Ventilation in Pacific hagfish (Eptatretus stoutii) during exposure to acute hypoxia or hypercapnia.

A technique was developed to measure ventilation in unrestrained Pacific hagfish (Eptatretus stoutii) by inserting and fastening into the nostril a flexible tube fitted with an ultrasonic flow probe. This technique permitted the continuous measurement of ventilation (respiratory) frequency (fR), stroke volume and minute ventilation (.V(E)) in real time in fish exposed to acute hypoxia or hypercapnia. Exposing fish to acute hypoxia (final PW(O2)=21.0 +/- 3.4 mm Hg) caused hypoxaemia and a marked increase in .V(E) of 350+/-71 ml min(-1)kg(-1) (from 235 to 585 ml min(-1)kg(-1)) owing exclusively to an increase in fR of 44+/-7 min(-1) (from 19 to 63 min(-1)). Because O(2) consumption (approximately 0.4 mmol kg(-1)h(-1)) was unaltered during hypoxia, there was an associated marked increase in the ventilation convection requirement from 36.7 to 81.8l mmol(-1). Injecting the O(2) chemoreceptor stimulant NaCN into inspired water (external CN-) or pre-branchial blood (internal CN-) evoked ventilatory responses that were similar to those observed during hypoxia although of a lesser magnitude. With external CN(-), V (E) increased maximally by 146+/-46 ml min(-1)kg(-1) and fR increased by 20+/-2 min(-1). With internal CN-, the maximal increase in .V(E) was 93+/-30 ml min(-1)kg(-1) and fR increased maximally by 19+/-6 min(-1). Exposure to acute hypercapnia (final PwC=7.0+/-0.2 mmHg) caused an increase in V (E) of 169+/-60 ml min(-1)kg(-1). These results provide compelling evidence for chemoreceptor-mediated control of breathing in hagfish and suggest that ventilatory responses to environmental hypoxia and hypercapnia in the vertebrates arose in the myxine lineage.

[Two suicide fatalities from sodium cyanide ingestion: differences in blood biochemistry].

We report a case of two suicide fatalities from sodium cyanide ingestion, which showed differences in pathology and blood biochemistry. The victims were a married couple in their 70 years of age, owners of a gilding factory. They were found dead in their bedroom by a family member. Suicide notes and sodium cyanide powder were found in the room. Autopsy revealed eroded gastric mucosae in both victims. In the male, the stomach showed a previous postoperative state of partial resection, and the lungs were more congested and edematous in the male than in the female. In both victims, cyanide was detected in the blood at markedly high concentrations. In postmortem blood biochemistry, a marked elevation of cardiac troponin T, I and CK-MB was observed in the peripheral blood of the male, whereas there was only a mild elevation in the female. In the male, erythropoietin was also markedly elevated. These observations suggested a difference in the dying process following sodium cyanide ingestion between the victims; survival time may have been longer in the male than the female. The absorption of cyanide may have been a contributory factor to the difference.

Effects on breathing of carotid body denervation in neonatal piglets.

The purpose of these studies was to test the hypothesis that carotid chemoreceptor activity is necessary for postnatal maturation of the ventilatory control system. By using a lateral surgical access, 17 piglets were carotid body denervated (CBD) and 14 were sham denervated at 3-25 days of age. After surgery, there was no irregular breathing in any group. There was no significant hypoventilation when CBD was performed at less than 5 days of age (n = 5) and only a mild (arterial PCO(2) 5 Torr; P < 0.05) to moderate, transient (arterial PCO(2) 8 Torr; P < 0.5) hypoventilation in piglets denervated at 10-15 (n = 6) and 20-25 (n = 6) days of age, respectively. Three weeks after surgery, both breathing of a hypoxic gas mixture and jugular venous NaCN injections elicited a hyperpnea in the CBD piglets that was attenuated compared with that in sham CBD piglets. In the CBD piglets, there was no response to injections of NaCN in the carotid arteries, but there was a response to NaCN injected into the proximal descending aorta, suggesting the residual peripheral chemosensitivity was of aortic origin. Carotid chemoreceptor-intact piglets had carotid and aortic NaCN chemosensitivity by 2 days of age. The carotid response persisted for the 40 days of the study, but the aortic reflex persisted only until approximately 8 days of age. We conclude that 1) the major effect of CBD per se in neonatal piglets is age-dependent hypoventilation and 2) there is a high degree of plasticity in peripheral chemosensitivity in neonates that may contribute to minimizing the changes in breathing after CBD.

