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Biomedical subjects

S M Liu

Publications and source records attributed to S M Liu.

At least 19 recordsLinked to original sources
PubMed2006

Increasing COPD awareness.

Early diagnosis and smoking cessation are the only available methods to stop the progression of chronic obstructive pulmonary disease (COPD). The aim of this study was to evaluate the effects of early detection of airflow limitation (AL) in a population with high risk for COPD, using spirometric screening. Smokers aged 40 yrs with a smoking history of 10 pack-yrs were invited to visit a local outpatient chest clinic for simple spirometry (forced expiratory volume in one second (FEV1) and forced vital capacity (FVC)). Smoking history was recorded, followed by smoking cessation advice relating the results of spirometry to the smoking behaviour. Subjects who did not fulfil the above criteria (younger and/or nonsmokers) were also screened. A total 110,355 subjects were investigated; they were aged 53.5+/-11.5 yrs and 58.2% were males. Of the total amount of subjects, 64% were current smokers, 25.1% were former smokers and 10.9% were lifelong nonsmokers. Spirometry tests were within normal values for 70.3%, and 20.3% showed signs of AL: this was mild in 7.6%, moderate in 6.7% and severe in 5.9%. The remaining 8.3% of subjects presented with a restrictive pattern of ventilatory impairment. Airflow limitation was found in 23% of smokers aged 40 yrs with a history of 10 pack-yrs. This study concluded that large-scale voluntary spirometry screening of the population with high risk for COPD detects a large number of subjects with AL.

Adult↗
PubMed2003

Teratogenic effects of chronic ingestion of high levels of vitamin A in cats.

High concentrations of retinoids occur in some commercial cat food formulations as a result of the use of animal liver as an ingredient. Our objective was to study the teratogenic potential of dietary vitamin A in cats. We investigated the incidence of birth defects in kittens of queens given diets with retinyl acetate concentrations of 6000, 306000, or 606000 retinol equivalents (RE)/kg diet (control, 306K, or 606K groups, respectively) for approximately 3 years [1 RE=1 micro g retinol=3.3 International Units (IU)]. Each group comprised 12-15 age-matched, nulliparous domestic short-haired queens that were exposed to toms. There were a total of 396 kittens born in 97 litters. Pregnancy rate, number of kittens per gestation and gestations per year were not significantly different among treatment groups. A total of 2, 5 and 11 malformed kittens occurred in the control, 306K and 606K groups, respectively. Malformations included cleft palate, cranioschisis, foreshortened mandible, stenotic colon, enlarged heart and agenesis of the spinal cord and small intestine, which are typical foetal defects consistent with ingestion of excess retinoids in other species. This study demonstrated that a concentration of 306000 RE/kg diet has a potential for causing birth defects in the kittens.

Abnormalities, Drug-Induced↗
PubMed2003

Cutaneous smooth muscle tumors in the dog and cat.

Cutaneous smooth muscle tumors may arise from arrector pili muscles and from smooth muscles of the dermal vasculature. This report describes histologic and immunohistochemical features of eight arrector pili hamartomas in 8 dogs, 15 piloleiomyomas in 10 dogs and 3 cats, 10 piloleiomyosarcomas in 9 dogs and 1 cat, 1 angioleiomyoma in 1 cat, and 9 angioleiomyosarcomas in 6 dogs and 3 cats. Hamartomas and tumors arising from arrector pili muscles preferentially originated from the dorsal trunk. 5/5 (100%) arrector pili hamartomas, 10/12 (83%) piloleiomyomas, 4/5 (80%) piloleiomyosarcomas, 1/1 (100%) angioleiomyoma, and 6/7 (86%) angioleiomyosarcomas were positive for smooth muscle actin. 5/5 (100%) arrector pili hamartomas, 10/12 (83%) piloleiomyomas, 4/5 (80%) piloleiomyosarcomas, 1/1 (100%) angioleiomyoma, and 1/7 (14%) angioleiomyosarcomas were positive for desmin. Two incompletely excised canine angioleiomyosarcomas recurred locally. Metastases were not reported.

Animals↗
PubMed2001

Prospective study of Helicobacter pylori eradication therapy in stage I(E) high-grade mucosa-associated lymphoid tissue lymphoma of the stomach.

