Struck Side Research Articles

Analysis of injury mechanism and thoracic response of elderly, small female PMHS in near-side impact scenarios

Objective In 2020, 17% of all crash fatalities were individuals aged 65 years or older. Crash data also revealed that for older occupants, thoracic related injuries are among the leading causes of fatality. Historically, the majority of near-side impact postmortem human subjects (PMHS) studies used a generic load wall to capture external loads that were applied to PMHS. While these data were helpful in documenting biofidelity, they did not represent a realistic response an occupant would undergo in a near-side crash. The objective of this research was to test small, elderly female PMHS in a repeatable, realistic near-side impact crash scenario to investigate current injury criteria as they relate to this vulnerable population. Method Ten small, elderly PMHS were subjected to a realistic near-side impact loading condition. The PMHS were targeted to be elderly females age 60+, approximately 5th percentile in height and weight, with osteopenic areal bone mineral density. Each subject was seated on a mass-production seat, equipped with a side airbag and standard three-point restraint with a pretensioner. Other boundary conditions included an intruding driver’s side door. PMHS instrumentation included strain gages on ribs 3-10 bilaterally to identify fracture timing. Two chestbands were used to measure chest deflection, one at the level of the axilla and one at the level of the xiphoid process. Results Injuries observed included rib fractures, particularly on the struck side, and in multiple cases a flail chest was observed. Eight of ten subjects resulted in AIS3+ thoracic injuries, despite previously tested ATDs predicting less than a 10% chance of AIS3+ injury. Subjects crossed the threshold for AIS3 injury in the range of only 1% − 9% chest compression. Additionally, mechanisms of injury varied, as some injuries were incurred by door interactions while others came during airbag interactions. Conclusions This research points to two areas of concern that likely require further analysis: (1) the appropriateness of potentially oversimplified PMHS testing to establish injury thresholds and define injury criteria for complicated crash scenarios; (2) the importance of identifying the precise timing of injuries to better understand the effect of current passive restraint systems.

Can emergency avoidance behavior reduce injuries to electric two-wheeler riders in vehicle collisions?

Objectives The aim of this study was to examine the effects of emergency avoidance behaviors on the kinematics and injuries of electric two-wheeler (ETW) riders. Methods Four typical riding postures of ETW riders before collisions, including one normal posture and three avoidance postures, were identified through analysis of 298 videos of vehicle to ETW accidents. Crash simulations were then performed using the Total Human Model of Safety (THUMS) occupant model, ETW and a sedan finite element (FE) model, and the kinematics of ETW riders were compared. The risk of head injury and lower extremity injury was also investigated. Results When the struck foot position of the ETW rider was lower than the ETW pedal, the lower extremity was struck by the sedan bumper and ETW frame from the right and left side respectively, and the upper body of the rider rotated around the hood leading edge. At a car velocity of 40 km/h, the rider was at high risk of head injury and the tibia was fractured. The medial cruciate ligament (MCL) was ruptured in both the 20 km/h and 40 km/h collisions. When the struck foot position of the ETW rider was higher than the pedal, the lower extremity was hit by the bumper and then rebounded. In this situation, the bending moments of the femur and tibia, as well as the bending angle and shear displacement of the knee joint were less than the injury threshold in all crash simulations. Furthermore, when the head was turned toward the colliding car, the risk of head injury varied with the emergency avoidance posture. Conclusions The height of the struck foot relative to the ETW pedal influenced the rider’s global kinematics, and head and lower extremity injuries risk. In the struck side foot landing and both feet landing postures, the lower extremity was restrained and compressed by the ETW frame, resulting in a high risk of tibia fracture and MCL rupture. Reducing the impact velocities could effectively mitigate the injury risk of the ETW riders; however, loading patterns remain an important factor influencing the risk of lower extremity injury.

