Parameters of the center of pressure displacement on the saddle during hippotherapy on different surfaces

Background: Hippotherapy uses horseback riding movements for therapeutic purposes. In addition to the horse's movement, the choice of equipment and types of floor are also useful in the intervention. The quantification of dynamic parameters that define the interaction of the surface of contact between horse and rider provides insight into how the type of floor surface variations act upon the subject's postural control. Objective: To test whether different types of surfaces promote changes in the amplitude (ACOP) and velocity (VCOP) of the center of pressure (COP) displacement during the rider's contact with the saddle on the horse's back. Method: Twenty two healthy adult male subjects with experience in riding were evaluated. The penetration resistances of asphalt, sand and grass surfaces were measured. The COP data were collected on the three surfaces using a pressure measurement mat. Results: ACOP values were higher in sand, followed by grass and asphalt, with significant differences between sand and asphalt (anteroposterior, p=0.042; mediolateral, p=0.019). The ACOP and VCOP values were higher in the anteroposterior than in the mediolateral direction on all surfaces (ACOP, p=0.001; VCOP, p=0.006). The VCOP did not differ between the surfaces. Conclusion: Postural control, measured by the COP displacement, undergoes variations in its amplitude as a result of the type of floor surface. Therefore, these results reinforce the importance of the choice of floor surface when defining the strategy to be used during hippotherapy intervention. .

The interface of oxytocin-labeled cells and serotonin transporter-containing fibers in the primate hypothalamus: a substrate for SSRIs therapeutic effects?

Oxytocin (OT) is a neuropeptide synthesized in the paraventricular (PVN) and supraoptic nuclei (SON) in the hypothalamus. Although OT is more commonly known for its role in the milk-ejection reflex, in recent years research has indicated that OT participates in the expression of social behavior, memory processing, modulation of fear, and stress responses. The demonstration that OT influences affiliative behaviors, such as parental care and reproduction, and decreases anxiety has lead to speculations that it may have a role in mood disorders. Evidence from pharmacologic studies, pointing out the modulation of the OT system by serotonin, has argued in favor of OT as a mediator of serotonin reuptake inhibitors (SSRIs) antidepressant properties. In the present study, we investigated the distribution and overlap of OT-labeled cells and serotonin transporter (5-HTT) immunoreactive (IR) fibers in the Macaque hypothalamus, utilizing immunocytochemical and double-immunofluorescent techniques. Consistent with previous reports, the distribution of OT-labeled cells in the hypothalamus is confined to the PVN and SON. In these nuclei, we demonstrate that the distribution of 5-HTT-labeled fibers follows the distribution of OT-labeled cells. Overlap of OT-labeled neurons and 5-HTT-IR fibers occurs in the parvicellular, magnocellular, dorsal, and posterior subdivisions of the PVN. In the SON, 5-HTT-labeled fibers and OT-labeled cells overlap in the ventromedial subdivision and in the 'capsular' part of the dorsolateral SON. These findings provide neuroanatomic support for the idea that SSRIs' therapeutic effects on social affiliation and anxiety may be mediated in part through components of the OT system.

Glial changes in primate cerebral cortex following long-term sensory deprivation.

Significant morphological modifications in the layout of primate-specific (interlaminar) astroglia were found in somatosensory areas 3a, 3b, 1 and 2 eleven to thirteen months after transection of the posterior spinal cord in adult Macaca monkeys. These observations plus lack of evidence of a persistent reactive astrocytosis suggest that changes in the spatial arrangement of interlaminar glia may be an integral part of the long-term process of structural reorganization of the cerebral cortex following cortical deafferentation.

Cognitive and behavioral deficits in nonhuman primates associated with very early embryonic binge exposures to ethanol.

This study was undertaken to evaluate teratogenesis associated with early weekly ethanol exposure followed by later gestational abstinence. Ethanol, 1.8 gm/kg, was orally administered weekly to gravid nonhuman primates (Macaca nemestrina) for the first 3, 6, or the entire 24 weeks of pregnancy. Control animals received weekly sucrose solution as did the 3- and 6-week cohort animals in subsequent weeks. Thirty-five viable infants were assessed for growth, malformations, and behavioral and cognitive dysfunction. Animals in the 6-week and 24-week cohorts were uniformly abnormal in behavior and inconsistently abnormal in physical development relative to the control animals. Animals in the 3-week cohort were equivocally normal. These results demonstrate ethanol's capacity to produce behavioral teratogenesis (brain dysfunction) in isolation from physical anomalies in the rest of the body. The results strongly suggest that binge drinking in the first 6 to 8 weeks of pregnancy (a period when women may not know that they are pregnant), followed by later gestational abstinence, is as dangerous to the fetus as exposure throughout gestation.

