scholarly journals THEORY AND MEASUREMENT OF VISUAL MECHANISMS

1939 ◽  
Vol 23 (1) ◽  
pp. 101-141 ◽  
Author(s):  
W. J. Crozier ◽  
A. H. Holway
Keyword(s):  
Exposure Time ◽  
White Light ◽  
Time Variability ◽  
Retinal Area ◽  
Simultaneous Excitation ◽  
Monocular Stimulation ◽  
Rectangular Area ◽  
The Mean ◽  
Simple Proportion ◽  
Stimulation Of

Measurements of ΔI as a function of retinal area illuminated have been obtained at various levels of standard intensity I1, using "white" light and light of three modal wave-lengths (λ465, 525, 680), for monocular stimulation and for simultaneous excitation of the two eyes ("binocular"), using several methods of varying (rectangular) area and retinal location, with control of exposure time. For data homogeneous with respect to method of presentation, log ΔIm = -Z log A + C, where ΔI = Ĩ2 – I1, A is area illuminated, and C is a terminal constant (= log ΔIm for A = 1 unit) depending on the units in which ΔI and A are expressed, and upon I1. The equation is readily deduced on dimensional grounds, without reference to specific theories of the nature of ΔI or of retinal area in terms of its excitable units. Z is independent of the units of I and A. Experimentally it is found to be the same for monocular and binocular excitations, as is to be expected. Also as is expected it is not independent of λ, and it is markedly influenced by the scheme according to which A is varied; it depends directly upon the rate at which potentially excitable elements are added when A is made to increase. For simultaneous excitation of the two eyes (when of very nearly equivalent excitability), ΔĪB is less than for stimulation of either eye alone, at all levels of I1, A, λ. The mean ratio (ΔĪL + ΔĪR)/2 to ΔIB was 1.38. For white light, doubling A on one retina reduces ΔIm in the ratio 1.21, or a little less than for binocular presentation under the same conditions. These facts are consistent with the view that the properties of ΔI are quantitatively determined by events central to the retina. The measure σ1ΔI of organic variation in discrimination of intensities and ΔIm are found to be in simple proportion, independent of I1, A, λ (and exposure time). Variability (σ1ΔI) is not a function of the mode of presentation, save that it may be slightly higher when both retinas are excited, and its magnitude (for a given level of ΔIm) is independent of the law according to which the adjustable intensity I2 is instrumentally controlled.

CHROMATOGRAPHY OF THE 17-KETOGENIC STEROIDS IN THE DIAGNOSIS AND CONTROL OF CONGENITAL ADRENAL HYPERPLASIA

1960 ◽  
Vol XXXIII (II) ◽  
pp. 230-250 ◽  
Author(s):  
Eileen E. Hill
Keyword(s):  
Congenital Adrenal Hyperplasia ◽  
List Type ◽  
Adrenal Hyperplasia ◽  
Normal Children ◽  
Paediatric Practice ◽  
The Mean ◽  
Cortisone Therapy ◽  
And Control ◽  
Clinical Problems ◽  
Stimulation Of

ABSTRACT A method for the fractionation of the urinary 17-ketogenic steroids with no oxygen grouping at C11 and those oxygenated at C11, is applied to the clinical problems of congenital adrenal hyperplasia. In normal children the mean ratio of the non-oxygenated to oxygenated steroids is 0.24. In childrern with congenital adrenal hyperplasia the ratio is 2.3. The reason for this difference in ratio is discussed. The changes in ratio found under stimulation of the adrenal gland with exogenous or endogenous corticotrophin and the suppression with cortisone therapy are studied. This test can be applied to isolated samples of urine, a major advantage in paediatric practice, and can be carried out in routine laboratories. It is found to be reliable in the diagnosis and sensitive in the control of congenital adrenal hyperplasia.