Optimal perturbations in time-dependent variable-density Kelvin–Helmholtz billows

We analyse the influence of the specific features of time-dependent variable-density Kelvin–Helmholtz (VDKH) roll-ups on the development of three-dimensional secondary instabilities. Due to inertial (high Froude number) baroclinic sources of spanwise vorticity at high Atwood number (up to 0.5 here), temporally evolving mixing layers exhibit a layered structure associated with a strain field radically different from their homogeneous counterpart. We use a direct-adjoint non-modal linear approach to determine the fastest growing perturbations over a single period of the time-evolving two-dimensional base flow during a given time interval $[t_{0},T]$. When perturbations are seeded at the initial time of the primary KH mode growth, i.e. $t_{0}=0$, it is found that additional mechanisms of energy growth are onset around a bifurcation time $t_{b}$, a little before the saturation of the primary two-dimensional instability. The evolution of optimal perturbations is thus observed to develop in two distinct stages. Whatever the Atwood number, the first period $[t_{0},t_{b}]$ is characterised by a unique route for optimal energy growth resulting from a combination of the Orr and lift-up transient mechanisms. In the second period $[t_{b},T]$, the growing influence of mass inhomogeneities raises the energy gain over the whole range of spanwise wavenumbers. As the Atwood number increases, the short spanwise wavelength perturbations tend to benefit more from the onset of variable-density effects than large wavelength ones. The extra energy gain due to increasing Atwood numbers relies on contributions from spanwise baroclinic sources. The resulting vorticity field is structured into two elongated dipoles localised along the braid on either side of the saddle point. In return they yield two longitudinal velocity streaks of opposite sign which account for most of the energy growth. This transition towards three-dimensional motions is in marked contrast with the classic streamwise rib vortices, so far accepted as the paradigm for the transition of free shear flows, either homogeneous or not. It is argued that the emergence of these longitudinal velocity streaks is generic of the transition in variable-density shear flows. Among them, the light round jet is known to display striking side ejections as a result of the loss of axisymmetry. The present analysis helps to renew the question of the underlying flow structure behind side jets, otherwise based on radial induction between pairs of counter-rotating longitudinal vortices (Monkewitz & Pfizenmaier, Phys. Fluids A, vol. 3 (5), 1991, pp. 1356–1361). Instead, it is more likely that side ejections would result from the convergence of the longitudinal velocity streaks near the braid saddle point. When the injection time is delayed so as to suppress the initial stage of energy growth, a new class of perturbations arises at low wavenumber with energy gains far larger than those observed so far. They correspond to the two-dimensional Kelvin–Helmholtz secondary instability of the baroclinically enhanced vorticity braid discovered by Reinaud et al. (Phys. Fluids, vol. 12 (10), pp. 2489–2505), leading potentially to another route to turbulence through a two-dimensional fractal cascade.

Comparison of pigmentary side effects of taxanes and anthracyclines: an onychoscopic evaluation

Background: Taxanes and anthracyclines are considered as fundamental drugs for the treatment of a broad range of cancers. They have several side effects, which may limit their usage. Drug-induced nail pigmentation (DHNP) has been reported as one of the most striking dermatological side effect of both taxanes and doxorubicin.Objective: This study aimed to evaluate and compare pigmentary side effects of taxanes and doxorubicin with the help of onychoscopy.Methods: Forty-one consecutive patients (30 women, 11 men) with a diagnosis of cancer (16 gastric cancer, 25 breast cancer) were prospectively enrolled in a period of six months. Patients were categorized according to the chemotherapy regimens they had been administered: docetaxel received group [docetaxel (60 mg/m2, day 1), cisplatin (60 mg/m2, day 1) and fluorouracil (500 mg/m2, days 1–5) every 3 weeks], paclitaxel received group [paclitaxel (80–175 mg/m2) every 21 days with or without trastuzumab/zoledronic acid] and doxorubicin received group [doxorubicin 50–60 mg/m2 and cyclophosphamide 600–750 mg/m2 every 21 days]. All the patients were asked whether they had diabetes mellitus (DM) and peripheral neuropathy. At the 16 weeks of chemotherapy, for each patient, all fingernails and toenails were evaluated in clinical and dermoscopic examinations for nail pigmentation. Dermoscopic examination was performed using a videodermatoscope. Descriptive statistics were computed for means, standard deviations, and frequencies. Chi-square test or Fisher’s exact tests were used for the statistical analysis, with a significance threshold of p < 0.05.Results: 34.1% of the patients (14/41) demonstrated clinical signs of nail pigmentation. Nail pigmentation was observed in 4 of 13 patients (30.8%), who had received doxorubicin; 10 of 28 patients (35.7%), who had received taxanes (docetaxel and paclitaxel). There was no statistically significant relationship between the nail pigmentation and the type of the chemotherapeutic regimen administered (Fisher’s exact test, p = 1.000). In addition, no statistically significant results were observed between nail pigmentation and DM (Fisher’s exact test, p = 0.393), and nail pigmentation and peripheral neuropathy (Fisher’s exact test, p = 1.000).Conclusions: DHNP may cause considerable distress to patients. Dermoscopy is a noninvasive imaging method that increases diagnostic accuracy of both pigmented and nonpigmented lesions. Typical dermoscopic features of DHNP consist of a homogeneous brownish-gray coloration of the background with thin, longitudinal, gray lines, which allow the examiner to clearly make the correct diagnosis. Further studies are needed to assess both clinical and dermoscopical findings of DHNP.

