Biomedical subjects

Xiaohong Xu

Publications and source records attributed to Xiaohong Xu.

At least 19 recordsLinked to original sources

PubMed2007

Low temperature CO oxidation over unsupported nanoporous gold.

Supported Au nanoclusters are well-known for their unusual properties in catalysis. We describe here that nanostructured porous Au made via dealloying represents a new class of unsupported catalysts with extraordinary activities in important reactions such as CO oxidation. Although nanoporous Au may contain some oxides on the surface, our results demonstrate that it is metallic Au that plays the main role in this catalytic reaction. Furthermore, this material has good low-temperature catalytic stability and is extremely CO tolerant.

Journal Article↗

PubMed2006

Effects of estradiol benzoate on learning-memory behavior and synaptic structure in ovariectomized mice.

There is increasing evidence that estrogen is involved in CNS activity, particularly memory. Several studies have suggested that estrogen improves memory by altering neuronal plasticity, including increased hippocampus CA1 dendritic spine density and enhanced long-term potentiation (LTP). In the present study, we investigated the effects of estrogen on the ultrastructural modifications in cerebral frontal cortex and hippocampus of female ovariectomized mice. One week after ovariectomy (Ovx), ICR female mice received daily injection of estradiol benzoate (EB, 20, 100, 200 microg/kg, s.c.) for 4-5 weeks. Spatial memory was then tested in the water maze, and the overall locomotor activity was monitored in open field. Synaptic morphologic parameters were examined using a graph analyzer. The results from open field did not show any alterations in locomotor activity following Ovx and EB replacement. Both the latency to find the platform and the distance to reach the platform were significantly reduced in Ovx mice by EB at 20 or 100 microg/kg when compared to vehicle treated Ovx mice. The results from synaptic ultrastructural measurement and analysis did not show any differences in hemispheric or hippocampal volumes, the numeric synaptic density, the length of active zones, or the curvature of synaptic interface among Sham, Ovx, and Ovx plus EB replacement mice. However, EB replacement effectively normalized the changes induced by Ovx, reducing the width of the synaptic cleft, enlarging the thickness of postsynaptic density (PSD), and increasing the number of synaptic vesicles in the presynapse in both cerebral cortex Fr1 and hippocampus CA1 areas. These results suggest that the beneficial effects of EB on improving memory behavior of Ovx female mice are associated with the changes of some subtle structural parameters of synapses, including the width of PSD and synaptic cleft rather than some basic and permanent structure in frontal cortex and hippocampus regions.

Animals↗

PubMed2006

HPLC determination and steady-state bioavailability study of levodropropizine sustained-release tablets in dogs.

A simple HPLC method using UV detection was developed and validated for the determination of levodropropizine (LDP) in dog plasma. The sample was prepared for injection using a liquid-liquid extraction method with 1-phenypiperazine as the internal standard. The mobile phase was methanol-diethylamine solution (0.05 M) (20:80, v/v, pH adjusted to 3.0 with H3PO4) with a detection wavelength of 240 nm. The limit of quantitation (LOQ) of LDP in a biological matrix was determined to be 25.25 ng/mL. The calibration curve was linear across the concentration range of 25.25 to 2020 ng/mL. The intra-day and inter-day precision values (CV %) were within 7% and accuracy (R.E. %) was within 6% of the nominal values for medium (252.5 ng/mL) and high (2020 ng/mL) LDP concentrations. For the LDP concentration at the LOQ, the intra-day and inter-day precision and accuracy were within 20% and 10%, respectively. The average absolute recovery for LDP was 70.28%. This method was successfully used to analyze plasma samples in a steady-state bioavailability study of a newly developed sustained-release LDP tablets (SR) using immediate-release tablets (IR) as the reference. The relative bioavailability of the SR was determined to be 106.3 +/- 12.8% (n=6). The Cmax of the SR was significantly lower (P<0.05), and the tmax was significantly longer than that of the IR (P<0.05). The results of ANOVA and two one-sided tests indicated that the SR exhibited acceptable sustained release properties and was bioequivalent to the IR.

