Protein tau concentration in blood increases after SCUBA diving: an observational study.

PURPOSE: It is speculated that diving might be harmful to the nervous system. The aim of this study was to determine if established markers of neuronal injury were increased in the blood after diving. METHODS: Thirty-two divers performed two identical dives, 48 h apart, in a water-filled hyperbaric chamber pressurized to an equivalent of 42 m of sea water for 10 min. After one of the two dives, normobaric oxygen was breathed for 30 min, with air breathed after the other. Blood samples were obtained before and at 30-45 and 120 min after diving. Concentrations of glial fibrillary acidic, neurofilament light, and tau proteins were measured using single molecule array technology. Doppler ultrasound was used to detect venous gas emboli. RESULTS: Tau was significantly increased at 30-45 min after the second dive (p < 0.0098) and at 120 min after both dives (p < 0.0008/p < 0.0041). Comparison of matching samples showed that oxygen breathing after diving did not influence tau results. There was no correlation between tau concentrations and the presence of venous gas emboli. Glial fibrillary acidic protein was decreased 30-45 min after the first dive but at no other point. Neurofilament light concentrations did not change. CONCLUSIONS: Tau seems to be a promising marker of dive-related neuronal stress, which is independent of the presence of venous gas emboli. Future studies could validate these results and determine if there is a quantitative relationship between dive exposure and change in tau blood concentration.

Biomarkers of neuronal damage in saturation diving-a controlled observational study.

PURPOSE: A prospective and controlled observational study was performed to determine if the central nervous system injury markers glial fibrillary acidic protein (GFAp), neurofilament light (NfL) and tau concentrations changed in response to a saturation dive. METHODS: The intervention group consisted of 14 submariners compressed to 401 kPa in a dry hyperbaric chamber. They remained pressurized for 36 h and were then decompressed over 70 h. A control group of 12 individuals was used. Blood samples were obtained from both groups before, during and after hyperbaric exposure, and from the intervention group after a further 25-26 h. RESULTS: There were no statistically significant changes in the concentrations of GFAp, NfL and tau in the intervention group. During hyperbaric exposure, GFAp decreased in the control group (mean/median - 15.1/ - 8.9 pg·mL-1, p < 0.01) and there was a significant difference in absolute change of GFAp and NfL between the groups (17.7 pg·mL-1, p = 0.02 and 2.34 pg·mL-1, p = 0.02, respectively). Albumin decreased in the control group (mean/median - 2.74 g/L/ - 0.95 g/L, p = 0.02), but there was no statistically significant difference in albumin levels between the groups. In the intervention group, haematocrit and mean haemoglobin values were slightly increased after hyperbaric exposure (mean/median 2.3%/1.5%, p = 0.02 and 4.9 g/L, p = 0.06, respectively). CONCLUSION: Hyperbaric exposure to 401 kPa for 36 h was not associated with significant increases in GFAp, NfL or tau concentrations. Albumin levels, changes in hydration or diurnal variation were unlikely to have confounded the results. Saturation exposure to 401 kPa seems to be a procedure not harmful to the central nervous system. TRIAL REGISTRATION: ClinicalTrials.gov NCT03192930.

Serum tau concentration after diving - an observational pilot study.

INTRODUCTION: Increased concentrations of tau protein are associated with medical conditions involving the central nervous system, such as Alzheimer's disease, traumatic brain injury and hypoxia. Diving, by way of an elevated ambient pressure, can affect the nervous system, however it is not known whether it causes a rise in tau protein levels in serum. A prospective observational pilot study was performed to investigate changes in tau protein concentrations in serum after diving and also determine their relationship, if any, to the amount of inert gas bubbling in the venous blood. METHODS: Subjects were 10 navy divers performing one or two dives per day, increasing in depth, over four days. Maximum dive depths ranged from 52-90 metres' sea water (msw). Air or trimix (nitrogen/oxygen/helium) was used as the breathing gas and the oxygen partial pressure did not exceed 160 kPa. Blood samples taken before the first and after the last dives were analyzed. Divers were monitored for the presence of venous gas emboli (VGE) at 10 to15 minute intervals for up to 120 minutes using precordial Doppler ultrasound. RESULTS: Median tau protein before diving was 0.200 pg·mL⁻¹ (range 0.100 to 1.10 pg·mL⁻¹) and after diving was 0.450 pg·mL⁻¹ (range 0.100 to 1.20 pg·mL⁻¹; P = 0.016). Glial fibrillary acidic protein and neurofilament light protein concentrations analyzed in the same assay did not change after diving. No correlation was found between serum tau protein concentration and the amount of VGE. CONCLUSION: Repeated diving to between 52-90 msw is associated with a statistically significant increase in serum tau protein concentration, which could indicate neuronal stress.

Increased Level of Serum Hepcidin in Female Adolescent Athletes.