Retinal toxicity of intravitreal gentamicin.

The short- and long-term effects of a 10-mg dose of intravitreal gentamicin were studied in the subhuman primate eye with regard to the changes in clinical appearance, fluorescein angiography, electroretinography, histopathologic finding, and electron microscopy. The gentamicin produced retinal whitening with a cherry-red spot, generalized vascular incompetence, diffuse retinal necrosis, thrombosis of the large retinal blood vessels, widespread loss of the retinal capillary pericytes and endothelial cells, and a rapid extinction of the electroretinogram.

Hyperthermia-induced cardiac arrest in dogs and monkeys.

The pattern of dying from immersion hyperthermia was documented in 8 dogs, 9 rhesus monkeys and 12 pigtail monkeys. Under light general anesthesia and spontaneous breathing, the animals were immersed into water of 45 degrees C, which was subsequently adjusted to control brain (parietal epidural) temperature at 42 +/- 0.5 degrees C. Transient initial hypertension, tachycardia, tachypnea and hypocarbia were followed by progressive hypotension with decreasing central venous pressure and pulmonary artery occlusion pressures (measured in three dogs only), bradycardia and bradypnea. Cardiac arrest occurred in the dogs after immersion of 288 +/- 66 min and more rapidly (P less than 0.02) in the rhesus monkeys (at 137 +/- 75 min) and pigtail monkeys (at 178 +/- 26 min). EEG silence occurred in the monkeys at MAP 40 mmHg and in the dogs at MAP 25 mmHg. Cardiac arrest occurred in form of sudden ventricular fibrillation (2/5 dogs, 2/9 rhesus monkeys, 3/12 pigtail monkeys), or later in electromechanical dissociation leading to electric asystole (3/5 dogs, 7/9 rhesus monkeys, 9/12 pigtail monkeys). The mean blood glucose levels decreased to less than 30 mg/dl (P less than 0.002), whereas hematocrit, serum osmolality, lactate and potassium levels increased. Necropsies revealed macroscopic petechial hemorrhages in all extracerebral organs, but not in the brain. There was no gross evidence of cerebral edema. Death seemed to be the result of primary cardiovascular failure leading to secondary (ischemic) cerebral failure (EEG silence) and apnea, which coincided with pulselessness.

Fetal alcohol syndrome: a new primate model for binge drinking and its relevance to human ethanol teratogenesis.

Ethanol was administered nasogastrically to four gravid pigtailed macaques (Macaca nemestrina) weekly from 40 days after conception to term. Three animals received 2.5 gm/kg and one received 4.1 gm/kg per dose. One animal aborted after the first dose of 2.5 gm/kg ethanol. Serum ethanol and acetaldehyde were measured after each dose in the other three animals, who carried to term. After delivery the infants were assessed for growth, dysmorphic features, and neurologic and psychological development over six months and were compared with 10 age- and sex-matched controls. Complete autopsies with neuropathologic examinations were performed. The animal exposed to the high dose had neurologic, developmental, and facial anomalies similar to those seen in human fetal alcohol syndrome. One of the animals exposed to the more moderate dosage was similarly but less severely affected. The study demonstrates that a model for binge drinking and fetal alcohol syndrome can be developed in a primate. The model should be useful in exploring the mechanisms of teratogenesis and in determining the median effective dose for the production of the various anomalies seen in fetal alcohol syndrome.

Is the CSF lactate measurement useful in the management of children with suspected bacterial meningitis?

The role of the cerebrospinal fluid lactate measurement was evaluated for the management of children with suspected bacterial meningitis. Although CSF lactate can be precisely measured, it provided no additional information over that which can be obtained from a CSF cell count. Reliance on the CSF lactate concentration alone would have increased the number of children being treated unnecessarily with antibiotics. There was neither clinical nor experimental evidence to suggest that the test should be used in the early diagnosis of meningitis. In patients with equivocal clinical and CSF findings, it failed to differentiate bacterial from nonbacterial infection. The data do not support the view that the measurement of CSF lactate has significant role in the management of children with suspected meningitis.