Sinus node electrogram recording in complete atrioventricular block

Surface electrocardiogram (ECG), sinus node electrogram (SNE), His bundle electrogram (HBE), and intracardiac electrogram of high right atrium (HRA) were recorded synchronously in 11 of the 14 consecutive cases with complete atrioventricular block (CAVB). SNE showed the presence of a pre-P wave that preceded in all the P wave on the ECG and had no relationship to QRS complex or TU repolarization. This confirmed that the pre-P wave arose from the sinus node. Direct sinoatrial conduction time (SACTd) in nine cases was within the normal range (less than 120 msec). SACTd in another two cases was prolonged to 185 msec and 210 msec, respectively, suggesting their abnormal sinus node conduction.

[The distribution, characteristics and effects of ir-BNP in central and peripheral tissues in rat]

The present study first investigated the distribution, biochemical characteristics, receptor binding and biological effects of immunoreactive brain natriuretic peptide (ir-BNP), in the central nervous system and some peripheral tissues in rats, using highly specific radioimmunoassay, radioreceptor assay and immunohistochemical method. The results suggest that BNP may be a novel neurotransmitter or circulatory hormone, which is widely distributed in various tissues and involved in the regulation of water electrolyte balance and cardiovascular activity.

Bioavailability of total iron from meat, spinach (Spinacea oleracea L.) and meat-spinach mixtures by anaemic and non-anaemic rats

1. Bioavailability of Fe from beef, spinach (Spinacea oleracea L.) and their mixtures was studied using anaemic and non-anaemic rats by haemoglobin regeneration efficiency (HRE) and apparent Fe absorption in two trials. 2. The initial haemoglobin levels of severely anaemic, mildly anaemic and non-anaemic rats were 63, 88 and 113 g/l, respectively. The Fe level in diets was about 30 mg/kg. All other nutrients equalled or exceeded the requirement of the growing rat. 3. The spinach Fe was well utilized by the rats with average HRE of 0.41, 0.53 and 0.36, and apparent Fe absorptions averaging 0.48, 0.59 and 0.37 for the severely anaemic, mildly anaemic and non-anaemic animals respectively. 4. Beef Fe was efficiently used by rats as reported by others. Average HRE were 0.42, 0.51 and 0.44, and average apparent Fe absorptions were 0.44, 0.47 and 0.46 for the severely anaemic, mildly anaemic and non-anaemic rats respectively. 5. When the percentage of meat Fe was increased from 0 to 25, 50, 75 or 100 of the dietary Fe, HRE and apparent Fe absorption were not increased significantly. A meat enhancement effect on total Fe absorption, reported by others for non-haem-Fe, did not occur in the present experiment. 6. Negative correlation coefficients between initial haemoglobin and HRE (r -0.79), and initial haemoglobin and apparent Fe absorption (r -0.73) were seen with the rats fed on dietary Fe from FeSO4.7H2O. This was not seen with the rats fed on dietary Fe from beef or spinach. 7. The Fe absorption pattern for the different Fe sources is evidence for a third Fe pool, a pool made up of highly soluble inorganic Fe salt, in addition to haem-Fe and non-haem-Fe complex pools. FeSO4.7H2O is not in the same gastrointestinal pool as non-haem-Fe complex such as spinach Fe. A suggested mechanism of absorption is discussed.

Missense Mutation in the Chlamydomonas Chloroplast Gene that Encodes the Rubisco Large Subunit

The 69-12Q mutant of Chlamydomonas reinhardtii lacks ribulose-1,5-bisphosphate carboxylase activity, but retains holoenzyme protein. It results from a mutation in the chloroplast large-subunit gene that causes an isoleucine-for-threonine substitution at amino-acid residue 173. Considering that lysine-175 is involved in catalysis, it appears that mutations cluster at the active site.

Residual tactile sensitivity with self-directed stimulation in hemianaesthesia

A case of hemianaesthesia caused by right hemisphere stroke was found to have good sensitivity and cutaneous localisation when she touched her impaired hand with her good contralateral hand or with a probe held by that hand. The capacity did not depend solely upon movement or positioning of her right arm, and she could also discriminate whether her own left fingers, as opposed to someone else's inter-digitated fingers, were being touched, but only when she did the touching. Thus, the threshold of the impaired hand appeared to be markedly affected by active involvement of the contralateral limb in delivering the stimulus.

Histone acetylation in chicken erythrocytes. Estimation of the percentage of sites actively modified

Within the N-terminal regions of the DNA-bound histone, 26 lysine residues per nucleosome may be acetylated and deacetylated. In the present paper the percentage of these residues actively acetylated and deacetylated in chicken erythrocytes was measured. This percentage is estimated as 3.7% in chicken immature, and 2.1% in chicken mature, erythrocytes. In metabolically active, dividing, cells one would predict that, after a few generations, each site would at some point in time be modified. We conclude that, in the relatively inactive immature chicken erythrocyte, no more than 1-2% of the genome is composed of dynamically acetylated and deacetylated histone, this percentage decreasing with cell maturity. The active histone acetylation and deacetylation may be confined to transcriptionally active or potentially active erythrocyte domains.