Dexmedetomidine promotes metastasis in rodent models of breast, lung, and colon cancers.

BACKGROUND: Perioperative strategies can significantly influence long-term cancer outcomes. Dexmedetomidine, an α2-adrenoceptor agonist, is increasingly used perioperatively for its sedative, analgesic, anxiolytic, and sympatholytic effects. Such actions might attenuate the perioperative promotion of metastases, but other findings suggest opposite effects on primary tumour progression. We tested the effects of dexmedetomidine in clinically relevant models of dexmedetomidine use on cancer metastatic progression. METHODS: Dexmedetomidine was given to induce sub-hypnotic to sedative effects for 6-12 h, and its effects on metastasis formation, using various cancer types, were studied in naïve animals and in the context of stress and surgery. RESULTS: Dexmedetomidine increased tumour-cell retention and growth of metastases of a mammary adenocarcinoma (MADB 106) in F344 rats, Lewis lung carcinoma (3LL) in C57BL/6 mice, and colon adenocarcinoma (CT26) in BALB/c mice. The metastatic burden increased in both sexes and in all organs tested, including lung, liver, and kidney, as well as in brain employing a novel external carotid-artery inoculation approach. These effects were mediated through α2-adrenergic, but not α1-adrenergic, receptors. Low sub-hypnotic doses of dexmedetomidine were moderately beneficial in attenuating the deleterious effects of one stress paradigm, but not of the surgery or other stressors. CONCLUSIONS: The findings call for mechanistic translational studies to understand these deleterious effects of dexmedetomidine, and warrant prospective clinical trials to assess the impact of perioperative dexmedetomidine use on outcomes in cancer patients.

Scopolamine bioavailability in combined oral and transdermal delivery.

Transdermal therapeutic system scopolamine (TTS-S) is effective in preventing motion sickness for 72 h. However, by this route a prophylactic effect is obtained 6 to 8 h postapplication. By the oral route, scopolamine is effective within 0.5 h for a period of 6 h. To achieve safe as well as effective protection against seasickness during the first hours of a voyage until the TTS-S patch takes effect, the pharmacokinetics of scopolamine was investigated after patch application in combination with oral tablets, 0.6 mg, 0. 3 mg, or placebo. Subjects were 25 naval-crew volunteers, randomly divided into three groups: group 1 (n = 9), TTS-S patch + 0.6 mg of scopolamine per os (p.o.); group 2 (n = 8), TTS-S patch + 0.3 mg of scopolamine p.o.; and group 3 (n = 8), TTS-S patch + placebo tablet. Blood samples were collected before treatment and 0.5, 1, 1.5, 2.5, 3.5, 6, 8, and 22 h post-treatment, and were analyzed for scopolamine levels using radioreceptor assay. Significantly higher plasma scopolamine levels were found in group 1 at 0.5, 1, 1.5, and 2.5 h, and in group 2 at 1 and 1.5 h post-treatment, compared with group 3. Thereafter, plasma levels did not differ significantly between the groups. In all subjects of group 1 and seven subjects (88%) of group 2, therapeutic levels (>50 pg/ml) were measured during the first 2.5 h, compared with only two subjects (25%) of group 3 (P < 0.05). Heart rate, blood pressure, visual accommodation, performance test results, and subjective complaints of adverse effects did not differ significantly. The combination of transdermal and oral scopolamine (0.3 or 0.6 mg) provides the required plasma levels to prevent seasickness, starting as early as 0.5 h post-treatment, with no significant adverse effects.

[Decompression sickness in divers treated at the Israel Naval Medical Institute between the years 1992 to 1997].

Clinical characteristics of 125 divers treated for decompression sickness (DCS) in the hyperbaric multiplace chambers of this Institute during 1992-1997 were analyzed retrospectively. In 62 (51%) the diagnosis was DCS Type I (joint pain or skin involvement) and in 60 (49%) DCS Type II (neurological, inner ear or pulmonary disease). Risk factors for the evolution of DCS were depth and duration of the dives involving accidents, violation of recommendations of the decompression tables, and repeated dives. Results were available for 112 of the 125 patients. 54 of them (48%) recovered completely, and another 54 recovered partially; 4 did not respond to treatment. Inner ear DCS was less responsive to hyperbaric oxygen treatment (p = 0.0001). There was significant improvement of neurological function in those with severe neurological injury (p = 0.0001). Rapid diagnosis and transportation of divers with DCS to a hyperbaric chamber is of crucial importance.