Animals↗

PubMed2006

Inhibitory effects of sildenafil on small intestinal motility and myoelectrical activity in dogs.

Previous studies have shown that sildenafil inhibits the esophageal motility in both humans and animals. The aim of this study was to investigate the effects of sildenafil on intestinal myoelectrical activity and motility. The study was composed of 2 experiments and performed in 7 healthy female dogs with a duodenal cannula 20 cm beyond pylorus (19-26 kg). The first experiment was designed to study the effects of sildenafil on intestinal myoelectrical activity and it included 2 sessions each consisting of 30-minute baseline, 15-minute posttreatment (placebo or 100 mg sildenafil) and 90 minutes after a liquid meal. Intestinal myoelectrical activity was recorded during the entire experiment period. The second experiment was aimed to investigate the effect of sildenafil on intestinal motility and was performed immediately after a solid meal. Intestinal motility was measured by a manometric catheter inserted into the small intestine via the duodenum cannula for 30 minutes at baseline and 60 minutes after sildenafil. Sildenafil significantly reduced the amplitude but had no effect on the frequency and regularity of the intestinal myoelectrical activity. Sildenafil significantly inhibited postprandial intestinal contractions. Although the frequency of the contractions was not altered, the mean area under the curve was significantly reduced during the first 30 minutes (P < .03) and second 30 minutes after sildenafil (P < .03); the power of intestinal contractile activities was also significantly reduced during the first 30 minutes (P < .0004) and second 30 minutes after sildenafil (P < .0003) in comparison with baseline. In conclusion, sildenafil inhibits the amplitude of both intestinal contractile activity and intestinal slow waves.

Animals↗

PubMed2006

Correlation between gastric myoelectrical activity recorded by multi-channel electrogastrography and gastric emptying in patients with functional dyspepsia.

OBJECTIVE: To investigate the correlation between the parameters of multi-channel electrogastrography (MEGG) and gastric emptying in patients with functional dyspepsia. MATERIAL AND METHODS: The MEGG study included 19 patients with functional dyspepsia and 19 healthy subjects. MEGG was recorded for 30 min in the fasting state and 60 min after a standard test meal (450 kcal). MEGG parameters included the power ratio (PR), the normal percentage of 2-4 cpm gastric slow waves (N%) and the percentage of slow wave coupling (%SWC). Gastric emptying was measured in the 19 patients by SPECT (single photon emission computerized tomography) and the gastric emptying parameters included lag phase (LP), half time of gastric emptying (T1/2), emptying rate of stable phase (ERSP), one hour retention rate (1HRR), and two hour retention rate (2HRR). RESULTS: No significant difference in MEGG parameters was found between normal subjects and patients. There was a significant negative correlation between postprandial N% and LP (r = - 0.52, p<0.05) and a significant negative correlation between fasting %SWC and 1HRR (r = - 0.48, p<0.04) or 2HRR (r = - 0.48, p<0.05). Compared with the patients in the PR > 1 group, patients in the PR < or = 1 group had significantly higher T1/2 and 2HRR but lower ERSP. CONCLUSIONS: Both the temporal regularity and spatial regularity of gastric slow waves have negative correlations with gastric emptying, which suggests that the impaired gastric myoelectrical activity may be responsible for the delayed gastric emptying in patients with functional dyspepsia.

Adult↗

PubMed2006

Reverse gastric pacing reduces food intake without inducing symptoms in dogs.

