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PubMed1997

Adrenocortical responses to repeated parachute jumping and subsequent h-CRH challenge in inexperienced healthy subjects.

The present study examined the adrenocortical response to 3 consecutive parachute jumps and a poststress h-CRH challenge. Fifteen participants in a parachute-jumping course took saliva samples for later cortisol analysis every 20 min throughout the day, when they accomplished their very first 3 parachute jumps and throughout a control day. The effects of an h-CRH challenge on salivary cortisol were assessed in the evening of the jumping day and on a control day. Parachute jumping induced 3 distinct highly significant adrenocortical responses. The respective cortisol increases for the first, second, and third jump were 39.4 +/- 26.5 nmol/1, 31.4 +/- 21.4 nmol/l, and 16.5 +/- 11.9 nmol/l. Cortisol responses to the first and second jump did not differ but the response to the third jump was significantly reduced [t(13) = 3.11; p = 0.008]. Two groups of subjects were identified, "decreasers," whose response decreased from one to the other jump, and "increasers," whose response remained unchanged or increased. The magnitude of the preceding cortisol response of decreasers exceeded that of increasers significantly by about 30 nmol. The mean adrenocortical effects of the poststress h-CRH challenge and the time-matched challenge on a control day did not differ although, in 4 subjects, the poststress adrenocortical response to h-CRH was completely suppressed.

Adrenal Glands↗

PubMed1978

The development of the parachute reaction: a visuo-vestibular response.

The development of the parachute reaction as a postural response has been tested under various optic stimuli in normal and statomotorically retarded infants. Complete reaction consists in symmetric extension of the arms with extension and spreading of the fingers on quick approach to visual surface. Using a glass plate with three different sized stimulus patterns the parachute response is scored as complete or incomplete. The complete reaction to large visual surface develops significantly earlier than to small visual surface. The response also requires simultaneously a visual and a vestibular sensory input. The developmental course of the parachute reaction is statistically significant linear correlated in double logarithmic transformation to the stimulus pattern and to the age indicating a complex biological maturating process. When the whole retinal area was stimulated by moving visual scenes similar to normal environmental conditions the reaction starts with about 4 months of age and is fully developed from 9 months onwards. The time of quickest development is around 6.3 months of age, a period where locomotor abilities shift from horizontal postiion to active verticalisation of the body. In statomotorically retarded infants the response develops significantly later according to their active motor behaviour. Brain integration and computing centers of sensory afferent input could be multilevel from reticular formation to cerebral cortex, wherein the latter, probable the parietal lobe should play the major role. It is concluded that the parachute reaction results from a combined visuovestibular mechanism of interaction in connection with sufficient kinesthetic experience in visuo-motor behaviour.

Age Factors↗

PubMed2005

Effectiveness of an outside-the-boot ankle brace in reducing parachuting related ankle injuries.

OBJECTIVES: To examine the efficacy of an outside-the-boot parachute ankle brace (PAB) in reducing risk of ankle injury to army paratrooper trainees and to identify inadvertent risks associated with PAB use. DESIGN: The authors compared hospitalization rates for ankle, musculoskeletal, and other traumatic injury among 223,172 soldiers trained 1985-2002 in time periods defined by presence/absence of PAB use protocols. Multiple logistic regression analysis estimated adjusted odds ratios (OR) and 95% confidence intervals for injury outcomes, comparing pre and post brace periods to the brace protocol period. SETTING: A research database consisting of training rosters from the US Army Airborne training facility (Fort Benning, GA) occupational, demographic, and hospitalization information. MAIN OUTCOME MEASURES: Injuries were considered training related if they occurred during a five week period starting with first scheduled static line parachute jump and a parachuting cause of injury code appeared in the hospital record. RESULTS: Of 939 parachuting related hospitalizations during the defined risk period, 597 (63.6%) included an ankle injury diagnosis, 198 (21.1%) listed a musculoskeletal (non-ankle) injury, and 69 (7.3%) cited injuries to multiple body parts. Risk of ankle injury hospitalization was higher during both pre-brace (adjusted OR 2.38, 95% CI 1.92 to 2.95) and post-brace (adjusted OR 1.72, 95% CI 1.27 to 2.32) periods compared with the brace protocol period. Odds of musculoskeletal (non-ankle) injury or injury to multiple body parts did not change between the brace and post-brace periods. CONCLUSION: Use of a PAB during airborne training appears to reduce risk of ankle injury without increasing risk of other types of traumatic injury.

Adolescent↗

PubMed2003

Parachute and lateral propping reactions in preterm children.

