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Biomedical subjects

B G Wang

Publications and source records attributed to B G Wang.

15 recordsLinked to original sources
PubMed2001

Aglacins A-D, first representatives of a new class of aryltetralin cyclic ether lignans from Aglaia cordata.

Four new metabolites, aglacins A-D (1-4), were identified from the methanol extract of the stem bark of Aglaia cordata. These compounds represent a new class of aryltetralin cyclic ether lignan. The structure of aglacin A (1) including the absolute configuration was elucidated by interpretation of spectral data, X-ray crystal structure determination, and employing the modified Mosher's method. In addition, three other derivatives, aglacins B-D (2-4), were isolated and identified by spectral means.

Chromatography, High Pressure Liquid↗
PubMed2001

[Determination of volatile organic compounds in atmospheric environment].

It is well known that volatile organic compounds (VOCs) are the main photochemical pollutants and ozone precursors of the photochemical smog. Investigation of photochemical pollution in the ambient air must focus on VOCs, but the concentration of VOCs in ambient air is in a very low level (10(-9)-10(-12), volume fraction), so there are difficulties in the determination of VOCs. In this work, based on the TO14A and TO15 methods recommended by the Environmental Protection Agency of United States, an improved method for the determination of fifty-six VOCs, mainly O3 precursors, in atmospheric environment was developed. Operating conditions of VOCs preconcentrator, gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were optimized. Air sample was first frozen by liquid nitrogen, and then H2O and CO2 were eliminated in the VOCs preconcentrator. The preconcentrated VOCs sample was injected to GC and detected by MS or hydrogen flame ionization detector (FID). The C2-C10 hydrocarbons were separated effectively in capillary columns under the high concentration of CO2. The detection limits were 0.1 microgram.m-3 and the relative standard deviations were in the range from 2.57% to 9.82%. This method has been used for the determination of VOCs in real samples. The results were satisfactory.

Air Pollutants↗
PubMed2000

Chemical constituents of two Chinese Magnoliaceae plants, Tsoongiodendron odorum and Manglietiastrum sinicum, and their inhibition of platelet aggregation.

Phytochemical investigations of Tsoongiodendron odorum and Manglietiastrum sinicum, both Magnoliaceae, led to the isolation of twenty compounds in total. Among them, one was a new sesquiterpene, 11-O-oleoyl-beta-eudesmol (2), and another, 1-(3,4-dimethoxypheny)-4-(3,4-methylenedioxyphenyl)-2,3-dimethy lbutane (12) was isolated as a natural product for the first time. Moreover, 13C-NMR spectral data of isoguaiacin (16) are reported here for the first time. Structure elucidations for compounds reported here were mainly based on their spectral data. The ethanolic extracts of T. odorum and M. sinicum, and six pure compounds, 4(15)-eudesmen-11-ol (beta-eudesmol) (1), 1 beta-hydroxy-4(15),11(13)-eudesmadien-12,6 alpha-olide (reynosin) (3), 3,11(13)-eudesmadien-12,6 alpha-olide (alpha-cyclocostunolide) (5), erythro-1-(4-hydroxy-3-methoxyphenyl)-4-(3,4-methylenedioxyphenyl)-2,3- dimethylbutane (11), nectandrin-B (18), and syringaresinol (19), displayed considerable inhibition against platelet aggregation induced by AA, by ADP, or by PAF.

Humans↗
PubMed2000

Structural revision of four spiramine diterpenoid alkaloids from the roots of Spiraea japonica.

On the basis of detailed 1H-NMR 13C-NMR spectral analysis, especially by 2D NMR experiments (1H-1H COSY, HMQC, HMBC, and NOESY) as well as by chemical transformations. four isoatisine type diterpenoid alkaloids, spiramines P and Q, and U and T, have been reassigned as the 6beta hydroxyl and 6beta acetoxyl substituents, respectively, rather than the previously assigned 15alpha counterparts in our further studies on chemical constituents of the roots of Spiraea japonica var. acuta.

