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At least 19 recordsLinked to original sources
PubMed1978

Slow and rapid responses to CW and pulsed microwave radiation by individual Aplysia pacemakers.

Specific absorption rates (SARs) of microwave energy that altered firing rates were determined for individual pacemaker neurons in the abdominal ganglion of Aplysia californica. A stripline apparatus provided both for artifact-free recording of transmembrane potentials and for precise determination of the rate of absorption of microwave energy. Exposure for two to three minutes at an SAR of only a few mW/g was capable of changing the firing rate of some pacemakers. Two types of responses were observed. The response that was seen in all neurons developed slowly, reaching a steady state in one to three minutes. The other response was seen in a few neurons and occurred within five seconds from the onset of irradiation. Similar responses were obtained for two microwave frequencies, 1.5 and 2.45 GHz. Pulsed radiation induced rapid changes of firing rate more readily than did CW radiation at the same SAR. A convective heating scheme was used to study the effects of temperature changes on the pacemakers' firing rates. Since all of the responses are not readily explained by general heating of the preparation, alternate mechanisms are suggested for the observed effects.

Action Potentials↗
PubMed1979

Organization of rapid responses to postural and locomotor-like perturbations of standing man.

This study has described the organization of EMG activities among the muscles of a standing subject's legs during rapid postural adjustments (95--120 ms latencies). Adjustments were elicited by the horizontal translation of both feet (causing antero-posterior sway), by the synchronous vertical displacement of both feet (causing changes in height) and by the reciprocal vertical displacement of the feet (causing changes in height) and by the reciprocal vertical displacement of the feet (causing a locomotor-like motion of the legs and lateral sway of the body). The resulting patterns of EMG activity were highly specific for each kind of displacement, and all subjects completely reorganized the pattern of activity from one form to another within the first trials, even immediately following unexpected stimulus changes. The organization of EMG activities during reciprocal vertical displacements was qualitatively quite similar to those observed during the comparable swing and stance phases of the locomotor step cycle; flexor muscles of the ankle and knee (those being shortened by the displacement) contracted in the upwardly displaced leg while extensor muscles were active in the downwardly displaced leg. This pattern was in marked contrast to the activation of lengthening muscles during synchronous vertical and antero-posterior sway displacements. Finally, electrical cutaneous stimulation of the dorsum of one foot during reciprocal vertical displacements always enhanced the EMG activity of the agonist leg muscles, in-phase with the vertical movement.

Ankle Joint↗
PubMed1976

Polyarthritis in adults with hypogammaglobulinaemia and its rapid response to immunoglobulin treatment.

Five patients with primary hypogammaglobulinaemia developed a severe polyarthritis that had some features in common with rheumatoid arthritis. Their joint disease could be distinguished from rheumatoid arthritis, however, by the dramatic improvement after gammaglobulin treatment. The arthritis of hypogammaglobulinaemia can, therefore, be included among the few potentially curable polyarthritides.

Adolescent↗
PubMed1979

A dryer for rapid response on-line expired gas measurements.

A dryer is described for use in on-line breath-by-breath gas analysis systems. The dryer continuously removes water vapor by condensation and controls the sample gas at 2 degrees C dew-point temperature or 5 Torr water vapor partial pressure. It is designed to operate at gas sampling flow rates from 0.5 to 1 1.min-1. The step-response time for the described system including a Beckman LB-2 CO2 analyzer, sampling tubing, and dryer is 120 ms at 1 l.min-1. The time required for gas samples to transport through the dryer is 105 ms at a gas sampling-flow rate of 1 l.min=1.

Desiccation↗
PubMedDate not supplied

The rapid response of ovarian and uterine veins of mice to sex hormones.

Subcutaneous injections in sesame oil of testosterone and estradiol-17 beta into ovariectomized and ovariectomized-hysterectomized young adult mice were followed in six hours or less by significant increases in the diameters of the ovarian and uterine veins as compared to the same vessels in sesame oil-injected controls. The circumflex iliac, femoral, and superior mesenteric veins and inferior vena cava failed to respond. The results demonstrate the specificity and speed of response of ovarian and uterine veins of mice and the control of the response by sex hormones.

Animals↗
PubMed1977

Sutural development: structure and its response to rapid expansion.

This fine structural study of the suture, its development, structure, and response to rapid expansion has shown that the sutural complex is best described in terms of the functional activity of two cell populations, namely, the osteocytic and fibrocytic series, which have the ability to remodel the tissues which they form. It is suggested that the previous detailed descriptions of differences in fiber orientation and vascular distribution reflect functional activity of a suture at any given time rather than immutable anatomic characteristics. Development of the suture and its rapid expansion showed many similarities in that growth during development and orthopedic expansion both separate the joint. If the initial inflammatory aspect of rapid expansion is ignored, the response of the suture is one of osteogenesis and fibrillogenesis, followed finally by remodeling. It is also suggested that sutural expansion involves injury followed by a proliferative repair phenomenon which, in other tissues, usually leads to the formation of scar tissue. However, the ability of sutural connective tissue fibroblasts to remodel ultimately leads to regeneration of the suture. Finally, programmed cell death has been shown to be an important feature in the development of the suture.

