[Effects and mechanism of pressure treatment on hemodynamic changes in patients with hypertrophic scar secondary to extensive burns].

Objective: To investigate the hemodynamic changes of the main arteries and veins of the extremities and the heart in patients with hypertrophic scar secondary to extensive burns after pressure treatment, and to analyze the relevant mechanisms. Methods: A retrospective before-after self-control study was conducted. From January 2017 to February 2022, 37 patients with hypertrophic scar secondary to extensive burns who met the inclusion criteria were hospitalized in the Burn Rehabilitation Department of Guangdong Industrial Injury Rehabilitation Hospital, including 25 males and 12 females, aged 23-52 years. The patients were admitted to the hospital within 12 weeks after wound healing, and within one week after admission, rehabilitation therapists, occupational therapists, and tailors custom-made pressure products such as full-body pressure garment, pressure pants, vests, split finger gloves, split finger socks, hoods, and plastic collars, with the pressure at each part maintained at 2.67-4.00 kPa when wearing. Before the first treatment with pressure products (hereinafter referred to as before pressure treatment) and at 1 h of the first treatment with pressure products (hereinafter referred to as 1 h of pressure treatment), color Doppler ultrasonography was performed to check the pulse rate of the axillary artery, the lumen diameter, peak systolic velocity (PSV), and resistance index of the axillary artery and femoral artery on the left side, the lumen diameter, cross-sectional area, and average blood flow velocity of the axillary vein and femoral vein, and the mitral valve E peak, mitral valve A peak, tricuspid valve E peak, aortic valve PSV, and pulmonary valve PSV of the heart; an optical chromatographic skin detector was used to detect the red color, red pigment, and surface brightness of the scar on the back of the hand to reflect the filling and distribution of the scar microvessels. Data were statistically analyzed with paired sample t test. Results: Compared with those before pressure treatment, the PSV of the axillary artery of patients was significantly slowed down at 1 h of pressure treatment (t=55.42, P<0.01); the average blood flow velocity of the axillary vein was significantly accelerated (t=-60.50, P<0.01); the pulse rate, lumen diameter, and resistance index of the axillary artery, as well as the lumen diameter and cross-sectional area of the axillary vein did not change obviously (P>0.05); the average blood flow velocity of the femoral vein was significantly accelerated (t=-80.52, P<0.01); the lumen diameter, PSV, and resistance index of the femoral artery, as well as the lumen diameter and cross-sectional area of the femoral vein had no significant change (P>0.05); the mitral valve E peak and mitral valve A peak of the heart decreased significantly (with t values of 10.71 and 21.96, respectively, P<0.01); the tricuspid valve E peak of the heart increased significantly (t=7.57, P<0.01); the PSV of the aortic valve and pulmonary valve of the heart did not change obviously (P>0.05). At 1 h of pressure treatment, the red color and red pigment values of the scar on the back of the hand of patients were 15.3±1.1 and 16.8±1.2, respectively, which were significantly lower than 24.5±1.3 and 23.8±1.2 before pressure treatment (with t values of 8.32 and 8.04, respectively, P<0.01). The brightness value of the scar surface on the back of the hand of patients at 1 h of pressure treatment was similar to that before pressure treatment (P>0.05). Conclusions: After pressure treatment for the hypertrophic scar in patients secondary to extensive burn, the average blood flow velocity of the axillary vein and femoral vein in patients are obviously accelerated, the PSV of the axillary artery is significantly slowed down, the peak values of mitral valve E and mitral valve A of the heart are significantly decreased, and the tricuspid valve E peak is significantly increased. These hemodynamic changes may be related to the reduction of microvascular blood flow in the local area of scar after systemic pressure treatment.

Balloon kyphoplasty versus vertebroplasty for treatment of osteoporotic vertebral compression fracture: a prospective, comparative, and randomized clinical study.