The purple urine bag syndrome: a visually striking side effect of a highly alkaline urinary tract infection

The purple urine bag syndrome: a visually striking side effect of a highly alkaline urinary tract infection

Bumper and Grille Airbags Concept for Enhanced Vehicle Compatibility in Side Impact: Phase II

Objectives: Fundamental physics and numerous field studies have shown a higher injury and fatality risk for occupants in smaller and lighter vehicles when struck by heavier, taller and higher vehicles. The consensus is that the significant parameters influencing compatibility in front-to-side crashes are geometric interaction, vehicle stiffness, and vehicle mass. The objective of this research is to develop a concept of deployable bumper and grille airbags for improved vehicle compatibility in side impact. The external airbags, deployed upon signals from sensors, may help mitigate the effect of weight, geometry and stiffness differences and reduce side intrusions. However, a highly reliable pre-crash sensing system is required to enable the reliable deployment, which is currently not technologically feasible. Methods: Analytical and numerical methods and hardware testing were used to help develop the deployable external airbags concept. Various Finite Element (FE) models at different stages were developed and an extensive number of iterations were conducted to help optimize airbag and inflator parameters to achieve desired targets. The concept development was executed and validated in two phases. This paper covers Phase II ONLY, which includes: (1) Re-design of the airbag geometry, pressure, and deployment strategies; (2) Further validation using a Via sled test of a 48 kph perpendicular side impact of an SUV-type impactor against a stationary car with US-SID-H3 crash dummy in the struck side; (3) Design of the reaction surface necessary for the bumper airbag functionality. The concept was demonstrated through live deployment of external airbags with a reaction surface in a full-scale perpendicular side impact of an SUV against a stationary passenger car at 48 kph. This research investigated only the concept of the inflatable devices since pre-crash sensing development was beyond the scope of this research. Results: The concept design parameters of the bumper and grille airbags are presented in this paper. Full vehicle-to-vehicle crash test results, Via sled test, and simulation results are also presented. Head peak acceleration, Head Injury Criteria (HIC), Thoracic Trauma Index (TTI), and Pelvic acceleration for the SID-H3 dummy and structural intrusion profiles were used as performance metrics for the bumper and grille airbags. Results obtained from the Via sled tests and the full vehicle-to-vehicle tests with bumper and grille airbags were compared to those of baseline test results with no external airbags.

Erythromycin

Erythromycin

The purple urine bag syndrome: a visually striking side effect of a highly alkaline urinary tract infection

