An electrical admittance based index of thoracic intracellular water during head-up tilt in humans

During 50 degrees head-up tilt (HUT), the number of erythrocytes within the thorax has been shown to be reduced by approximately 25% and this level is retained during a maintained tilt, whilst that in the thigh increases by approximately 70%. To evaluate whether the electrical admittance of intracellular water (ICW) may be used to monitor this redistribution of red cells in humans, we determined the regional difference in the reciprocal value of the impedance at 1.5 and 100 kHz for the thorax (thoraxICW) and for the leg (legICW). In ten subjects all variables remained unchanged during head-down tilt but during HUT, presyncopal symptoms were induced in eight subjects after a mean of 27 (SEM 7) min as mean heart rate dropped from 85 (SEM 4) to 66 (SEM 3) beats x min(-1), mean arterial blood pressure from 80 (SEM 3) to 60 (SEM 5) mmHg, and mean oxygen saturation of venous blood from 76 (SEM 2)% to 73 (SEM 3)% (P < 0.05). The mean haematocrit increased from 50 (SEM 5)% to 52.5 (SEM 3.5)% (P < 0.01) and mean central venous pressure decreased during tilting (from a mean of 1 (SEM 1) to a mean of -1 (SEM 1) mmHg; P < 0.05) and returned to value at rest during the maintained tilt. Mean thoracic impedances increased by 7.0 (SEM 1.0) ohms (1.5 kHz) and 5.4 (SEM 1.2) ohms (100 kHz), and mean leg impedances decreased by 9.3 (SEM 1.2) ohms (1.5 kHz) and 3.1 (SEM 1.0) ohms (100 kHz) (P < 0.01). Mean thoraxICW decreased at 40 degrees HUT and remained reduced by 11 (SEM 2) S x 10(-4) (P < 0.05) until the presyncopal symptoms developed, at which time it was lower by 16 (SEM 2) S x 10(-4) (P < 0.01). Mean legICW increased from 97 (SEM 15) to 99 (SEM 15) S x 10(-4) (P = 0.08) during HUT but decreased during maintained tilt (to 94 (SEM 15) S x 10(-4); P < 0.05). The results suggested that during HUT, the difference in electrical admittance at a high and a low frequency current reflects the reduced number of red cells within the thorax.     

The cytotoxic HLA-DQ3 reactive human hybridoma antibody 4166 that May distinguish DQ7 + 8 from DQ9

The human cytotoxic hybridoma antibody 4166 (IgM_χ) was generated by fusing an in vitro EBV-transformed B-LCL from a multiparous woman with the mouse-human heteromyeloma fusion partner CB-F7. In microcytotoxicity and IIF tests with B-LCLs as target cells, the mAb 4166 was specific for DQ3 ( = DQ7 + 8 + 9). However, when used for DQ typing of class-II-positive PBMCs, 4166 could be rendered functionally specific for DQ7 + 8and did not react with DQ9⁺ PBMCs. Binding of mAb 4166 to DQ8-positive cells was efficiently blocked by several allotype-specific mAbs recognizing DQ8. Other HLA class-II-specific mAbs were unable to inhibit. With the use of mAb 4166, it is possible to discriminate DQ7 + 8 from DQ9 in serologic DQ typing.     

Distribution of whaleworm (Anisakis simplex,Nematoda, Ascaridoidea) L3 larvae in three species of marine fish; saithe (Pollachius virens (L.)), cod (Gadus morhua L.) and redfish (Sebastes marinus (L.)) from Norwegian waters

The frequency distribution of Anisakis simplex L3 larvae between host tissues was investigated in three host species: saithe, cod and redfish. Fish were sampled from Norwegian coastal waters and examined for the presence of A. simplex in muscle and viscera. In all three of the host species, A. simplex larvae were most frequently detected in the viscera; the percentages of total infection for saithe, cod and redfish were 99.6%, 97.8% and 88.0%, respectively. In general, the distribution patterns of A. simplex L3 between muscle and viscera were not significantly affected by host size. The observations that distributions vary between species and are not affected by host size do not support an earlier hypothesis which states that A. simplex L3 distributions are determined by an optimal pre-encapsulation migratory distance within host tissues. In contrast, it is suggested that A. simplex L3 distributions are governed by the conditions encountered within host tissues, and are possibly related to the availability of nutrients. Received: 9 July 1997 / Accepted: 15 September 1997     

Muscle fibre type,efficiency, and mechanical optima affect freely chosen pedal rate during cycling