PURPOSE: High-grade mucosa-associated lymphoid tissue (MALT) lymphomas of the stomach are generally believed to be Helicobacter pylori-independent, autonomously growing tumors. However, anecdotal cases of regression of high-grade lymphomas after the cure of H pylori infection had been described. The present prospective study was conducted to evaluate the effect of anti-H pylori therapy in stage I(E) high-grade gastric MALT lymphomas. PATIENTS AND METHODS: Sixteen patients with H pylori infection and stage I(E) gastric high-grade MALT lymphoma consented to a brief antibiotic therapy as first-line treatment from June 1995 through April 2000. Then, patients underwent intensive endoscopic follow-up examinations (+/- endoscopic ultrasonography) with biopsy to evaluate tumor response. Patients with significant improvement of gross lesions that accompanied regression of large cells were followed up without additional treatment. Patients without significant improvement were immediately referred to systemic chemotherapy. RESULTS: Eradication of H pylori was achieved in 15 patients and was accompanied by rapid gross tumor regression and disappearance of large cells in 10. All 10 of these patients with early response had subsequent complete histologic remission of lymphoma. The complete remission rate was 62.5% (95% confidence interval, 35.8% to 89.1%). The response rate was not affected by the tumor grading (proportion of large blast cells within the tumor) but was adversely affected by the depth of tumor invasion. At a median follow-up of 43.5 months (range, 21.1 to 67.4 months), all 10 of these patients remained lymphoma-free. The median duration of complete response was 31.2 months (range, 14.4 to 49.1 months). CONCLUSION: These results suggest that high-grade transformation is not necessarily associated with the loss of H pylori dependence in early-stage MALT lymphomas of the stomach.

Adult↗
PubMed2001

[Study of acute supratentorial and infratentorial localized lesions by transcranial Doppler].

OBJECTIVE: To evaluate the correlation between increased intracranial pressure in supratentorial, infratentorial and TCD parameters of basal arteries. METHODS: Sixteen New Zealand white rabbits were randomly divided into two groups: supratentorial group and infratentorial group. Intracranial pressures were raised after inflation of a preplaced epidural balloons. TCD parameters of the BA, rMCA were examined at intervals of 15 minutes after inflation of the balloon. ICP, ASP, HR, R were also recorded simultaneously. RESULTS: 1. The normal spectra of BA were characterized by a high-resistance, low-flow waveform. 2. At the 0.4 ml, 0.5 ml balloon volume level, ICP in supratentorial group was significantly increased than that in infratentorial group; 3. The correlation between ICP and MCA's TCD parameters were better than that between ICP and BA's TCD parameters in the supratentorial group. In the infratentorial group, the correlation between ICP and BA's TCD parameters were better than that between ICPs and MCA's TCD. CONCLUSIONS: 1. There are intracranial pressure gradients in mass lesions, so fibroptic probe should be placed at the place where the mass lesion takes place. 2. To perform non-invasive ICP monitoring by TCD, the basal artery should be chosen according to the mass lesions.

Acute Disease↗
PubMed2001

[Changes in somatosensory evoked potentials and brainstem auditory evoked potentials during acute intracranial hypertension in rabbits].

OBJECTIVE: To study the changes in somatosensory evoked potentials (SEPs) and brainstem auditory evoked potentials (BAEPs) during intracranial hypertension. METHOD: A rabbit model of acute intracranial hypertension was developed. Thirty New Zealand rabbits were divided into 3 group. Both Group A and B were groups with intracranial hypertension; Group C was the control group. In Group A, balloons were placed to the right parietal lobe beneath the dura mater; in Group B, to temporal at the middle fossa near the brainstem. RESULT: (1) In Group A, when ICP rose to (1.48 +/- 0.35) kPa, P1 amplitude of SEPs was significantly changed, whereas latencies of Wave IV, V, and VII of BAEPs were prolonged when ICP rose to (9.40 +/- 1.60) kPa. In group B, P1 amplitude of SEPs was changed when ICP reached (8.10 +/- 1.25) kPa, and latency of Wave III of BAEPs was prolonged when ICP rose to (3.11 +/- 0.80) kPa. (2) P1 amplitude increased with ICP value when the balloon volume increased from V = 0.0 ml, ICP = (0.43 +/- 0.10) kPa to V = 0.4 ml, ICP = (2.44 +/- 0.65) kPa and then decreased afterward. CONCLUSIONS: (1) Changes in SEPs and BAEPs relate to not only ICP value but also the location of the balloon. (2) With the increasing of ICP, P1 amplitude increases firstly and then decreases.