Activator Appliances↗
PubMed1975

Evaluation of the lymphocyte blastogenic response by rapid flow analysis.

The data presented show that the blastogenic response of human peripheral lymphocytes to mitogens and specific antigens can be easily evaluated with rapid flow analysis of mithramycin stained cells. The precision, reproducibility and rapidity of the method make it highly suitable to study lymphocyte response to antigens in patient populations.

Cell Division↗
PubMed1979

Counterregulatory hormonal responses to rapid glucose lowering in diabetic man.

To define whether rapid rate of fall in blood glucose stimulates counterregulatory hormonal responses in diabetic man, blood glucose in eight hyperglycemic diabetic subjects was rapidly lowered by intravenous insulin administration. Despite precipitous declines in blood glucose, plasma epinephrine and growth hormone remained virtually unchanged. In contrast, norepinephrine and cortisol increased significantly (P less than 0.025) in the face of hyperglycemia or euglycemia, while glucagon was suppressed (P less than 0.025). A transient modest fall in mean arterial pressure and a rise in pulse rate were noted. No correlation was observed between glucose disappearance rate or decrement in glucose concentration and the hormonal responses. After sham insulin administration, no change was observed in plasma epinephrine, norepinephrine, and cortisol levels. These findings suggest that rate of fall in blood glucose per se is not a primary signal for counterregulatory hormonal response. Cortisol but not growth hormone release during falling blood glucose in diabetic subjects can occur despite elevated blood glucose levels. The etiology of norepinephrine and cortisol change is unclear.

Adult↗
PubMed1979

The hypotensive response to rapid intravenous administration of hypertonic solutions in man and in the rabbit.

Transient hypotension has been observed in patients after rapid intravenous administration of mannitol, 25 per cent, in clinical doses. These studies were conducted to determine the mechanism for the hypotension, to determine dose and rate of injection response curves in rabbits, and to determine which vascular beds were most reactive. Studies in six patients showed mean decreases in blood pressure of 23 +/- 6.0 per cent (+/-SE) and in total peripheral resistance of 38 +/- 7 per cent after infusion of mannitol. Studies in 18 patients during cardiopulmonary bypass with mechanically fixed cardiac output demonstrated decreases in mean blood pressure of 30 +/- 5 to 40 +/- 3 per cent, depending on dose and rate of administration of mannitol. Patients not on bypass compensated for large decreases in total peripheral resistance by increases in cardiac output (3.6 +/- .4 at baseline to 4.4 +/- .4 l/min) during mannitol-induced hypotension with no change in heart rate. Serum osmolality increased as blood pressure decreased. Significant but clinically unimportant decreases in sodium and potassium ions, hemoglobin, pH, and base excess values were observed. Studies in 18 rabbits showed that the greater the dose or rate of injection of mannitol the greater the decrease in blood pressure. Injection of radiolabeled microspheres in rabbits demonstrated a near doubling of blood flow to skeletal muscle tissue during the hypotension. This occurred with both equiosmotic hypertonic glucose (17 +/- 3 to 32 +/- 7 per cent) and mannitol (17 +/- 1 to 31 +/- 5 per cent), but not after isotonic saline solution. Changes in blood flow to other organ beds were variable and unimportant. The results suggest that hypotension following the intravenous administration of hyperosmotic solutions is due primarily to vasodilation in skeletal muscle.

Acid-Base Equilibrium↗
PubMed1979

Syngeneic transplantation of fetal rat pancreas. III. Effect of insulin treatment on the growth and differentiation of the pancreatic implants after reversal of diabetes.

Eight 18-316 fetal pancreases were transplanted to syngeneic alloxan diabetic male rats. Some of the recipients were treated with insulin for a 7-day period immediately after transplant. By previously published clinical criteria, three groups of recipients could be identified after reversal of diabetes by the transplanted tissue: insulin-treated rapid reversal; insulin-treated slow reversal; and control (not treated with insulin). Five animals in each group were sacrificed after glucose tolerance testing for morphologic and hormonal analysis of the transplanted tissue. The insulin-,glucagon-, and somatostatin-positive islet cell masses of the fetal pancreatic implants were quantitated. There was a correlation between the beta cell mass of the implants and the glucose tolerance exhibited by the host animals. The rapid response insulin-treated recipients had significantly greater implant beta cell mass and insulin content compared with the other groups. There was no difference in implant alpha cell mass among the groups, but the insulin-treated implants had a significantly greater glucagon content. The delta cell mass of insulin-treated rapid response was less than that of the other two groups. The results are discussed in relation to previously reported morphometric analysis 15 days after transplantation. The relationships of transplanted beta cell mass, beta cell differentiation, transplant site, and cell-to-cell interactions within the transplanted islet to the control of glucose homeostasis are also discussed.

