Pulmonary barotrauma-induced cerebral arterial gas embolism with spontaneous recovery: commentary on the rationale for therapeutic compression.

Pulmonary barotrauma-induced cerebral arterial gas embolism (CAGE) continues to complicate compressed gas diving activities. Inadequate lung ventilation secondary to inadvertent breath holding or rapid buoyant ascent can quickly generate a critical state of lung over-pressure. Pulmonary over-pressurization may also occur as a consequence of acute and chronic pulmonary pathologies. Resulting barotrauma frequently causes structural failure within the terminal distal airway. Respiratory gases are then free to embolize the systemic circulation via the pulmonary vasculature and the left heart. The brain is a common target organ. Bubbles that enter the cerebral arteries coalesce to form columns of gas as the vascular network narrows. Small amounts of gas frequently pass directly through the cerebral circulation without occlusion. Larger columns of gas occlude regional brain blood flow, either transiently or permanently, producing a stroke-like clinical picture. In cases of spontaneous redistribution, a period of apparent recovery is frequently followed by relapse. The etiology of relapse appears to be multifactoral, and chiefly the consequence of a failure of reperfusion. Prediction of who will relapse is not possible, and any such relapse is of ominous prognostic significance. It is advisable, therefore, that CAGE patients who undergo spontaneous recovery be promptly recompressed while breathing oxygen. Therapeutic compression will serve to antagonize leukocyte-mediated ischemia-reperfusion injury; limit potential re-embolization of brain blood flow, secondary to further leakage from the original pulmonary lesion or recirculation of gas from the initial occlusive event; protect against embolic injury to other organs; aid in the resolution of component cerebral edema; reduce the likelihood of late brain infarction reported in patients who have undergone spontaneous clinical recovery; and prophylax against decompression sickness in high gas loading dives that precede accelerated ascents and omitted stage decompression.

Effective treatment strategies for diabetic foot wounds.

Nonhealing foot ulcers in patients with diabetes are the leading cause of complications such as infection and amputation. This is a review of the traditional methods of good wound care for the diabetic foot ulcer. We also introduce newer methods for the treatment of these ulcers including hyperbaric oxygen therapy, bioengineered tissue, and recombinant platelet-derived growth factor-BB. By using a multidisciplinary team approach to care and integrating traditional and new wound-healing technologies, the goal of the US Department of Health and Human Services to lower the diabetic amputation rate by 40% may be achieved.

Real-time two-photon confocal microscopy using a femtosecond, amplified Ti:sapphire system.

The bilateral imaging approach known from confocal applications operating in the line mode was used to realize real-time two-photon imaging. It is shown that the sectioning inherent to two-photon imaging could be improved by the introduction of a confocal line aperture in the imaging path. Using a high-power, low-repetition-rate amplified Ti:sapphire system, various biological objects were visualized including live boar sperm.

The cloned neurotensin receptor mediates cyclic GMP formation when coexpressed with nitric oxide synthase cDNA.

Rat neurotensin (NT) receptor (NTR) cDNA was subcloned into the pRC-CMV expression vector and transfected into 293 cells, and cellular clones that stably expressed the NTR were isolated and characterized. [3H]NT binding to membranes prepared from the NTR cDNA-transfected cells displayed specificity and saturability, with an apparent Kd of 1.25 nM and a Bmax of 43.4 pmol/mg of protein (approximately 3.5 x 10(6) binding sites/cell). NT stimulated an increase in [3H]inositol phosphate levels in the NTR-expressing cells up to 2500% of basal levels. The response was time and dose dependent, with an EC50 of 10.4 nM. NT also stimulated cAMP formation in these cells, with an EC50 of 27.0 nM. In addition, NT evoked an increase in the level of intracellular calcium. Approximately 60% of the calcium rise was attributable to the release of intracellular stores and 40% was attributable to calcium influx. Although NTR occupancy has been shown to stimulate cGMP formation in several brain preparations and cell lines, NT was unable to mediate cGMP synthesis in the NTR-expressing 293 cells. We found that 293 cells have guanylate cyclase activity but have undetectable levels of nitric oxide synthase (NOS) activity. Because it was possible that the production of nitric oxide is required as the mediator of NT-induced cGMP synthesis, we subcloned NOS cDNA into the pCEP4 expression vector and transiently expressed it in the NTR cells. We report that NT increased cGMP levels up to 375% of basal levels when NOS cDNA was coexpressed and that the increase was completely inhibited by the NOS inhibitor N omega-nitro-L-arginine. NT-induced cGMP accumulation was time and dose dependent, with an EC50 of 1.7 nM. To our knowledge, this is the first report of NT mediating cGMP formation with a cloned receptor and the first evidence that NT-induced cGMP accumulation requires the production of nitric oxide.

Barrett's oesophagus: effect of antireflux surgery on symptom control and development of complications.

Forty-five patients with histologically proven Barrett's columnar-lined oesophagus (CLO) were treated in one unit over a 9-year period. Patients were studied prospectively as part of a surveillance programme; all initially received standard conservative treatment including high-dose H2-receptor antagonists. A satisfactory initial response was seen in 21 patients, but in 24 the symptoms were unchanged or progressed; 19 patients in the latter group were considered suitable for antireflux surgery and underwent fundoplication. Symptoms of heartburn or dysphagia persisted or recurred in 88 per cent of patients receiving medical treatment alone and complications developed in 38 per cent, including nine strictures and one adenocarcinoma. In patients undergoing antireflux surgery, symptoms persisted or recurred in 21 per cent and complications developed in 16 per cent (P < 0.01). Complete regression of Barrett's CLO occurred in two patients (11 per cent) after antireflux surgery. The results of this study suggest the superiority of antireflux surgery over pharmacological acid suppression in the control of symptoms and prevention of complications in patients with Barrett's CLO.

The efficacy of intraoperative autologous transfusion in major shoulder surgery.

Perioperative blood loss associated with 36 cases of major shoulder surgery in which an intraoperative autologous transfusion device was used was compared with a control group of 36 shoulder surgery patients to determine the effectiveness of intraoperative autologous transfusion (IAT). Total blood loss in this retrospective review was evaluated by assessing the volume of transfused banked blood and the change in hematocrit. All surgical cases were performed by the same surgeon. The procedures considered in the study were humeral head and total shoulder replacement. Use of an intraoperative autotransfusion device was associated with fewer units of transfused banked blood and similar or smaller drops in hematocrit. While shoulder surgery can involve substantial blood loss, the authors recommend intraoperative autologous transfusion for revision of failed shoulder surgery, arthrodesis, joint replacement, or repairs of massive cuff tears when mobilization and tendon transfers are anticipated. The risk of disease transmission through banked blood, especially of acquired immune deficiency syndrome (AIDS) and hepatitis viruses, has increased the need for a heightened awareness and use of alternative blood sources such as IAT.