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Biomedical subjects

T Mäkinen

Publications and source records attributed to T Mäkinen.

At least 19 recordsLinked to original sources
PubMed2005

In situ measurements of the physical characteristics of Titan's environment.

On the basis of previous ground-based and fly-by information, we knew that Titan's atmosphere was mainly nitrogen, with some methane, but its temperature and pressure profiles were poorly constrained because of uncertainties in the detailed composition. The extent of atmospheric electricity ('lightning') was also hitherto unknown. Here we report the temperature and density profiles, as determined by the Huygens Atmospheric Structure Instrument (HASI), from an altitude of 1,400 km down to the surface. In the upper part of the atmosphere, the temperature and density were both higher than expected. There is a lower ionospheric layer between 140 km and 40 km, with electrical conductivity peaking near 60 km. We may also have seen the signature of lightning. At the surface, the temperature was 93.65 +/- 0.25 K, and the pressure was 1,467 +/- 1 hPa.

Journal Article↗
PubMed2002

Simulated parachute descent in the cold: thermal responses and manual performance.

BACKGROUND: Ejection from a fighter aircraft can expose the pilot to extreme cold and windy conditions. Knowledge of the effects of such conditions on thermal responses and performance of the pilot is scarce. HYPOTHESIS: It is expected that the temperature of bare skin and fingers may decrease to the level where health and/or performance are hampered. METHODS: Seven fighter pilots performed a simulated parachute descent (SPD) at ambient temperature (Ta) of -35 degrees C and wind velocity of 10 m x s(-1). The 8-min SPD was followed by a 60-min cold exposure (CE) at Ta of -20 degrees C. Flight garments with or without immersion suit were used. During SPD the subjects performed basic survival tasks. Rectal and skin temperatures were measured and manual performance was tested. RESULTS: Thermal responses did not significantly differ between the clothing ensembles. Mean skin temperature was 28 degrees C and 27 degrees C at the end of SPD and CE, respectively. The cheek temperature was 9 degrees C (range 3.2-13.8 degrees C) at the end of SPD. Finger skin temperature was 7 degrees C and 9 degrees C at the end of SPD and CE, respectively. The subjects could perform the defined tasks during SPD while manual performance was slightly impaired during CE. CONCLUSIONS: Subjects could tolerate the 8-min SPD and the following CE in the studied conditions without a loss of vital performance in basic survival actions. However, the risk of frostbite on the uncovered skin area as well as numbness of the fingers may jeopardize pilots' health and performance during parachuting.

Adaptation, Physiological↗
PubMed2001

Isolated lymphatic endothelial cells transduce growth, survival and migratory signals via the VEGF-C/D receptor VEGFR-3.

Vascular endothelial growth factor receptor-3 (VEGFR-3/Flt4) binds two known members of the VEGF ligand family, VEGF-C and VEGF-D, and has a critical function in the remodelling of the primary capillary vasculature of midgestation embryos. Later during development, VEGFR-3 regulates the growth and maintenance of the lymphatic vessels. In the present study, we have isolated and cultured stable lineages of blood vascular and lymphatic endothelial cells from human primary microvascular endothelium by using antibodies against the extracellular domain of VEGFR-3. We show that VEGFR-3 stimulation alone protects the lymphatic endothelial cells from serum deprivation-induced apoptosis and induces their growth and migration. At least some of these signals are transduced via a protein kinase C-dependent activation of the p42/p44 MAPK signalling cascade and via a wortmannin-sensitive induction of Akt phosphorylation. These results define the critical role of VEGF-C/VEGFR-3 signalling in the growth and survival of lymphatic endothelial cells. The culture of isolated lymphatic endothelial cells should now allow further studies of the molecular properties of these cells.

Apoptosis↗
PubMed2001

Inhibition of lymphangiogenesis with resulting lymphedema in transgenic mice expressing soluble VEGF receptor-3.

The lymphatic vasculature transports extravasated tissue fluid, macromolecules and cells back into the blood circulation. Recent reports have focused on the molecular mechanisms regulating the lymphatic vessels. Vascular endothelial growth factor (VEGF)-C and VEGF-D have been shown to stimulate lymphangiogenesis and their receptor, VEGFR-3, has been linked to human hereditary lymphedema. Here we show that a soluble form of VEGFR-3 is a potent inhibitor of VEGF-C/VEGF-D signaling, and when expressed in the skin of transgenic mice, it inhibits fetal lymphangiogenesis and induces a regression of already formed lymphatic vessels, though the blood vasculature remains normal. Transgenic mice develop a lymphedema-like phenotype characterized by swelling of feet, edema and dermal fibrosis. They survive the neonatal period in spite of a virtually complete lack of lymphatic vessels in several tissues, and later show regeneration of the lymphatic vasculature, indicating that induction of lymphatic regeneration may also be possible in humans.

