[Fetal thoracopagus. Echographic diagnosis at 26 weeks]. / Foetus thoracopages. Diagnostic échographique à 26 semaines.

The authors report on one case of thoracopagus discovered by echography carried out after 26 weeks of amenorrhoea. The pregnancy was terminated therapeutically by hysterotomy when common viscera were identified (heart and liver). Echographic diagnosis during the first part of pregnancy allows evacuation to be carried out by the vaginal approach. The authors summarize the criteria for echographic diagnosis and also the epidemiological and embryological data required for assessing the prognosis.

[Chlamydia trachomatis perihepatitis (Fitz Hugh-Curtis syndrome). Apropos of 20 cases]. / Périhépatites à Chlamydia trachomatis (syndrome de Fitz-Hugh et Curtis). A propos de 20 cas.

We report a retrospective series of 20 cases of peri-hepatitis diagnosed using the laparoscope. They were all young women who were nulliparous or primiparous. In eight cases, the dominant clinical picture was of acute cholecystitis. In the other cases, asymptomatic peri-hepatitis was discovered when the laparoscope had been used to try to diagnose acute salpingitis. Chlamydia trachomatis is the principal aetiological agent (in 18 cases) and it has overtaken the gonococcus which was the common one in early publications but here was responsible for only one case. Treatment with tetracyclines or quinolones always brings about a cure. Whenever a young woman complains of pain in the right hypochondrium, one has to think of this infection as well as diagnosing and treating the associated salpingitis early.

Measurement of effective pulmonary capillary pressure using the pressure profile after pulmonary artery occlusion.

Pulmonary artery catheters are frequently used to measure pulmonary vascular pressures, particularly the pulmonary wedge pressure (Pw), which reflects pulmonary venous and ideally left atrial pressures. However, the pulmonary capillary pressure (Pc) is the major force in the formation of pulmonary edema. Unfortunately, Pw has been interpreted as being identical to Pc. In this study we used 7-Fr pulmonary artery catheters to measure effective Pc in closed-chest animals and patients. The decreasing pressure profile after pulmonary artery occlusion was separated into fast and slow components, with the inflection point between them representing Pc. Pc was also estimated by mathematically analyzing the curves in terms of a precapillary resistance, a large pulmonary capillary capacitor, and a postcapillary resistance. In dogs, Pc was determined after pulmonary vascular resistance had been increased by infusing serotonin and histamine. While Pw remained unchanged, serotonin increased pulmonary artery pressure (Ppa) 52% and Pc 16%, whereas histamine increased Ppa only 25%, but increased Pc by 35%. This is consistent with studies showing that serotonin primarily elevates precapillary resistance, and histamine increases postcapillary resistance. In thoracic surgery patients, Pc was not consistently related to Pw. This measurement was simple, reproducible, and provided a more precise capillary filtration pressure than Pw. It should be clinically useful in monitoring patients with pulmonary hypertension and adult respiratory distress syndrome, especially those with pulmonary artery catheters.

Pharmacological protection of reoxygenation damage to in vitro brain slice tissue.

Pharmacological protection of central neural function against damage by hypoxia and reoxygenation was studied electrophysiologically and biochemically in hippocampal brain slices. Hypoxia causes a loss of both orthodromically and antidromically evoked potentials in CA1 pyramidal cell neurons. Damage due to hypoxia lasting more than 10 min cannot be restored by reoxygenation. Following pretreatment with methylprednisolone (10(-5) M), indomethacin (10(-5) M) or allopurinol (10(-5) M), reoxygenation after 10 min of hypoxia resulted in complete recovery of the evoked activity. Na+,K+-ATPase activity was not reduced by 10 min of hypoxia, but was reduced by 50% during the first 10 min of subsequent reoxygenation. Allopurinol (10(-5) M) protected against loss of this enzyme activity. The protective action by these drugs of both electrophysiological and biochemical aspects of neural function is consistent with the hypothesis that secondary ischemic damage is caused by the formation of oxygen-derived free radicals during reperfusion.

Central and peripheral causes of hyperreflexia in humans breathing 5% trimix at 650 m.