A non-controlled, prognostic cohort study was performed with the aim of establishing markers of neurological development and defining a clinical and epidemiological profile of preterm newborns at 3, 6, 9, and 12 months of gestation-corrected age in terms of parachute and lateral propping reactions. Newborns with gestational age of up to 36 weeks and 6 days, weighing 2,000 g or less at birth, were included in the study At 6 months of age, parachute and lateral propping reactions were present in 8.1% of the patients. At 9 months, the parachute reaction was present in 87.5%, and the lateral propping reaction was present in 90% of the children. It was possible to assess parachute and lateral propping reactions in preterm children in the first year of life. Alterations in trunk-limb coordination may be evidenced in the 1st year of life through postural reactions, which are maintained as prematurity markers until school age.

Child Development↗

PubMed1999

Biochemical changes of plasma in paratroops after parachuting: a preliminary investigation.

OBJECTIVE: To study whether physiological and psychological stresses during parachuting jumps may result in biochemical changes of plasma in parachutists. METHOD: Differences in the levels of hormones (cortisol, growth hormone, insulin, pancreatic glucagon, endothelin, angiotonin I and II, aldosterone), activities of enzymes (superoxide dismutase, glutathione peroxidase, glutathione S transferase), levels of the free radical damage indicator malondialdehyde (MDA), tumor necrosis factor alpha (TNF-alpha), and the main heat stress protein, HSP70, in the plasma and serum were investigated in control (non-parachuting) and parachuting paratroops. RESULT: Significantly higher levels of serum hormones such as growth hormone, insulin, angiotonin 1, renin activities, as well as MDA and plasma TNF-alpha and HSP70 were observed in the parachuting group. CONCLUSION: Whether these changes can potentially serve as useful biomarkers to assess possible abnormal stress in parachutists and to evaluate the health condition and to select parachutists remains to be further studied.

Adolescent↗

PubMed2003

Risk factors for injuries during military parachuting.

INTRODUCTION: Parachuting is an activity performed by a variety of occupational groups including the military, firefighters (smoke jumpers), and rescue groups. METHODS: This paper systematically reviewed the literature on injury risk factors for soldiers performing static line parachuting from military aircraft. Jump-related injuries were defined as those occurring from the time the soldier exited the aircraft until he or she released their parachute harness on the ground. RESULTS AND DISCUSSION: Despite methodological differences, where two or more studies examined a particular risk factor, results were generally similar. Higher injury risk was associated with higher wind speed, night jumps, jumps from airplanes (vs. balloons and helicopters), jumps wearing additional equipment jumps without ankle braces, uneven terrain on the drop zone, and female gender. Risk factors identified in only single studies included a greater number of soldiers exiting the aircraft, winds from the rear of the aircraft, simultaneous exits from doors on opposite sides of the aircraft, smaller parachute canopies, higher ambient air temperatures, and airborne refresher courses (vs. introductory courses). Further studies are needed which use a multivariate approach to evaluate the relative impact of the various risk factors and their interactions. CONCLUSIONS: This paper identified a number of risk factors relevant to all parachutists (e.g., wind speed, female gender) and some relevant primarily to the military and other tactical parachutists such as smoke jumpers (e.g., equipment weight). Knowledge of these risk factors can assist parachutists and those that train them in their risk analysis.

Accidents, Occupational↗

PubMed1980

Ventricular septal defect with aneurysm of the membranous septum and a parachute mitral valve. Echocardiographic findings.

The echocardiographic findings in a case of ventricular septal defect with aneurysm of the membranous septum and a parachute mitral valve, are analyzed. An abnormal linear echo was recorded within the left ventricular outflow tract and in the aortic root, and in close relationship with the tricuspid valve. No abnormal systolic echoes were seen neither anterior to the interventricular septum nor in the right ventricular outflow tract. The hypothesis that a parachute m. An abnormal linear echo was recorded within the left ventricular outflow tract and in the aortic root, and in close relationship with the tricuspid valve. No abnormal systolic echoes were seen neither anterior to the interventricular septum nor in the right ventricular outflow tract. The hypothesis that a parachute m. An abnormal linear echo was recorded within the left ventricular outflow tract and in the aortic root, and in close relationship with the tricuspid valve. No abnormal systolic echoes were seen neither anterior to the interventricular septum nor in the right ventricular outflow tract. The hypothesis that a parachute mitral valve without significant obstruction at the infravalvar level is not distinguishable echocardiographically from a normal mitral valve, is confirmed in this patient. This case example further clarifies the origin of the anterior cusp echo of the aorta, due to the close proximity between the membranous septum and the right aortic cusp.

Echocardiography↗

PubMed1982

Potentially parachute mitral valve in common atrioventricular canal: pathological anatomy and surgical importance.