Animals↗
PubMed2001

Blood pressure and endocrine responses of healthy subjects in cold pressor test after acutely increased dietary sodium intake.

The objective of the study was to compare blood pressure and endocrine responses in a cold pressure test in young healthy subjects who had shown increased blood pressure during an acutely increased sodium intake. Subjects (n = 53) added 121 mmol sodium into their normal diet for one week. If the mean arterial pressure had increased by a minimum of 5 mmHg compared to the control measure, they were selected for the experiments. The selected subjects (n = 8) were given 121 mmol supplemental sodium d-1 for 14 days after which they immersed the right hand into a cold (+10 degrees C) water bath for 5 min. The blood pressure increased (P < 0.05) during the test and was independent of the sodium intake. The plasma noradrenaline increased from 2.41 +/- 0.38 nmol l-1 to 2.82 +/- 0.42 nmol l-1 (P < 0.05) with normal diet and from 1.85 +/- 0.29 nmol l-1 to 2.40 +/- 0.37 nmol l-1 (P < 0.05) with high sodium diet. The starting concentrations and the endpoint concentrations were statistically similar. The plasma levels of natriuretic peptides (NT-proANP, ANP and BNP) did not change during the test, and the concentrations were independent of the sodium diet. To conclude, acutely increased sodium intake does not change blood pressure or hormonal responses in a cold pressor test in young healthy subjects.

Adult↗
PubMed2001

Prostate cancer screening within a prostate specific antigen range of 3 to 3.9 ng./ml.: a comparison of digital rectal examination and free prostate specific antigen as supplemental screening tests.

PURPOSE: Performing biopsy in all men with a serum prostate specific antigen (PSA) of 3 to 3.9 ng./ml. increases the sensitivity of prostate cancer screening compared with a PSA cutoff of 4 ng./ml. but decreases specificity and may contribute to over diagnosis. Therefore, we evaluated the detection rate and specificity attributable to digital rectal examination and percent free PSA within the PSA range of 3 to 3.9 ng./ml. MATERIALS AND METHODS: Serum PSA was determined in 20,716 participants in the Finnish population based screening trial. Supplementary digital rectal examination was offered to men with a PSA of 3 to 3.9 ng./ml. during 1996 to 1998 (protocol 1). Those with a suspicious digital rectal examination finding were referred for biopsy. The screening algorithm was modified by substituting percent free PSA for digital rectal examination with a cutoff of 16% as a biopsy criterion in 1999 (protocol 2). In addition, biopsies were performed in all men with PSA 4 ng./ml. or greater. RESULTS: A total of 23 cancers (2.9%) were detected by digital rectal examination among 801 men, while percent-free PSA resulted in the diagnosis of 13 cases (4.8%) among 270 men with a PSA of 3 to 3.9 ng./ml. The detection rate of tumors with a Gleason score of 5 or greater increased from 1.6% (13 of 801 cases) to 4.4% (12 of 270) in the modified screening program. The PSA cutoff of 3 ng./ml. alone showed 88.6% and 87.5% specificity in protocols 1 and 2 but specificity increased to 93.3% and 91.7% using digital rectal examination and percent free PSA, respectively. CONCLUSIONS: Using percent free PSA increased the detection rate of aggressive disease compared with digital rectal examination and provided higher specificity than PSA alone.

Aged↗
PubMed2000

Face temperature and cardiorespiratory responses to wind in thermoneutral and cool subjects exposed to -10 degrees C.

The effects of the thermal state of the body (slightly cool and neutral) and moderate wind speeds on face temperature, blood pressure, respiratory function and pain sensation during cold exposure were studied on eight healthy male subjects. They were dressed in cold-protective clothing and preconditioned at + 20 degrees C (TN) and -5 degrees C (CO) for 60 min, then exposed to -10 degrees C and 0 m x s(-1) (NoW), 1 (W1) and 5 (W5) m x s(-1) wind for 30 min. Thus, each individual was exposed six times. The exposure to wind entailed a combination of strong cooling of the bare face and mild body cooling. The forehead, cheek and nose temperatures decreased during cold exposure, and the decrease was greater at higher air velocities (P < 0.0001). All subjects reported pain sensations at 5 m x s(-1). At the end of exposure only the nose temperature was significantly lower in CO than in TN subjects; it was about 2 degrees C and reached 0 degrees C in two experiments. The systolic and diastolic blood pressure (SBP and DBP, respectively) increased significantly by 7.7 and 5.9 mmHg, respectively, during preconditioning at -5 degrees C, but did not change at + 20 degrees C. SBP and DBP increased during exposure to -10 degrees C in TN by approximately 9 mmHg. However, the total average increase of blood pressure (1-90 min) was similar in TN and CO (SBP 15 mmHg and DBP 13 mmHg). SBP and DBP increased more during exposure to 5 m x s(-1) at -10 degrees C than NoW. Blood pressure responses as observed in this study (SBP and DBP up to 51 and 45 mmHg, respectively) are potential health risks for hypertensive individuals and angina patients. Respiratory functions (FVC, FEV1) were reduced by about 3% by the cold (-5 and -10 degrees C) compared to pre-experiment values. Furthermore, the Wind Chill Index seems to underestimate the cooling power of 5 m x s(-1) at -10 degrees C of bare skin (e.g. face). Therefore it needs to be revised and we suggest that it is expanded to include risk levels for pain sensation.

