Archive for category Animal Models

Abstract

Objective:

The main objective of the study was to explore the effect of Activator manipulation in OVX rats.

Methods:

Animals
The protocol, using a limited number of female Sprague-Dawley rats (6 months of age) (Charles Rivers International, Barcelona, Spain) undergoing either shamoperation (Sh) (n=10) or ovariectomy (OVX) (n=15), was approved by the Institutional Animal Care and Use Committee at the IIS-Fundación Jiménez Díaz, according to the European Union guidelines for decreasing animal pain. We complied with the 3R (‘‘replace, reduce, and refine”) experimental design recommendation aimed to reduce the number of experimental animals [21]. Rats were placed in cages under standard conditions (room temperature 20 ± 0.5ºC, relative humidity 55 ± 5% and illumination with a 12 h/12 h light/dark photoperiod), given food and water ad libitum and allowed to move without restriction.

Animal procedures
Both Sh and OVX rats were weighed and divided in two groups, respectively: not manipulated (NM) animals or those manipulated (M) using the setting 1 of the Activator V Adjusting Instrument® (Activator Methods International, Phoenix, AZ) with preload of 3.705 pounds/inch spring rate, applied onto the tibial tubercle at a 90º angle from medial to lateral side [22]. In rats of the M group (Sh =5, OVX=10), right hind limbs were adjusted with true chiropractic manipulation (TM), whereas corresponding left hind limbs were subjected to false chiropractic manipulation (FM) by firing the Activator V in the air and gently touching the tibial tubercle. These procedures were repeated 3 times/week for 6 weeks, starting once bone loss was confirmed in OVX rats (10 weeks after OVX). At the end of treatments, bone mass was determined in anesthetized (ketamine/xilacine) rats. Thereafter, animals were sacrificed by isoflurane inhalation, followed by removal of the long bones, spine and muscles (quadriceps femoris, soleus, tibialis anterior and tibialis posterior) for analysis as described below

Results:

Chiropractic manipulation improves OVX-related bone loss in rats
Although total body weight was higher in OVX rats than in Sh animals (456 ± 12 g vs 351 ± 8 g, respectively; p<0.01), bone loss occurred in the former rats as confirmed by DXA. In the long bones and vertebrae of NM-OVX rats (similar to that in FM-OVX rats when appropriate), bone mass parameters were lower than those in Sh animals (Table 1a). ActivatorV® adjustment in the tibial tubercle of the right hind limbs produced higher BMD and BMC in both the distal femur and the proximal tibia of OVX rats (TM group), even though not reaching the corresponding values in Sh rats (Table 1b). In contrast, BMD and BMC values in the proximal femur or L3-L4 vertebrae (axial bone subjected to physiological mechanical loading) were similar in both manipulated and not manipulated groups of OVX rats (Tables 2 and 3). BMD and BMC values were similar in both the long bones and vertebrae among all experimental groups of Sh rats

Chiropractic manipulation compensates in part trabecular bone alterations induced by OVX in rats
Next, we aimed to confirm whether the aforementioned improvement of bone mass was related to parallel changes in bone structure elicited by the chiropractic manipulation in OVX rats. Using CT, we evaluated several trabecular and cortical bone parameters in the long bones of the different groups of rats studied. Consistent with the observed bone mass loss in OVX rats, BV/TV and Tb.N were found to be lower, and Tb.S higher, in trabecular bone of the distal femur and the proximal tibia in both NM-OVX and FM-OVX groups of rats, compared to those in NM-Sh rats (Tables 4 and 5). It is worth noting that the TM-OVX group showed a significant improvement of these bone structure parameters (BV/TV, Tb.N and Tb.S) at both skeletal locations (Table 5). In contrast, we failed to detect any significant change in the cortical bone parameters tested (Ct. Th and M.Ar) in OVX rats, subjected or not to chiropractic manipulation (Table 5).

