Biomedical subjects

Jana Kohl

Publications and source records attributed to Jana Kohl.

5 recordsLinked to original sources

PubMed2006

The influence of a mouthpiece and noseclip on breathing pattern at rest is reduced at high altitude.

The effects of the instrumentation by a mouthpiece (MP) and a noseclip (NC) on the ventilatory response to short time hypobaric hypoxia were studied in 10 healthy volunteers at rest. The subjects were exposed to simulated altitude of 500 m, 3000 m, 4000 m and again 500 m, each altitude being applied for 30 min in a hypobaric chamber. Resting minute ventilation (VE), tidal volume (VT) and respiratory frequency (fR) using inductive plethysmography were continuously measured in all subjects in a standardized half lying position. The recordings were carried out at each altitude during the first 10 min without MP and NC, then 10 min with them, and the last 10 min again without them. At 500 m during MP+NC breathing VE and VT were increased, whereas fR was not significantly changed. At 3000 m, the VE increase with MP+NC was no more significant and fR was decreased. These effects of MP+NC on respiration disappeared at 4000 m and reappeared after the descent to 500 m. Furthermore, with and without MP and NC the variability of VE at 4000 m was significantly higher than at 500 m before ascent, and in all altitudes the variability of VT was significantly reduced by the MP+NC. It is concluded that the influence of MP+NC on VE, VT and fR is reduced or even abolished at high altitude, whereas the hypoxia induced increase of VE variability is not affected by the instrumentation.

Acclimatization↗

PubMed2004

Increased expression of ADAM family members in human breast cancer and breast cancer cell lines.

PURPOSE: ADAMs (A Disintegrin and Metalloprotease) are multifunctional, membrane-bound cell surface glycoproteins, which have numerous functions in cell growth, differentiation, and motility. We wished to investigate the expression of ADAM 9, 10, 12, 15, and in human breast cancer. METHODS: Expression of ADAMs was determined in breast cancer specimens and the corresponding non-neoplastic breast tissue from 24 patients, and in the MCF-7 and MDA-MB 453 breast cancer cell lines via quantitative RT-PCR and immunohistochemistry. The effects of anti-ADAM antibodies on cell proliferation were assessed by measuring DNA-synthesis. RESULTS: Breast cancer tissue samples showed increased mRNA expression of ADAM 9, 12, and 17, whereas ADAM 10 and 15 were not differently expressed. Protein expression was studied by immunohistochemistry. All ADAMs were expressed in MCF-7 and MDA-MB453 cell lines, with the highest expression levels being observed for ADAM 9, 12, and 17. Application of anti-ADAM 15 and anti-ADAM 17 antibodies significantly inhibited the proliferation of both MCF-7 and MDA-MB453 breast cancer cell lines. In contrast, the growth of MCF-7 cells appeared to be stimulated by the administration of anti-ADAM 12 antibody. CONCLUSION: The results of this study suggest that ADAMs are differentially expressed in human breast cancer and are capable of modulating tumour cell growth.

ADAM Proteins↗

PubMed2003

Influence of hypoxia on coordination between breathing and cycling rhythms in women.

To investigate interactions between neural (movement) and chemical (hypoxia) respiratory drives during exercise, we analyzed coordination between breathing and cycling rhythms in normoxia (N) and hypoxia (H, 14.5% O(2)). Twenty women [28 (1) years old] cycled for 6 min at three workloads (55%, 75%, and 95% peak oxygen consumption, VO(2peak); WL1, WL2, and WL3) in N and H. Leg movements, respiratory parameters, peripheral oxygen saturation, and heart rate were continuously recorded. The degree of coordination (%COORD) was quantified as the percentage of breaths starting during the same phase of leg movement. Ventilatory response to isocapnic hypoxia (VRH) was assessed at rest during an exposure to an end-tidal PO(2) of 50 mmHg. There were no differences in %COORD between N and H at any of the three workloads, but %COORD increased significantly from WL1 to WL3 in H. There was no correlation between VRH and %COORD. In conclusion, chemical and neural respiratory drives did not competitively interact: coordination between breathing and cycling rhythms was not reduced during H and did not depend on individual VRH.