OBJECTIVE: To investigate the therapeutic potential of reverse gastric pacing (RGP) for obesity by studying the effects of RGP on food intake and symptoms in dogs. MATERIAL AND METHODS: The study was performed in 9 dogs in 3 sessions (control, strong RGP and moderate RGP). Gastric myoelectrical activity and food intake were measured in each session. RGP was performed using serosal electrodes implanted in the distal stomach at the physiological frequency of the intrinsic gastric myoelectrical activity with a pulse width of 550-950 ms. The amplitude of the stimulus was set at a level maximally tolerable by the animals in the strong RGP session and 50% of the maximum level in the moderate session. RESULTS: 1) Compared with the control, strong RGP (p<0.001) and moderate RGP (p<0.01) significantly reduced the amount of food intake by 62.9% and 31.7%, respectively (p<0.05, ANOVA). 2) Whereas strong RGP induced significant symptoms, moderate RGP did not induce any significant symptoms in comparison with the control session. 3) The regularity and coupling of gastric myoelectrical activity were significantly impaired with both strong RGP and moderate RGP in the fasting state. CONCLUSIONS: RGP impairs intrinsic gastric myoelectrical activity and substantially and acutely reduces food intake. The reduced food intake and freedom from symptoms resulting from moderate RGP are indicative of the therapeutic potential of RGP in obesity.

Animals↗

PubMed2006

Shared long-range regulatory elements coordinate expression of a gene cluster encoding nicotinic receptor heteromeric subtypes.

The nicotinic acetylcholine receptor (nAChR) beta4/alpha3/alpha5 gene cluster encodes several heteromeric transmitter receptor subtypes that are essential for cholinergic synaptic transmission in adrenal gland, autonomic ganglia, pineal gland, and several nuclei in the central nervous system. However, the transcriptional mechanisms coordinating expression of these subunit genes in different cell populations are unknown. Here, we used transgenic methods to investigate long-range transcriptional control of the cluster. A 132-kb P1-derived artificial chromosome (PAC) encoding the rat cluster recapitulated the neurally- and endocrine-restricted expression patterns of the endogenous beta4/alpha3/alpha5 genes. Mutation of ETS factor binding sites in an enhancer, beta43', embedded in the beta4 3'-untranslated exon resulted in greatly diminished beta4, alpha3, and alpha5 expression in adrenal gland and to a lesser extent in the superior cervical ganglion (SCG) but not in other tissues. Phylogenetic sequence analyses revealed several conserved noncoding regions (CNRs) upstream of beta4 and alpha5. Deletion of one of them (CNR4) located 20 kb upstream of beta4 resulted in a dramatic decrease in beta4 and alpha3 expression in the pineal gland and SCG. CNR4 was sufficient to direct LacZ transgene expression to SCG neurons, which express the endogenous beta4alpha3alpha5 subunits, and pineal cells, which express the endogenous beta4alpha3 combination. Finally, CNR4 was able to direct transgene expression to major sites of expression of the endogenous cluster in the brain. Together, our findings support a model in which cell type-specific shared long-range regulatory elements are required for coordinate expression of clustered nAChR genes.

Animals↗

PubMed2005

Identification of a transiently exposed VE-cadherin epitope that allows for specific targeting of an antibody to the tumor neovasculature.

VE-cadherin is an adhesion molecule localized at the adherens junctions of endothelial cells. It is crucial for the proper assembly of vascular structures during angiogenesis and maintaining vascular integrity. We have studied 3 monoclonal antibodies (mAbs) against murine VE-cadherin that inhibit angiogenesis and tumor growth. Two of these, BV13 and 10G4, also disrupted normal vessels, resulting in severe vascular leakage, whereas the third, E4G10, did not. The goal of the current report was to identify the epitope of E4G10 and distinguish it from those of the disruptive mAbs. We mapped the epitope of E4G10 to within the first 10 amino acids of mature VE-cadherin and demonstrated that conserved tryptophan residues in this sequence are required for VE-cadherin-mediated trans-adhesion. The disruptive mAbs target a different epitope within amino acids 45 to 56, which structural homology modeling suggests is not involved in trans-adhesion. From our studies, we hypothesize that E4G10 can only bind the neovasculature, where VE-cadherin has not yet engaged in trans-adhesion and its epitope is fully exposed. Thus, E4G10 can inhibit junction formation and angiogenesis but is unable to target normal vasculature because its epitope is masked. In contrast, BV13 and 10G4 bind an epitope that is accessible regardless of VE-cadherin interactions, leading to the disruption of adherens junctions. Our findings establish the immediate N-terminal region of VE-cadherin as a novel target for inhibiting angiogenesis.