Chiropractic manipulation counteracts the low muscle MGF protein expression in OVX rats
We also evaluated whether chiropractic stimulus produced by the Activator V® would affect MGF production in rat skeletal muscles, related to the observed bone alterations in OVX rats. A lower MGF protein expression was observed in the quadriceps femoris, and in the tibialis anterior and posterior, but not in the soleus in NM-OVX rats in comparison to the NM-Sh group (Fig.1). This difference was counteracted by chiropractic manipulation (TM-OVX group) in both the quadriceps femoris and tibialis anterior (Fig.1). In view of these results, we decided to confirm whether TM on the right hind limbs of OVX rats could affect the FM on the contralateral hind limbs of these rats. Thus, we compared the expression of MGF in quadriceps femoris and tibialis anterior between both hind limbs in both Sh and OVX rats. We failed to observe any significant alteration in this protein expression between the left and the corresponding right muscles in both NM-Sh and NM-OVX groups, although these values of the latter group were lower than those of the former group (Fig. 2). Moreover, these values were similar in both NM-OVX and FM-OVX rats. On the other hand, higher levels of MGF protein occurred in these muscles of TM-OVX rats, compared to FM-OVX rats, confirming the local action of Activator V® (Fig.2)

Chiropractic manipulation interferes with the elevated MGF expression in the long bones of OVX rats
Considering the observed variations in MGF protein expression in the rat skeletal muscle, we proceeded to assess the possible MGF alterations which might have occurred in the rat long bones associated with Activator V® manipulation in OVX rats. We focused on osteocytes, which express MGF and are the most abundant cells in the cortical bone matrix. In both femur and tibia, MGF immunostaining in these cells was increased in OVX rats, compared to that in the NM-Sh group, but this increase was abrogated by chiropractic manipulation in these rats (Fig. 3).

Conclusion:

In conclusion, even considering the limitations of the present pre-clinical study as stated above in the Discussion, the present findings support the notion that chiropractic manipulation can improve osteoporotic bone at least in part by targeting skeletal muscle. This experimental study provides novel scientific data that open new avenues to supporting the application of chiropractic manipulation in bone loss-related situations.


Author information: A. López-Herradón, R. Fujikawa, M. Gómez-Marín, J. P. Stedile-Lovatel, F. Mulero, J. A. Ardura, P. Ruiz, I. Muñoz, P. Esbrit, I. Mahíllo-Fernández, A. Ortega-de Mues. Madrid College of Chiropractic; Madrid, Spain.

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Abstract

Objective:

The purpose of this preliminary study is to determine muscle spindle response characteristics related to the use of 2 solenoid powered clinical mechanically assisted manipulation (MAM) devices.

Methods:

L6 muscle spindle afferents with receptive fields in paraspinal muscles were isolated in 6 cats. Neural recordings were made during L7 MAMthrusts using the Activator V (Activator Methods Int. Ltd., Phoenix, AZ) and/or Pulstar (Sense Technology Inc., Pittsburgh, PA) devices at their 3 lowest force settings. Mechanically assisted manipulation response measures included (a) the time required post-thrust until the first action potential, (b) differences in mean frequency (MF) and mean instantaneous frequency (MIF) 2 seconds before and after MAM, and (c) the time required for muscle spindle discharge (MF and MIF) to return to 95% of baseline after MAM.

Results:

Depending on device setting, between 44% to 80% (Pulstar) and 11% to 63% (Activator V) of spindle afferents required N6 seconds to return to within 95% of baseline MF values; whereas 66% to 89% (Pulstar) and 75% to 100% (Activator V) of spindle responses returned to within 95% of baseline MIF in b6 seconds after MAM. Nonparametric comparisons between the 22N and 44N settings of the Pulstar yielded significant differences for the time required to return to baseline MF and MIF.

Conclusion:

Short duration (b10 ms) MAM thrusts decrease muscle spindle discharge with a majority of afferents requiring prolonged periods (N6 seconds) to return to baseline MF activity. Physiological consequences and clinical relevance of described MAM mechanoreceptor responses will require additional investigation.


Author information: William R. Reed, DC, PhD, Joel G. Pickar, DC, PhD, Randall S. Sozio, BS, LATG, Michael A.K. Liebschner, PhD,  Joshua W. Little, DC, PhD, and Maruti R. Gudavalli, PhD. Palmer Center for Chiropractic Research, Palmer College of Chiropractic, Davenport, IA.