The purple urine bag is a visually striking and rarely seen side effect of a urinary tract infection. The change in colour is purely within the bag itself; interestingly, the urine itself remains unchanged in colour. Our patient, an 82-year-old female, had a long-standing supra pubic catheter (SPC) in situ; she presented for her routine 6-week SPC change. During this visit, the colour change of the urine drainage bag was noted. The change in colour was consistent throughout the bag and extended to the urinary catheter, although not in the same shade of deep purple noted in the drainage bag (Fig. 1). The urine from the bag contained sediment which was sent for analysis. Fig. 1. The urine bag still attached to the removed supra pubic catheter. Colour change in consistent throughout the bag and extends (red in colour) into the catheter. The urine contained within the purple drainage bag was not purple on visual examination (Fig. 2), although the urine collected following the re-insertion of a new SPC was noticeably lighter in colour. There was no hindrance to the removal of the old SPC, although the patient complained of mild discomfort upon removal. The new SPC was inserted without difficulty. Our patient denied any recent history of nausea, fevers, sweats, chills or vomiting. The patient also denied any recent changes to her medication regimen or unusual dietary changes. Fig. 2. Urine collected from the purple urine bag. The urine itself was dark in colour but not purple in colour. Urinary dipstick analysis indicated the presence of large leucocytes, positive nitrates and a pH of 8.5. Following consultation with our hospitals infectious diseases team, the patient started on a course of amoxicillin/clavulanic acid 875/125 mg BD for 5 days, while urine microscopy/culture/sensitivity (M/C/S) was conducted. Culture revealed the presence of Proteus mirabilis, sensitive to amoxicillin/clavulanic acid. Microscopy revealed the presence of phosphate crystals within the sediment from the purple urine bag (Fig. 3), while a smaller volume of phosphate crystals were noted in the second batch of urine from the fresh catheter/collection bag. The presence of phosphate crystals is a known side effect of a Proteus mirabilis infection. Fig. 3. Microscopy of the sediment collected from the urine sample within the purple urine bag, power of 10, indicating phosphate crystals. Based upon the patient’s history and the microbiology results, a diagnosis of purple urine bag syndrome was made. This is a rarely reported state where the urine collection bag is noted to change to purple. The condition is most common in patients with permanent urinary catheterization, either urethral or supra pubic, in combination with a highly alkaline urinary tract infection (UTI). Numerous organisms have been reported as being responsible for the purple urine bag and include Providencia bacteria, Escherichia coli, Proteus mirabilis or Klebsiella pneumonie.1,2 The pathogenesis of purple urine bag syndrome is due to the metabolism of tryptophan by bacteria to indole and later converted to indicant in the liver.3 This is excreted and broken down in the urine by bacteria possessing one or both enzymes, sulphatise and phosphatase that metabolize this pigment to indirubin and indigo in an alkaline environment (urine). The exact cause of the colour change in purple urine bag syndrome is still unclear. Dealler and colleagues suggest it is due to tryptophan being metabolized to indole which is absorbed into the portal system and converted to indicant by the liver.1,3 This, in turn, is excreted into the urine where the presence of an alkaline environment and bacteria are capable of metabolizing indicant to indirubin and indigo.1,3 The indigo can also be present in the catheter itself, giving a blue discolouration.4 While purple urine bag syndrome may seem harmless, the underlying UTI can lead to serious consequences in a patient with a long-term urinary catheter in which the standard warning signs of dysuria may not be apparent on top of other medical comorbidities. Medical management of purple urine bag syndrome does not require any special treatment apart from changing the catheter and administering appropriate antimicrobial therapy to treat the underlying bacterial infection.

New algorithm and accelerometer locations for frontal crash discrimination

Several crash discrimination algorithms have been developed in order to have timely air bag deployment during frontal crashes. However, it is still challenging to have timely air bag deployment, especially during pole, underride, oblique and offset crashes. Therefore, in this paper, a new algorithm for frontal crash discrimination is proposed, with the summation of the absolute value of the deceleration change being used as a metric and with the metric and its threshold being processed as a function of the velocity change. The new algorithm was applied to frontal crashes of a minivan and a sports utility vehicle, and it resulted in timely air bag deployment for frontal crashes, including pole, underride, oblique and offset crashes. Moreover, it is proposed that an accelerometer be installed on each side of the rockers or pillars to assess the crash severity of each side and to deploy driver and passenger air bags at different times, especially during an asymmetric crash such as an oblique and an offset crash. As an example, the deceleration signals measured at the left and right B-pillar/rocker locations were processed through the algorithm, and earlier time-to-fires (TTFs) were obtained for the air bag on the struck side than for the air bag on the non-struck side.

The Importance of Non-struck Side Occupants in Side Collisions

Current occupant protection assessment for side impact is focused on struck side occupants sitting alone. In a representative sample of tow-away side collisions from the UK, only one-third of front seat occupants in side collisions were alone, on the struck side of the car. The other two-thirds were either a non-struck side occupant alone or a situation where the adjacent seat was also occupied. In terms of restraint protection for non-struck side occupants, belts appeared to be less effective in perpendicular compared to oblique side crashes. Front seat occupancy had bearing on injury outcome. With both front seats occupied, there was a reduction in AIS 27+ injury to belted non-struck side occupants due to a reduction in chest and lower limb injuries. Struck side occupants sustained increased injury rates to the extremities when accompanied by a belted non-struck side occupant but no notable increases in moderate to serious injury to the head, chest, abdomen or pelvis.

