scholarly journals Subcutaneous microdialysis in the awake rat.

2017 ◽  
Author(s):  
Marije Risselada ◽  
Kristen M Messenger
Keyword(s):  
Extracellular Fluid ◽  
Drug Distribution ◽  
Poloxamer 407 ◽  
Implantation Technique ◽  
Microdialysis Catheter ◽  
Functional Part ◽  
Awake Rat ◽  
The Right ◽  
Cervical Area ◽  
Placement Technique

Background. Microdialysis is a valued method to study the pharmacokinetics of drug distribution from an injection site or to a tumor site. The objective of this study was to assess the feasibility of prolonged use of subcutaneously implanted microdialysis catheters to assess local retention and systemic uptake of carboplatin in rats post anesthetic recovery. Methods. Twelve rats were used: one control rat and 11 treatment rats. The control rat was used to outline the surgical implantation technique of the microdialysis catheter. Treatment rats were administered 5mg carboplatin in poloxamer 407 and divided in two treatment cohorts. Microdialysis catheters were used in both cohorts to collect extracellular fluid. Placement technique was modified between the two cohorts. Treatment cohort 1 (n=6) had the microdialysis catheter implanted in the wound bed, sutured in place and tunneled subcutaneously along the dorsum to exit dorsally in the cervical area. The ends were secured to a Velcro strip sutured to the dorsal cervical skin to avoid trauma by the rat. Treatment cohort 2 (n=5) had the catheter looped around the right hind limb, with the functional part sutured in place in the wound bed, and tunneled through a subcutaneously implanted sterile intravenous line exiting dorsally in the cervical area. The ends were maintained within the IV line and held in place with wound clips. Results. All 11 microdialysis catheters in the treatment cohorts were functional immediately after implantation, but only one out of 11 microdialysis catheters in the treatment cohorts was functional at 24hrs, and none at 48hrs. Discussion. The results of this study suggest that microdialysis catheters cannot be maintained in unanesthetized rats without further modification of the implantation protocol.

scholarly journals Subcutaneous microdialysis in the awake rat.

2017 ◽  
Author(s):  
Marije Risselada ◽  
Kristen M Messenger
Keyword(s):  
Extracellular Fluid ◽  
Drug Distribution ◽  
Poloxamer 407 ◽  
Implantation Technique ◽  
Microdialysis Catheter ◽  
Functional Part ◽  
Awake Rat ◽  
The Right ◽  
Cervical Area ◽  
Placement Technique

Background. Microdialysis is a valued method to study the pharmacokinetics of drug distribution from an injection site or to a tumor site. The objective of this study was to assess the feasibility of prolonged use of subcutaneously implanted microdialysis catheters to assess local retention and systemic uptake of carboplatin in rats post anesthetic recovery. Methods. Twelve rats were used: one control rat and 11 treatment rats. The control rat was used to outline the surgical implantation technique of the microdialysis catheter. Treatment rats were administered 5mg carboplatin in poloxamer 407 and divided in two treatment cohorts. Microdialysis catheters were used in both cohorts to collect extracellular fluid. Placement technique was modified between the two cohorts. Treatment cohort 1 (n=6) had the microdialysis catheter implanted in the wound bed, sutured in place and tunneled subcutaneously along the dorsum to exit dorsally in the cervical area. The ends were secured to a Velcro strip sutured to the dorsal cervical skin to avoid trauma by the rat. Treatment cohort 2 (n=5) had the catheter looped around the right hind limb, with the functional part sutured in place in the wound bed, and tunneled through a subcutaneously implanted sterile intravenous line exiting dorsally in the cervical area. The ends were maintained within the IV line and held in place with wound clips. Results. All 11 microdialysis catheters in the treatment cohorts were functional immediately after implantation, but only one out of 11 microdialysis catheters in the treatment cohorts was functional at 24hrs, and none at 48hrs. Discussion. The results of this study suggest that microdialysis catheters cannot be maintained in unanesthetized rats without further modification of the implantation protocol.

scholarly journals Standardized fluoroscopy-guided implantation technique enables optimal electrode placement in sacral neuromodulation: a cadaver study

2020 ◽  
Author(s):  
C. Müller ◽  
L. F. Reissig ◽  
S. Argeny ◽  
W. J. Weninger ◽  
S. Riss
Keyword(s):  
Sacral Neuromodulation ◽  
Close Contact ◽  
Treatment Success ◽  
Cadaver Study ◽  
Electrode Placement ◽  
Implantation Technique ◽  
The Third ◽  
Median Distance ◽  
Significant Difference ◽  
The Right