An essentially single focus of left ventricular chordal insertion was found in 23 of 164 autopsied cases of common atrioventricular canal (CAVC) with a normally formed spleen (14%). Suture closure of the cleft of the mitral valve in such cases results in the surgical creation of parachute mitral valve, often with fatal iatrogenic mitral stenosis. In such patients, the cleft of the mitral valve is its main orifice and must not be sutured closed. There are four anatomic types of potentially parachute mitral valve in CAVC: (1) with one papillary muscle group and one mitral orifice (type 1A), in 10 cases (43%); (2) with one papillary muscle group and two mitral orifices (type 1B), in one case (4%); (3) with two papillary muscle groups and one mitral orifice (type 2A), in five cases (22%); and (4) with two papillary muscle groups and two mitral orifices (type 2B), in seven cases (30%). Parachute mitral valve exists only when the AVC is divided, either naturally or surgically. The essence of parachute mitral valve is an essentially single focus of chordal insertion. One or both left ventricular papillary muscle groups may be present. The presence of only one focus of left ventricular chordal insertion contraindicates cleft closure.

Adolescent↗

PubMed1998

Parachuting injuries: a retrospective study of 43,542 military jumps.

Parachuting is regarded as relatively safe. This study was conducted to describe the rates and patterns of parachuting injuries at the Parachuting Israeli Training Center to those at other training centers. Data on 43,542 military jumps were collected from accident reports and flight manifests. Two categories of injuries were defined: major (fractures, dislocation, head trauma) and minor (contusion, bruises, sprains). The overall injury rate was 0.89%. The injury rate for major injuries was 0.21%; the most frequent major injuries were ankle fractures and head trauma. The minor injury rate was 0.68%; the most frequent minor injury was ankle sprain. We conclude that our data at the parachuting center matched those at other training centers in terms of injury rate and distribution of injuries.

Ankle Injuries↗

PubMed1979

Parachute mitral valve, coarctation of aorta, radius aplasia, and omphalocele in an infant with the trisomy 18 syndrome.

A premature infant with trisomy 18 had cardiac defects including parachute mitral valve, coarctation of the aorta, and a subcristal ventricular septal defect. The parachute mitral valve was funnel-shaped with a moderately-thick cone of fibrous tissue around the annulus and an eccentric orifice. Many forms of congenital cardiac defects have been described in the 18 trisomy syndrome. However, parachute mitral valve has not, to our knowledge, been part of the spectrum of cardiac defects in trisomy 18. Other anomalies were absent radii, omphalocele, and cleft palate and cleft lip; these have been observed previously in the 18 trisomy syndrome.

Abnormalities, Multiple↗

PubMed1993

Determination of optimal location for parachute ripcord handle in a suspended position.

A number of parachuting fatalities are attributed every year to the inability of the parachutist to pull the ripcord. The purpose of this study was to determine a location for the ripcord handle in parachutes, which would be most compatible with human capabilities. Eight different ripcord handle locations were selected for this investigation. Eighteen male and 18 female subjects participated in the study. The subjects were tested while being suspended 5 cm above floor level wearing a parachute harness. Maximum voluntary force exertions were measured with the subjects pulling the ripcord handle using their left, right and both hands at all locations. The results indicate that the thigh locations are superior in regard to pull forces for all hand applications (left, right, and both). Also, two-handed pulls yield the largest forces at all locations.

Journal Article↗

PubMed1996

The parachute reactions in normal and late walkers.

To study the relationship of the parachute responses to the age of independent walking, three groups of infants were prospectively examined: a normal sitting, normal walking group; a late sitting, normal walking group; and a late sitting, late walking group. All other spheres of the neurodevelopmental examination were normal. It was found that when the parachute responses appeared by age 10 months in the late sitting infants, most of them would achieve independent walking by 15 months. A delay in the parachute reaction in these infants predicted a delay in walking.

Child Development↗

PubMed2004

Design, synthesis, and photophysical studies of a porphyrin-fullerene dyad with parachute topology; charge recombination in the marcus inverted region.