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Abstract STUDY DESIGN: Comparative study using robotic replication of spinal manipulative therapy (SMT) vertebral kinematics together with serial dissection. OBJECTIVE: The aim of this study was to quantify loads created in cadaveric spinal tissues arising from three different forms of SMT application. SUMMARY OF BACKGROUND DATA: There exist many distinct methods by which to apply […]

Abstract

STUDY DESIGN:

Comparative study using robotic replication of spinal manipulative therapy (SMT) vertebral kinematics together with serial dissection.

OBJECTIVE:

The aim of this study was to quantify loads created in cadaveric spinal tissues arising from three different forms of SMT application.

SUMMARY OF BACKGROUND DATA:

There exist many distinct methods by which to apply SMT. It is not known presently whether different forms of SMT application have different effects on spinal tissues. Should the method of SMT application modulate spinal tissue loading, quantifying this relation may help explain the varied outcomes of SMT in terms of effect and safety.

METHODS:

SMT was applied to the third lumbar vertebra in 12 porcine cadavers using three SMT techniques: a clinical device that applies forces through a hand-held instrument (INST), a manual technique of applying SMT clinically (MAN) and a research device that applies parameters of manual SMT through a servo-controlled linear actuator motor (SERVO). The resulting kinematics from each SMT application were tracked optically via indwelling bone pins. The L3/L4 segment was then removed, mounted in a parallel robot and the resulting kinematics from SMT replayed for each SMT application technique. Serial dissection of spinal structures was conducted to quantify loading characteristics of discrete spinal tissues.

RESULTS:

In terms of load magnitude, SMT application with MAN and SERVO created greater forces than INST in all conditions (P < 0.05). Additionally, MAN and SERVO created comparable posterior forces in the intact specimen, but MAN created greater posterior forces on IVD structures compared to SERVO (P < 0.05).

CONCLUSION:

Specific methods of SMT application create unique vertebral loading characteristics, which may help explain the varied outcomes of SMT in terms of effect and safety.


Spine (Phila Pa 1976). 2017 May 1;42(9):635-643. PMID: 28146021 

Author information: Funabashi M, Nougarou F, Descarreaux M, Prasad N, Kawchuk GN. University of Alberta, Edmonton, AB, Canada.


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Abstract

OBJECTIVES:

The purpose of this study was to investigate roles of the anti-inflammatory cytokine interleukin (IL) 10 and the proinflammatory cytokines IL-1β and tumor necrosis factor α (TNF-α) in spinal manipulation-induced analgesic effects of neuropathic and postoperative pain.

METHODS:

Neuropathic and postoperative pain were mimicked by chronic compression of dorsal root ganglion (DRG) (CCD) and decompression (de-CCD) in adult, male, Sprague-Dawley rats. Behavioral pain after CCD and de-CCD was determined by the increased thermal and mechanical hypersensitivity of the affected hindpaw. Hematoxylin and eosin staining, whole-cell patch clamp electrophysiological recordings, immunohistochemistry, and enzyme-linked immunosorbent assay were used to examine the neural inflammation, neural excitability, and expression of c-Fos and PKC as well as levels of IL-1β, TNF-α, and IL-10 in blood plasma, DRG, or the spinal cord. We used the activator adjusting instrument, a chiropractic spinal manipulative therapy tool, to deliver force to the spinous processes of L5 and L6.

RESULTS:

After CCD and de-CCD treatments, the animals exhibited behavioral and neurochemical signs of neuropathic pain manifested as mechanical allodynia and thermal hyperalgesia, DRG inflammation, DRG neuron hyperexcitability, induction of c-Fos, and the increased expression of PKCγ in the spinal cord as well as increased level of IL-1β and TNF-α in DRG and the spinal cord. Repetitive Activator-assisted spinal manipulative therapy significantly reduced simulated neuropathic and postoperative pain, inhibited or reversed the neurochemical alterations, and increased the anti-inflammatory IL-10 in the spinal cord.

CONCLUSION:

These findings show that spinal manipulation may activate the endogenous anti-inflammatory cytokine IL-10 in the spinal cord and thus has the potential to alleviate neuropathic and postoperative pain.


J Manipulative Physiol Ther. 2016 Jan;39(1):42-53. [PMID:26837229]

Author information: Song XJ, Huang ZJ, Song WB, Song XS, Fuhr AF, Rosner AL, Ndtan H, Rupert R5. Parker University, Parker Research Institute, Dallas, TX.


