Lumbosacral movement in the sit-and-reach and in Cailliet's protective-hamstring stretch.

STUDY DESIGN: This study analyzed movement characteristics of subjects as they performed two different hamstring stretching activities. OBJECTIVES: The study determined if there were differences in lumbosacral movement as the subjects performed the two stretches. SUMMARY OF BACKGROUND DATA: Cailliet contends that his protective hamstring stretch is less apt to be stressful to the structures of the spine than is a more commonly done sit-and-reach stretching activity. No previous biomechanical investigation has tested his contention. METHODS: Lumbosacral movement was measured with an Ady-Hall lumbar monitor as 40 university students (20 males, 20 females) performed a popular sit-and-reach test and a sit-and-reach test that subscribed to Cailliet's protective hamstring stretch protocol. RESULTS: Lumbosacral movement was almost identical in the two stretching activities. CONCLUSIONS: If lumbosacral movement is the only criterion to consider in evaluating the safety of these two stretching activities, it makes little difference which activity is chosen. If moment of inertia were the dependent variable rather than lumbosacral movement, possibly one activity may be less stressful to the structures of the spine than the other.

Biomechanics of the normal and abnormal hip joint.

Static analysis of the canine hip has given some insight to the nature and trend of the force and subsequent stress that is normally applied to the joint. Using the static model, the magnitude and direction of force and stress worsens in the hip with the anatomic and stability changes associated with CHD. More sophisticated dynamic models that take into account unbalanced forces and moments with the resultant motion are needed to better understand the mechanics of the hip joint.

Recording and processing aneurysmal vibration signals in dogs.

A specially designed computerized acoustic aneurysm detection system has been developed and used for recording the acoustic signal produced by aneurysms in dogs. Two transducer types, a modified horn-coupled microphone and a microvascular intra-operative Doppler flowmeter have been used. The results show that the aneurysm signal is time-varying and that a stronger vibration signal can be obtained if a proximal stenosis presents. With direct contact recording, the acoustic signals from aneurysms and parent arteries show different characteristics that can be easily distinguished. The aneurysm signals are processed by spectrograms, and a smoothing technique for suppressing noise is introduced.

Intra-aneurysmal pressure measurements in experimental saccular aneurysms in dogs.

Intra-aneurysmal pressure was studied in an experimental model of saccular aneurysm in dogs, using a vein pouch grafted onto a common carotid arterial bifurcation. The mean and the pulse pressures were recorded simultaneously from within the aneurysm and within the common carotid artery, before and after 50% proximal carotid artery stenosis. These experiments were performed under systemic normotension, hypotension, and hypertension. Normal data suggest that mean intracarotid and intra-aneurysmal pressures are similar and relate in a nearly linear fashion to mean arterial pressure. However, after 50% stenosis, the data had a cubic relationship, the reduction of pressure occurring only in the middle range of mean arterial pressure. Both intra-aneurysmal and intracarotid pulse pressures displayed less dependence on mean arterial pressure. However, sigmoid curves also were observed with the pulse pressures after 50% proximal common carotid artery stenosis. In all cases, after 50% stenosis, the rate of increase of the pulse pressures with mean arterial pressure was greater for higher mean arterial pressures. Our preliminary data indicate that a detailed study of intra-aneurysmal pressure and blood flow in relation to systemic variables such as mean arterial pressure, cardiac output, and peripheral resistance may not only suggest improved means of managing patients with intracranial aneurysms, but also may raise the possibility that, under certain conditions, higher intra-aneurysmal pressures may be induced by downstream stenosis.

An acoustic aneurysm-detector.

Intracranial aneurysms have a high prevalence in the adult population; and if they rupture, significant morbidity almost always ensues. However, pulsatile blood flow through aneurysms produces vibrational sound patterns that may be detected extracranially. Thus, an acoustic aneurysm-detector has been developed to detect the sounds produced by intracranial aneurysms prior to rupture. The design is based on the utilization of a hydrophone for signal detection and computational signal processing for signal extraction. Data are examined in the time domain, the frequency domain, and the time-frequency plane. Examples are presented from an animal model and from a patient with a known aneurysm.

Placental contribution to lactate production by the human fetoplacental unit.

Umbilical cord blood levels of lactate, base deficit, and pH were measured in 452 liveborn infants. In vigorous newborns, the mean umbilical arterial and venous concentrations of lactate were lowest with elective cesarean section, higher with cesarean section performed during labor, and highest with vaginal delivery (P less than .001). This suggests a rise in the fetal lactate level in response to labor. However, there was no concomitant increase in the mean umbilical arteriovenous lactate differences, indicating that both fetus and placenta increase their lactate production proportionately with labor. Depressed newborns had higher umbilical lactate levels than vigorous newborns irrespective of the method of delivery (P less than .001). Depressed newborns also had a higher mean umbilical arteriovenous lactate difference than vigorous newborns (P less than .001). This suggests that, under conditions that lead to neonatal depression, the fetus is the major source of the increased lactate produced, with a smaller contribution from the placenta. The fetal lactate level may be a good indicator of fetal stress in labor.