Abstract Background Sacral neuromodulation (SNM) is an established treatment option for patients with faecal incontinence. The location of the stimulating electrode is considered to be essential for treatment success. The purpose of this study was to evaluate the position of SNM electrodes after using a standardized fluoroscopy-guided implantation technique. Methods For this cadaver study, SNM electrodes were implanted bilaterally in 5 lower body specimens. The lower edge of the sacroiliac joint and the medial edge of the sacral foramina were marked using fluoroscopy to draw an ‘H’ with the crossing points identifying S3. After electrode placement the pelvis was dissected to describe the exact position of the SNM electrodes. Results The electrodes were inserted at an angle with a median degree measure of 60° (range 50–65°) to the skin, with a median distance of 9 mm (range 0–13 mm) from the S3 marking. All electrodes entered the third sacral foramen. The median distance of the electrodes to the sacral nerve was 0 mm (range 0–3 mm) for the most proximal, 0.5 mm (range 0–5 mm) for the second, 2.25 mm (range 0–11 mm) for the third and 1.75 mm (range 0–16 mm) for the most distant electrode. There was neither a significant difference in the proximity of the electrodes to the nerve between the right and left side (proximal to distal electrode: p = 0.18, p = 0.16, p = 0.07, p = 0.07) nor between male and female cadavers (p = 0.25, p = 0.21, p = 0.66, p = 0.66). Conclusions A standardized fluoroscopy-guided implantation technique enables a close contact between electrode and nerve. This can potentially result in an improved clinical outcome.

Sternotomy Sparing Thoratec Heartmate 3 Implantation via Bilateral Minithoracotomy

2018 ◽  
Vol 13 (1) ◽  
pp. 74-76 ◽  
Author(s):  
Julia Riebandt ◽  
Dominik Wiedemann ◽  
Guenther Laufer ◽  
Daniel Zimpfer
Keyword(s):  
Left Ventricular ◽  
Ascending Aorta ◽  
Intercostal Space ◽  
Implantation Technique ◽  
Thromboembolic Complications ◽  
Short Term ◽  
Short Term Mortality ◽  
Transplant Candidates ◽  
The Right ◽  
Outflow Graft

A novel sternotomy sparing implantation technique for the Thoratec HeartMate 3 is described. Cannulation of the left ventricular apex is performed via a minithoracotomy in the left fourth or fifth intercostal space. The outflow graft is advanced through the pericardium to a second minithoracotomy in the right second intercostal space and then anastomosed to the ascending aorta. This approach was performed in three patients so far with no need for conversion. We did not observe any perioperative adverse events, such as bleeding or thromboembolic complications, as well as no short-term mortality. This technique is especially appealing in multimorbid and frail patients, future transplant candidates, and patients with impaired right ventricular function.

scholarly journals Why are mini-implants lost: The value of the implantation technique!

2015 ◽  
Vol 20 (1) ◽  
pp. 23-29 ◽  
Author(s):  
Fabio Lourenço Romano ◽  
Alberto Consolaro
Keyword(s):  
Orthodontic Treatment ◽  
Alveolar Bone ◽  
Implantation Technique ◽  
Success Rates ◽  
Mini Implants ◽  
Scientific Curiosity ◽  
Implant Placement ◽  
Treatment Demand ◽  
Implant Size ◽  
Placement Technique

The use of mini-implants have made a major contribution to orthodontic treatment. Demand has aroused scientific curiosity about implant placement procedures and techniques. However, the reasons for instability have not yet been made totally clear. The aim of this article is to establish a relationship between implant placement technique and mini-implant success rates by means of examining the following hypotheses: 1) Sites of poor alveolar bone and little space between roots lead to inadequate implant placement; 2) Different sites require mini-implants of different sizes! Implant size should respect alveolar bone diameter; 3) Properly determining mini-implant placement site provides ease for implant placement and contributes to stability; 4) The more precise the lancing procedures, the better the implant placement technique; 5) Self-drilling does not mean higher pressures; 6) Knowing where implant placement should end decreases the risk of complications and mini-implant loss.