Animals↗
PubMed2001

Biotransformation of p-toluic acid in anoxic estuarine sediments under a CO2 or N2/H2 atmosphere.

The composition of the headspace gas affected the growth dynamics of microbial populations and the biotransformation pattern of p-toluic acid in anoxic estuarine sediments. Under CO2 atmosphere, p-toluic acid was transformed by the sediment microorganisms without a lag period, while under N2/H2 atmosphere, p-toluic acid was transformed after a lag period of 55 days. Under the N2/H2 atmosphere, the methanogen population, following a rapid increase of almost two orders of magnitude, remained at a high level until just before the onset of biotransformation. We hypothesize that during the lag period, the hydrogenotrophic methanogens were removing the H2, a step which is essential before the reaction can be exergonic. Acetogenic bacteria did not initiate decarboxylation as the first step of biotransformation under either atmosphere. Neither the methanogens nor the acetogenic bacteria appeared to be directly involved in the biotransformation of p-toluic acid under either atmosphere. Under the CO2 atmosphere, biotransformation of p-toluic acid involved sulfate-reducing bacteria, while under N2/H2, both sulfate-reducing bacteria and other eubacteria were involved.

Bacteria↗
PubMed2001

Anaerobic biodegradation of DDT residues (DDT, DDD, and DDE) in estuarine sediment.

The potential for anaerobic biodegradation of 1,1,1-trichloro-2,2-bischlorophenylethane (DDT), 1,1-dichloro-2,2,-bischlorophenylethane (DDD), and dichlorodiphenylchloroethylene (DDE) in anoxic sediment slurries collected from the Keelung River was investigated in this study. o,p'- and p,p'-DDT were dechlorinated to o,p'- and p,p'-DDD, respectively, and then transformed to other compound(s). 1-Chloro-2,2-bis (p-chlorophenyl) ethylene (DDMU) and trace amount of dichlorobenzophenone (DBP) were detected in sediment slurries amended with p,p'-DDT or p,p'-DDD. DDMU was also detected in sediment slurries amended with p,p'-DDE. The relative transformation rates for both o,p'- and p,p'-isomers of DDT, DDD, and DDE were DDT>DDD>DDE. Re-addition of DDT, DDD, or DDE to the sediment slurries after initial removal enhanced the respective dechlorination rates. The transformation rates of the p,p'-isomers of both DDT and DDD were faster than those of the respective o,p'-isomers. p,p'-DDT dechlorination in the p,p'-DDT-adapted sediment slurries were inhibited by the addition of molybdate, or molybdate plus sulfate, but not inhibited by the addition of sulfate. Addition of bromoethane-sulfonic acid (BESA) slightly inhibited p,p'-DDT dechlorination. Non-adapted sediment slurries lost the ability to dechlorinate pentachlorophenol during adaptation to p,p'-DDT. p,p'-DDD was the major transformation product of p, p'-DDT in 3,4,4',5-tetrachlorobiphenyl-adapted sediment slurries, which suggested that the microbial community in the 3,4,4',5-CB-adapted sediment was unable to remove chlorine from the aromatic rings of p,p'-DDT.

Alkanesulfonic Acids↗
PubMed2001

Transgenic complementation of leptin-receptor deficiency. I. Rescue of the obesity/diabetes phenotype of LEPR-null mice expressing a LEPR-B transgene.