This study investigated the variation in freely chosen pedal rate between subjects and its possible dependence on percentage myosin heavy chain I (%MHC I) in m. vastus lateralis, maximum leg strength and power, as well as efficiency. Additionally, the hypothesis was tested that a positive correlation exists between percentage MHC I and efficiency at pre-set pedal rates but not at freely chosen pedal rate. Twenty males performed cycling at low and high submaximal power output ( approximately 40 and 70% of the power output at which maximum oxygen uptake (VO(2max)) was attained at 80 r.p.m.) with freely chosen and pre-set pedal rates (61, 88, and 115 r.p.m.). Percentage MHC I as well as leg strength and power were determined. Freely chosen pedal rate varied considerably between subjects: 56-88 r.p.m. at low and 61-102 r.p.m. at high submaximal power output. This variation was only partly explained by percentage MHC I (21-97%) as well as by leg strength and power. Interestingly, %MHC I correlated significantly with the pedal rate at which maximum peak crank power occurred (r = -0.81). As hypothesized, %MHC I and efficiency were unrelated at freely chosen pedal rate, which was in contrast to a significant correlation found at pre-set pedal rates (r = 0.61 and r = 0.57 at low and high power output, respectively). Conclusions: Subjects with high percentage MHC I chose high pedal rates close to the pedal rates at which maximum peak crank power occurred, while subjects with low percentage MHC I tended to choose lower pedal rates, favouring high efficiency. Nevertheless, the considerable variation in freely chosen pedal rate between subjects was neither fully accounted for by percentage MHC I nor by leg strength and power. Previously recognized relationships between percentage Type I ( approximately %MHC I) and efficiency as well as between pedal rate and efficiency were confirmed for pre-set pedal rates, but for freely chosen pedal rate, these variables were unrelated.     

Long QT syndrome with a high mortality rate caused by a novel G572R missense mutation in KCNH2

In a four-generation family with long QT syndrome, syncopes and torsades de pointes ventricular tachycardia (TdP) were elicited by abrupt awakening in the early morning hours. The syndrome was associated with a novel KCNH2 missense mutation, G572R, causing the substitution of a glycine residue at position 572, at the end of the S5 transmembrane segment of the HERG K(+)-channel, with an arginine residue. This segment is involved in the channel pore and the mutation may cause a reduction in the rapidly activating delayed rectifier K+ current (Ikr), or changed gating properties of the ion channel, leading to prolonged cardiac repolarization. The electrocardiograms of affected persons showed prolonged QT interval and notched T waves. Despite treatment with atenolol, 200 mg twice daily, the proband still experienced TdP episodes. Three untreated relatives of the proband died suddenly, and unexpectedly, at 18, 32, and 57 years of age. The G572R mutation is thus associated with a high mortality rate, and the clinical presentation illustrates that some mutations may not be controllable by just beta-blockade.     

Quantitative determination of cell surface β-adrenoceptors in different rat skeletal muscles

In the present study, the density of cell surface beta-adrenergic receptors was determined in different skeletal muscles using the hydrophilic ligand [3H]CGP 12177. The density of beta-adrenergic receptors was highest in the slow-twitch soleus muscle (32.8+/-0.9 fmol mg dw(-1)) and lowest in the fast-twitch glycolytic white gastrocnemius (10.4+/-0.5 fmol mg dw(-1)) beta-Adrenoceptor density correlated closely with the percentage of type-I fibres (r=0.979; P<0.0001) and inversely with the percentage of type-IIB fibres (r=696; P<0.03). Incubation with isoprenaline (10 microM) for 30 min decreased the density of beta-adrenergic receptors in the cell surface from 32.9+/-0.8 to 19.3+/-0.7 fmol mg dw(-1) in the soleus and from 16.8+/-1.0 to 12.0+/-0.7 fmol mg dw(-1) in the epitrochlearis. Internalisation appeared rapid (half-time less than 5 min). To study externalisation of beta-adrenergic receptors, soleus strips were incubated 30 min with 10 microM isoprenaline and then transferred to buffer without agonist. The first incubation reduced the density to approximately 50%, the subsequent incubation without agonist increased cell surface receptor density to approximately 80% of the initial density after 1 h. No further increase was observed over the next 2 h, suggesting that some of the receptors had been degraded. Insulin or contractile activity did not influence rate of externalisation.     

Familial occurrence of histiocytosis.

The clinical and histological findings of four children with lethal histiocytosis are reported. The children belonged to two sibships and originated from a Swedish geographical isolate. Consanguinity between the parents was established for one of the sibships, belonging to a pedigree in which malignant disease occurred in two generations. The observations indicate that the type of histiocytosis investigated is caused by homozygosity for a single recessive gene. The association between histiocytosis and malignancy is discussed.     

Arterial and venous measurement in resting forearm of metabolic indicators during rest and leg exercise

We compared the levels of various metabolic indicators in arterial and venous forearm blood during maximal treadmill leg exercise, and the subsequent 9 min in nine volunteers aged 31-56 years. At maximal exercise plasma lactate was 13.2 +/- 3.1 mmol l-1 arterially, while venous was 41% lower, but increased more than arterial after exercise. There was a linear relationship between arterial and venous samples during and after exercise, but not at baseline. Plasma pyruvate increased on the arterial side from 49 +/- 8 to 172 +/- 30 mumol l-1 at maximal exercise, maximal venous was 21% lower. Free fatty acids were not different at rest, but decreased during exercise by 52 and 38% on the arterial and venous side. There was no relationship between arterial and venous levels. Changes in these three variables occurred significantly earlier on the arterial side. Arterial cyclic AMP rose from 97.3 +/- 28.4 to 262.7 +/- 67.5 nmol l-1 from rest to exercise, and was linearly inversely related to the decrease in free fatty acids. The mean venous pH was lower than arterial at rest, but was the same as arterial at maximal exercise and after. Thus, venous plasma lactate and pyruvate, but not free fatty acids, are linearly related to arterial measurements during maximal exercise, while pH is identical. Non-working muscle modifies exercise-induced changes, and therefore venous and arterial forearm blood sampling give more information than either alone.