Noninvasive detection of intracranial vascular lesions using an electronic stethoscope.

Using an electronic stethoscope, the authors have attempted noninvasive detection of intracranial aneurysms, arteriovenous malformations (AVM's), and carotid cavernous fistulas in 45 patients. A microphone of older design and a newly designed horn-coupled probe microphone were used to record the sound signals emanating from the cranium. A trigger pulse recorded by another microphone placed over the carotid area or the precordium was used to time the intracranial signals. The sound signals were converted to electrical signals, amplified, filtered, and analyzed using fast Fourier transformation to give plots of amplitude versus frequency of the signals. A spike at a certain frequency or a bruit over a band of frequencies was considered a positive finding. The records of 18 of the patients were not satisfactory for analysis, mainly due to external noise interference. Eight of 11 aneurysm patients with satisfactory recordings emitted resonant spikes, turbulent bruits, or combinations of the two. The other three records were negative. Four patients with AVM's and two with carotid cavernous fistulas exhibited broad-band bruits representing turbulent flow. Neither spikes nor bruits were demonstrable in three patients with brain tumors or in seven patients without intracranial vascular lesions. Experimental vein pouch aneurysms were also induced in two dogs. Recordings from these animals revealed resonant spikes. The limitations and scope of electronic stethoscope audiometry are discussed.

Human maternal-fetal lactate relationships.

This study attempts to determine the major source of lactate in the normal and in the depressed human fetus, in order to assess the applicability of fetal blood lactate measurement for the evaluation of fetal stress during labor. We obtained umbilical arterial and venous blood samples at delivery in 132 liveborn infants, together with simultaneous maternal radial arterial samples. All samples were analyzed immediately for pH, blood gases, and lactate. In vigorous newborns (1-minute Apgar score greater than or equal to 7), umbilical arterial and venous lactate levels were lowest with elective cesarean section done before the onset of labor, higher with cesarean section performed during labor, and highest at the time of vaginal delivery (p less than 0.001, Tab. I). Fetal lactate levels were also significantly higher than maternal levels in vigorous newborns (p less than 0.01), the lactate difference between umbilical artery and maternal artery being lowest with elective cesarean section, higher with cesarean section performed during labor, and highest with vaginal delivery (p less than 0.02, Tab. II). Depressed newborns (1-minute Apgar score less than 7) had higher umbilical lactates and higher fetal-maternal lactate differences than vigorous newborns (p less than 0.01, Tab. III). Our results indicate that the blood lactate levels in both mother and fetus increase with labor and reach their highest values at the time of vaginal delivery. The lactate levels are highest in the umbilical artery, lower in the umbilical vein, and lowest in the maternal artery before the onset of labor.(ABSTRACT TRUNCATED AT 250 WORDS)

Contributions of engineering to the neurological sciences.

Engineering technology has made several important contributions to the basic and clinical neurological sciences. However, technology has been criticized for dehumanizing patient care and for escalating the cost of medical care. We review several areas where engineering technology has advanced neuroscientific knowledge and improved the care of neurologically ill and impaired and also areas where significant contributions may be expected. Some of the problems of technological innovation such as cost, equipment failure, and standardization are discussed. The importance of focusing on ethical issues raised by technological progress is pointed out. Some suggestions are made for furthering the applications of technology to the neurological sciences.

Ultrasonic B-scan echoarteriographic imaging of experimentally induced thrombi in dogs.

Ultrasonic echoarteriography is a noninvasive method of visualizing extracranial arteries in health and disease. The real-time echoscanning device developed at the University of Cincinnatti utilizes a 5-MHz (center frequency) pulse-echoimaging system. B-mode pictures of the tissues studied are obtained and displayed on a video screen, real-time operation being provided by the scanning mechanism operating at 30 frames per second. In our experiments internal arterial damage produced by surgically scraping the intima induced experimental thrombosis in nine carotid in nine carotid and three femoral arteries in dogs. Where pathologically demonstrated, the thrombi were demonstrated by ultrasonic echoarteriography in every instance. Echoarteriography seemed more sensitive than contrast arteriography in the detection of a partially occlusive thrombus.

Electronic stethoscope for detection of cerebral aneurysm, vasospasm and arterial disease.

A specially designed acoustic stethoscope electronic-computer-analysis system has repeatedly detected and identified angiographically demonstrated anteriorly located intracranial aneurysms by their characteristic signals. The system has detected and measured clinically significant disease in the carotid siphon and bifurcation, even in cases with normal angiograms, and has recorded the onset and disappearance of cerebral vasospasm. Our data suggests that an aneurysm may act as a flexible Helmholtz resonator, possibly being driven by vortex shed or turbulence. Our goal is the development of a safe, non-invasive method by which the physician could investigate warning symptoms of aneurysms, cerebral vasospasm, and arterial disease in order to recommend preventive surgery or medical treatment early before the patient's condition might deteriorate. Individual cases, falsely positive and negative results are discussed.