological procedures have ignited, causing rupture. Alcohol-based skin cleaning agents have resulted in severe burns to the skin. Equipment used for storage and delivery of oxygen to patients has caused fires in a variety of ways. Adhesive skin drapes have resulted recently in two tragic deaths. The increasing use of laser therapy, particularly in ear, nose and throat surgery, and in oral surgery, has brought about a renewed awareness of the risk of fire. The relevant factors which should be borne in mind and the precautions which should be adopted when laser therapy is to be used in the airway are discussed.

Useful investigations in a refractory case of 'myositis'.

The diagnosis of polymyositis is made on the basis of clinical features, muscle enzymes, EMG studies and muscle biopsy. Treatment requires corticosteroids often in combination with immunosuppressive agents, and relapse in spite of treatment may render management difficult. The case described below appeared to demonstrate features from which the diagnosis could be made, but in which the almost complete resistance to conventional therapy led to a correct reappraisal of the diagnosis. This illustrates an unusual cause for diagnostic confusion and the value of diagnosis reassessment under such circumstances.

A short history of fires and explosions caused by anaesthetic agents.

The first recorded fire resulting from the use of an anaesthetic agent occurred in 1850, when ether caught fire during a facial operation. Many subsequent fires and explosions have been reported, caused by ether, acetylene, ethylene and cyclopropane, and there has been one reported explosion involving halothane. Although some of the earlier incidents caused more consternation than injury, many of the later ones caused much death and destruction, particularly after the practice of administering oxygen, instead of air, became established. Many incidents have never been reported and many of those which have reached publication do not record essential details. The use of flammable agents has decreased significantly in recent years and although fires and explosions from nonanaesthetic causes, for example gastrointestinal gases, skin sterilizing agents and laser surgery, may continue to occur, those from gaseous and volatile anaesthetic agents may now be of historical interest only. This article reviews some of the more relevant and enlightening reports of the past 150 yr.

Effects of hormone replacement therapy in rheumatoid arthritis: a double blind placebo-controlled study.

AIMS: To study the effects of ovarian hormone replacement therapy (HRT) on bone mineral density and disease activity in postmenopausal women with rheumatoid arthritis (RA). METHOD: A placebo controlled double-blind study was carried out on 62 patients with RA, 22 on placebo and 40 on HRT (transdermal oestradiol patches twice weekly for 48 weeks plus norithisterone tablets when clinically indicated). Bone mineral density of spine, hip and wrist was measured at 0 and 48 weeks and clinical and laboratory measures of general well-being and disease activity at 0, 12, 24 and 48 weeks. RESULTS: Thirteen of 22 (59%) of placebo and 31 of 40 (78%) of the HRT group completed 48 weeks in the study. At entry, bone mineral density (BMD) values in the lumbar spine and femoral neck were similar to those in age and sex matched controls in both treatment groups, whereas at the distal radius, BMD was significantly reduced to approximately 50% of control values (both p < 0.001 from controls). In the HRT group, spine BMD increased significantly by a median of +0.94% at 48 weeks (p = 0.024), but did not change significantly in the placebo group. BMD at the femoral neck and distal radius did not change in either group. In the HRT group, there was significant improvement in well being as assessed by the Nottingham Health Care Profile (p < 0.01) and in the articular index (p < 0.05). There were no significant changes in ESR or CRP in either group. CONCLUSION: Transdermal HRT was well tolerated, increased well being, reduced articular index and increased lumbar spine bone density over a one year period in postmenopausal women with RA. Although no laboratory evidence was found of a disease modifying effect, the symptomatic benefits and improvements in bone density indicate that HRT may be a valuable adjunct to conventional antirheumatic therapy in RA.