Twin transfusion syndrome associated with placental venous calcification.
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Adult↗
Biomedical subjects
C J Chuong
Publications and source records attributed to C J Chuong.
Medical history in women with premenstrual syndrome.
This study was designed to identify significant factors in the medical history of women with premenstrual syndrome (PMS). Medical history variables of 190 women with PMS were compared with those of a group of 182 women without premenstrual symptoms who sought gynecological care (control group). All the participants were carefully selected by interview and designated questionnaires. Women with a past or present psychiatric history were excluded. The results showed that age, number of children, age of menarche, smoking history and family history of psychiatric disorders of the women with PMS and the controls were similar. Women with PMS exhibited a significantly greater frequency of postpartum depression (43% versus 12%), past birth control pill use (91.6% versus 45.9%), alcohol use (39.5% versus 14.8%) and drug use (48.4% versus 14.1%) than did the controls respectively; all p values were < 0.05). Our data suggest an association between these factors and PMS. They should be identified in women with premenstrual complaints during the initial visit, and the roles of these factors in the pathophysiology of PMS need to be further investigated.
Adult↗
Zinc and copper levels in premenstrual syndrome.
OBJECTIVE: To determine whether changes in peripheral zinc and copper levels are associated with symptoms of premenstrual syndrome (PMS). DESIGN: Ten PMS patients and 10 controls gave blood at 2- or 3-day intervals through three menstrual cycles. Serum zinc and copper were measured by flameless atomic absorption spectrophotometry. RESULTS: In the controls zinc values were not significantly different between the follicular and the luteal phases. In the patients, the values were significantly lower during the luteal phase than during the follicular phase. Lower levels of zinc during the luteal phase in PMS patients, compared with the controls, were noted. Copper levels were noted to be higher during the luteal phase in PMS patients compared with the controls. Because copper competes with zinc for intestinal absorption and serum protein binding sites, zinc:copper ratio can reflect the availability of zinc in the body. The computation of this ratio revealed that the ratio was significantly lower in the patients than those in the controls during the luteal phase. CONCLUSIONS: Our data suggest that zinc deficiency occurs in PMS patients during the luteal phase, and the availability of zinc in PMS patients during the luteal phase is further reduced by the elevated copper.
Adult↗
Periovulatory beta-endorphin levels in premenstrual syndrome.
OBJECTIVE: To determine whether changes in peripheral beta-endorphin levels during the periovulatory phase are associated with symptoms of premenstrual syndrome (PMS). METHODS: Twenty-one PMS patients and ten controls were studied. All were in general good health and had no history of psychiatric disorders. They were between 21-44 years of age, had had regular menses for at least six previous cycles, and were carefully selected by charting the Visual Linear Analogue Scale and basal body temperature daily for 1 month. After an overnight fast, the subjects had blood drawn between 8:00 and 10:00 AM daily for 8 days, starting on the tenth day of the menstrual cycle, for one cycle. Beta-endorphin and LH were measured by radioimmunoassay. The day of the LH peak was defined as day LH 0. The beta-endorphin levels were expressed as the number of days before or after the LH surge. RESULTS: Beta-endorphin levels throughout the periovulatory phase were lower in PMS patients than in controls, and the differences were more remarkable on LH days 0 and 4. CONCLUSION: Our data suggest that an aberration of normal changes in beta-endorphin activity in PMS patients may occur around the time of ovulation.
Adult↗
Effect of naloxone on luteinizing hormone secretion in premenstrual syndrome.
OBJECTIVES: To investigate the theory of brain opioid activity disregulation in premenstrual syndrome (PMS) and to discover the changes of central beta-endorphin activity during the menstrual cycle in PMS patients. DESIGN: Prospective study. SETTING: University-based PMS clinic. PATIENTS: All the patients and controls were between 20 and 45 years of age, with regular menses for at least six previous cycles. All the patients demonstrated at least 30% score increase in designated symptoms on the Visual Linear Analog Scale during the luteal phase compared with the follicular phase. In contrast, the score changes in the controls were < 30%. INTERVENTIONS: All subjects underwent LH-releasing hormone (LH-RH) stimulation test on days 2 to 3 of the cycle. Five naloxone infusions were administered on days 7 to 8 and 10 to 11, 1 day, 3 to 4 days, and 12 to 13 days after the LH surge as detected by the ovulation prediction kit. MAIN OUTCOME MEASURES: Luteinizing Hormone levels were recorded for 1 hour, followed by naloxone infusion at 2 mg/h for 4 hours. Blood samples were collected for LH tests every 15 minutes for 1 hour before, during, and for 1 hour after the infusion. RESULTS: All subjects had similar LH response to LH-RH. The integrated area of LH response to naloxone as expressed by percentage of the baseline on each of the 5 days did not show significant differences between the patients and the controls. CONCLUSIONS: The central beta-endorphin changes, if any, in PMS patients could not be demonstrated in our study.