Mice homozygous for the Leprdb3J (db3J) mutation are null for all known isoforms of the leptin receptor (LEPR). These animals are obese, hyperphagic, cold intolerant, insulin resistant, and infertile. Mice homozygous for the Leprdb (db) mutation (lacking the B isoform only) have the same phenotype as db3J animals. To better understand the function(s) of the LEPR isoforms in vivo, we generated db3J/db3J and db/db mice bearing a transgene (neuron-specific enolase [NSE]-Rb) expressing the B isoform of LEPR, the isoform capable of activating the signal transducer and activator of transcription (STAT) pathway, under the control of the neuron-specific enolase enhancer/promoter. The NSE-Rb transgene was expressed in the brain, with low levels of expression in adrenals, testis, and white adipose tissue. LEPR-B transgene expression in NSE-Rb db3J/db3J mice partially corrected the increased fat mass, hyperphagia, and glucose intolerance while restoring fertility in males and rescuing the cold intolerance in both sexes. The body weights of NSE-Rb transgenic mice that possessed the full complement of short LEPR isoforms (NSE-Rb db/db mice) were similar to those of NSE-Rb db3J/db3J mice, suggesting that the short LEPR isoforms play little role in body weight regulation. Based on quantitative analysis of hypothalamic neuropeptide gene expression in the transgenic animals, we infer full restoration of leptin sensitivity to proopiomelanocortin (POMC) neurons, partial correction of leptin sensitivity in agouti gene-related protein (AGRP)/neuropeptide Y (NPY) neurons, and a lack of effect on leptin sensitivity of melanin concentrating hormone neurons. Thus, hypothalamic POMC and AGRP/NPY neurons are primary candidates as the mediators of the effects of the NSE-Rb transgene on energy homeostasis, ingestive behavior, the neuroendocrine system, and glucose metabolism.

Adaptation, Physiological↗
PubMed2001

Methods to improve the preservation of peritoneal tissues.

Peritoneal mesothelial cells are easily detached during conventional tissue processing, which may result in artifacts in peritoneal tissue examination. Therefore, in the present study, we investigated several methods to improve the preservation of the anterior parietal peritoneal tissues. Peritoneal tissue from the anterior abdominal wall was taken from each of 5 rats killed for the experiment. Tissue samples were immediately treated by one of these methods: (1) fixed with 10% formaldehyde; (2) fixed with Bouin's solution; (3) fixed with Helly's solution. After fixation, the samples were dehydrated with one of (a) ethanol, 1 hour in each step; (b) ethanol, 15 minutes in each step; or (c) tertiarybutyl alcohol. Five sections were taken from each tissue and stained with hematoxylin and eosin. The quality of tissue fixation was evaluated by image analysis. Peritoneal mesothelial cells were well preserved after fixation with Helly's solution or Bouin's solution. With 10% formaldehyde, about 40% of the mesothelial cells were lost. Dehydration with ethanol--especially long-duration dehydration--increased the loss. However, dehydration with tertiarybutyl alcohol avoided the increased loss of mesothelial cells. The submesothelial extracellular matrix was well preserved with Bouin's solution, but not with the other fixatives. Our results suggest that fixation with formaldehyde and dehydration with ethanol results in significant loss of peritoneal mesothelial cells and submesothelial extracellular matrix in peritoneal tissues. Fixation with Bouin's solution and dehydration with tertiary-butyl alcohol may be a better method of preserving peritoneal tissue.

Animals↗
PubMed2001

Increased peritoneal membrane permeability is associated with abnormal peritoneal surface layer.

OBJECTIVES: We recently showed that the peritoneal surface layer may be an important barrier in modulating peritoneal membrane permeability. In the present study, we investigated the relationship between an increased peritoneal transport rate and the peritoneal surface layer. METHODS: Male Sprague-Dawley rats (n = 8) received intraperitoneal injections of 4.25% glucose dialysate daily for 1 week. Forty-eight hours after the last injection, a 4-hour dwell study using 25 mL 4.25% glucose dialysate was performed in each rat. The results were compared with those from control rats that received no intraperitoneal injections (n = 8). The peritoneal fluid and small-solute transport characteristics were evaluated. The peritoneal surface layer was studied using an electron microscope. The phospholipids content of the dialysate was also evaluated. RESULTS: Peritoneal fluid removal was significantly reduced in the daily injection group (30.6 +/- 1.3 mL) as compared with the control group (38.2 +/- 0.6 mL). The peritoneal fluid absorption rate and small-solute transport rate were also significantly higher in the daily injection group as compared with the control group. The amounts of phospholipids in the dialysate were significantly lower in the daily injection group--especially the quantity of phosphatidylcholine. However, lysophosphatidylcholine increased significantly in the daily injection group. Electron microscopy showed that the peritoneal surface layer was almost completely gone in the daily injection group, but that a dense and thick (average 4 microm) peritoneal surface layer was present on the top of the mesothelial cells in the control group. CONCLUSIONS: Our results suggest that daily injection of hypertonic glucose dialysate significantly increased the peritoneal transport rate. The increased peritoneal transport rate was associated with a significant reduction in the peritoneal surface layer and the phospholipids content of the dialysis effluent.