Deep brain stimulation of the posterior limb of the internal capsule in the treatment of central poststroke neuropathic pain of the lower limb: case series with long-term follow-up and literature review

2020 ◽  
Vol 133 (3) ◽  
pp. 830-838 ◽  
Author(s):  
Andrea Franzini ◽  
Giuseppe Messina ◽  
Vincenzo Levi ◽  
Antonio D’Ammando ◽  
Roberto Cordella ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Lower Limb ◽  
Internal Capsule ◽  
Posterior Limb ◽  
Vas Score ◽  
The Mean ◽  
Deep Brain ◽  
Stimulation Of

OBJECTIVECentral poststroke neuropathic pain is a debilitating syndrome that is often resistant to medical therapies. Surgical measures include motor cortex stimulation and deep brain stimulation (DBS), which have been used to relieve pain. The aim of this study was to retrospectively assess the safety and long-term efficacy of DBS of the posterior limb of the internal capsule for relieving central poststroke neuropathic pain and associated spasticity affecting the lower limb.METHODSClinical and surgical data were retrospectively collected and analyzed in all patients who had undergone DBS of the posterior limb of the internal capsule to address central poststroke neuropathic pain refractory to conservative measures. In addition, long-term pain intensity and level of satisfaction gained from stimulation were assessed. Pain was evaluated using the visual analog scale (VAS). Information on gait improvement was obtained from medical records, neurological examination, and interview.RESULTSFour patients have undergone the procedure since 2001. No mortality or morbidity related to the surgery was recorded. In three patients, stimulation of the posterior limb of the internal capsule resulted in long-term pain relief; in a fourth patient, the procedure failed to produce any long-lasting positive effect. Two patients obtained a reduction in spasticity and improved motor capability. Before surgery, the mean VAS score was 9 (range 8–10). In the immediate postoperative period and within 1 week after the DBS system had been turned on, the mean VAS score was significantly lower at a mean of 3 (range 0–6). After a mean follow-up of 5.88 years, the mean VAS score was still reduced at 5.5 (range 3–8). The mean percentage of long-term pain reduction was 38.13%.CONCLUSIONSThis series suggests that stimulation of the posterior limb of the internal capsule is safe and effective in treating patients with chronic neuropathic pain affecting the lower limb. The procedure may be a more targeted treatment method than motor cortex stimulation or other neuromodulation techniques in the subset of patients whose pain and spasticity are referred to the lower limbs.

Comparison of the Renin Response to Dopamine and Noradrenaline in Normal Subjects and Patients with Autonomic Insufficiency

1974 ◽  
Vol 46 (4) ◽  
pp. 481-488 ◽  
Author(s):  
C. S. Wilcox ◽  
M. J. Aminoff ◽  
A. B. Kurtz ◽  
J. D. H. Slater
Keyword(s):  
Autonomic Failure ◽  
Sodium Intake ◽  
Plasma Renin ◽  
Normal Subjects ◽  
Control Groups ◽  
Autonomic Reflexes ◽  
Fractional Increase ◽  
The Mean ◽  
Autonomic Insufficiency ◽  
Stimulation Of

1. The effect on plasma renin activity (PRA) of dopamine and noradrenaline infusions was studied in three patients with Shy—Drager syndrome, three patients with Parkinson's disease and normal autonomic reflexes, and three healthy volunteers. The patients with the Shy—Drager syndrome had functional evidence of a peripheral lesion of the sympathetic nervous system and subnormal PRA on a controlled sodium intake. 2. In all subjects catecholamines were infused step-wise for 4 min until a 30% rise in systolic blood pressure occurred. 3. In each subject, PRA fell after noradrenaline but rose after dopamine. The mean fractional increase in PRA after dopamine was no less in the Shy—Drager patients than in the control groups. 4. The results suggest, first, that stimulation of dopamine receptors can release renin, and secondly, that inadequate renin stores cannot explain the low PRA found in our patients with autonomic failure.

