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Biomedical subjects

H C Yeh

Publications and source records attributed to H C Yeh.

At least 55 records · Page 3Linked to original sources
PubMed1989

Deposition of cigarette smoke particles in the rat.

The fractional deposition of cigarette smoke particles in the respiratory tracts of rats was studied. Male and female rats were conditioned in nose-only exposure tubes 25 min/day for 2 days, exposed to cigarette smoke at mass concentrations of 95 or 341 mg/m3, 25 min/day for 3 days, and then exposed to smoke at mass concentrations of 212 and 657 mg/m3, 25 min/day for 5 days. Mainstream cigarette smoke was generated by a modified Walton smoking machine from two 1R3 research cigarettes burned sequentially for each exposure. Deposition studies were conducted by placing the rats in plethysmograph tubes to allow respiratory minute volume measurements during exposure, then exposing them to [14C]dotriacontane-labeled cigarette smoke at mass concentrations of 202 or 624 mg/m3 for 25 min, using the same smoking machine. Size distribution, real-time concentration, and 14C activity of the smoke particles were determined using a multijet Mercer impactor, a real-time aerosol monitor, and filter samples, respectively. Immediately after the exposure, the rats were terminated to determine the distribution of the 14C. Individual lung lobes, trachea and lobar bronchi, head, larynx, kidneys, liver, gastrointestinal (GI) tract, blood, and depleted carcass of each rat were analyzed for 14C content. Results showed that the GI tract contained 16-31% of the total activity, indicating significant clearance from the large airways and nose to the GI tract during the exposure and during the 10-15 min between the cessation of the exposure and the removal of the organs. Total deposition of the inhaled 14C activity was 20.1 +/- 1.6% for both exposure concentrations. The intrapulmonary deposition fractions (lung lobes plus airways below the lobar bronchi) were 12.4 +/- 0.9 and 15.9 +/- 1.4% for concentrations of 202 and 624 mg/m3, respectively, suggesting a slight enhancement in upper airway deposition for animals exposed to the higher smoke concentration.

Alkanes↗
PubMed1989

Lung retention and binding of [14C]-1-nitropyrene when inhaled by F344 rats as a pure aerosol or adsorbed to carbon black particles.

1-Nitropyrene (NP), as found in the environment, is more typically associated with carbonaceous particles than found as an aerosol of the pure compound. To determine whether (and why) an association with particles resulted in prolonged lung retention of NP, rats were exposed to 14C-NP as a pure aerosol or adsorbed on carbon black particles. Total 14C retained in the lung was greater at all times from 0.5 h to 30 d after exposure to 14C-NP adsorbed to carbon black particles than after exposure to pure 14C-NP (p less than .05). The fraction of total 14C in lung bound to carbon black particles decreased steadily with time after exposure, indicating in vivo removal of NP from the particles. At 0.5 h after exposure, the fraction of the estimated deposited 14C that was covalently bound to lung macromolecules was twofold greater for NP adsorbed on carbon black than for pure NP. Covalently bound 14C in lungs increased with time after exposure to 14C-NP adsorbed to carbon black, reaching levels of approximately 1% of the deposited radioactivity at 7-30 d after exposure, whereas levels of covalently bound 14C declined with time after exposure to pure NP. Thus, at 30 d after exposure, the amount of 14C covalently bound to lung macromolecules was approximately 10-fold greater (p less than .05) in rats that inhaled 14C-NP adsorbed on carbon black particles than in rats that inhaled pure 14C-NP aerosols. These results suggest that association of NP with carbon black particles augments the interaction of reactive metabolites of NP with target macromolecules. This phenomenon is thought to be related to the slow release of NP from carbon black particles, and may augment the biological effects of inhaled NP when adsorbed on carbon black or similar particles in the environment.

Aerosols↗
PubMed1989

Experimental measurements of the diffusion coefficient of 212Pb.

Knowledge of the diffusion coefficient of Rn progeny is necessary for assessing the radiation exposure resulting from exposure to Rn and its progeny. The diffusion coefficient for 220Rn progeny was determined in ambient air by two independent methods, measuring deposition using a cylindrical tube or screens. A sampling train consisting of a diffusion tube and a screen-type diffusion battery was used for the experimental study. A range of flow rates and relative humidities was investigated. For 35% less than or equal to RH less than or equal to 85%, results from the two systems agree with each other. The diffusion coefficient of 212Pb was 0.036 +/- 0.002 cm2 s-1 and 0.037 +/- 0.004 cm2 s-1 for the tube and screen penetration methods, respectively. In low humidity air (RH less than 30%), a linear relationship between the diffusion coefficient of 212Pb and relative humidity was observed. The observed diffusion coefficient is strongly affected by the amount of material agglomerated onto the 212Pb atom. Further studies on the effects of trace gases and organics are required to fully understand the results.

Bismuth↗
PubMed1988

The prevalence of hyperandrogenism in 109 consecutive female patients with diffuse alopecia.

Endocrine dysfunction was studied in 109 consecutive female patients with moderate to severe alopecia, mostly of a diffuse pattern. The study included an evaluation of associated hirsutism and/or menstrual dysfunction, plasma hormonal measurements, and ultrasonography of the ovaries. A control group of 24 ovulatory, nonhirsute, nonalopecia individuals was also studied. Of the 109 patients, 70 (64.2%) had no clinical evidence of hirsutism or menstrual dysfunction. Two of 44 patients tested with cosyntropin (Cortrosyn) had 21-hydroxylase deficiency, whereas two other patients had hyperprolactinemia caused by pituitary tumors. Hyperandrogenism was defined as an increase in any of the plasma androgens (testosterone, non-sex hormone-binding globulin bound testosterone, dehydroepiandrosterone sulfate, androstenedione, or dihydrotestosterone) and was noted in 42 of the 109 patients studied (38.5%). Of these 42 patients, 11 were ovulatory with no evidence of clinical hirsutism, 13 were ovulatory and hirsute, and 18 had oligomenorrhea or amenorrhea with or without hirsutism with confirmatory evidence of polycystic ovarian disease. Patients with diffuse alopecia may demonstrate hyperandrogenism, even in the absence of hirsutism, oligomenorrhea, or amenorrhea. The most common endocrine disorder in this series of patients with diffuse alopecia was polycystic ovarian disease.