Angiogenesis Inhibitors↗

PubMed2005

Pyloric electrical stimulation reduces food intake by inhibiting gastric motility in dogs.

BACKGROUND & AIMS: The pylorus plays an important role in regulating gastric emptying. The aim of this study was to investigate the therapeutic potential of pyloric electrical stimulation (PES) for obesity in dogs. METHODS: The study was composed of 3 separate experiments. The first experiment was designed to study the effects of PES with various parameters on gastric emptying and gastric slow waves in 5 sessions. The second experiment was used to test the effects of PES on antral contractions. The acute effect of PES on food intake was studied in the third experiment. RESULTS: (1) Pyloric myoelectrical recording showed dual frequencies. The lower frequency was identical to the frequency of the gastric slow waves, and the higher frequency was similar to that of the intestinal slow waves. (2) Gastric emptying was significantly delayed with PES, and the delay in gastric emptying was significantly and negatively correlated with stimulation energy ( r = -.673; P < .001). (3) PES significantly impaired the regularity and coupling of the intrinsic gastric myoelectrical activity in an energy-dependent manner. The delayed gastric emptying was significantly correlated with the impairment of the coupling of gastric myoelectrical activity ( r = .441; P < .02). (4) Antral contractions on the fed state were significantly and substantially inhibited with PES. (5) Acute PES significantly reduced food intake. CONCLUSIONS: PES reduces food intake that may be attributed to its inhibitory effects on intrinsic gastric myoelectrical activity, antral contractions, and gastric emptying.

Animals↗

PubMed2005

The Neuroprotection of puerarin against cerebral ischemia is associated with the prevention of apoptosis in rats.

Previous work has shown that puerarin (Pur), extracted from the dried root of Pueraria lobata (Wild) Ohwi, increases cerebral blood flow in dogs and attenuates cerebral and spinal cord injury resulting from ischemia and reperfusion in rats and rabbits. The present study further demonstrates the neuroprotective effects of Pur on cerebral ischemic injury in rats and the mechanisms underlying the protective effects. Male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAo) for 50 min followed by reperfusion for 24 h. Pur (50, 100 mg/kg, i.p) was administered at the onset of MCAo. Twenty-four hours after reperfusion, neurological deficits were evaluated in Pur- and vehicle-treated rats. The infarct volume and edema ratios were assessed from stained brain slices. The results showed that Pur (100 mg/kg) markedly decreased the infarct volume by 34 % ( P < 0.01) in cerebral cortex and improved the neurological functions ( P < 0.05) after MCAo. Furthermore, flow cytometric analysis of annexin-V and PI labeling cells showed that the percentages of apoptosis and necrosis in the dorsolateral cortex were significantly reduced by 38.6 % and 28.5 % ( P < 0.01 and P < 0.05) following treatment with Pur (100 mg/kg) in MCAo rats. Caspase-3 activity, a biochemical marker of apoptosis, was significantly inhibited after treatment with Pur in the dorsolateral cortex. In agreement with this result, the expression of the X-chromosome-linked inhibitor of apoptosis protein (XIAP) was obviously up-regulated after administration of Pur (100 mg/kg), while caspase-3 gene was down-regulated in the dorsolateral cortex. These results suggest that the neuroprotection of puerarin against cerebral ischemia is associated with anti-apoptosis.

Animals↗

PubMed2005

Alteration of gastric myoelectrical and autonomic activities with audio stimulation in healthy humans.