Animals↗
PubMed2000

Interlaboratory study of identification and quantitation of multiresidue pyrethroids in agricultural products by gas chromatography-mass spectrometry.

This paper deals with the different GC-MS analytical conditions adopted by four laboratories in an attempt to confirm the accuracy of the GC-electron-capture detection (ECD) analytical results during the international collaborative study for the establishment of the AOAC Official Method 998. 01. What is especially noted is that two laboratories have conducted comparative analysis of the respective 12 blind samples with both methods of GC-ECD and GC-MS, and the analytical results of the two methods turn out to be basically identical. This fully demonstrates that GC-MS is not only an effective confirmation tool in the analysis of the pyrethroid residues but also of sufficient sensitivity regarding the maximum residue limit of determination prescribed by FAO/WHO. Moreover, its selectivity is better than GC-ECD.

Gas Chromatography-Mass Spectrometry↗
PubMed2000

Control strategies for initiation of human gait are influenced by accuracy constraints.

The accuracy of placement of swing limb heel-strike was used to determine strategies of motor control of the stance limb during gait initiation (GI). Subjects initiated gait as fast as possible with the swing limb heel-strike landing on either a small or large target. Stance limb ground reaction forces, electromyogram duration and temporal data for GI were measured. It was hypothesized that accuracy would affect movement speed and the rate of rise, or the slope, of the ground reaction forces that control GI. The slopes of the stance limb forces that coincide with swing limb toe-off remained invariant. However, the slopes of forces and peak forces related to swing limb heel-strike were significantly less for the small target. These initial data suggest that principles of upper extremity motor control may be generalized to the initiation of movement from upright stance.

Adult↗
PubMed2000

Effects of intravitreal corticosteroids in the treatment of Bacillus cereus endophthalmitis.

OBJECTIVE: To investigate whether intravitreal corticosteroid therapy reduces the extent of inflammatory intraocular tissue damage caused by Bacillus cereus endophthalmitis. METHODS: New Zealand white rabbits were inoculated with 1 x 10(6) B cereus organisms and randomized to receive no treatment (control eyes; n=14), intravitreal vancomycin hydrochloride (n=13), or a combination of intravitreal vancomycin and dexamethasone sodium phosphate (n=13) after 24 hours. The eyes were examined and graded for clinical signs of infection and inflammation on days 7 and 14, followed by enucleation for histopathologic analysis. RESULTS: Both treated groups had significantly less clinical sequelae than controls on day 7. By day 14, eyes given combination treatment had significantly less clinically graded corneal (P=.03) and conjunctival (P=.007) inflammation than eyes treated with vancomycin. Histopathologic analysis revealed a significant decrease in inflammatory changes between all treated eyes and controls at day 14. The only statistically significant difference between eyes given combination treatment and eyes given vancomycin alone was in the retina (P=.03). CONCLUSIONS: Intravitreal corticosteroids may enhance the recovery from B cereus endophthalmitis when given in conjunction with intravitreal antibiotics. The beneficial effect of corticosteroids is noted clinically, but not histologically, by day 14 after single-dose treatment in rabbits. CLINICAL RELEVANCE: This study provides evidence that the use of intravitreal corticosteroids with antibiotics for the treatment of B cereus endophthalmitis may lead to an improvement compared with the use of antibiotics alone. Arch Ophthalmol. 2000;118:803-806

Animals↗
PubMed2000

Signet-ring cell carcinoma of the breast.