UNLABELLED: Bone pain and spinal axial deformity are major concerns in aged patients suffering from osteoporotic vertebral compression fracture (VCF). Pain can be relieved by vertebroplasty or kyphoplasty procedures, in which the compressed vertebral body is filled with substitutes. We randomly assigned 100 patients with osteoporotic compression fracture at the thoraco-lumbar (T-L) junction into two groups: vertebroplasty and kyphoplasty; we used polymethylmethacrylate (PMMA) as the bone filler. Pain before and after treatment was assessed with visual analog scale (VAS) scores and vertebral body height and kyphotic wedge angle were measured from reconstructed computed tomography images. More PMMA was used in the kyphoplasty group than in the vertebroplasty group (5.56 +/- 0.62 vs. 4.91 +/- 0.65 mL, p < 0.001). Vertebral body height and kyphotic wedge angle of the T-L spine were also improved (p < 0.001). VAS pain scores did not differ significantly between the treatment groups. The duration of follow-up was 6 months. Two patients in the kyphoplasty group had an adjacent segment fracture. In terms of clinical outcome there was little difference between the treatment groups. Thus, owing to the higher cost of the kyphotic balloon procedure, we recommend vertebroplasty over kyphoplasty for the treatment of osteoporotic VCFs. INTRODUCTION: Spinal axial deformities are major concerns in aged patients suffering from osteoporotic vertebral compression fracture. Pain may be relieved by vertebroplasty or kyphoplasty. We investigated the radiological and clinical outcomes of these procedures. METHODS: One hundred cases of VCF at the thoraco-lumbar junction were randomly assigned into two groups: vertebroplasty or kyphoplasty (50 cases each). We used polymethylmethacrylate as the bone filler. Pain before and after treatment was assessed with visual analog scale scores and vertebral body height and kyphotic wedge angle were measured from reconstructed computed tomography images. RESULTS: More PMMA was used in the kyphoplasty group than in the vertebroplasty group (5.56 +/- 0.62 vs. 4.91 +/- 0.65 mL, p < 0.001). Vertebral body height and kyphotic wedge angle of the T-L spine were also improved (p < 0.001). VAS pain scores did not differ significantly between the treatment groups. The duration of follow-up was 6 months. Two patients in the kyphoplasty group had an adjacent segment fracture. CONCLUSIONS: In terms of clinical outcome there was little difference between the treatment groups. Thus, with the higher cost of the kyphotic balloon procedure, we recommend vertebroplasty over kyphoplasty for the treatment of osteoporotic VCFs.

Effects of a calcineurin inhibitor, tacrolimus, on glutamate-dependent potentiation in pelvic-urethral reflex in anesthetized rats.

Effects of tacrolimus, a protein phosphatase 2B inhibitor, on the reflex plasticity between the pelvic afferent nerve fibers and the urethra were examined in urethane-anesthetized rats. Repetitive stimulation (1 Hz) induced a potentiation (0.9+/-0.2 and 10.5+/-1.6 spikes in control and repetitive stimulation groups, respectively, P<0.01, N=10) in the activities of the pelvic-urethral reflex. Intrathecal tacrolimus (0.1 mM, 10 microl, bolus) blocked repetitive stimulation-induced potentiation in pelvic-urethral reflex activities (3.2+/-0.9 spikes in tacrolimus group versus 10.5+/-1.6 spikes in repetitive stimulation group, P<0.01, N=10). Glutamate (intrathecal, 0.1 mM, 10 microl, bolus) and N-methyl-D-aspartic acid (intrathecal, 0.1 mM, 10 microl, bolus) both reversed the blocking effects exerted by tacrolimus on repetitive stimulation-induced pelvic-urethral reflex potentiation (15.0+/-1.4 spikes in glutamate group and 11.4+/-1.4 spikes in N-methyl-D-aspartic acid group versus 3.2+/-0.9 spikes in tacrolimus-treated repetitive stimulation group, P<0.01, N=7). In addition, the reversal effect elicited by these two agonists of glutamate receptors showed no statistical difference (P=NS, N=7). All these results demonstrated that tacrolimus could block glutamatergic N-methyl-D-aspartic acid receptor-mediated potentiation in pelvic-urethral reflex activities. This finding may be pathologically relevant in patients who take tacrolimus as immunosuppressant therapy. Whether tacrolimus will induce urine incontinence in such patients or not needs further investigation.

GABAergic modulation of ventilatory response to acute and sustained hypoxia in obese Zucker rats.