Adult↗
Successful pregnancy after treatment with recombinant human follicle stimulating hormone.
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Adult↗
A constitutive relation for passive right-ventricular free wall myocardium.
We applied the pseudostrain energy function of Humphrey et al. [J. biomech. Engng 112, 333-346 (1990a, b)] to characterize the passive biaxial mechanical properties of the right ventricle free wall myocardium [Sacks and Chuong, J. biomech. Engng 115, 202-205 (1993)]. The myocardium was assumed to be incompressible, pseudoelastic, and transversely isotropic, with transmural variations in fiber orientation within test specimens accounted for by the strain energy function. Using nonlinear regression, material constants were determined for the right ventricle free wall myocardium from the sinus and conus regions. The pseudostrain energy function was found to model the biaxial mechanical data well (r2 > 0.99). Transmural variations in Cauchy stresses, as well as the magnitude of the in-plane shear stress, were found to be small. Although comparisons with the left ventricle midwall myocardium data [Humphrey et al., J. biomech. Engng 112, 340-346 (1990b)] show clear quantitative differences, there is an overall qualitative similarity in the mechanical behavior of ventricular myocardium.
Animals↗
Pregnancy after metroplasty for uterine anomalies.
OBJECTIVE: To clarify the relation between metroplasty for correction of uterine anomalies and subsequent pregnancy, we reviewed the charts of all patients for whom a diagnosis of bicornuate, septate, or didelphic uterus had been made between 1972 and 1982 and analyzed their obstetric outcomes. DESIGN: Of the 146 patients evaluated, 23 received a metroplasty procedure, and 123 patients did not have surgical intervention. Fifteen of the nonsurgical patients could be matched with 15 of the surgical patients by age, chief complaint, gravidity, and type of anomaly and therefore served as matched controls. RESULTS: The percentage of patients with living children after the diagnosis of uterine anomaly was 67% for the matched nonsurgical group and 73% for the patients who underwent metroplasty. The difference was not statistically significant. Although marked improvement in fetal salvage rates was noted when reproductive outcomes before and after metroplasty were compared, the obstetric outcome was similar to that of the control groups after the diagnosis was made and surgery deferred. CONCLUSION: The efficacy of metroplasty in the treatment of multiple pregnancy losses is thus being questioned.
Adult↗
Term pregnancy after fallopian tube transposition.
A 28-year-old woman suffered from pelvic pain and secondary infertility. She previously had right salpingo-oophorectomy because of ruptured right cornual EP. She was found to have a normal appearing left fallopian tube that entered into a noncommunicating residual horn of the uterus. Microsurgical transposition of the left tube and tubouterine implantation was performed successfully. For cases in which tubocornual anastomosis of the transposed tube is impossible because of previous cornual resection, our technique remains an option.
Adult↗
Acoustic and mechanical properties of renal calculi: implications in shock wave lithotripsy.
The acoustic and mechanical properties of renal calculi dictate how a stone interacts with the mechanical forces produced by shock wave lithotripsy; thus, these properties are directly related to the success of the treatment. Using an ultrasound pulse transmission technique, we measured both longitudinal and transverse (or shear) wave propagation speeds in nine groups of renal calculi with different chemical compositions. We also measured stone density using a pycnometer based on Archimedes' principle. From these measurements, we calculated wave impedance and dynamic mechanical properties of the renal stones. Calcium oxalate monohydrate and cystine stones had higher longitudinal and transverse wave speeds, wave impedances, and dynamic moduli (bulk modulus, Young's modulus, and shear modulus), suggesting that these stones are more difficult to fragment. Phosphate stones (carbonate apatite and magnesium ammonium phosphate hydrogen) were found to have lower values of these properties, suggesting they are more amenable to shock wave fragmentation. These data provide a physical explanation for the significant differences in stone fragility observed clinically.
Humans↗
Biaxial mechanical properties of passive right ventricular free wall myocardium.
