Cochlear microvasculature in normal and damaged ears

The minute vessels of the cochlea were examined post mortem in normal guinea pigs and in others exposed to intense noise or treated with the ototoxic drugs gentamicin and quinine. The benzidine stain was used to display the capillary networks, and osmic acid for surface preparations, “thick” sections, and ultrathin sections for electron microscopic examination. The capillaries of the spiral ligament, i.e., the so-called arteriovenous anastomoses, do not show the characteristics of the muscular shunts described by Chambers and Zweifach. They are divided into two groups, the adstrial capillaries closely applied to the basal surface of the stria vascularis, and the poststrial capillaries which supply the tissue of the spiral ligament. Continuing beneath the floor of the external sulcus they form an alternating pattern with the root cells, and are surrounded by a specialized pericapillary tissue which resembles that found around the capillaries of the spiral prominence. These tissues are readily destroyed by gentamicin and other ototoxic aminoglycosidic antibiotics. Vasoconstriction of the outer and inner spiral vessels in response to noise and quinine appears to involve both contraction of pericytes and swelling of the endothelial cells. After prolonged exposure to noise or treatment with gentamicin, degeneration of capillaries with formation of intervascular strands and avascular channels is found in the suprastrial network of the spiral ligament. Similar capillary changes are seen in presbycusis, and in the deaf Dalmatian dog.     

Effects of cedilanid-D and alprenolol in angina pectoris

Summary The haemodynamic effects of cedilanid-D and the -blocker, alprenolol, have been studied in 10 patients with angina pectoris. The patients received alprenolol orally and cedilanid-D or saline adminstered intravenously in a double-blind, cross-over trial. The combination caused shortening both of left ventricular ejection time and of the pre-ejection period in the same order of magnitude as found after cedilanid-D without -blockade. The patient's average work capacity, expressed as total work or terminal work load, was not changed by cedilanid-D compared to a placebo. No relationship was found between the initial size of the heart and the effect of cedilanid-D on capacity for physical work. It appears, therefore, that there is no indication for routine use of digitalis combined with -blockers in patients with angina pectoris, who do not have cardiac failure.     

The Right to Withdraw Consent to Research on Biobank Samples

Ethical guidelines commonly state that research subjects should have a right to withdraw consent to participate. According to the guidelines we have studied, this right applies also to research on biological samples. However, research conducted on human subjects themselves differs in important respects from research on biological samples. It is therefore not obvious that the same rights should be granted research participants in the two cases. This paper investigates arguments for and against granting a right to withdraw consent to research on biobank samples. We conclude that (1) there are no explicit arguments for such a right in the guidelines we have studied, (2) the arguments against such a right are inconclusive, (3) considerations of autonomy, privacy, personal integrity, and trust in medical research provide sufficient reasons for granting a right to withdraw consent to research on biobank samples, (4) in certain cases, research participants should be allowed to waive this right.     

A flexible apparatus for continuous recording of water uptake by plants

An apparatus for the continuous and automatic recording of water uptake by small plants or single shoots is described. The root system of the plant (or plants) to be investigated is submerged in a water supply vessel. The water decrease in the vessel is detected, and the water is replaced by pumping new water into the vessel in a stepwise fashion. The apparatus can be used for measuring the total amount of water taken up, and the rate of water uptake. A water uptake of less than 0·1 mm³ can be reliably determined in the present applications. An example from measurements of cyclic uptake of water by one single oat plant is given.     

Wireless oesophageal pH monitoring: feasibility, safety and normal values in healthy subjects

OBJECTIVE: A new wireless technique for oesophageal pH monitoring has recently been introduced (Bravo). To implement this technique in clinical practice, values of normal oesophageal acid exposure need to be defined in a large age- and gender-matched healthy population. The aims of this study were to investigate the feasibility and safety of the wireless technique and to establish normal values for oesophageal acid exposure. MATERIALS AND METHODS: Fifty-seven asymptomatic subjects underwent upper gastrointestinal endoscopy with transoral placement of a radio-transmitting capsule 6 cm above the squamocolumnar junction. Oesophageal acid exposure was monitored via a portable receiver during 48 h. RESULTS: Seven men were excluded from the study: capsule dysfunction in 1 and oesophagitis in 6. Fifty subjects (25 M, 25 F, median age 42 years) were included in the study. The radio-transmitting capsule was successfully attached to the oesophageal mucosa in all cases and there were no complications. During pH monitoring 2 capsules were prematurely detached after 32 and 36 h, respectively. The median percentage time with oesophageal pH of less than 4 was 0.7% on day 1 and 1.0% on day 2 (p = 0.033) and the 95th percentile for the 48-h recordings was 4.4%. CONCLUSIONS: Ambulatory pH monitoring using the Bravo system is feasible and appears to be safe. This is the first study to establish normal values for oesophageal acid exposure in a large age- and gender-matched healthy population and offers a basis for the use of the wireless technique in clinical practice.     

The graft content of hyaluronan is increased during xenograft rejection

BACKGROUND: Hyaluronan, a macromolecule with strong water binding capacity, is associated with interstitial oedema during rejection of allogeneic transplants. However, the involvement of hyaluronan during xenograft rejection has previously not been investigated. The aims of this study were to characterize hyaluronan content and distribution during rejection of concordant mouse-to-rat cardiac xenografts, and to explore the effects of hyaluronidase (HAse) on xenograft survival. METHODS: Graft recipients were treated with 15-deoxyspergualin (DSG) or both HAse and DSG. Grafts were removed on day 5 from some of the animals to analyse hyaluronan and water content, while other animals were used to investigate graft survival. The hyaluronan content was measured by a radiometric assay and the distribution was analysed by histochemical staining. RESULTS: In xenografts undergoing rejection (the DSG group) there was a strong increase of the hyaluronan [555 +/- 93 microg/g dry weight (dw)] and water (82.7 +/- 0.4%) contents compared with normal mouse heart tissue (166 +/- 10 microg/g dw; P < 0.01 and 78.6 +/- 0.5%; P < 0.001, respectively). The combined use of HAse and DSG reduced the accumulation of hyaluronan (284 +/- 43 microg/g dw; P < 0.05 vs. DSG) but did not affect the average water content. The average graft survival time did not differ between the groups; however, three grafts in the HAse + DSG-treatment group survived much longer than the longest-surviving grafts in the DSG group. CONCLUSIONS: These data suggest that the graft content of hyaluronan considerably increases during xenograft rejection. HAse effectively reduces this accumulation, but does not affect the average water content.