Adult↗
PubMed2000

Thermal responses to cold wind of thermoneutral and cooled subjects.

The effects of initial thermal state on thermoregulatory responses to cold (-10 degrees C) in a 0.2 (still air), 1.0, and 5.0 m. S(-1) wind speed were studied. Eight young male subjects were first preconditioned in thermoneutral (+20 degrees C, TN) or cool (-5 degrees C, CO) environment for 60 min. After preconditioning the subjects were exposed to wind at -10 degrees C in a standing position, facing the wind, for 30 min. Precooling decreased mean skin temperature (Tsk) by 4.0 (SEM 0.1) degrees C (P < 0.001) and increased heat flux by 57 (SEM 2) W x m(-2) (P < 0.001) in comparison to TN. Cooling rate of Tsk was faster (P < 0.001) in TN than in CO at every wind speed. Even so, Tsk ended up at a lower level in CO (P < 0.001-0.01) than in TN at every wind speed. Local skin temperatures of hand, finger, foot and toe were significantly lower in CO than in TN at the end of all exposures to wind. Heat flux from the skin was 8% higher (NS) in TN at 5.0 m x s(-1) wind speed in comparison to CO. A 5.0 m x s(-1) wind speed increased oxygen consumption significantly (P < 0.001) in both CO and TN in comparison to still air. At 5.0 m x s(-1) wind speed the general thermal sensation was the same (cold) in both TN and CO, despite the higher Tsk in TN. In conclusion, Tsk decreased more rapidly in TN, probably due to rapid skin vasoconstriction and redistribution of circulation to the central body. Probably for the same reason, dry heat loss from the skin was at nearly the same level in both TN and CO. Although the initial thermal state did not affect the amount of heat loss, it significantly affected the peripheral temperatures and thermal sensations and should therefore be taken into consideration in the prediction of thermophysiological responses to wind.

Adult↗
PubMed1999

Blood pressure and hormonal responses to short whole body cold exposure in subjects with high dietary salt intake.

The objective of the present study was to test a hypothesis that a high dietary salt intake potentiates a cold induced increase in blood pressure in normotensive men. Male subjects (n = 12) were given 7 g day-1 sodium chloride during the cold months of the year, divided in 3-4 doses per day and dissolved in water, for 14 days additional to their normal diet which contained on the average 9.7 g sodium chloride per day. The same subjects, having their normal diet, served as controls. The resting blood pressure was measured on the fourteenth day seven times at the intervals of five minutes in a climatic chamber in thermoneutral conditions. Then the subjects, wearing a three-layer winter clothing, moved into a wind tunnel (-15 degrees C, air velocity 3.5 ms-1) in which they stayed for fifteen minutes and the blood pressure was recorded at the intervals of three minutes. After the cold exposure, the subjects moved back into the climatic chamber for 30 min and the blood pressure was measured as before the cold exposure. Blood samples were drawn before and after the experiment for ion and hormone measurements. A 12 h urine sample was collected just prior to the cold exposure. A significant difference both in systolic (7 mmHg) and in diastolic (7 mmHg) blood pressure was found between a salt load group and control group under thermoneutral conditions, repeatedly measured over 30 min (paired Student's t-test; p < 0.05). During the whole body cold exposure, blood pressure significantly increased both with and without the extra salt load (repeated measures ANOVA, Student-Newman-Keuls; p < 0.05). The level to which the mean arterial pressure increased during the exposure was independent of the salt intake and the profile of the mean arterial pressure curve was similar in both groups. The systolic pressure increased by a 25 mmHg in both groups during the cold exposure. The increase in the diastolic pressure was significantly (paired Student's t-test, p < 0.05) higher in the high salt group (18 +/- 4 mmHg) than in the control group (12 +/- 3 mmHg) thus supporting partly our hypothesis. After the two-week high salt intake, serum Na+, K+, Cl-, Hct, and plasma Hb were at the similar level as before the extra salt intake. Plasma renin activity, NT-proANP, ANP, and serum aldosterone were not different between the groups, both before and after the cold exposure. The main findings are: 1) the mean arterial pressure increases to the same level and in the same manner independent of the salt load during a short whole body cold exposure and 2) in cold the diastolic blood pressure increases significantly more in people under a very high salt diet.