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Abstract

Introduction:

Mechanoreceptor stimulation is theorized to contribute to the therapeutic efficacy of spinal manipulation. Use of mechanically-assisted spinal manipulation (MA-SM) devices is increasing among manual therapy clinicians worldwide. The purpose of this pilot study is to determine the feasibility of recording in vivo muscle spindle responses during a MA-SM in an intervertebral fixated animal model.

Methods:

Intervertebral fixation was created by inserting facet screws through the left L5-6 and L6-7facet joints of a cat spine. Three L6 muscle spindle afferents with receptive fields in back muscles were isolated. Recordings were made during MA-SM thrusts delivered to the L7 spinous process using an instrumented Activator IV clinical device.

Results:

Nine MA-SM thrusts were delivered with peak forces ranging from 68-122N and with thrust durations of less than 5ms. High frequency muscle spindle discharge occurred during MA-SM. Following the MA-SM, muscle spindle responses included returning to pre-manipulation levels, slightly decreasing for a short window of time, and greatly decreasing for more than 40s.

Conclusion:

This study demonstrates that recording in vivo muscle spindle response using clinical MA-SM devices in an animal model is feasible. Extremely short duration MA-SM thrusts (<5ms) can have an immediate and/or a prolonged (> 40s) effect on muscle spindle discharge. Greater peak forces during MA-SM thrusts may not necessarily yield greater muscle spindle responses. Determining peripheral response during and following spinal manipulation may be an important step in optimizing its’ clinical efficacy. Future studies may investigate the effect of thrust dosage and magnitude.


J Nov Physiother Phys Rehabil 2015 Apr;2(3): 047-054.

Author information: Reed WR, Liebschner MAK, Sozio RS, Pickar JG, Gudavalli MR. Palmer Center for Chiropractic Research, Davenport, IA, USA.


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Abstract

OBJECTIVE:

The purpose of this study was to determine how the preload that precedes a high-velocity, low-amplitude spinal manipulation (HVLA-SM) affects muscle spindle input from lumbar paraspinal muscles both during and after the HVLA-SM.

METHODS:

Primary afferent activity from muscle spindles in lumbar paraspinal muscles were recorded from the L6 dorsal root in anesthetized cats. High-velocity, low-amplitude spinal manipulation of the L6 vertebra was preceded either by no preload or systematic changes in the preload magnitude, duration, and the presence or absence of a downward incisural point. Immediate effects of preload on muscle spindle responses to the HVLA-SM were determined by comparing mean instantaneous discharge frequencies (MIF) during the HVLA-SM’s thrust phase with baseline. Longer lasting effects of preload on spindle responses to the HVLA-SM were determined by comparing MIF during slow ramp and hold movement of the L6 vertebra before and after the HVLA-SM.

RESULTS:

The smaller compared with the larger preload magnitude and the longer compared with the shorter preload duration significantly increased (P = .02 and P = .04, respectively) muscle spindle responses during the HVLA-SM thrust. The absence of preload had the greatest effect on the change in MIF. Interactions between preload magnitude, duration, and downward incisural point often produced statistically significant but arguably physiologically modest changes in the passive signaling properties of the muscle spindle after the manipulation.

CONCLUSION:

Because preload parameters in this animal model were shown to affect neural responses to an HVLA-SM, preload characteristics should be taken into consideration when judging this intervention’s therapeutic benefit in both clinical efficacy studies and in clinical practice.


J Manipulative Physiol Ther. 2014 Feb;37(2):68-78. [PMID:24387888]

Author information: Reed WR, Long CR, Kawchuk GN, Pickar JG.  Palmer Center for Chiropractic Research, Palmer College of Chiropractic, Davenport, Iowa.


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Abstract

OBJECTIVE:

Mechanical characteristics of high-velocity, low-amplitude spinal manipulations (HVLA-SMs) can vary. Sustained changes in peripheral neuronal signaling due to altered load transmission to a sensory receptor’s local mechanical environment are often considered a mechanism contributing to the therapeutic effects of spinal manipulation. The purpose of this study was to determine whether variation in an HVLA-SM’s thrust amplitude and duration alters the neural responsiveness of lumbar muscle spindles to either vertebral movement or position.