Animals↗
PubMed2024

One-pot Golden Gate Assembly of an avian infectious bronchitis virus reverse genetics system.

Avian infectious bronchitis is an acute respiratory disease of poultry of particular concern for global food security. Investigation of infectious bronchitis virus (IBV), the causative agent of avian infectious bronchitis, via reverse genetics enables deeper understanding of virus biology and a rapid response to emerging variants. Classic methods of reverse genetics for IBV can be time consuming, rely on recombination for the introduction of mutations, and, depending on the system, can be subject to genome instability and unreliable success rates. In this study, we have applied data-optimized Golden Gate Assembly design to create a rapidly executable, flexible, and faithful reverse genetics system for IBV. The IBV genome was divided into 12 fragments at high-fidelity fusion site breakpoints. All fragments were synthetically produced and propagated in E. coli plasmids, amenable to standard molecular biology techniques for DNA manipulation. The assembly can be carried out in a single reaction, with the products used directly in subsequent viral rescue steps. We demonstrate the use of this system for generation of point mutants and gene replacements. This Golden Gate Assembly-based reverse genetics system will enable rapid response to emerging variants of IBV, particularly important to vaccine development for controlling spread within poultry populations.

Infectious bronchitis virus↗
PubMed1977

Response of rapidly and slowly adapting mechanoreceptors and vibratory sensitivity in human hairy skin.

Single unit activity was recorded percutaneously with microelectrodes from 38 rapidly adapting (RA) mechanoreceptors of the dorsal surface of the hand in 49 awake human subjects. Tuning characteristics were determined for 28 RA-fibers at various frequencies between 5 and 100 cps of sinusoidal mechanical stimulation. In separate experiments human thresholds of vibration perception were studied under comparable conditions. Several RA-mechanoreceptive fibers were broadly tuned, showing no clearly defined best frequency in the range between 5 and 20 cps. Other RA-fibers had a minimum of sensitivity between 20 and 40 cps. For either lower or higher frequencies, stronger stimuli were required to elicit one nerve impulse per stimulus cycle. These RA-receptors may be related to the perception of low frequency oscillation (flutter). They cannot account for human vibration sensitivity in the higher frequency range, since tuning of the receptors required considerably higher amplitudes than perception. Sixteen slowly adapting (SA) mechanoreceptors of Type I and II showed a frequency modulation in phase with low frequency mechanical oscillations of stimulus amplitudes far below human thresholds for perception of movement.

Action Potentials↗
PubMed2024

The association between neighbourhood marginalization and SARS-CoV-2 outcomes in patients presenting to emergency departments.

OBJECTIVE: Social and economic marginalizations have been associated with inferior health outcomes in Canada. Our objective was to describe the relationship between neighbourhood marginalization and COVID-19 outcomes among patients presenting to Canadian emergency departments (ED). METHODS: We conducted an observational study among consecutive COVID-19 patients recruited from 47 hospitals participating in the Canadian COVID-19 ED Rapid Response Network (CCEDRRN) between March 3, 2020, and July 24, 2022. We linked data with the Canadian Marginalization Index (CAN-Marg). We used multivariable, multi-level logistic regression models to understand the association between dimensions of neighbourhood marginalization, and severe COVID-19 and in-hospital mortality. RESULTS: There were 55,588 eligible patients. Those from neighbourhoods with a higher proportion of recent immigrants (OR = 0.86 per unit increase [0.81, 0.92]), lower workforce participation (OR = 0.84 per unit increase [0.75, 0.94]), and more housing insecurity (OR = 0.81 per unit increase [0.77, 0.86]) were less likely to present to EDs with severe COVID-19. However, patients from materially marginalized neighbourhoods had increased odds of dying in hospital (OR = 1.19 per unit increase [95% CI 1.09, 1.30]) compared to patients from less materially marginalized neighbourhoods. Patients living in neighbourhoods with a higher proportion of recent immigrants (OR = 0.83 per unit increase [0.78, 0.91]) and lower participation in the workforce (OR = 0.77 per unit increase [0.66, 0.87]) experienced lower odds of dying. CONCLUSION: Despite no association with severe COVID-19 at ED presentation, the only marginalization domain associated with in-hospital mortality was material deprivation. Our findings present insights on ED-seeking behaviour, hospital access, and care that population studies could not.

Humans↗