The biaxial mechanical properties of right ventricular free wall (RVFW) myocardium were studied. Tissue specimens were obtained from the sub-epicardium of potassium-arrested hearts and different stretch protocols were used to characterize the myocardium's mechanical response. To assess regional differences, we excised tissue specimens from the conus and sinus regions. The RVFW myocardium was found to be consistently anisotropic, with a greater stiffness along the preferred (or averaged) fiber direction. The anisotropy in the conus region was more pronounced than in the sinus region. A comparison with studies of left ventricle (LV) midwall myocardium revealed that, 1) the fiber direction stiffnesses are greater in the RVFW than in the LV, 2) the degree of anisotropy is greater in the RVFW than in the LV.
Animals↗
Propagation of shock waves in elastic solids caused by cavitation microjet impact. I: Theoretical formulation.
To understand the physical process of the impingement of cavitation microjet and the resultant shock wave propagation in an elastic solid, a theoretical model using geometrical acoustics was developed. Shock waves induced in both the jet head (water) and the solid were analyzed during a tri-supersonic impact configuration when the contact edge between the jet head and the elastic boundary expands faster than the longitudinal wave speed in the solid. Impact pressure at the boundary was solved using continuity conditions along the boundary normal. Reflection and refraction of shock waves from a solid-water interface were also included in the model. With this model, the impact pressure at the solid boundary and the stress, strain as well as velocity discontinuities at the propagating shock fronts were calculated. A comparison with results from previous studies shows that this model provides a more complete and general solution for the jet impact problem.
Models, Theoretical↗
Propagation of shock waves in elastic solids caused by cavitation microjet impact. II: Application in extracorporeal shock wave lithotripsy.
To better understand the mechanism of stone fragmentation during extracorporeal shock wave lithotripsy (ESWL), the model developed in Part I [P. Zhong and C.J. Chuong, J. Acoust. Soc. Am. 94, 19-28 (1993)] is applied to study cavitation microjet impingement and its resultant shock wave propagation in renal calculi. Impact pressure at the stone boundary and stress, strain at the propagating shock fronts in the stone were calculated for typical ESWL loading conditions. At the anterior surface of the stone, the jet induced compressive stress can vary from 0.82 approximately 4 times that of the water hammer pressure depending on the contact angles; whereas the jet-induced shear stress can achieve its maximum, with a magnitude of 30% approximately 54% of the water hammer pressure, near the detachment of the longitudinal (or P) wave in the solid. Comparison of model predictions with material failure strengths of renal calculi suggests that jet impact can lead to stone surface erosion by combined compressive and shear loadings at the jet impacting surface, and spalling failure by tensile forces at the distal surface of the stone. Comparing responses from four different stone types suggests that cystine is the most difficult stone to fragment in ESWL, as observed from clinical experience.
Kidney Calculi↗
Microhardness measurements of renal calculi: regional differences and effects of microstructure.
Microhardnesses of five types of renal calculi: calcium apatite (82.5%)/magnesium ammonium phosphate hydrogen (10%)/calcium oxalate monohydrate (7.5%); calcium apatite (95%)/calcium oxalate monohydrate (5%); magnesium ammonium phosphate hydrogen (90%)/calcium apatite (10%); calcium oxalate monohydrate (85%)/calcium apatite (15%); and cystine (100%) were measured. Using Knoop and Vickers indenters the effects of chemical composition and microstructure on the microhardness measurement were assessed. Calcium oxalate monohydrate, magnesium ammonium phosphate hydrogen, and cystine stones, without apparent structure pattern, showed neither regional nor directional differences in their microhardness. In contrast, calcium apatite stones, with distinctly concentric laminae structure, showed regional variations which were correlated with the chemical composition of stone constituents. Scanning electron microscopy of the indenter impressions were taken to help in interpreting the directional dependence in Knoop hardness measurements with respect to the microstructure of the calculi. Vickers measurements showed the crystalline stones were isotropic within a layer. Combined results of Knoop and Vickers measurements indicate that the anisotropic Knoop hardness readings seen in the laminated regions were structural but not material-based. Implications of the results for the fragmentation of renal calculi in extracorporeal shock wave lithotripsy are discussed.
Hardness Tests↗
A comparison of stone damage caused by different modes of shock wave generation.