Manufacturability Analysis of Flatness Tolerances in Solid Freeform Fabrication

1999 ◽  
Vol 123 (1) ◽  
pp. 148-156 ◽  
Author(s):  
Ramakrishna Arni ◽  
S. K. Gupta
Keyword(s):  
Systematic Approach ◽  
Solid Freeform Fabrication ◽  
Freeform Fabrication ◽  
Geometric Tolerances ◽  
Design Tolerance ◽  
Functional Part ◽  
Low Volume ◽  
The Right ◽  
The Given ◽  
Manufacturing Problems

Increasingly, Solid Freeform Fabrication (SFF) processes are being considered for creating functional parts. In such applications, SFF can either be used for creating tooling (i.e., patterns for casting, low volume molds, etc.) or directly creating the functional part itself. In order to create defect free functional parts, it is extremely important to fabricate the parts within allowable dimensional and geometric tolerances. This paper describes a systematic approach to analyzing manufacturability of parts produced using SFF processes with flatness tolerance requirements on the planar faces of the part. Our research is expected to help SFF designers and process providers in the following ways. By evaluating design tolerances against a given process capability, it will help designers in eliminating manufacturing problems and selecting the right SFF process for the given design. It will help process providers in selecting a build direction that can meet all design tolerance requirements.

scholarly journals Unusual Pharyngo-Esophageal Dysphagia Caused by a High-Riding Right Brachiocephalic Artery

2021 ◽  
Vol 45 (1) ◽  
pp. 79-82
Author(s):  
Ki Hoon Park ◽  
Sora Baek ◽  
Eun Kyoung Kang
Keyword(s):  
Filling Defect ◽  
Neck Mass ◽  
Solid Food ◽  
Brachiocephalic Artery ◽  
Food Bolus ◽  
Videofluoroscopic Swallowing Study ◽  
Esophageal Dysphagia ◽  
Left Neck ◽  
The Right ◽  
Cervical Area

High-riding right brachiocephalic and subclavian arteries are often asymptomatic and rare vascular variations. We present a patient with high-riding right brachiocephalic and subclavian arteries that caused compressive pharyngeal and cervical esophageal dysphagia. An 82-year-old woman presented to our hospital with dysphagia that worsened with solid food. A pulsatile lump was observed on the right neck side. A videofluoroscopic swallowing study showed a deviated food bolus movement anterolaterally from the normal vertical pharyngoesophageal transition, with a filling defect in the lower pharynx through the upper esophagus. Neck computed tomography (CT) showed high-riding right brachiocephalic and subclavian arteries and a tortuous right common carotid artery located adjacent to the trachea in the cervical area. The cervical midline structures were deviated to the left neck side. A neck mass with vascular variation should be considered as a cause of dysphagia that worsens with solid food; CT should be considered to determine its cause.

scholarly journals Modeling the Effect of Binding Kinetics in Spatial Drug Distribution in the Brain

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Nelson Kashaju ◽  
Mark Kimathi ◽  
Verdiana G. Masanja
Keyword(s):  
Specific Binding ◽  
Extracellular Fluid ◽  
Drug Distribution ◽  
Drug Binding ◽  
Binding Kinetics ◽  
Binding Parameter ◽  
Specific Binding Sites ◽  
Distribution Process ◽  
Parameter Values ◽  
The Brain

A 3-dimensional mathematical model is developed to determine the effect of drug binding kinetics on the spatial distribution of a drug within the brain. The key components, namely, transport across the blood-brain barrier (BBB), drug distribution in the brain extracellular fluid (ECF), and drug binding kinetics are coupled with the bidirectional bulk flow of the brain ECF to enhance the visualization of drug concentration in the brain. The model is developed based on the cubical volume of a brain unit, which is a union of three subdomains: the brain ECF, the BBB, and the blood plasma. The model is a set of partial differential equations and the associated initial and boundary conditions through which the drug distribution process in the mentioned subdomains is described. Effects of drug binding kinetics are investigated by varying the binding parameter values for both nonspecific and specific binding sites. All variations of binding parameter values are discussed, and the results show the improved visualization of the effect of binding kinetics in the drug distribution within the brain. For more realistic visualization, we suggest incorporating more brain components that make up the large volume of the brain tissue.