OBJECTIVE: To determine whether altered central and/or peripheral gamma-aminobutyric acid (GABA)ergic mechanisms acting in GABA(A) receptors contribute to the abnormal ventilatory response to acute and sustained hypoxia in obese Zucker rats. METHODS: In all, 10 lean and 10 obese Zucker rats were studied at 12 weeks of age. Ventilation (V(.-)(E)), tidal volume (V(T)), and breathing frequency (f) during room air breathing and in response to sustained (30 min) hypoxic (10% O(2)) challenges were measured on three separate occasions by the barometric method following the randomized blinded administration of equal volumes of DMSO (vehicle), bicuculline methiodide (B(M), 1 mg/kg, peripheral GABA(A) receptor antagonist), or bicuculline hydrochloride (B(HCl), 1 mg/kg, peripheral and central GABA(A) receptor antagonist). RESULTS: Administration of B(M) and B(HCl) in lean animals had no effect on ventilation either during room air breathing or 30 min of sustained exposure to hypoxia. Similarly, B(M) failed to alter ventilation in obese rats. In contrast, B(HCl) significantly (P<0.05) increased V(.-)(E) and V(T) during room air breathing and 10-30 min of hypoxic exposure in obese rats. During 5 min of acute hypoxic exposure, V(T) remained elevated with B(HCl) in obese rats, but the V(.-)(E) appeared not to be increased with B(HCl) due to a decrease in f. CONCLUSION: Thus, endogenous GABA modulates both ventilation during room air breathing and ventilatory response to sustained hypoxia in obese, not in lean, Zucker rats by acting specifically on GABA(A) receptors located within the central, not peripheral, nervous system. However, endogenous GABA does not modulate ventilation but the pattern of breathing during acute hypoxia in obesity in a different manner from that during sustained hypoxia.

Dynamic pelvic-pudendal reflex plasticity mediated by glutamate in anesthetized rats.

Reflex plasticity between pelvic afferent nerve (PAN) and pudendal efferent nerve (PEN), as well as external-urethral sphincter (EUS) activity was examined in anesthetized rats. A progressive increase in the number of evoked action potentials per stimulus occurred in PEN and EUS activity when PAN was repetitively stimulated (1 Hz). This potentiation in pelvic-pudendal reflex (PPR) activity induced by repetitive stimulation was abolished by APV (D-2-amino-5-phosphonoraleric acid, i.t. 100 microM, 2-5 microl) and attenuated by the NBQX (2, 3-dihydroxy-6-nitro-7-sulfamoyl-benzo (F) quinoxaline, i.t. 20 microM, 2-5 microl) but was not affected by the presence of bicuculline (i.t. 10 microM, 2-5 microl). The duration of contraction wave of intra-urethral pressure (IUP) elicited by a single electric shock was elongated by potentiated PPR, while the peak pressure was not affected. Both intrathecal application of glutamate (i.t. 0.1 mM, 2-5 microl) and NMDA (N-methyl-D-aspartic acid, i.t. 0.1 mM, 2-5 microl) induced spontaneous repetitive (0.31+/-0.02 Hz) burst discharges in PEN and EUSE and produced small contraction wave in IUP, which is similar to the high frequency oscillation phase during a voiding cycle of urinary bladder in rats. All these results demonstrate that repetitive stimulation of PAN can induce a distinct and long-lasting modulation in PPR activity and this change may be physiologically relevant in urinary continence.

Structural influence of hanatoxin binding on the carboxyl terminus of S3 segment in voltage-gated K(+)-channel Kv2.1.

The voltage-sensing domains of voltage-gated potassium channels Kv2.1 (drk1) contain four transmembrane segments in each subunit, termed S1 to S4. While S4 is known as the voltage sensor, the carboxyl terminus of S3 (S3C) bears a gradually broader interest concerning the site for gating modifier toxins like hanatoxin and thus the secondary structure arrangement as well as its surrounding environment. To further examine the putative three-dimensional (3-D) structure of S3C and to illustrate the residues required for hanatoxin binding (which may, in turn, show the influence on the S4 in terms of changes in channel gating), molecular simulations and dockings were performed. These were based on the solution structure of hanatoxin and the structural information from lysine-scanning results for S3C fragment. Our data suggest that several basic and acidic residues of hanatoxin are electrostatically and stereochemically mapped onto their partner residues on S3C helix, whereas some aromatic or hydrophobic residues located on the same helical fragment interact with the hydrophobic patch of the toxin upon binding. Therefore, a slight distortion of the S3C helix, in a direction toward the N-terminus of S4, may exist. Such conformational change of S3C upon toxin binding is presented as a possible explanation for the observed shift in hanatoxin binding-induced gating.

Evidence for the involvement of dopamine D(1) and D(2) receptors in mediating the decrease of food intake during repeated treatment with amphetamine.