OBJECTIVE: Cold or emotional stress was reported to affect gastric myoelectrical activity. The aim of this study was to investigate the effects of music or noise on gastric myoelectrical activity and autonomic function in healthy volunteers. MATERIALS AND METHODS: The study was performed in 10 fasted healthy volunteers and included 30 min at baseline, 30 min of classical music via headphones and 30 min of loud household noises via headphones. The electrogastrogram (EGG) readings were recorded simultaneously with the electrocardiogram (ECG) recording. RESULTS: Both classical music and noise altered the regularity of gastric slow waves. The percentage of normal 2-4 cycles/min (cpm) waves was reduced from 77.9 +/- 4.7% at baseline to 66.9 +/- 5.4% during music (p < 0.006) and 67.7 +/-5.4% during noise (p < 0.05). The reduction was attributed to a significant increase in bradygastria (15.8 +/- 3.9% versus 9.8 +/- 2.6%, p < 0.04) with the music and a significant increase in arrhythmia (7.4 +/- 1.6% versus 2.0 +/- 1.1%, p < 0.02) with the noise. The dominant frequency and power of the EGG were, however, not altered with either music or noise. Neither music nor noise had any effect on the autonomic function assessed by the heart rate variability. CONCLUSIONS: Audio stimulation, with both music and noise, alters the rhythmicity of gastric slow waves. Classical music seems to increase bradygastria, whereas, household noise may increase arrhythmia. The effect of audio stimulation on the gastric slow wave does not seem to involve sympathetic or vagal efferent pathways assessed by the spectral analysis of heart rate variability.

Acoustic Stimulation↗

PubMed2005

Effects of enhanced viscosity on canine gastric and intestinal motility.

BACKGROUND AND AIM: The aim of this study was to investigate the effect of enhanced viscosity on gastric emptying and gastrointestinal motor and myoelectrical activities in dogs. METHOD: The study was performed in eight healthy female hound dogs chronically implanted with four pairs of gastric and two pairs of intestinal serosal electrodes and a duodenal fistula. Each dog was studied in three sessions and fed with three test meals with different viscosity. Gastric emptying was monitored for 2 h simultaneously with gastric and intestinal myoelectrical recordings. RESULTS: The liquid test meal containing either 0.78% or 1.21% of galactomannan significantly delayed gastric emptying but had no effect on postprandial blood glucose levels in comparison with the meal containing no galactomannan. The liquid test meal containing either 0.78% or 1.21% of galactomannan significantly increased the frequency and strength of intestinal motility but had no effect on intestinal slow wave rhythms. The product with enhanced viscosity had no effect on gastric motor activity or gastric slow waves. CONCLUSION: It was concluded that enhanced viscosity delays gastric emptying, increases postprandial intestinal but not gastric motility, and has no effects on gastric or intestinal slow waves.

Animal Feed↗

PubMed2005

Patients with systemic sclerosis have unique and persistent alterations in gastric myoelectrical activity with acupressure to Neiguan point PC6.

OBJECTIVE: To assess the effect of acupressure on gastric myoelectrical activity (GMA) in patients with systemic sclerosis (SSc) and its possible influence on SSc-associated gastrointestinal (GI) dysmotility disorders. METHODS: Acupressure to Neiguan point PC6 (GI, antiemetic point) was applied while SSc patients and healthy control subjects were monitored by 4-channel surface electrogastrography (EGG) during 30-minute baseline, acupressure, and recovery intervals. Frequency of GI symptoms and modified Rodnan skin scores (mRSS) of SSc patients were recorded. Acupressure to PC10 (non-GI, sham) was also performed on SSc patients to assess the validity of PC6 as a modulator of GI gastric rhythms. RESULTS: In the SSc patients, PC6 acupressure resulted in significant, persistent percentage mean normal wave decreases with concomitant percentage mean bradygastria and tachygastria increases during the recovery interval. Increases in percentage mean coupling seen in controls were blunted in SSc patients. In SSc patients, PC6 acupressure resulted in significant percentage normal wave and percentage bradygastria changes in the recovery interval that were not obtained with PC10 acupressure. In SSc patients, mRSS were significantly correlated to baseline GMA percentage mean normal waves and bradygastria and frequency of abdominal bloating. The frequency of symptoms for heartburn were significantly correlated with changes in GMA (deltaGMA, baseline vs recovery). CONCLUSION: In SSc patients, PC6 acupressure revealed significant, persistent, and possibly unique alterations in GMA during the recovery interval. deltaGMA was significantly correlated with the frequency of heartburn symptoms. Further studies will assess if acupressure to PC6 can provide a therapeutic or prognostic utility with GMA or GI symptoms in SSc patients.