METHODS:

Anesthetized cats (n = 112) received L6 HVLA-SMs delivered to the spinous process. Cats were divided into 6 cohorts depending upon the peak thrust force (25%, 55%, 85% body weight) or thrust displacement (1, 2, 3 mm) they received. Cats in each cohort received 8 thrust durations (0-250 milliseconds). Afferent discharge from 112 spindles was recorded in response to ramp and hold vertebral movement before and after the manipulation. Changes in mean instantaneous frequency (∆MIF) during the baseline period preceding the ramps (∆MIFresting), during ramp movement (∆MIFmovement), and with the vertebra held in the new position (∆MIFposition) were compared.

RESULTS:

Thrust duration had a small but statistically significant effect on ∆MIFresting at all 6 thrust amplitudes compared with control (0-millisecond thrust duration). The lowest amplitude thrust displacement (1 mm) increased ∆MIFresting at all thrust durations. For all the other thrust displacements and forces, the direction of change in ∆MIFresting was not consistent, and the pattern of change was not systematically related to thrust duration. Regardless of thrust force, displacement, or duration, ∆MIFmovement and ∆MIFposition were not significantly different from control.

CONCLUSION:

Relatively low-amplitude thrust displacements applied during an HVLA-SM produced sustained increases in the resting discharge of paraspinal muscle spindles regardless of the duration over which the thrust was applied. However, regardless of the HVLA-SM’s thrust amplitude or duration, the responsiveness of paraspinal muscle spindles to vertebral movement and to a new vertebral position was not affected.


J Manipulative Physiol Ther. 2013 Feb;36(2):68-77. [PMID:23499141]

Author information: Cao DY, Reed WR, Long CR, Kawchuk GN, Pickar JG. Palmer Center for Chiropractic Research, Davenport, IA 52803, USA.


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Abstract

OBJECTIVE:

The purpose of this study was to evaluate the mechanical allodynia in animals after immobilization and chiropractic manipulation using the Activator instrument (Activator Methods International, Phoenix, Ariz) through the Von Frey test in an animal model that had its hind limb immobilized as a form to induce mechanical allodynia.

METHOD:

Eighteen adult male Wistar rats were used and divided into 3 groups: control group (C) (n = 6) that was not immobilized; immobilized group (I) (n = 6) that had its right hind limb immobilized; immobilized and adjusted group (IAA) (n = 6) that had its right hind limb immobilized and received chiropractic manipulation after. The mechanical allodynia was induced through the right hind limb immobilization. At the end of the immobilization period, the first Von Frey test was performed, and after that, 6 chiropractic manipulations on the tibial tubercle were made using the Activator instrument. After the manipulation period, Von Frey test was performed again.

RESULTS:

It was observed that after the immobilization period, groups I and IAA had an exacerbation of mechanical allodynia when compared with group C (P < .001) and that after the manipulation, group IAA had a reversion of these values (P < .001), whereas group I kept a low pain threshold when compared with group C (P < .001).

CONCLUSION:

This study demonstrates that immobilization during 4 weeks was sufficient to promote mechanical allodynia. Considering the chiropractic manipulation using the Activator instrument, it was observed that group IAA had decreased levels of mechanical allodynia, obtaining similar values to group C.


J Manipulative Physiol Ther. 2012 Jan;35(1):18-25. [PMID:22054875]

Author information: Trierweiler J, Göttert DN, Gehlen G. Academic of Chiropractic from the University Feevale, Laboratory of Comparative Histophysiology, ICS, University Feevale, Novo Hamburgo, RS, Brazil.

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Abstract

OBJECTIVE:

The aim of this study was to quantify and compare the 3-dimensional intersegmental motion responses produced by 3 commonly used chiropractic adjusting instruments.