Hyperbaric oxygen therapy for massive arterial air embolism during cardiac operations.

BACKGROUND: Massive arterial air embolism is a rare but devastating complication of cardiac operations. Several treatment modalities have been proposed, but hyperbaric oxygen is the specific therapy. METHODS: The Israel Naval Medical Institute is the only referral hyperbaric center in this country for acute care patients. We reviewed our experience in the hyperbaric oxygen treatment of massive arterial air embolism during cardiac operations. RESULTS: Seventeen patients were treated between 1985 and 1998. Eight patients (47.1%) experienced a complete neurologic recovery; 6 patients (35.3%) remained unconscious at discharge, and 3 patients (17.6%) died. Mean (+/- SD) delay from the end of the operation to hyperbaric therapy was 9.6 +/- 7.4 hours (range, 1-20 hours). This delay was 4.0 +/- 3.4 hours (1-12 hours) for patients who had a full neurologic recovery, 12.8 +/- 7.1 hours (5-20 hours) for patients with severe neurologic disability, and 18.0 +/- 2.0 hours (16-20 hours) for patients who died (1-way analysis of variance; P =.002). The source of variance among the groups mainly resulted from the short delay for patients who experienced complete recovery compared with the other 2 groups (Tukey test). All 5 patients who were treated within 3 hours from the operation and 50% (2 of 4 patients) of those patients treated 3 to 5 hours from operation experienced a full neurologic recovery. With a delay of 9 to 20 hours, only 1 of 8 patients had a full neurologic recovery. The association between outcome and treatment delay was found to be statistically significant (tau = 0.65 with exact 2-sided P value =.0007). CONCLUSION: Hyperbaric oxygen therapy should be administered as soon as possible after massive arterial air embolism during cardiac operations.

The effect of coenzyme Q10 on sperm motility and function.

In sperm cells, the majority of coenzyme Q10 (CoQ10) an energy promoting agent and antioxidant, is concentrated in the mitochondria of the midpiece, so that the energy for movement and all other energy-dependent processes in the sperm cell also depend on the availability of CoQ10. The reduced form of CoQ10-ubiquinol also acts as an antioxidant, preventing lipid peroxidation in sperm membranes. The objective of the study was to evaluate the effect of CoQ10 on sperm motility in vitro, after incubation with 38 samples of asthenospermic and normal motility sperm, and to evaluate the effect of CoQ10 administration in vivo in 17 patients with low fertilization rates after in vitro fertilization with intracytoplasmic sperm injection (ICSI) for male factor infertility. All 38 sperm samples from patients registered in our infertility clinic had normal concentrations and morphology. Of these, 16 patients had normal motility (mean 47.5%) and 22 patients were asthenospermic (mean motility 19.1%). Sperm samples were divided into four equal parts and incubated for 24 h in: HAM's medium alone, in HAM's medium with 1% DMSO and HAM's with 5 microM or 50 microM CoQ10. While no significant change in motility after incubation was observed in the samples with initial normal motility, a significant increase in motility was observed in the 50 microM CoQ10 subgroup of sperm from asthenospermic men, with a motility rate of 35.7 +/- 19.5%, as compared to 19.1 +/- 9.3% in the controls (P < 0.05). The 17 patients with low fertilization rates after ICSI were treated with oral CoQ10, 60 mg/day, for a mean of 103 days before the next ICSI treatment. No significant change was noted in most sperm parameters, but a significant improvement was noted in fertilization rates, from a mean of 10.3 +/- 10.5% in their previous cycles, to 26.3 +/- 22.8% after CoQ10 (P < 0.05). In conclusion, the administration of CoQ10 may result in improvement in sperm functions in selective patients. Further investigation into the mechanisms related to these effects is needed.