Side Impact Protection - Occupants in the Far-Side Seat

Much of the applied vehicle side impact occupant protection research to date has concentrated on occupants seated beside the struck side of vehicles. These occupants are defined as ‘near-side occupants’. Regulatory side impact test standards focus exclusively on this scenario. Real world crash evidence however has shown that occupants seated on the side away from the struck side, defined as ‘far-side occupants’, are still subject to a risk of injury. Relatively little research literature is available that addresses the protection of far-side occupants. Existing three-pint seat belt restraint systems were primarily designed for frontal impacts. Consequently, there is an inability for these systems to perform as effectively under lateral loading, compared to longitudinal loading. This is particularly the case for far-side occupant restraints, where the occupant's upper tom has often been observed to slip out from under the sash part of the seat belt system. This paper examines side impact epidemiology from an injury causation perspective, and endeavours to explain evidence indicating head injuries and seat belt related injuries constitute a significant proportion of all far-side impact injuries. Injury mechanisms and key dynamic parameters governing injury severity are detailed. Computer models simulating the dynamic motion of vehicle far-side occupants are described. Occupant kinematics and injury parameters from the models are then compared with real world crash case studies. The paper finally suggests vehicle design strategies which are likely to reduce far-side injuries. Some alternative restraint systems are proposed as potential countermeasures to reduce occupant injuries.

Two-vehicle side impact crashes: The relationship of vehicle and crash characteristics to injury severity

Injury type and severity among front outboard occupants of passenger vehicles struck in the side by another passenger vehicle and recorded in the United States National Accident Sampling System Crashworthiness Data System were examined in relation to the location of impact, the angle of impact, occupant gender and age, seat belt use, the weight and body style of the side-impacted vehicle, and the weight and body style of the striking vehicle. Elderly occupants were three times as likely as younger occupants in similar crashes to be seriously injured. Serious injuries were also more likely for occupants seated on the struck side and occupants of lightweight passenger vehicles. After accounting for vehicle weight differences, struck-side occupants of cars were still much more likely to be seriously injured than struck-side occupants of light trucks. However, among occupants seated on the side of the vehicle opposite the impact, the likelihood of serious injury was higher for those seated in light trucks.

Medical Record Documentation of Head Injury

Name: Roger Horton1 Date of Birth: June 1, 19842 Drug Allergies: None known3 Immunizations: Complete4 Wednesday, June 9, 1993 1 PM CHIEF COMPLAINT: Fell and hit side and head. PRESENT ILLNESS: At 12:15 PM was swinging high on swing at schoolyard. Fell off at top of arc and landed on hard ground, striking right side of body and right side of head. Remembers landing and "seeing stars," then being surrounded by others. Does not think he lost consciousness. Walked into school, with help. PAST MEDICAL HISTORY (as recorded on problem list): Occasional wheezing, relieved by albuterol inhaler. Fracture, left radius, age 6. PHYSICAL EXAMINATION: Slim, pale boy, sitting quietly on table. Complains of headache; feels "sick to my stomach" and cold. Right shoulder and hip hurt; neck does not. Weight: 58 lb Temperature: 98.2°F, orally Pulse rate: 92 beats/min Respiratory rate: 20 breaths/min Blood pressure: 120/70 Head: Tender and mildly swollen over right parietal area. Eyes: Sclerae clear. Pupils equal in size and reactive. Extraocular movements full without nystagmus. Media clear. Optic discs sharp. Venous pulsations noted. No retinal hemorrhages. Acuity 20/26 in each eye. Ears: Clear tympanic membranes without blood. Nose: Clear; no discharge. Mouth/throat: Clear; no injury noted. Neck: Full movement without pain. Mild tenderness on right side. Chest: Breathing easily. Clear sounds. No tenderness of ribs. Heart: Good sounds in regular rhythm without murmurs.

Life-threatening and disabling injuries in car-to-car side impacts—implications for development of protective systems

Improvements to the passive safety of cars in lateral collisions are of great importance. This study of injuries in car side collisions in Sweden by the use of two evaluation methods has been performed to establish the basis for future development of protective systems for this type of accident. The Folksam car accident data file has been used. Injuries were found to be twice as common for near-side than for far-side ∗ ∗ Near side: occupant is on the struck side; far side: occupant is on the nonstruck side. occupants in car to car impacts. Serious to fatal (AIS 3–6) injuries to belted front seat occupants in near side impacts (10% of all injuries) were compared with the estimated number of injuries to different parts of the body with risk of serious consequences (RSC)—either deaths or permanent disabilities (4.5% of all injuries). The two injury evaluation methods resulted in different ranking orders. AIS 3–6 injuries were received by the chest (37%), abdomen/pelvis (25%), and the head (15%). The RSC method gave a ranking order of head (25%), neck (21%), leg (15%), chest (14%), and abdomen/pelvis (11%). The method of evaluating AIS 3–6 injuries emphasizes only the threat to life. The RSC method also takes into account the risk of disabilities. Injuries to the neck and the leg were found to be most disabling, whilst the injuries to the head, chest, and abdomen/pelvis were the most life threatening. The study also shows that elderly people receive significantly more chest injuries (relative to the number of head injuries), on average four times more than young people. Males receive twice as many chest injuries (relative to the number of head injuries) as females in near-side impacts. The implications from this study for the development of side-impact protective systems should be that such systems must improve protection all the way from the head to the leg for struck-side occupants. Protection of the chest should also take into account the reduced tolerance of injuries of elderly people.