Abstract 650: Animal Study Results Support that Biometal Artificial Muscle Restores Atrial Kick and Could Replace Oral Anticoagulation in Permanent Atrial Fibrillation

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Piergiorgio Tozzi ◽  
Daniel Hayoz ◽  
Francois Salchli ◽  
Ludwig K von Segesser
Keyword(s):  
Atrial Fibrillation ◽  
Thrombus Formation ◽  
Anticoagulation Therapy ◽  
Control Unit ◽  
Artificial Muscle ◽  
Persistent Atrial Fibrillation ◽  
Implantation Technique ◽  
Spontaneous Echo Contrast ◽  
Study Results ◽  
The Right

Treatment of persistent atrial fibrillation (AF) consists of ventricular rhythm control and the use of anticoagulant agents to decrease the high risk of stroke. However, patients under lifetime anticoagulation therapy are exposed to hemorrhagic stroke (1–3% patients/year). The best treatment to prevent stroke may induce stroke itself. Because decreased flow within the fibrillating atrium is associated with spontaneous echo contrast, thrombus formation and embolic events, any device able to restore the atrial kick (AK) should significantly reduce the risk of stroke and eventually improve cardiac output (CO). A motorless, volume displacement pump based on artificial muscle technology could reproduce the AK when placed onto a fibrillating atrium. This study has been designed to assess mechanical effects of this pump on the right cavities in an animal model of AF. Atripump (Nanopowers SA, Switzerland) is a dome shape silicone coated biometal actuator 5 × 45mm. The biometal is electrically actuated by a pacemaker like control unit. In 10 sheep the right atrium (RA) was surgically exposed and the dome sutured onto it. AF was induced with rapid epicardial pacing (600 beats/min). RA ejection fraction (EF) and spontaneous echo contrast was assessed with intracardiac ultrasound in baseline, AF and assisted AF status. A flow meter placed on pulmonary artery measured CO. Results The dome’s contraction rate was 60/min. Mean temperature on the RA was 39±1.5 °C. RA EF was 30% in baseline, 5% in AF and 22% in assisted AF conditions. During the AF state, spontaneous echo contrast was present in all animals and in 2 a thrombus appeared in the right appendix. Neither spontaneous echo contrast nor thrombi were present in baseline and AF assisted status. Thrombi were washed out when the pump was turned on. CO was 5.3±0.3 l/min in baseline, 4.4±0.6 l/min in AF and 5.1±0.3 l/min in assisted AF status (p<0.01). Placed on the right side, the artificial muscle restores the AK, improves CO and shows a mechanical anti coagulant effect. In patients with permanent AF, if implanted on both sides, it would improve CO and prevent embolism of cardiac origin. The implantation technique could be comparable to that of a pacemaker.

scholarly journals Certain Forms of Matrix Metalloproteinase-9 Accumulate in the Extracellular Space after Microdialysis Probe Implantation and Middle Cerebral Artery Occlusion/Reperfusion

2002 ◽  
Vol 22 (8) ◽  
pp. 918-925 ◽  
Author(s):  
Anna M. Planas ◽  
Carles Justicia ◽  
Sònia Solé ◽  
Bibiana Friguls ◽  
Álvaro Cervera ◽  
...  
Keyword(s):  
Western Blot ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Blot Analysis ◽  
Extracellular Space ◽  
Western Blot Analysis ◽  
Extracellular Fluid ◽  
Microdialysis Probe ◽  
The Right ◽  
The Brain

Matrix metalloproteinases (MMPs) are activated in focal cerebral ischemia. The activation of MMP-9 is involved in blood—brain barrier breakdown and tissue remodeling. The MMPs are released to the extracellular space, but the form and fate of secreted enzymes in brain are unknown. Using microdialysis in vivo, the authors studied whether ischemia-induced MMP-9 in brain tissue was related to free MMP-9 in the extracellular fluid. A microdialysis probe was placed into the right striatum and microdialysis was initiated 24 hours later in controls (n = 7). One hour prior to microdialysis, a group of rats (n = 7) was subjected to 1-hour occlusion of the right middle cerebral artery, followed by reperfusion. Dialysates were collected at discrete time points up to 24 hours, and subjected to zymography and Western blot analysis. The MMP-9 was released after ischemia and accumulated in the extracellular space at 24 hours ( P < 0.05). Free MMP-9 forms include mainly the 95-kd proform, and, to a lesser extent, dimers and cleaved active forms (70 kd), but not the 88-kd form found in tissue. Probe implantation and microdialysis increased free MMP-9 in the dialysate. This increase was concomitant with neutrophil infiltration after the mechanical lesion, as myeloperoxidase was found by means of Western blot analysis in the brain hemisphere subjected to microdialysis ( P < 0.005), and immunohistochemistry revealed the presence of myeloperoxidase stain surrounding the site of probe implantation. The results suggest that certain forms of MMP-9 are released and accumulate in the extracellular space after brain injury, and that vascular alterations and neutrophil recruitment elicit MMP-9 activation in the brain after focal ischemia and trauma.

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