OBJECTIVE: To determine the serum hepcidin concentration and standard hematological parameters in a group of female adolescent athletes, compared with a group of nonathlete females. DESIGN: A case-control study. SETTING: A senior high school for athletes in Gothenburg, Sweden. PARTICIPANTS: All female athletes (70), at the school were offered to take part. Fifty-six athletes accepted. From a random sample of age-matched nonathletes, 71 students were recruited to the control group. MAIN OUTCOME MEASURES: Iron deficiency (ID) was determined by levels of serum iron, total iron-binding capacity, transferrin saturation (TS), and ferritin. Serum hepcidin was determined by a mass spectrometry method. All samples were taken at least 12 hours after training. RESULTS: The main result was the finding of a significantly elevated serum hepcidin level in the athlete group, 4.7 nmol/L compared with 3.3 nmol/L (P < 0.001) in the nonathlete group. In the athlete group, the serum iron concentration was significantly lower, 14.0 µmol/L compared with 17.6 µmol/L (P = 0.003) in the nonathlete group. No difference was found regarding TS, total iron binding capacity, and ferritin. There was no difference in the occurrence of ID or iron deficiency anaemia (IDA). CONCLUSIONS: These findings show an increase in serum hepcidin in a large group of female athletes. The elevated hepcidin levels may affect the iron balance of the athletes, adding to the traditional explanation of dietary intake/iron loss balance.

[The use of treatment table COMEX 30 for severe neurological decompression sickness]. / COMEX 30 för behandling av tryckfallssjuka med neurologiska symtom.

The use of treatment table COMEX 30 for severe neurological decompression sickness Decompression sickness (DCS) can occur after all dives. It often requires treatment in a pressure chamber. DCS with symptoms from the nervous system is particularly serious. In certain cases, the commonly used recompression table (USN TT6) does not suffice to revert severe neurological symptoms. A more advanced recompression table, COMEX 30, can be utilized in these cases. We report three cases of DCS where treatment according to COMEX 30 successfully resolved neurological symptoms. These cases illustrate the importance of fast and proper management of severe DCS and the need of hyperbaric centers staffed and equipped to give correct treatment. National coordination is paramount in order to be able to provide optimal care for both recreational and commercial divers afflicted by DCS.

Helicobacter pylori antibodies and iron deficiency in female adolescents.

OBJECTIVE: Iron deficiency (ID) is a common clinical problem worldwide, affecting primarily females. Helicobacter pylori (HP) infection has been shown to be associated with ID. The objective of this study was to define the prevalence of HP antibodies in female adolescents, and to find out if there was a correlation between HP infection and ID. The secondary aim was to study if regularly performed sporting activity, have any association to HP infection, in itself. DESIGN: A controlled clinical trial. SETTING: A senior high school in Gothenburg, Sweden. SUBJECTS: All female athletes at a senior high school for top-level athletes were offered to take part, and 56 athletes took part in the study. The control group consisted of a random sample of age-matched non-athlete students of which 71 entered the study. MAIN OUTCOME MEASURES: Iron deficiency (ID) and iron deficiency anaemia (IDA) were defined by the use of levels of haemoglobin, serum iron, total iron-binding capacity, transferrin saturation, and serum ferritin, as previously described. HP IgG-antibodies were detected by ELISA. RESULTS: 18 of 127 (14%) adolescent females had antibodies against HP. Only 3% had IDA, while 50% had ID. In total, 66% of the HP positive females had ID compared to 48% of the negative females (p = 0.203). No correlation between sporting activity and HP infection was found. Regarding ethnicity, 11/28 of subjects from medium-high risk areas were HP-positive, compared to 7/99 coming from low-risk areas (p<0.001). CONCLUSION: The main finding of this study is that the prevalence of HP IgG antibodies was 14% in adolescent females. We could not find any difference regarding frequency of ID and IDA, between HP positive and negative individuals. Ethnicity is of great importance for the risk of HP infection, while sporting activity itself seems to have no association to HP-infection.

Iron deficiency in adolescent female athletes - is iron status affected by regular sporting activity?

OBJECTIVE: To determine the prevalence of iron deficiency (ID) and iron deficiency anemia (IDA) among a group of female athletes and compare with an age-matched group of female nonathletes. To study lifestyle factors that could play a role in the development of ID and IDA and compare these factors between the groups. DESIGN: A controlled clinical trial. SETTING: A senior high school for athletes in Gothenburg, Sweden. PARTICIPANTS: All female athletes at a senior high school for top-level athletes were offered to take part. Fifty-seven female athletes accepted to participate in the study. The control group consisted of a random sample of 130 age-matched nonathlete students; 92 accepted to participate in the study. INTERVENTION: Intervention was not an actual part of this study but those with ID and IDA were treated with iron by the regular school doctor. MAIN OUTCOME MEASURES: Iron deficiency anemia and ID were determined by levels of hemoglobin, serum iron, total iron-binding capacity, transferrin saturation, and serum ferritin. RESULTS: The main result of the study is the finding that ID and IDA are common among young adolescent female athletes and that there was no difference between female athletes and nonathletes. In the athlete group, 30 of 57 individuals (52%) had ID compared with 43 of 92 individuals (48%) in the nonathlete group (P > 0.3). Comparisons of the 2 groups showed no significant difference in hemoglobin (P > 0.30). In total, we found that 5 of 57 athletes (8.6%) had IDA compared with 3 of 92 nonathletes (3.3%), the difference being not statistically significant (P = 0.24). CONCLUSIONS: The main finding of this study is that ID and IDA are common among female adolescents but not more common among athletes than nonathletes. The results are despite factors that should favor a better iron status in the athlete group, such as better iron intake and less menstrual bleeding. Other factors that might have an impact on iron balance, must therefore be considered.