Suicidal cyanide ingestion as detailed in Final Exit.

Final Exit is an "informational aid" advocating the practice of active euthanasia and describing the proper method for the foolproof commission of suicide. Although it has been directed toward assisting the terminally ill patient who desires to terminate suffering, it has been suggested that the widespread availability of this book may result in its abuse. Specifically, there is growing concern that "do-it-yourself suicide manuals" could bring about the fruition of suicidal ideations that are relatively common among mentally ill patients and impressionable adolescents. Described is the suicidal ingestion of cyanide by a physically healthy 30-year-old man. His diary, found next to the body, contains a recipe for suicide copied verbatim from Derek Humphry's Final Exit. Although the decedent's history, the scene investigation, and the external examination strongly suggest an underlying psychiatric disorder, postmortem examination disclosed minimal underlying physical disease. This case graphically illustrates the abuse potential of this literary genre. To our knowledge, this is the first case of its kind to appear in the literature. We recommend that forensic pathologists and medical investigators familiarize themselves with the methods of suicide described in Final Exit.

1H NMR spin-echo spectroscopy of human erythrocytes. Transformation of exogenous compounds.

1H NMR spin-echo spectroscopy has been used to study the metabolism of exogenous compounds in human erythrocytes. The non-invasive nature of the technique and the continuous monitoring makes it ideal to investigate both the conversion of substrates and the occurrence and the nature of the products. Hydrolysis rates may be determined and the hydrolysis of alkyl, vinyl, and aryl acetates are shown to be due to A-esterase activity. The conversion products are normally observed, but in the case of dimethyl phthalate and methyl acetate only part of the methanol is found. An interesting case is the hydrolysis of vinyl acetate and the consecutive conversion of the vinyl alcohol to acetaldehyde (hydrate). Coupling of glutathione to a variety of vinyl derivatives is also observed. Oxidation of acetaldehyde can also be followed. Styrene and 5-chloro-2-methylaniline are slowly converted in what is believed to be oxidation reactions. Changes in 1H chemical shifts are observed for a number of compounds upon uptake into human erythrocytes, a shift that is suggested to be due to binding to haemoglobin.

[Inhibition of anion transport in human erythrocyte ghosts under diverse experimental conditions]. / Inibizione del trasporto anionico in ghosts di eritrociti umani in diverse condizioni sperimentali.

The anion and cation permeability of the red blood cells can be modified by a large variety of chemical agents. The interaction of many of these agents with the membrane seem to involve a reaction with positively charged groups. A series of unrelated amphiphilic compounds which should not react with amino-groups nevertheless, produce reciprocal effects on anion and cation permeability. An important exception to the pattern of reciprocal anion-cation effects is found with the disulfonic stilbene derivate, SITS, developped by Maddy as a covalent bonding agent for amino groups of the cell surface. As derivative we used H2DIDS. This agent is just effective as other in reducing anion permeability, but has no effect on cation permeability. The unique specificity of H2DIDS has been attributed to its inability to penetrate into membrane and reacts with a small sites superficially located on the outer face of the membrane. We studied the inhibition of 35SCN efflux by mean H2DIDS in the human red cell ghosts as a function of concentration, incubation time, pH in the medium. We found that the best concentration to obtain the maximum of inhibition is about 50 microM H2DIDS, increasing H2DIDS concentration does not produce further inhibition. Incubation time must be around one hour, increasing the incubation time, there isn't any variation in the inhibition. H2DIDS acts better in a basic range then in an acid one.