Thoracic Leg Control of Abdominal Extension in the Crayfish, Procambarus Clarkii

1981 ◽  
Vol 90 (1) ◽  
pp. 85-100
Author(s):  
CHARLES H. PAGE
Keyword(s):  
Procambarus Clarkii ◽  
Mean Values ◽  
Extensor Muscles ◽  
Carpal Joint ◽  
The Mean ◽  
Leg Movement ◽  
Abdominal Appendages ◽  
Thoracic And Abdominal ◽  
Abdominal Movement ◽  
Stimulation Of

Postural extensions of the abdomen of the crayfish, Procambarus clarkii, could be evoked by mechanical stimulation of a single thoracic leg. Movement of a single leg joint was sufficient to initiate an extension response. Vigorous abdominal extensions were initiated either by depression of the whole leg (WLD) or by flexion of the mero-carpal joint (MCF). Weaker extension responses were obtained by depression of the thoracic-coxal and coxo-basal joints. Similar stimulation of the chelipeds did not elicit an abdominal extension response. Single-frame analysis of motion pictures of crayfish responding to WLD or MCF stimulation of a 2nd thoracic leg showed that the responses evoked by the two different stimulus situations were nearly identical. They differed principally in the responses of the leg located contralateral to the stimulated leg. Movements of most of the cephalic, thoracic and abdominal appendages accompanied the abdominal extension response. Only the eyes remained stationary throughout the response. The mean values of the latencies for the initiation of appendage movement ranged from 125 to 204 ma; abdominal movement had a mean latency of about 220 ms. The abdominal extension reflex resulted from the activity of the tonic superficial extensor muscles. The deep phasic extensor muscles were silent during the response. The mean latencies for the initiation of superficial extensor muscle activity by WLD and MCF stimulation were 53·7 and 50·0 ms respectively.

Properties of Unitary IPSCs in Hippocampal Pyramidal Cells Originating From Different Types of Interneurons in Young Rats

1997 ◽  
Vol 77 (4) ◽  
pp. 1939-1949 ◽  
Author(s):  
Mohamed Ouardouz ◽  
Jean-Claude Lacaille
Keyword(s):  
Reversal Potential ◽  
Pyramidal Cells ◽  
Mean Amplitude ◽  
Paired Pulse ◽  
Young Rats ◽  
Different Types ◽  
The Mean ◽  
Paired Pulse Depression ◽  
Types Of Interneurons ◽  
Stimulation Of

Ouardouz, Mohamed and Jean-Claude Lacaille. Properties of unitary IPSCs in hippocampal pyramidal cells originating from different types of interneurons in young rats. J. Neurophysiol. 77: 1939–1949, 1997. Whole cell recordings were used in hippocampal slices of young rats to examine unitary inhibitory postsynaptic currents (uIPSCs) evoked in CA1 pyramidal cells at room temperature. Loose cell-attached stimulation was applied to activate single interneurons of different subtypes located in stratum oriens (OR), near stratum pyramidale (PYR), and at the border of stratum radiatum and lacunosum-moleculare (LM). uIPSCs evoked by stimulation of PYR and OR interneurons had similar onset latency, rise time, peak amplitude, and decay. In contrast, uIPSCs elicited by activation of LM interneurons were significantly smaller in amplitude and had a slower time course. The mean reversal potential of uIPSCs was −53.1 ± 2.1 (SE) mV during recordings with intracellular solution containing potassium gluconate. With the use of recording solution containing the potassium channel blocker cesium, the reversal potential of uIPSCs was not significantly different (−58.5 ± 2.6 mV), suggesting that these synaptic currents were not mediated by potassium conductances. Bath application of the γ-aminobutyric acid-A (GABAA) receptor antagonist bicuculline (25 μM) reversibly blocked uIPSCs evoked by stimulation of all interneuron subtypes. In bicuculline, the mean peak amplitude of uIPSCs recorded with potassium gluconate was reduced to 3.5 ± 4.4% of control ( n = 7). Similarly, with cesium methanesulfonate, the mean amplitude in bicuculline was 2.9 ± 3.1% of control ( n = 13). Application of the GABAB receptor antagonist CGP 55845A (5 μM) resulted in a significant and reversible increase in the mean amplitude of uIPSCs recorded with cesium-containing intracellular solution. Thus uIPSCs from all cell types appeared under tonic presynaptic inhibition by GABAB receptors. Paired stimulation of individual interneurons at 100- to 200-ms intervals did not result in paired pulse depression of uIPSCs. For individual responses, a significant negative correlation was observed between the amplitude of the first and second uIPSCs. A significant paired pulse facilitation (154.0 ± 8.0%) was observed when the first uIPSC was smaller than the mean of all first uIPSCs. A small, but not significant, paired pulse depression (90.8 ± 4.0%) was found when the first uIPSC was larger than the mean of all first uIPSCs. Our results indicate that these different subtypes of hippocampal interneurons generate Cl−-mediated GABAA uIPSCs. uIPSCs originating from different types of interneurons may have heterogeneous properties and may be subject to tonic presynaptic inhibition via heterosynaptic GABAB receptors. These results suggest a specialization of function for inhibitory interneurons and point to complex presynaptic modulation of interneuron function.