Repeated treatment with amphetamine (AMPH), a well-known anorectic agent, into animals could induce anorexia on day 1 and produce a gradual reversion of food intake (tolerant anorexia) on the following days. It is unknown whether these feeding changes are related to dopamine (DA) and/or noradrenergic neurotransmission. Thus, the present study investigated the subtype of receptor mediating AMPH-induced anorexia. Daily food intake was measured after various drugs were given. Pretreatment with haloperidol, an antagonist of DA receptors, may lead to inhibition of AMPH-induced anorexia. However, pretreatment with the alpha-adrenoceptor antagonist phentolamine, and the beta-adrenoceptor antagonist propranolol, failed to modify the action of AMPH, suggesting the involvement of DA receptors but not adrenoceptors in the action of AMPH-induced anorexia. Furthermore, pretreatment with SCH 23390 at a dose sufficient to block D(1) receptors or pimozide at a dose sufficient to inhibit D(2) receptors blocked AMPH-induced anorexia, indicating the involvement of D(1) and D(2) receptors. In a study of tolerant anorexia, repeated treatment with the D(1)/D(2) agonist apomorphine, but not the D(1) agonist SKF 38393 or D(2) agonist quinpirole, induced an AMPH-like tolerant feeding response, providing evidence for conjoint action of D(1) and D(2) receptors in the effect. The present results suggest that both D(1) and D(2) receptors are involved in anorexia and tolerant anorexia induced by chronic intermittent administration of AMPH.

Effect of electroacupuncture on blood pressure and adrenal nerve activity in anesthetized rats.

The neural mechanism underlying the effect of electroacupuncture (Ea) on arterial blood pressure (BP) and adrenal nerve activity (ANA) was investigated in anesthetized rats. Tsusanli (St-36) and Hoku (Li-4) were tested with combinations of two different frequencies (3 and 30 Hz) with various stimulation intensities of Ea. At Tsusanli, no effect was found, while at Hoku, an elevation of BP in parallel with ANA was elicited during Ea when the intensity was 5xT or higher. The pattern of the pressor response caused by the low frequency Ea (LFEa, 3 Hz) was a tonic one, while a phasic one was induced by the high frequency Ea (HFEa, 30 Hz). When both Hoku were simultaneously stimulated with the same frequency, the latency to reach the maximal effect was shortened. However, when two different frequencies were used instead, a response characterized by a combination of both phasic and tonic effect was obtained. In bilateral Ea with idential frequency but different onset time, the pressor effect elicited by the latter Ea showed no further increase during the stimulation period, however, when different frequencies were employed, each Ea elicited its own effect independently. The pressor effect elicited by Ea was abolished by regitine but not affected by adrenalectomy. It is concluded that a LFEa and a HFEa at Hoku with appropriate stimulation parameters can increase BP which is mainly due to potentiation of the sympathetic vasoconstrictor tone but via different central mechanisms.

Neural mechanisms of impaired micturition reflex in rats with acute partial bladder outlet obstruction.

To determine the contribution of neural elements to micturition, we evaluated, in intact rats, the cystometrogram, pelvic afferent nervous activity, pelvic efferent nervous activity and external urethral sphincter-electromyogram activity in the normal and acute partial bladder outlet obstruction states. In the normal state, in response to saline filling, mechanoreceptor-dependent pelvic afferent nervous activity gradually activated and finally triggered a voiding reflex, including four phases of detrusor contractions. Phase 1 was characterized by an initial rising intravesical pressure, Phase 2 was characterized by a series of high-frequency oscillations in intravesical pressure, Phase 3 contraction was characterized by a rebound intravesical pressure and Phase 4 contraction was characterized by a rapid fall in intravesical pressure. In the acute partial bladder outlet obstruction state, Phase 1 contraction rose and high-frequency oscillations fell in Phase 2. This voiding dysfunction is ascribed to the bursting extraurethral sphincter activity being converted to tonic extraurethral sphincter activity. In summary, the suppressed high-frequency oscillations in Phase 2 of the detrusor muscle contraction could be detrimental to efficient voidings in the acute partial bladder outlet obstructed rat.

Contralaterally induced dorsal root reflex shares common final pathway with ipsilaterally elicited ones in Wistar rats.

The dorsal root reflex (DRR) in single fibers, recorded in the severed L5 dorsal root central stump, initiated by sciatic nerve (SN) stimulation (St), was studied in anesthetized rats. Both ipsi- and contralateral Sts elicited DRR, with central delays of 4.6 +/- 0.3 (n = 10) and 27.3 +/- 2.5 (n = 5) ms, respectively. Ipsilaterally induced DRRs showed repetitive firing (mean = 3 +/- 0.5 spikes, n = 5), while contralaterally induced ones were abolished after spinalization (T13). When the time interval between two ipsilateral suprathreshold Sts was less than 12 +/- 2.4 ms (n = 12), the second DRR was abolished. On the other hand, when it between two ipsilateral subthreshold Sts was less than 4.8 +/- 0.3 ms (n = 7), DRR was activated. Contralaterally induced DRR also showed temporal inhibition and facilitation with time intervals similar to that in ipsilateral cases. Furthermore, when the latency between a contralaterally and a ipsilaterally induced DRR was less than 10.8 +/- 1.8 ms (n = 5), the later DRR was blocked by the former, and vice versa. Facilitation can be also shown by a contralateral and a ipsilateral subthreshold St. These results suggested that contralaterally induced DRRs may share part of final common pathway with ipsilaterally induced ones.