Alkaloids↗
PubMed1999

Local recurrence risk after skin-sparing and conventional mastectomy: a 6-year follow-up.

In this study, the records of all patients at the University of Texas M. D. Anderson Cancer Center with T1 or T2 breast cancer who were treated between March of 1986 and November of 1990 with mastectomy followed by immediate breast reconstruction were reviewed for the presence of recurrent disease. Patients with in situ disease were not included. Patients were included in the study if a local recurrence occurred (regardless of the length of follow-up) or if a follow-up of 6 years or longer could be obtained. Patients were grouped according to the use or nonuse of skin-sparing mastectomy, by tumor stage, and by nuclear grade of the tumor. The series included 154 patients, of whom 114 had skin-sparing mastectomies and 40 had nonskin-sparing mastectomies. The local recurrence rate in the skin-sparing mastectomy group was 7.0 percent, whereas in the nonskin-sparing mastectomy group it was 7.5 percent. The sample size in the nonskin-sparing mastectomy group was too small for meaningful statistical analysis, but the data suggest that there is no clinically important difference in recurrence rates between the two groups. We conclude that the use of skin-sparing technique for early breast cancer patients does not significantly increase the risk of tumor recurrence after mastectomy.

Breast Neoplasms↗
PubMed1998

Drug-induced vasodilation: in vitro and in vivo study on the effects of lidocaine and papaverine on rabbit carotid artery.

Flap ischemia is often encountered during pedicled and free tissue transfer. In this study, the vascular effects of varying doses of lidocaine, papaverine, and a combination of the two agents were evaluated and compared in an in vitro and in vivo model in the rabbit carotid artery. In the in vitro study, 14 rings from the rabbit carotid artery were bathed in Krebs-Ringers solution and stretched progressively to an optimal tension of 3.7-4.2 grams. Their isometric contractile activity was measured. The specimens were precontracted with norepinephrine (1 microM), and a dose response curve was established by adding cumulatively either lidocaine (to 7 arterial rings) or papaverine (to 7 arterial rings) at increasing concentrations. In the in vivo study, microvascular anastomoses were performed bilaterally in the rabbit carotid artery in 30 animals using 9-0 nylon suture and standard microsurgical techniques. In each animal, one side was treated with heparinized sodium chloride and served as the control. The other side was treated blindly, during and after the anastomoses, with a topical application of 1 ml of either lidocaine 2% (n = 5), lidocaine 20% (n = 5), papaverine (30 mg/ml, n = 5), lidocaine 2% combined with papaverine (30 mg/ml, n = 5), or lidocaine 20% combined with papaverine (30 mg/ml, n = 5). For 30-60 minutes after the procedure, blood flow changes in the vessels were continuously monitored with a transonic doppler applied to both carotid arteries. The 20% lidocaine group was flushed with saline at the end of the first hour and monitored for an additional 60 minutes. Papaverine elicited a concentration-dependent relaxation of norepinephrine precontracted carotid artery rings in vitro. Lidocaine elicited a biphasic response, with low concentrations (10(-6)-10(-4) M) increasing the norepinephrine-induced contraction and high concentrations (10(-4)-10(-2) M) relieving this contraction. Microsurgical anastomosis produced a significant decrease of blood flow through the rabbit carotid artery as measured by the transonic doppler. Drug application did not alter the systemic blood pressure of the animals. Topical application of lidocaine 2% did not significantly change the blood flow after microvascular anastomosis. Topical application of lidocaine 20%, papaverine (30 mg/ml), or lidocaine (2% or 20%) combined with papaverine significantly increased the blood flow in the rabbit carotid artery. In the lidocaine 20% group, the blood flow remained significantly increased after the drug was flushed with heparinized saline solution. These results demonstrate that topical lidocaine 20%, papaverine, and lidocaine 2% or 20% combined with papaverine significantly increase blood flow in the rabbit carotid artery after microvascular anastomosis. The data confirm the use of papaverine and lidocaine 20%, alone or in combination, as spasmolytics during clinical microsurgery. This suggests that lidocaine 2% alone is not the ideal drug to relieve vascular constriction, and further studies on the clinical use of low concentrations of topical lidocaine in microsurgery is warranted.