Responses of neurons in rostral ventrolateral medulla to activation of cardiac receptors in rats

2000 ◽  
Vol 279 (5) ◽  
pp. H2549-H2557 ◽  
Author(s):  
De-Pei Li ◽  
Hui-Lin Pan
Keyword(s):  
Rostral Ventrolateral Medulla ◽  
Ventrolateral Medulla ◽  
Single Unit Activity ◽  
Afferent Pathways ◽  
Sympathetic Control ◽  
Stellate Ganglia ◽  
Cervical Vagotomy ◽  
The Mean ◽  
Cardiac Receptors ◽  
Stimulation Of

Ischemic stimulation of cardiac receptors reflexly excites the cardiovascular system. However, the supraspinal mechanisms involved in this reflex are not well defined. This study examined the responses of barosensitive neurons in the rostral ventrolateral medulla (RVLM) to stimulation of cardiac receptors and the afferent pathways involved in these responses. Single-unit activity of RVLM neurons was recorded in α-chloralose-anesthetized rats. Cardiac receptors were stimulated by epicardial application of 10 μg/ml of bradykinin (BK). Barosensitive neurons were silenced by stimulation of baroreceptors. Application of BK increased the mean arterial pressure from 65.2 ± 1.9 to 89.3 ± 2.9 mmHg and excited RVLM barosensitive neurons from 6.2 ± 0.7 to 10.7 ± 0.9 impulses/s ( P < 0.05, n = 40). BK had no effect on 21 nonbarosensitive neurons. Blockade of stellate ganglia abolished the response of barosensitive neurons to BK. Cervical vagotomy significantly increased the baseline discharges of RVLM barosensitive neurons but had no effect on their responses to BK. Thus this study indicates that stimulation of cardiac receptors selectively activates RVLM barosensitive neurons through sympathetic afferent pathways. This information suggests that the RVLM barosensitive neurons are likely involved in the sympathetic control of circulation during myocardial ischemia.

scholarly journals The Bactericidal Effect of CO2 Laser on Pseudomonas aeruginosa Isolated from Wound and Burn Infections, In-Vitro

2015 ◽  
Vol 12 (3) ◽  
pp. 485-495
Author(s):  
Baghdad Science Journal
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Laser Irradiation ◽  
Virulence Factors ◽  
Co2 Laser ◽  
Exposure Time ◽  
Antibiotic Susceptibility ◽  
Bactericidal Effect ◽  
Bacteriological Diagnosis ◽  
The Mean ◽  
Power Densities