Acupressure↗

PubMed2004

Anti-dysrhythmic effects of long-pulse gastric electrical stimulation in dogs.

BACKGROUND/AIM: The aim of this study was to investigate the anti-dysrhythmic effect of long-pulse gastric electrical stimulation (GES) in dogs. METHODS: The study was performed in 7 healthy dogs implanted with 4 pairs of serosal gastric electrodes. Each dog was studied in three sessions on 3 separate days in a randomized order with recordings of gastric slow waves. In session 1 or 2, infusion of either saline or glucagon (0.1 U/kg in 20 ml saline instilled in 40 min) was given during the 2nd and 3rd 20-min periods. The protocol of session 3 was the same as that of session 2 except that GES was performed during the 2nd 20-min period. RESULTS: (1) Glucagon induced gastric dysrhythmia and decreased gastric slow-wave coupling (ANOVA, p < 0.001). The long-pulse GES normalized glucagon-induced gastric dysrhythmia and the uncoupling of slow waves. (2) Glucagon induced symptoms and behaviors suggestive of nausea and the symptoms were not improved by long-pulse GES. CONCLUSION: (1) Glucagon induces gastric dysrhythmias, slow-wave uncoupling and symptoms, and (2) long-pulse GES normalizes glucagon-induced gastric dysrhythmia and slow-wave uncoupling with no improvement in symptoms.

Animals↗

PubMed2004

Multichannel electrogastrography (EGG) in normal subjects: a multicenter study.

The aim of this study was to record gastric myoelectric activity using multichannel electrogastrography (EGG) and to determine if there are differences due to age, gender, body mass, and study location. In 61 normal subjects from four centers, fasting multichannel EGG was recorded for 1 h, followed by two 1-h postprandial recordings after a test meal. Variables assessed included dominant frequency (DF) and its power, percentage time in 2- to 4-cpm frequency, and percentage slow-wave coupling (%SWC). There were no significant differences in EGG parameters with respect to gender or age. Subjects with a BMI > 25 had a decrease in the absolute DF power but a similar increase in the postprandial DF power. Subjects with a BMI > 25 had a postprandial decrease in the %SWC compared to those with a BMI < 25. There was a decrease in postprandial %SWC in European/Asian centers compared to American centers. In conclusion, multichannel EGG provides assessment of electrical slow-wave coupling in addition to determining dominant frequency, power, and percentage normal rhythm. This multicenter study of normal subjects shows similar multichannel EGG values among different genders and ages. Body mass and ethnicity may impact on some of the EGG values.

Adolescent↗

PubMed2004

Effects of puerarin on learning-memory and amino acid transmitters of brain in ovariectomized mice.

In the present study, the protective effects of puerarin (Pur) on learning and memory in ovariectomized mice were investigated. One week after ovariectomy (Ovx) or sham operation, female mice were given a 4-week treatment of Pur (50 or 100 mg/kg,i.p.) or estradiol benzoate (EB, I or 5 pg/day, i.p.). The results showed that, following treatment with 50 or 100 mg/kg Pur in Ovx mice, the training times for achieved learning criterion in aY-maze declined by 11.8 % and 17.8 % (P > 0.05 and P < 0.05), and that memory retention increased by 23.3 % and 28.3 % (P < 0.05 and P < 0.05), respectively. In addition, the prolonged escape latency of platform finding in a water maze was shortened by 15.5% and 23.8% (P < 0.05 and P < 0.05). After a behavior test,the levels of glutamate (Glu) and GABA in the frontal cortex and hippocampus were assessed using high-performance liquid chromatography (HPLC). The results showed that 100 mg/kg Pur normalized the levels of Glu and GABA in the hippocampus of Ovx mice, while the Glu level was significantly elevated from 24.1+/- 4.5 to 27.9+/- 3.5 mg/g protein (P < 0.05), and GABA was decreased from 5.64+/- 1.06 to 4.73+/- 0.85 mg/g protein (P < 0.05). The results indicated that Pur possessed phytoestrogen activity,and long-term treatment of Pur ameliorated learning and memory deficits of Ovx mice through affecting the activity of the glutamatergic/GABAergic system in the hippocampus.