Animals↗
PubMed1998

A comparison of resource costs of immediate and delayed breast reconstruction.

The resource cost (cost to our hospital) of providing mastectomy plus breast reconstruction was calculated for 276 patients who had received both mastectomy and breast reconstruction at our institution. All patients had completed the entire reconstructive process, including reconstruction of the nipple. The resource costs of providing mastectomy with immediate breast reconstruction were compared with those of mastectomy with subsequent delayed reconstruction. We found that the mean resource cost for the 57 patients who had separate mastectomy followed by delayed breast reconstruction ($28,843) was 62 percent higher than that of mastectomy with immediate reconstruction ($17,801; n = 219, p < 0.001). Similar differences were found when patients were subgrouped by type of reconstruction (TRAM versus tissue expansion and implants), by laterality (unilateral versus bilateral), and by history of preoperative irradiation. We conclude that mastectomy with immediate breast reconstruction is significantly less expensive than mastectomy followed by delayed reconstruction and can potentially conserve resources.

Breast Neoplasms↗
PubMed1998

Fat necrosis in free and pedicled TRAM flaps.

One purported advantage of the free transverse rectus abdominis musculocutaneous (TRAM) flap for breast reconstruction is that, compared with the conventional TRAM flap, it has a better blood supply and therefore a lower incidence of fat necrosis. We tested this claim by reviewing the incidence of fat necrosis, both clinically and mammographically, in a group of 110 patients with 116 TRAM flap breast reconstructions who had undergone mammography of their reconstructed breasts. Of the 49 breasts reconstructed with free TRAM flaps, 4 (8.2 percent) had clinically evident fat necrosis, and 1 (2.0 percent) had fat necrosis that was detectable by mammography. Of the 67 breasts reconstructed with conventional TRAM flaps, 18 (26.9 percent) had clinically detectable fat necrosis, and 9 (13.4 percent) had fat necrosis that was detectable mammographically. Both of these differences were statistically significant (p = 0.0113 for clinical fat necrosis; p = 0.031 for mammographic fat necrosis). Fat necrosis was more common in patients who were obese or had a history of smoking, but neither association was statistically significant. We conclude that the use of the free TRAM flap reduces the incidence of fat necrosis in the reconstructed breast.

Abdominal Muscles↗
PubMed1997

A comparison of resource costs for head and neck reconstruction with free and pectoralis major flaps.

A series of 178 immediate reconstructions with regional or distant tissue for repair of oropharyngeal defects caused by treatment of head and neck cancer was reviewed to determine whether reconstruction with free flaps was more or less expensive than reconstruction with regional myocutaneous flaps. In this series, three types of flaps were used: the radial forearm free flap (n = 89), the rectus abdominis free flap (n = 56), and the pectoralis major myocutaneous flap (n = 33). Resource costs were determined by adding all costs to the institution of providing each service studied using salaried employees (including physicians). The two free-flap groups were combined to compare free flaps with the pectoralis major myocutaneous flap, a regional myocutaneous flap. Failure rates in the two groups were similar (3.0 percent for pectoralis major myocutaneous flap, 3.4 percent for free flaps). The mean costs of surgery were slightly higher for the free flaps, but the subsequent hospital stay costs were lower. Therefore, the total mean resource cost for the free-flap group ($28,460) was lower than the cost for the myocutaneous flap group ($40,992). The pectoralis major myocutaneous flap may have been selected for more patients with advanced disease and systemic medical problems, contributing to longer hospitalization and added cost. Nevertheless, this study suggests that free flaps are not more expensive than other methods and may provide cost savings for selected patients.

Age Factors↗
PubMed1997

Comparison of nipple projection with the modified double-opposing tab and star flaps.