A standard stone phantom was used to compare stone damage after extracorporeal shock wave administration from electrohydraulic, electromagnetic and piezoelectric lithotripters. For each machine, a low and high shock wave intensity setting was chosen: 18 & 24 kV for electrohydraulic; 16 & 19 kV for electromagnetic; power levels 1 and 4 for piezoelectric. The shock wave was focused either at the front (surface facing the wave source) or back surface of the stone and 50, 100, 200 or 400 shocks were delivered to different stone groups. Effects of varying physical properties in the stone phantom were also investigated. Stone damage was described in terms of volume loss and both depth and width of the resulting damage crater. At the lower intensity settings, all three machines produced stone volume loss which was linearly related to the number of shock delivered. At higher intensity settings, volume loss increased rapidly as the number of shocks increased. With the same number of shocks, stone volume loss was greatest with the electrohydraulic machine, followed by electromagnetic and piezoelectric lithotripters for both low and high intensity settings. Damage craters from the piezoelectric device were narrow and deep; those from the electromagnetic machine were of the shape of a right angle circular cone; whereas those from the electrohydraulic lithotripter were shallow and wide. At the high intensity settings, damage from the piezoelectric and electrohydraulic lithotripters appeared to depend upon the position of the focal point with a higher volume loss when the shock waves were targeted at the front surface of the stone. For the electromagnetic device, a higher volume loss was found when we positioned the focal point at the back surface of the stone phantom. Stone phantoms with lower mechanical strength and acoustic impedance were more easily damaged than those with higher values. Finally, a computer regression model was developed to express volume loss in terms of the intensity setting, focal position and number of shocks for each lithotripter.
Calculi↗
Critical evaluation of nutritional factors in the pathophysiology and treatment of premenstrual syndrome.
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Diet↗
Characterization of collagen fiber architecture in the canine diaphragmatic central tendon.
The diaphragmatic central tendon (DCT), a collagenous soft tissue membrane, acts as a mechanical buffer between the costal and crural muscles. Its direction of mechanical anisotropy has been shown to correspond to the collagen fiber preferred directions. These preferred directions were determined by gross histological examination, and were thus qualitative. In this work we quantified the collagen fiber architecture throughout the DCT using small angle light scattering (SALS). Helium-Neon laser light was passed through tendon specimens and the resultant scattered light distribution, which characterized the local collagen fiber architecture, was recorded with a linear array of five photodiodes. Throughout the DCT two distinct collagen fiber populations were consistently found. For each population three parameters were determined: 1) the preferred directions of collagen fibers, 2) the volume fraction (Vf) of fibers, 3) OI, an orientation index, which ranges from 0 percent for a random network to 100 percent for a perfectly oriented network. Vector maps were used to display results from 1) and 2), and showed a primary group (G1) going from the crural to costal muscles and a secondary one (G2) running perpendicular to G1. Comparisons of Vf between G1 and G2 showed that G1 contained about three times as many fibers as G2, a ratio similar to that found for the degree of mechanical anisotropy. OI were found to be about 60 percent, indicating a high degree of orientation, with no significant regional or population differences (p less than 0.05). These quantitative results suggest that throughout the DCT the degree of mechanical anisotropy is controlled exclusively by Vf.
Animals↗
On the anisotropy of the canine diaphragmatic central tendon.
We studied the mechanical and anatomical anisotropy of the canine diaphragmatic central tendon (CT). Dumb-bell-shaped strips with effective dimensions of 10 x 2 mm (length x width) were cut from different regions of the canine diaphragmatic CT in two different orientations relative to the direction of neighboring muscle fibers. Specimens sampled with their long axial dimension oriented parallel to the neighboring muscle fibers were named Group-1 and those sampled with an orientation perpendicular to the neighboring muscle fibers were named Group-2. Results from one-dimensional stress-strain and tensile failure strength tests revealed that the CT is a nonlinear, inelastic, and anisotropic material. Group-1 specimens were found to have a higher stiffness, higher failure strength and higher strain energy density at failure than Group-2 specimens. Polarized microscopy showed that multiple sheets of collagen fiber bundles formed an orthogonal network in the tendon. Collagen fiber bundles along Group-1 direction formed parallel trajectory lines connecting the neighboring costal and crural muscles; bundles along Group-2 direction were observed to orient 90 degrees away. At the central apex region of the CT, collagen bundles of Group-1 formed a fan-like trajectory pattern. This collagen network architecture was compared favorably to the trajectories of an approximated principal stress field in the CT due to simulated contractile forces from its adjacent costal and crural muscles. These combined results suggest a structure-function relationship for the anatomical and mechanical anisotropy in the canine diaphragmatic CT.
Animals↗