As part of a continuing investigation of the topological control of intramolecular electron transfer (ET) in donor-acceptor systems, a symmetrical parachute-shaped octaethylporphyrin-fullerene dyad has been synthesized. A symmetrical strap, attached to ortho positions of phenyl groups at opposing meso positions of the porphyrin, was linked to [60]-fullerene in the final step of the synthesis. The dyad structures were confirmed by (1)H, (13)C, and (3)He NMR, and MALDI-TOF mass spectra. The free-base and Zn-containing dyads were subjected to extensive spectroscopic, electrochemical and photophysical studies. UV-vis spectra of the dyads are superimposable on the sum of the spectra of appropriate model systems, indicating that there is no significant ground-state electronic interaction between the component chromophores. Molecular modeling studies reveal that the lowest energy conformation of the dyad is not the C(2)(v)() symmetrical structure, but rather one in which the porphyrin moves over to the side of the fullerene sphere, bringing the two pi-systems into close proximity, which enhances van der Waals attractive forces. To account for the NMR data, it is proposed that the dyad is conformationally mobile at room temperature, with the porphyrin swinging back and forth from one side of the fullerene to the other. The extensive fluorescence quenching in both the free base and Zn dyads is associated with an extremely rapid photoinduced electron-transfer process, k(ET) approximately 10(11) s(-)(1), generating porphyrin radical cations and C(60) radical anions, detected by transient absorption spectroscopy. Back electron transfer (BET) is slower than charge separation by up to 2 orders of magnitude in these systems. The BET rate is slower in nonpolar than in polar solvents, indicating that BET occurs in the Marcus inverted region, where the rate decreases as the thermodynamic driving force for BET increases. Transient absorption and singlet molecular oxygen sensitization data show that fullerene triplets are formed only with the free base dyad in toluene, where triplet formation from the charge-separated state is competitive with decay to the ground state. The photophysical properties of the P-C(60) dyads with parachute topology are very similar to those of structurally related rigid pi-stacked P-C(60) dyads, with the exception that there is no detectable charge-transfer absorption in the parachute systems, attributed to their conformational flexibility. It is concluded that charge separation in these hybrid systems occurs through space in unsymmetrical conformations, where the center-to-center distance between the component pi-systems is minimized. Analysis of the BET data using Marcus theory gives reorganization energies for these systems between 0.6 and 0.8 eV and electronic coupling matrix elements between 4.8 and 5.6 cm(-)(1).

Journal Article↗

PubMed2001

Discovery of a parachute mitral valve complex (Shone's anomaly) in an adult.

Parachute mitral valve complex is an unusual congenital anomaly described by Shone et al. It is characterized by a parachute deformity of the mitral valve associated with additional forms of left heart anomalies, such as aortic valvular stenosis and coarctation of the aorta. Fewer than 50 cases of Shone's complex have been reported in the literature, and it has only been observed in children. We report the case of a 33-year-old man who was referred to our department because of atrial fibrillation. Echocardiographic evaluation and aortogram evidenced a Shone's complex, including a parachute mitral valve anomaly, an aortic bicuspid valvular anomaly, and a coarctation of the aorta.

Abnormalities, Multiple↗

PubMed1991

Stress and trance in freefall parachuting: a pilot study.

Freefall parachuting is a demanding activity which, at times, is profoundly stressful. Fifty-nine freefall parachutists completed a survey which dealt with parachuting experience, levels of perceived stress, sources of stress, episodes of altered consciousness, and use of hypnotic techniques in preparation for freefall. Over one third admitted to having experienced a "trance-like state" before, during, or after a jump; the same was true of a state of "altered consciousness." The great majority used mental imagery or another mental or physical technique to prepare for freefall. These results recall the theory that stress predisposes to hypnotic trance. Trance, when unconsciously evoked during emergencies (spontaneous dissociation), may account for some parachuting accidents. When consciously pursued, however, self-hypnosis may provide the jumper with a way to control his level of arousal, facilitate cognitive rehearsal, and enhance performance.

Adaptation, Psychological↗

PubMed2006

"Parachuting" meth: a novel delivery method for methamphetamine and delayed-onset toxicity from "body stuffing".

BACKGROUND: Methamphetamine is an illicit stimulant that is typically smoked, insufflated, or injected. We report an unusual method of ingesting methamphetamine called "parachuting" and its implications for the treatment of "body stuffers." CASE REPORT: A 25-year-old man wrapped methamphetamine into a plastic baggie and ingested it in an attempt to "parachute." He presented to an Emergency Department 10 hours after his ingestion because he realized that he forgot to puncture the baggie. He had no complaints and had a transient tachycardia. He was treated with activated charcoal and whole bowel irrigation, observed for 24 hours, and discharged. He returned 42 hours after his ingestion with tachycardia (220 bpm), agitation, hypertension (179/74 mmHg), and rhabdomyolysis (CPK 7771 U/L), requiring mechanical ventilation and a midazolam drip (10 mg/hr). CONCLUSION: "Parachuting" is a novel method of ingesting methamphetamine. We report a case of a single-packet "body stuffer" with severe symptom onset that was delayed over 36 hours. Treatment protocols for "body stuffers" using this technique may require more prolonged observation and/or imaging studies to determine the absence of gastrointestinal packets.

Administration, Oral↗

PubMed1987

Analysis of opening shock of a chest mounted reserve parachute.

The effect of opening shock of a chest-mounted reserve parachute on the head/neck dynamics is studied. Comparisons are made with similar effects of a back-mounted reserve parachute. The analysis employs a biodynamic computer model developed in earlier research. The results show that there are significant advantages of a chest-mounted over a back-mounted reserve parachute.

Aviation↗

PubMed1986