Primary signet-ring cell carcinoma of the breast is a very rare tumor and is not recognized as an independent entity of the World Health Organization classification of breast tumor. Primary signet-ring cell carcinoma of the breast is usually considered as a variant of mucinous carcinoma or lobular carcinoma and usually originates from the lobular epithelium. A case of primary signet-ring cell carcinoma of the breast in a 68-year-old woman is presented. Histologically, the majority of neoplastic cells had an intracytoplasmic mucin collection. The histological presence of ductal carcinoma in situ, absence of lobular lesion and immunoreactivity for estrogen and progesterone receptors implicated the tumor cells arising from ductal epithelium. The papillary or organoid growth pattern is characteristic in this case. The patient underwent a modified radical mastectomy and was subsequently followed up for 6 months.

Aged↗
PubMed2000

Spontaneous mutation in the db gene results in obesity and diabetes in CD-1 outbred mice.

Five allelic mutants of the diabetes (db) gene have been previously described in mice and rats causing obesity, infertility, and varying degrees of diabetes. We have identified a new, spontaneous mutation resulting in obesity and diabetes in a colony of CD-1 outbred mice, Mus musculus domesticus. Genetic complementation studies indicated that the new mutation was an allele of the diabetes locus. Sequence analysis of cDNA fragments showed a deletion of one G residue located in exon 12 of the leptin receptor gene. The mutation, Lepr(db-NCSU), results in a frameshift and reduces Lepr transcript levels 10-fold. Mutant mice drank up to four times more water and were up to two times heavier than wild-type mice. Blood glucose and plasma insulin and leptin concentrations were sexually dimorphic among affected mice, suggesting an effect of sex steroids. Mortality of affected males was 100% by 5 mo, whereas affected females survived up to 10 mo of age.

Alleles↗
PubMed2000

Effects of leptin receptor mutation on Agrp gene expression in fed and fasted lean and obese (LA/N-faf) rats.

Agouti-related protein provides an orexigenic signal, probably through interaction with central melanocortin receptors. Expression of Agrp is markedly increased in the hypothalamus of mice deficient in leptin (Lep(ob)/Lep(ob)) or its receptor (Lepr(db)/Lepr(db)), suggesting that leptin mediates signals suppressing Agouti-related protein production. The regulation of Agrp expression in the rat hypothalamus has not been reported. We, therefore, analyzed the expression of Agrp in the medial basal hypothalamus of lean (+/+, +/fa(f)) and obese leptin receptor-deficient (fa(f)/fa(f)) LA/N rats. Using a sensitive solution hybridization/S1 nuclease protection assay, we found no significant difference in Agrp messenger RNA (mRNA) levels (pg/microg total RNA +/- SEM) in obese rats (n = 5), compared with lean controls (n = 5): 0.46 +/- 0.06 vs. 0.47 +/- 0.06 (P = 0.9). Similarly, no difference in Agrp expression was found using in situ hybridization or semiquantitative RT-PCR. In contrast to Agrp, Pomc mRNA levels were significantly suppressed in the obese, compared with the lean, rats (P = 0.001). Thus, the ratio of Pomc to Agrp mRNA is decreased in the obese rats and may be an important modulator of food intake. To assess the physiological regulation of Agrp in rats, we examined the effect of food deprivation in lean Sprague Dawley (SD) rats. There was a 273% increase in medial basal hypothalamus Agrp mRNA in SD rats fasted for 48 h (n = 8), compared with rats fed ad libitum (n = 8): 0.82 +/- 0.23 vs. 0.30 +/- 0.08 (P = 0.0001). Lean LA/N rats (n = 7) fasted for 48 h also showed a 231% increase in Agrp expression, compared with fed lean controls (n = 8): 0.74 +/- 0.11 vs. 0.32 +/- 0.03 (P = 0.002), whereas Pomc expression was decreased by 32% in fasted animals from the same experiment (0.34 +/- 0.05 vs. 0.50 +/- 0.07; P = 0.03). There were no significant differences in Agrp or Pomc mRNA levels between fasted and fed obese LA/N-fa(f) rats. These results suggest that, in the rat, the Agrp response to fasting may involve leptin-mediated phenomena, but factors in addition to leptin must also be involved in the regulation of Agrp gene expression.

Agouti-Related Protein↗