Adult↗
PubMed1998

Vascular endothelial growth factor D (VEGF-D) is a ligand for the tyrosine kinases VEGF receptor 2 (Flk1) and VEGF receptor 3 (Flt4).

We have identified a member of the VEGF family by computer-based homology searching and have designated it VEGF-D. VEGF-D is most closely related to VEGF-C by virtue of the presence of N- and C-terminal extensions that are not found in other VEGF family members. In adult human tissues, VEGF-D mRNA is most abundant in heart, lung, skeletal muscle, colon, and small intestine. Analyses of VEGF-D receptor specificity revealed that VEGF-D is a ligand for both VEGF receptors (VEGFRs) VEGFR-2 (Flk1) and VEGFR-3 (Flt4) and can activate these receptors. However. VEGF-D does not bind to VEGFR-1. Expression of a truncated derivative of VEGF-D demonstrated that the receptor-binding capacities reside in the portion of the molecule that is most closely related in primary structure to other VEGF family members and that corresponds to the mature form of VEGF-C. In addition, VEGF-D is a mitogen for endothelial cells. The structural and functional similarities between VEGF-D and VEGF-C define a subfamily of the VEGFs.

Adult↗
PubMed1998

Three hands: fragmentation of human bodily awareness.

We describe patient E.P. who occasionally perceives a 'ghost' hand which copies the previous positions of the left hand with a 0.5-1 min time lag, but follows the movement patterns of the right hand. The symptoms started after an operation of a ruptured aneurysm, followed by an infarction of the right frontal lobe; E.P. also has a previously lesioned corpus callosum. Neuromagnetic recordings revealed that activity of the left secondary somatosensory cortex was strongly suppressed during the ghost arm percept, thereby providing an objective correlate for E.P.'s sensations. We conclude that simultaneous mental contents about body scheme may be based on neural information extracted at considerably different times, resulting in fragmentation of bodily awareness.

Adult↗
PubMed1998

Heat balance at -5 degrees C after cold water immersion.

Two different possible behaviors at -5 degrees C after cold water immersion were studied. A test subject wearing winter clothing walked (5 km/h) on a treadmill for 45 minutes at -5 degrees C and at a wind velocity of 3 m/s with dry clothing, immediately after a thorough immersion in 5 degrees C water, or after immersion and wringing, freezing, and beating of the clothing (to remove ice). A marked heat debt (ca. 1000 kJ) was measured at the end of the cold water immersion. Attempts to dry the clothing caused an additional heat debt of ca. 300 kJ. After 45 minutes walking, the difference in heat depth between the treatments was nearly the same as before the exercise. The difference in clothing weight was only 0.9 kg between the two treatments after walking. Beating frozen clothing items could remove ice corresponding to only 0.7% of the wet weight of the clothing. Results suggest that after cold water immersion in winter, the undressing procedure could not be recommended. Instead, after initially removing boots, mittens, and hat, the subject should start walking. The water accumulated in boots and mittens should be poured out when necessary.

Adult↗
PubMed1997

[Primary nursing in day case surgery].

This article deals with primary nursing in day case surgery. Primary nursing is considered through the following concepts: accountability, independence, coordination, comprehensiveness and continuity of care. Day case surgery nursing is planned and implemented according to the patients perspective.

Ambulatory Surgical Procedures↗
PubMed1996

Energy cost and thermoregulation of unrestrained rats during exercise in the cold.

The effect of cold ambient temperature on the energy cost and thermoregulation during exercise was studied in 18 male Sprague-Dawley rats accustomed to running for 2 weeks. For measuring T(b) and ensuring an unrestrained exercise performance, the rats were implanted with intraperitoneal telemetric radio transmitters. The rats ran at three submaximal exercise intensities (10, 15 and 20 m.min-1) at different T(a) values (22 degrees, 0 degree, -10 degrees and -20 degrees C) for 30 min. VO2 and Tb were continuously measured. During exercise at 0 degree C a 100% substitution of thermoregulatory heat production by exercise thermogenesis was observed. At T(a) values below 0 degree C the physical strain of exercise increased considerably: Vo2 increased 34-61% at -10 degrees C and 51% at -20 degrees C compared to the corresponding exercise intensity at T(a) 22 degrees C. A partial substitution of thermoregulatory heat production by exercise thermogenesis was observed in the cold. At -10 degrees C the cost for thermoregulation during exercise was 28% and at -20 degrees C 31% lower than at rest at the corresponding T(a) values. The rat could not maintain normal Tb during exercise below 0 degrees C. The T(b) dropped 1.5-1.8 degrees C at -10 degrees C and 2.5 degrees C at -20 degrees C. It is concluded that exercising below 0 degree C at submaximal levels (below 50% of VO2max) partially substitutes for thermoregulatory costs but is thermally unfavorable for the small-sized rat.

Animals↗