Forschung / Research


 

With respect to both, the physiologic as well as the psychological aspects of Maritime Medicine, the research projects of the group are separated in Maritime Physiology and Maritime Psychology.

 

Current research projects in Maritime Medicine:

In diving with a self contained breathing apparatus (SCUBA) the changes in the partial pressures of the inhaled oxygen and nitrogen lead to a number of particular risks for the safety of the diver.

 Hyperoxia can cause significant oxidative stress to the organism, and this may be due to reactions outside the breathing chain, e.g. the Haber-Weiss- and the Fenton-reaction. However, it is unclear up to now, if this oxidative stress only causes increases in specific markers, or if it has a medical relevance on the diver´s health.

Furthermore, it needs to be evaluated, to what extent additional physical strain under hyperoxic conditions influences the level of oxidative stress in the organism.

Currently we monitor markers of oxidative stress in diving from recreational compressed-air diving to challenging closed-circuit oxygen diving and are focussed on changes in Dihydroxylated Bencoates (DHB) in urine as a marker of the OH.-radical production and the single cell gel electrophoresis (SCGE, „Comet Assay“) for the detection and quantification of DNA damages (Fig. 1).

Extreme hyperoxia, particular above 160 kPa oxygen partial pressure, can cause acute neurotoxic effects, ranging from twitchings to generalized cerebral seizures that can be a deadly risk under water.

We investigate the characteristics of the acute oxygen toxicity in physiologic test settings and under controlled conditions with a focus on changes in cerebral blood flow during hyperoxia. Therefore we use the method of trancranial Doppler-ultrasound (TCD) during routine-exposures to hyperoxia in the hyperbaric facilites of the German Naval Medical Institute (Fig. 2).

Our aim is to characterize the timecourse, the initial symptoms, and the influences of physical exercise as well as ambient coldness on the acute neurotoxic reaction to hyperoxia in order to increase divers´ safety in future.

Diving accidents which may cause significant neurological problems are becoming more frequent as scuba diving is an increasingly popular leisure activity. Although modern decompression tables and diving computers help to reduce diving-associated risks to a minimum, decompression related incidents with neurological symptoms are estimated to occur in 2.7 out of 10,000 dives. The neurological symptoms in these cases vary between minor neurological complaints and stroke-like, life threatening symptoms. Thus, it is still of interest to further optimize decompression procedures.

A new approach is decompression with intermittend changes in depth, so-called Jojo-decompression.

We are currently partner of a study in the hyperbaric facilities of the Berufsgenossenschaftliche Unfallklinik Murnau HBO Druckkammerzentrum, where this new approach is tested with persistent foramen ovale (PFO)-negative volunteers. The PFO-diagnostics is carried out by our group.

Hyperbaric oxygenation (HBO) has been used before in some experimental clinical settings for radio-sensitizing in oncology, but failed in combination with conventional irradiation therapy, because of the time window between HBO and irradiation.

A new approach has recently been followed in cooperation with the Clinic of Nuclear Medicine of the University Medical Center Schleswig-Holstein (Prof. Dr. Henze). In a pilot study a limited number of patients was treated with Yttrium-DOTATOC therapy and simultaneous HBO for radio-sensitizing.

Now we begin to study the specific effects of this combination in an in-vitro cell culture setting with Y-DOTATOC and incubation of the cells in our experimental hyperbaric chamber.

It is the aim of the study to compare the effectiveness of a combination of Y-DOTATOC and HBO on tumor cell control with Y-DOTATOC or HBO alone against a shame procedure.

Sea sickness is one of the most challenging problems aboard ships and can cause severe health problems in adverse weather conditions. All available drugs for sea sickness-control show side-effects, which can significantly reduce vigilance and are therefore problematic in professional seafaring.

Vitamine C is known to have an antihistaminic effect, which is sometimes used as an adjunctive treatment in allergology.

In cooperation with the Floridsdorfer Allergiezentrum in Wien (Prof. Dr. Jarisch) we have tested the preventive effect of oral Vitamin C (2 g) on the symptoms of acute sea sickness in a prospective, double-blind and placebo-controlled study in 70 volunteers exposed to 1 m swell for 20 min in a life raft. In this study in a swimming pool with artifical waves Vitamin C was significantly superior to placebo.

At present a Phase II-study according to BfArm-rules aboard Navy-ships to test the preventive effect of Vitamin C in sea sickness under real open sea conditions is in preparation.

 

 

Fig-1

 

Fig. 1: Single cell gel electrophoresis (SCGE, „Comet Assay“) showing four different stages of DNA-damage

 

Fig-2

 

Fig. 2.

Typical changes in CBFV and ECG in acute oxygen-induced neurotoxicity

 

Fig-3

 

Fig. 3:

CBFV recordings with Transcranial Doppler-ultrasound showing a high number of HITS (high intensity transient signals) due to right- to left-shunting via a persistent foramen ovale (PFO)

 

Fig-4

 

Fig. 4:

Sailing ship in rough sea