METHODS:

Six adolescent Merino sheep were examined at the Institute for Medical and Veterinary Science, Adelaide, Australia. In all animals, triaxial accelerometers were attached to intraosseous pins rigidly fixed to the L1 and L2 spinous processes under fluoroscopic guidance. Three handheld mechanical force chiropractic adjusting instruments (Chiropractic Adjusting Tool [CAT], Activator Adjusting Instrument IV [Activator IV], and the Impulse Adjusting Instrument [Impulse]) were used to randomly apply posteroanterior (PA) spinal manipulative thrusts to the spinous process of T12. Three force settings (low, medium, and high) and a fourth setting (Activator IV only) were applied in a randomized repeated measures design. Acceleration responses in adjacent segments (L1 and L2) were recorded at 5 kHz. The multiaxial intersegmental (L1-L2) acceleration and displacement response at each force setting was computed and compared among the 3 devices using a repeated measures analysis of variance (alpha = .05).

RESULTS:

For all devices, intersegmental motion responses were greatest for axial, followed by PA and medial-lateral (ML) measurement axes for the data examined. Displacements ranged from 0.11 mm (ML axis, Activator IV low setting) to 1.76 mm (PA axis, Impulse high setting). Compared with the mechanical (spring) adjusting instruments (CAT, Activator IV), the electromechanical Impulse produced the most linear increase in both force and intersegmental motion response and resulted in the greatest acceleration and displacement responses (high setting). Significantly larger magnitude intersegmental motion responses were observed for Activator IV vs CAT at the medium and high settings (P < .05). Significantly larger-magnitude PA intersegmental acceleration and displacement responses were consistently observed for Impulse compared with Activator IV and CAT for the high force setting (P < .05).

CONCLUSIONS:

Larger-magnitude, 3D intersegmental displacement and acceleration responses were observed for spinal manipulative thrusts delivered with Impulse at most force settings and always at the high force setting. Our results indicate that the force-time characteristics of impulsive-type adjusting instruments significantly affects spinal motion and suggests that instruments can and should be tuned to provide optimal force delivery.


J Manipulative Physiol Ther. 2006 Jul-Aug;29(6):425-36. [PMID:16904488]

Author information: Keller TS, Colloca CJ, Moore RJ, Gunzburg R, Harrison DE, Harrison DD. Musculoskeletal Research Foundation, Florida Orthopaedic Institute, Temple Terrace, Fla., USA.

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Abstract

OBJECTIVE:

To document potential mediating effects of the Activator-assisted spinal manipulative therapy (ASMT) on pain and hyperalgesia after acute intervertebral foramen (IVF) inflammation.

METHODS:

The IVF inflammation was mimicked by in vivo delivery of inflammatory soup directly into the L5 IVF in adult male Sprague-Dawley rats. Thermal hyperalgesia and mechanical allodynia were determined by the shortened latency of foot withdrawal to radiant heat and von Frey filament stimulation to the hind paw, respectively. Intracellular recordings were obtained in vitro from L5 dorsal root ganglion (DRG) somata. DRG inflammation was examined by observation of the appearance and hematoxylin and eosin staining. ASMT was applied to the spinous process of L4, L5, and L6. A series of 10 adjustments were initiated 24 hours after surgery and subsequently applied daily for 7 consecutive days and every other day during the second week.

RESULTS:

(1) ASMT applied on L5, L6, or L5 and L6 spinous process significantly reduced the severity and duration of thermal and mechanical hyperalgesia produced by the IVF inflammation. However, ASMT applied on L4 did not affect the response in rats with IVF inflammation or the controls; (2) electrophysiological studies showed that hyperexcitability of the DRG neurons produced by IVF inflammation was significantly reduced by ASMT; (3) pathological studies showed that manifestations of the DRG inflammation, such as the increased vascularization and satellitosis, were significantly reduced 2 to 3 weeks after ASMT.

CONCLUSIONS:

These studies show that ASMT can significantly reduce the severity and shorten the duration of pain and hyperalgesia caused by lumbar IVF inflammation. This effect may result from ASMT-induced faster elimination of the inflammation and recovery of excitability of the inflamed DRG neurons by improving blood and nutrition supplement to the DRG within the affected IVF. Manipulation of a specific spinal segment may play an important role in optimizing recovery from lesions involving IVF inflammation.


J Manipulative Physiol Ther. 2006 Jan;29(1):5-13. [PMID:16396724]

Author information: Song XJ, Gan Q, Cao JL, Wang ZB, Rupert RL. Department of Neurobiology, Parker College Research Institute, Dallas, TX 75229, USA.

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