To clarify the mechanism of increased stretch reflex responsiveness in deep divers (hyperbaric hyperreflexia), comparative studies of stretch (T) and Hoffmann (H) reflexes were done on three men breathing 5% N2-0.5 bar O2-balance He at pressures up to 650 m of seawater (msw) (Atlantis IV simulated dive, F.G. Hall Laboratory, Duke Medical Center). Electromyography revealed increases at depth of up to 160% in the T reflex recruitment ratio (T reflex/Mmax) compared with surface controls. The H reflex recruitment ratio (Hmax/Mmax) did not change significantly. It is concluded that hyperbaric hyperreflexia is mainly due to increased muscle spindle sensitivity, presumably arising as a central effect on gamma-motoneuron activity. However, a purely peripheral effect of pressure on the spindle end-organ itself is not ruled out. Increases of 100-200% in muscle twitch peak force are reported and provide evidence that pressure can act directly on peripheral physiology. Postreflex clonic potentials (rebounds) during voluntary plantar flexion were significantly increased both in amplitude and number, leading to sustained clonus in one subject. In this respect, 5% N2 was less effective than 10% N2 of Atlantis III in controlling underdamping of the reflex loop. Conversely, the twitch contraction rate and clonic frequency in this study were only half as slowed compared with results from the earlier dive.

Anesthetic antagonism of the effects of high hydrostatic pressure on locomotory activity of the brine shrimp Artemia.

The locomotory activity of small groups of brine shrimp (Artemia salina) was studied under conditions of high hydrostatic pressure, varying temperatures and exposure to several gaseous anesthetics. Both compression and exposure to anesthesia reduced the animal's swimming activity, while temperature increased or decreased activity as it was raised or lowered from ambient. The effect of the anesthetics was less during periods of simultaneous exposure to high hydrostatic pressure. It is concluded that pressure antagonism of anesthesia is demonstrable in invertebrate organisms and may represent a fundamental interaction of these parameters in biological systems.

Oxygen toxicity of hippocampal tissue in vitro.

The effects of hyperbaric oxygen have been studied on synaptic transmission in the hippocampal brain slice. Oxygen enhances both the prevolley and postsynaptic potential of extracellularly recorded responses following focal stimulation of afferent fiber bundles, but synaptic efficiency is reduced. It is suggested that hyperbaric oxygen causes changes in potassium distribution in the slice.

Hydrostatic pressure reduces synaptic efficiency by inhibiting transmitter release.

The amplitude of post-synaptic potentials at an identified synapse in the Aplysia central nervous system can be modulated by the application of hydrostatic pressure. Postsynaptically controlled functions, including responses to acetylcholine and the time course of decay of the synaptic responses, remain unaffected by compression. In contrast, frequency facilitation and posttetanic potentiation, which result from presynaptic processes, are altered by pressure in a manner similar to that of agents that block transmitter release. It is concluded that pressure reduces synaptic efficiency by interfering with certain presynaptic mechanisms associated with transmitter release.

A versatile high-pressure chamber for electrophysiological measurements.

A modular high-pressure chamber is described. This chamber will allow stable microelectrode recordings to be made for a variety of intracellular preparations at pressure of 200-300 atmospheres absolute. Its features include internal temperature control, easy visibility, continuous perfusion, electrical penetrations, and manipulation of several internal controls while the system is at pressure. The small size and high versatility of the Wilson chamber make it a convenient and inexpensive research unit for experiments in the moderately high-pressure ranges that affect biological preparations.

Effect of interaction of volatile anesthetics and high hydrostatic pressure on central neurons.

Autoactive neurons in the central nervous system of Helix and Aplysia were studied after exposure to several volatile anesthetics and under compression by mineral oil. Voltage clamp studies reveal that halothane will eliminate the slow inward current that underlies oscillatory activity in burster neurons, while high pressure shifts the negative resistance region of the current without causing its elimination. Simultaneous application of the anesthetic and pressure results in the loss of inward current over a time course similar to that of halothane application alone. It is concluded that in this system, pressure and anesthetics are not acting antagonistically at the site in the membrane that controls slow wave conductances.