Adult↗

PubMed2003

Gender differences in workload effect on coordination between breathing and cycling.

PURPOSE: To investigate the gender differences in the effect of increasing workload level and thus of an increasing metabolic drive to ventilation on the degree of coordination between breathing and cycling rhythms. METHODS: Twenty-one men and 21 women cycled on an electromagnetically braked ergometer while breathing through a pneumotachograph at workloads corresponding to 55, 75, and 95% of V0(2peak) (WL1, WL2, and WL3). Leg movements, respiratory parameters, and heart rate were continuously recorded. The degree of coordination (%coord) was quantified as the percentage of breaths starting during the same phase of leg movement. RESULTS: In men, %coord increased with increasing exercise intensity (WL1: mean +/- SE = 18.8 +/- 2.6%, WL2: 30.9 +/- 4.9%, WL3: 40.9 +/- 5.6%), whereas in women exercise intensity had no influence on %coord (WL1: 25.0 +/- 5.0%, WL2: 29.7 +/- 5.1, WL3: 31.7 +/- 4.7%). There were no gender differences in breathing pattern during high metabolic demands. A major effect on %coord came from the regularity of the breathing rhythm, whereas cycling frequency, fitness level, or cycling experience exerted no influence. CONCLUSIONS: The present study demonstrates that the effect of exercise intensity on the occurrence of coordination between breathing and cycling rhythms differs between men and women.

Adult↗

PubMed2002

Characteristics of the ventilatory response in subjects susceptible to high altitude pulmonary edema during acute and prolonged hypoxia.

The present study compares the changes in ventilation in response to sustained hypobaric hypoxia and acute normobaric hypoxia between subjects susceptible to high altitude pulmonary edema (HAPE-S) and control subjects (C-S). Seven HAPE-S and five C-S were exposed to simulated high altitude of 4000 m for 23 h in a hypobaric chamber. Resting minute ventilation (V(E)), tidal volume (V(T)), and respiratory frequency (f(R)), as well as the end-tidal partial pressures of oxygen (P(ET(O2))) and carbon dioxide (P(ET(CO2))) were measured in all subjects sitting in a standardized position. Six measurement periods were recorded: ZH1 at 450 m at Zurich level, HA1 on attaining 3600 m altitude, HA2 after 20 min at 4000 m, HA3 after 21 h and HA4 after 23 h at 4000 m altitude, and ZH2 immediately after recompression to Zurich level. At ZH1 and HA3, the measurements were first done in lying, then in sitting, and afterwards in standing. Peripheral arterial oxygen saturation (Sa(O2)) was continuously recorded. All respiratory parameters were also measured during exercise lasting 30 min, the work load being 50% of maximal oxygen consumption (V(O2max)) at Zurich level and 26% of the Zurich V(O2max) at 4000 m. V(E), P(ET(O2)) and P(ET(CO2)) did not significantly differ between HAPE-S and C-S at rest and during exercise periods at Zurich level and at high altitude. However, Sa(O2) was significantly lower in HAPE-S than in C-S at rest and during exercise at 4000 m. Breathing through the mouthpiece during ventilation measurements increased significantly the Sa(O2) in HAPE-S in posture tests at HA3. This effect was most pronounced in the supine posture, in which HAPE-S had the lowest Sa(O2) values. These data provide evidence that (1) gas exchange might be impaired on the level of ventilation-perfusion mismatch or due to diffusion limitation in HAPE-S during the first 23 h of exposure to a simulated altitude of 4000 m, and (2) contrary to C-S, the Sa(O2) in HAPE-S is significantly affected by body position and by mouthpiece breathing.

Acute Disease↗