Nicotine-induced hyperlocomotion is not modified by the estrous cycle, ovariectomy and estradiol replacement at physiological level.

The present study was designed to investigate whether nicotine's effect on locomotion might be modulated by the ovarian hormone at physiological level. Rats at normal cycling of estrus and diestrus were selected for the comparison of nicotine-induced hyperlocomotion based on the document that the release of striatal dopamine was greatest at the estrous phase. Ovariectomized rats primed with or without estrogen at physiological level were also selected for comparison. Increase in spontaneous locomotion by nicotine was statistically significant at the doses of 0.15 and 0.3 mg/kg (p < 0.001). The stimulating effect of nicotine led the locomotor response to almost the same magnitude in all hormonal groups studied. Nicotine-induced hyperlocomotion appeared to be mediated by central nicotinic receptor because it was blocked by mecamylamine (0.5 and 1.0 mg/kg, i.p.). Also it was blocked by haloperidol (0.04 and 0.08 mg/kg, i.p.) indicating the involvement of dopaminergic neurotransmission. These effects were similar in all groups regardless of the estrous cycle or ovariectomy. The observed data provided behavioral evidence to suggest that the effect of nicotine on locomotion-related dopaminergic neurons might not be modified by the physiological action of estrogen.

Which afferents induce and transmit dorsal root reflex in rats?

The dorsal root reflex (DRR) in single fibers, recorded in the severed L5 dorsal root central stump, initiated spontaneously or by electric stimulation (St) of sciatic nerve, was studied in anesthetized rats. The excitation of group II afferents were the major inputs to induce DRRs which were transmitted mainly in fibers with conduction velocity below 20 m/s, and its central delay was 3-5 ms. The firing frequency of both spontaneous and evoked DRRs were increased two to four times after spinalization (T13). These results suggested that the DRR may play an important role in the modulation of sensory afferent inputs regulated by supraspinal structures.

Low and high frequency electroacupuncture at Hoku elicits a distinct mechanism to activate sympathetic nervous system in anesthetized rats.

To address the effect of electroacupuncture (Ea) on autonomic nerve activity, the responses of rhythmic micturition contraction (RMC), urine excretion (UE), blood pressure (BP), renal sympathetic nerve activity (RNA) and pelvic parasympathetic nerve activity (PNA) to Ea were investigated in urethane-anesthetized rats. The acupoint Hoku (Li-4) was tested with two different stimulation frequencies (2 Hz and 20 Hz). Elongation of the RMC cycle and an increase in UE associated with the elevation of BP and RNA was elicited during Ea at Hoku. However, the pressor response induced by low frequency Ea (LFEa) was different from that by high frequency Ea (HFEa), i.e. a tonic effect was elicited by LFEa, while a phasic one was induced by HFEa. These results imply that: (1) Ea at Hoku may selectively activate the sympathetic, but not the parasympathetic nervous system, (2) Ea at Hoku with a different stimulation frequency may elicit a distinct mechanism to activate the sympathetic nervous system and (3) Ea at Hoku may ameliorate the hyperactive bladder in clinical therapy.

Can antidromic stimulation of rat muscle afferents modulate the sensitivity of muscle spindles?

The sensitivity of muscle spindles in gastrocnemius-soleus (GS) muscles following dorsal root (DR) antidromic stimulation (ASt) was investigated in anesthetized rats, in which the hindleg was totally denervated except the GS muscle, ventral roots from L3 to S1 and DRs from L4 to L6, which were severed after laminectomy. The peripheral end of a teased DR filament with single unit tonic discharges from a constantly stretched muscle spindle were recorded and antidromically stimulated after identification. In response to ASt with various frequencies, two different types of ending were found: (1) type I, its tonic discharge was not altered following ASt at 100 Hz for 10 s, while type II was significantly inhibited even at a frequency of 50 Hz; (2) at 300 Hz, both types of endings were inhibited, however, type I recovered in less than 4 s, while type II took more than 15 s to return to control level, and a silent period (1-5 s) was found in type II but not in type I; (3) the effective minimum inhibitory frequency for type I and type II was 200 and 50 Hz, respectively. These results suggest that type I and type II endings may correspond to the primary and the secondary endings of the muscle spindle whose sensitivity may be modulated antidromically by the dorsal root reflex.