A total of 60 cotton swabs are collected from patients suffering from burn wound and surgical site infections admitted to Baghdad Teaching Hospital and Burn Specialist Hospital in Baghdad city during 9/2013 to 11/2013. All cotton swabs are cultured initially on blood agar and MacConkey agar and subjected for standard bacteriological procedures for bacteriological diagnosis. Twenty samples out of sixty are identified as Pseudomonas aeruginosa by conventional methods. The results of antibiotic susceptibility test illustrate that the antibiotics resistance rate of Pseudomonas aeruginosa isolates is as follows:100% (2020) for ceftriaxone, cefepime and carbencillin, 70% (14/20) for amikacin, 65%(13/20) for tobramycin, ceftazidim and gentamycin, 55% (11/20) for ciprofloxacin and norfloxacin, 50% (10/20) for piperacillin and impeneme, 30% (6/20) for aztreonam. All Pseudomonas aeruginosa isolates are investigated for detection of some virulence factors (haemolysin, protease, lipase enzymes, and extracellular pigments) and biofilm formation. The results of virulence factors reveal that all the isolates are haemolysin, protease, lipase enzymes and extracellular pigments producer, while 95% of the isolates are biofilm producer. Six isolates are selected to irradiation by using CO2 laser according to the results of antibiotic susceptibility and virulence factors at power densities (2000, 2500, and 3000) W/cm2 with exposure time (60 and 90) second. The results of CO2 laser irradiation illustrate that CO2 laser irradiation lead to a reduction in the mean value of the viable number CFU/ml of Pseudomonas aeruginosa isolates with the increase of the power density and exposure time. The results of the statistical analysis by using analysis of variance (ANOVA) one way and least significant differences-LSD show that there are statistical significant differences in the mean of the viable number CFU/ml between different power densities and different exposure times. After irradiation, antibiotic susceptibility and virulence factors tests of the irradiated strains are performed. The current study concludes that CO2 laser has bactericidal effect on P. aeruginosa isolates without any effect on its antibiotics susceptibility and virulence factors.

Abstract WP389: Anatomical Trajectory for Focused Ultrasound Stimulation of Fastigial Nucleus for Neuroprotection in Human Cerebral Ischemia

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Mersedeh Bahr Hosseini ◽  
Norman Spivak ◽  
Martin Monti ◽  
Alex Korb ◽  
Jeffrey L Saver
Keyword(s):  
Ischemic Stroke ◽  
Focused Ultrasound ◽  
Brain Mri ◽  
Skin Surface ◽  
Fastigial Nucleus ◽  
Neutral Position ◽  
Neck Flexion ◽  
Ultrasound Stimulation ◽  
The Mean ◽  
Stimulation Of

Introduction: In multiple animal models of ischemic stroke, cerebellar fastigial nucleus stimulation (FNS) via implanted electrode has been shown to exert strong neuroprotective and collateral enhancement effects. Translational studies of FNS have been precluded due to the invasive nature of direct electrical stimulation. Recently, low-intensity focused ultrasound pulsation (LIFUP) has been used to stimulate deep hemispheric targets. Identifying achievable anatomic trajectories for LIFUP delivery is required for human trials. Method: Sagittal brain MRI T1 from 10 patients were analyzed. Potential pathways from the suboccipital (SO) region (transducer placement site) to the roof of the 4 th ventricle (location of FN) were traced, evaluating paths both via the thinnest portion of the occipital bone (OB) and via the transforaminal window (TFW). Interindividual variations in trajectory distances (cm), thickness of the OB through which the beam passes (cm), and the projected neck flexion degree from neutral position required to achieve a TFW path were measured. Results: An achievable anatomic pathway for stimulation of the FN via LIFUP was identified in 100% of patients (Fig 1). In standard MR positioning, 90% had an available path through thin portions of the OB and 10% had a projected path through TFW. The mean distance from the skin at the SO region to the roof of 4 th ventricle/FN was 7.2 cm (± 0.64cm). The mean OB thickness traversed by the beam was 0.3cm (±0.1). The projected required neck flexion to enable a TFW in all subjects was mean 9.3° (±5°). Conclusions: The distance for the LIFUP beam to travel from skin surface to FN via a suboccipital approach is well within the LIFUP penetration depth and all individuals had an accessible trajectory via the TFW through attainable degrees of head flexion, affording minimal ultrasonic energy dispersion and maximal focality. Ultrasound stimulation of fastigial nucleus is a feasible treatment strategy in human acute ischemic stroke.