Electrophysiological responses of Didinium nasutum to Paramecium capture and mechanical stimulation

Didinium nasutum is a carnivorous ciliate with a preference for feeding on species of Paramecium. Accidental contact between a Paramecium and the proboscis of a hungry Didinium (Fig. 1a) causes instantaneous discharge of extrusive organelles from the proboscis. If the strike is successful, some of these organelles penetrate the Paramecium, which immediately stops swimming and discharges many trichocysts, mostly from the struck side (Fig. 1b). Cytoplasmic streaming pulls the discharged organelles inward, the captured Paramecium reaches the proboscis, and then the Didinium swallows the prey, opening its proboscis1–10 (Fig. 1c and d). On the other hand, a hungry Didinium does not discharge extrusive organelles when it collides with a glass wall. Instead it shows an avoiding reaction. When a Paramecium collides with the proboscis of a fed Didinium, the proboscis similarly does not discharge extrusive organelles, and the fed Didinium makes an avoiding response. We found that a hungry Didinium held steady by two glass capillary microneedles performed normal capture and ingestion in a solution containing Paramecium caudatum. We describe here an electrophysiological investigation of Didinium nasutum in collision with P. caudatum or with a glass rod while held still by glass capillary microneedles.

Calcium Oxalate Stone Disease: Effects and Side Effects of Cellulose Phosphate and Succinate in Long-term Treatment of Absorptive Hypercalciuria or Hyperoxaluria

AbstractAbsorptive hypercalciuria was treated in 27 patients with cellulose phosphate. In all patients urinary calcium decreased and stone formation virtually ceased. The most striking side effect was an excessive hyperoxaluria, necessitating withdrawal of the drug in 8 patients. Succinate decreased the hyperoxaluria in 14 of 19 patients. All patients had mild hypercalciuria and hypermagnesiuria.This study was done to determine the therapeutic value and the side effects in the treatment of absorptive hypercalciuria with sodium cellulose phosphate and of hyperoxaluria with succinate.

Inhibitory role of the serotoninergic system in hypoglycaemia-induced growth hormone release in the dog.

The effect of functional activation of the serotoninergic system on base line plasma growth hormone (GH) levels and the participation of serotonin (5-HT) in the GH response evoked by insulin-induced hypoglycaemia were studied in the unanaesthetized dog with the aid of a specific and sensitive homologous radioimmunoassay method. In 4 dogs, intravenous injection of insulin (0.4 IU/kg iv) or infusion of L-tryptophan (TP, 2.0 g over 30 min) showed the latter stimulus to be by far less potent in eliciting growth hormone (cGH) release. Intravenous injection of L-5-hydroxytryptophan (5-HTP, 10 mg/kg iv) in 5 dogs induced a clear-cut rise in cGH, but was accompanied by striking side effects. In 9 dogs, administration of p-chlorophenylalanine (PCPA, 100 mg/kg po daily × 5 days), an inhibitor of 5-HT synthesis, did not modify base line cGH and glucose levels, caused a marked decrease of blood 5-HT and resulted in a magnification of the insulin-induced cGH release. In 8 dogs, similarly treated with PCPA, administration of 5-HTP (10 mg/kg iv), 10 min before the hypoglycaemic stimulus, blunted the GH secretory response to the latter. Chronic feeding of a TP-deficient diet in 5 dogs, was accompanied by a progressive decrease of total and "free" plasma TP, no significant changes in base line cGH and blood glucose levels and a GH response to the insulin stimulus (0.2 IU/kg iv) almost super-imposable to that elicitable in the same animals under normal conditions. TP infusion (2.0 g over 30 min) in 3 TP-deficient dogs, induced a striking reduction of the hypoglycaemia-induced GH release. Collectively, this study suggests that 5-HT does not have a noticeable effect on base line plasma cGH levels but exerts an inhibitory role in hypoglycaemia-induced cGH release.