This study compared nipple projection after nipple reconstruction (following breast mound reconstruction) with either the modified double-opposing tab flap or the star flap. Areolar reconstruction and pigmentation of the nipple were achieved with tattooing. Nipple projection for 153 nipples was measured at least 6 months after the reconstruction, when projection was believed to have become stable. Mean follow-up was 2.27 years. In the 106 nipples reconstructed with modified double-opposing tab flaps, the mean projection was 2.4292 mm, while in the 47 nipples reconstructed with star flaps, the mean projection was 1.9681 mm (p = 0.021). We conclude that although both methods are effective, the modified double-opposing tab flap has slightly more projection after approximately 2 years. It is not known, however, whether this is because of reduced flap atrophy or longer initial projection by the modified double-opposing tab flap; further studies are ongoing.

Female↗
PubMed1994

[A study on combined acupuncture and enflurane anesthesia for craniotomy].

The reinforcing effect of transcutaneous acupoint electric stimulation (TAES) with enflurane anesthesia during craniotomy was studied. 110 neurosurgical patients were randomly divided into three groups. Anesthesia was maintained with enflurane in group A (n = 40); in group B, enflurane anesthesia was supplemented by TAES with Han's acupoint nerve stimulator (HANS) at Hegu, Yuyao and Fengchi points on the operated side (n = 40); in group C, enflurane anesthesia was supplemented by TAES and scalp infiltration with 0.5% procaine (n = 30). The results showed that the minimum alveolar concentration (MAC) of enflurane in group B and C decreased 37.8-47.0% and 42.1-66.1% respectively than that in group A. The hemodynamics was more stable during operation, and the patients recovered faster after operation in group B and C. It was concluded that TAES with HANS significantly potentiated the anesthetic effect and decreased the side effects of enflurane during operation, and that the triple combination of TAES, enflurane and scalp infiltration with procaine proved to be a better anesthetic method for craniotomy.

Acupuncture Analgesia↗
PubMed1994

Bilateral breast reconstruction: conventional versus free TRAM.

Free TRAM flap transfer is now routinely offered to patients requiring breast reconstruction. This study compares results of conventional superior-pedicled TRAM flaps and free TRAM flaps in bilateral breast reconstructions. A total of 92 breasts were reconstructed in 46 patients. Eighteen patients had free TRAM flap reconstructions, and 28 patients were reconstructed with conventional TRAM flaps. Comparison of average operative blood loss and average operative time for the two techniques showed blood loss of 575 cc and an operative time of 9.6 hours for the free TRAM reconstructions and a blood loss of 313 cc and an operative time of 6.6 hours for the conventional TRAM reconstructions. For free TRAM flap reconstructions, both blood loss and operative time decreased significantly between the first and second group of nine patients: from 819 to 360 cc of blood loss and from 10.5 to 8.9 hours of operative time. Partial flap loss (skin and fat necrosis) and fat necrosis only occurred in 13 and 7 percent, respectively, of conventional TRAM flaps, but neither occurred in free TRAM flaps. However, early in the series, three free flaps were lost in two patients, requiring implant placement. Bilateral breast reconstruction using the free TRAM flap may offer a lower complication rate than the conventional TRAM flap by virtue of improved blood supply and less abdominal wall disruption. Surgeons, however, are forewarned that this procedure has a steep learning curve, and surgeons lacking microsurgical expertise may be better served by the conventional TRAM flap.

Blood Loss, Surgical↗
PubMed1989

Aircraft noise-induced temporary threshold shift.

Audiograms were taken on 20 young men before and immediately after exposure to Fighter-6 ground running-up noise, and their course of recovery was followed. The sound levels at the engine hatch were 117-128 dB(A). The noise-induced temporary threshold shift was more than 13 dB. The maximum threshold shift occurred at 4 kHz. The shift in the low and speech frequencies recovers more rapidly and is completed in 30 min, whereas that in the high-frequency range recovers much more slowly, not returning to normal until 24 h later. High-frequency hearing loss is at risk in groundcrew. In order to prevent hearing damage, they ought to wear ear-protectors. We discovered that the V-shaped depression was not at 4 kHz but at 6 kHz. The former view concerning the pathogenesis of "4 kHz depression", therefore, is open to question. This interesting subject warrants further study.

Adolescent↗