Efficacy of Widely Used Hand Disinfectants Against Human Echovirus Type 11 in China

2020 ◽  
Author(s):  
Lei Zhang ◽  
Xunmin Ji ◽  
Tuohua Peng ◽  
Chiming He ◽  
Xiaoling Zheng ◽  
...  
Keyword(s):  
Hand Hygiene ◽  
Exposure Time ◽  
Neurological Complications ◽  
Reduction Factor ◽  
Virucidal Activity ◽  
Log10 Reduction ◽  
Epidemic Season ◽  
The Mean ◽  
Echovirus Type ◽  
Significant Health

Abstract Background: In the summer of 2019 an outbreak of Nosocomial infections in a newborn nursery occurred in a Shunde hospital near Foshan, resulting in five babies deaths. Echovirus-11 was proven to be the responsible agent. Echovirus-11 infections are a significant health threat in the hospitals and occasionally cause severe neurological complications and even death in children. Although good hand hygiene is important for controlling infection, relevant data regarding the efficacy of widely used hand disinfectants against Echovirus-11 are still lacking. Aim: To investigate the virucidal activity of widely used hand disinfectants against Echovirus-11. Methods: The 13 widely used hand disinfectants from Guangdong hospitals were tested for virucidal activity against Echovirus-11 with the identification test of residual disinfectants removal and the suspension test with a 60 s exposure time based on Technical Standard For Disinfection (2002). Findings: Both Disinfectant A and Disinfectant C achieved a mean log10 reduction factor in Echovirus-11 titre of ≥ 5.00, respectively, within 60 s. Disinfectant B, Disinfectant D, Disinfectant H and Disinfectant M had an effect on Echovirus-11 in a mean log10 reduction factor of ≥ 4.00.By contrast, Disinfectant E, Disinfectant F, Disinfectant G, Disinfectant I, Disinfectant J, Disinfectant K and Disinfectant L didn't improved the mean log10 reduction factor in Echovirus-11 titre with producing a factor of ＜4 after a 60 s exposure time.Conclusions: 46.2% (6/13 products) of widely used hand disinfectants have effectiveness against Echovirus-11. In general, it is risky to rely too much on hand disinfectants. In case of epidemic season or definite enterovirus contamination, washing hands with soap and water is recommended for reducing viral contamination of enterovirus 11 in clinical practice, rather than hand hygiene with alcohol-based hand disinfectants alone.

Brain stem responses to electrical stimulation of ventral vagal gastric fibers

1989 ◽  
Vol 257 (1) ◽  
pp. G24-G29
Author(s):  
W. D. Barber ◽  
C. S. Yuan
Keyword(s):  
Electrical Stimulation ◽  
Brain Stem ◽  
Time Of Arrival ◽  
Neuronal Responses ◽  
Proximal Stomach ◽  
Afferent Fibers ◽  
Sensory Modalities ◽  
The Mean ◽  
The Brain ◽  
Stimulation Of

The brain stem neuronal responses to electrical stimulation of gastric branches of the ventral vagal trunk serving the proximal stomach were localized and evaluated in anesthetized cats. The responses were equally distributed bilaterally in the region of nucleus solitarius in the caudal brain stem. The mean latency of the response was 289 +/- 46 (SD) ms, which translated into a conduction velocity of less than 1 m/s based on the distance between the stimulating and recording electrodes. The responses consisted of single and multiple spikes that showed slight variability in the latency, indicating orthodromic activation via a synapse in approximately 98% of the responses recorded. Forty two percent of the units tested showed evidence of convergence of input from vagal afferent fibers in different branches of the ventral vagal trunk that served the proximal stomach. The resultant activity pattern of the unitary response appeared to be the product of 1) the gastric sensory input or modality conveyed by the afferent source and 2) the time of arrival and diversity of modalities served by other gastric afferents impinging on the unit. This provides a mechanism capable of responding on the basis of specific sensory modalities that dynamically reflect ongoing events monitored and conveyed by other gastric afferents in the region.

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