Animals↗

PubMed2003

[Determination of salbutamol in human plasma by column-switching HPLC with UV detection].

OBJECTIVE: To make better the RP-HPLC method with column-switching technique for the determination of salbutamol in human plasma. METHODS: A high-pressure flow channel selection valve and Kromasil C18 pretreatment column (20 x 4 mm, 5 microns), Ultrasphere Cyano analysis column (250 mm x 4.6 mm, 5 um, Beckman) were used. To the plasma sample 1.0 ml, 0.5 ml phosphate buffer (2.0 mol/L, pH 9.0) containing 0.4% diphenylboric acid 2-aminoethyl ester was added, then extraction was performed with the use of 4.0 ml chloroform containing 1% tetraoctylammonium bromide. The organic layer was removed and extracted again with 300 microliters (0.08 mol/L) acetic acid. 100 microliters of the acid layer was injected onto the column. The mobile phase of pH 2.8, 0.025 mol/L phosphate buffer-acetonitrile-methanol (95:4:1) was pumped at the rate of 0.9 and 1.0 ml.min-1 through the pretreatment and analysis column, respectively. The column-switching time was from 0.7 min to 1.5 min. The detector at 0.002 aufs was set at 224 nm. RESULTS: The retention time for salbutamol was 6.7 min and that for internal standard (morphine) 7.6 min. The standard curve was linear over the concentration range from 0.5 to 32 micrograms/L. The lowest concentration of detection in plasma was 0.5 microgram/L. The method recovery was 96%-107%; the intra-day RSD less than 5%; the inter-day RSD less than 8%. CONCLUSION: This method was found to be simple, rapid, sensitive and accurate for determination of salbutamol in human plasma.

Adrenergic beta-Agonists↗

PubMed2002

Is there a one-to-one correlation between gastric emptying of liquids and gastric myoelectrical or motor activity in dogs?

The aim of this study was to investigate the correlation of gastric emptying with gastric myoelectrical activity recorded from internal serosal electrodes and with gastric motility measured from strain gauges. The study was performed in eight healthy dogs chronically implanted with four pairs of electrodes and two strain gauges on the gastric serosa and equipped with a duodenal fistula for the assessment of gastric emptying. Each dog was fed four liquid test meals on four separate days with identical calories (320 kcal) and volume (473 ml). A correlation was found between gastric emptying and the energy of contraction in the frequency band of 3.75-7.50 cycles/min during the first 30 min after the meal (r = 0.46, P < 0.05). While none of the parameters of gastric myoelectrical activity was correlated with gastric emptying, two major parameters, percentage of regular gastric slow waves and percentage of slow-wave coupling, were found to be associated with delayed gastric emptying. A significant correlation was found between the frequency of gastric slow waves and that of the contractions in both fasting (r = 0.83, P < 0.001) and fed state (r = 0.70, P < 0.001 at 30 min, r = 0.86, P < 0.001 at 60 min). It was concluded that gastric emptying is correlated with the strength of gastric contractions in a frequency range identical to that of the gastric slow waves, and there is no one-to-one correlation between gastric emptying of liquids and any parameters of gastric myoelectrical activity. However, major parameters of gastric myoelectrical activity are associated with gastric emptying.

Animals↗