Adolescent↗
PubMed1988

Amniotic sac development: ultrasound features of early pregnancy--the double bleb sign.

The amniotic sac-embryo-yolk sac complex can be seen with ultrasonography (US) as two small blebs of almost equal size attached to the wall of the early gestational sac. We have called this the double bleb sign. Since the developing embryo and its cardiac pulsation are located between these two blebs, the size of an early embryo can be measured. The crown-rump length thus measured corresponds well to that described in embryologic textbooks, and an embryo as small as 2 mm (5 weeks 3 days) can be measured with use of this method. Three stages of development of the amniotic sac-embryo-yolk sac complex can be identified with US, and they are useful in dating the pregnancy. These three stages are 1, a simple double bleb, 2, a double bleb with a stalk, and 3, a double bleb with a separating yolk sac. As the amniotic sac enlarges, strands of echoes may be seen within the chorionic cavity and should be differentiated from amniotic bands, which may cause serious fetal abnormality. Separation of the amniotic from the chorionic membrane before the 13th week is normal but may be abnormal after the 17th week of gestation. Separation of the chorionic membrane from underlying decidua, however, is abnormal at any stage of pregnancy.

Adolescent↗
PubMed1988

Deposition and retention patterns for 3-, 9-, and 15-micron latex microspheres inhaled by rats and guinea pigs.

This study was designed to determine the deposition patterns and fate of large particles inhaled by two species of small laboratory animals during nose breathing. Rats and guinea pigs inhaled 3-, 9-, or 15 micron polystyrene latex microspheres labeled with 46Sc. Approximately 1.4% and 0.55% of the initial internally deposited body burden of 3-micron microspheres was in the alveolar region of the respiratory tract of rats and guinea pigs, respectively. None of the 9- or 15-micron microspheres were detected in the alveolar regions of the rats or guinea pigs. Ninety-five to 99% of the deposited microspheres cleared from these animals with biological half-times of 0.5-1.0 day. Most of the cleared radioactivity was in the feces. Approximations for long-term biological half-times for alveolar retention of the 3-micron microspheres were 63 days for rats and 83 days for guinea pigs. About 1% of the initial lung burden of 3-micron microspheres was translocated from lung to lung-associated lymph nodes in both species; none of the 9- or 15-micron microspheres were detected in those lymph nodes. Small fractions of the microspheres initially deposited in the airways of the head were retained with biological clearance half-times ranging from 9 to 350 days. Results from this study do not allow projections for deposition and retention patterns for similar particles inhaled by humans. Such projections must come from studies with humans, or from studies with animal species having deposition patterns for inhaled materials more comparable to those of humans.

Air Pollutants↗
PubMed1988

Sonographic signs of early pregnancy.

The early embryo (blastocyst) is implanted about 6 to 7 days after fertilization and becomes completely imbedded within the decidua at 9.5 days. As the exocoelomic cavity (or early gestational sac) enlarges, it becomes visible by ultrasonography. The gestational sac, however, remains within markedly thickened ipsilateral decidua. The uterine cavity remains relatively undistorted (i.e., straight) and can be delineated by ultrasonography. The gestational sac, therefore, can be seen adjacent to a straight uterine cavity within a thickened decidua. This is called an intradecidual sign. Before the appearance of a visible gestational sac, an echogenic area within the thickened decidua may be seen. This is the earliest sign of intrauterine gestation, and it can be seen as early as 25-days menstrual age. The earliest evidence of an embryo is seen about 2 weeks later, when two small bubbles (amniotic and yolk sacs) attach to the wall of the gestational sac. The embryonic disc is located between the two bubbles. This is called the double-bleb sign. The intradecidual and double-bleb signs represent the most important signs of early intrauterine pregnancy.

Abortion, Missed↗
PubMed1988

Ultrasonographic study of ovaries of 19 women with weight loss-related hypothalamic oligo-amenorrhea.

A study of 19 nonhirsute women with weight loss-related hypothalamic oligo-amenorrhea revealed evidence of multifollicular ovaries in 17. Enlarged ovaries greater than 10 cm3 were found in 8 of these subjects (42.1%). High-resolution real-time ultrasonography of the pelvis of 19 weight loss-related oligo-amenorrheic subjects revealed a mean +/- SD maximum ovarian volume (MOV) of 11.8 +/- 7.0 cm3, which was significantly different from those of control subjects whose mean +/- SD MOV was 5.2 +/- 1.9 cm3 (P = less than 0.001). The data do not allow a specific ultrasonographic distinction between hyperandrogenic women with polycystic ovarian disease and women with weight loss-related hypothalamic amenorrhea.

Adolescent↗
PubMed1987

Adrenal gland and nonrenal retroperitoneum.

Ultrasound, as the initial cross-sectional imaging technique, confirmed the value of axial records. Although computerized tomography and possibly magnetic resonance offers better resolution, ultrasonography has the advantage of being less expensive, convenient, and highly portable. With these specific indications and reservations, ultrasonography of the adrenal and retroperitoneum has an accepted role in imaging.

Adrenal Gland Diseases↗
PubMed1987

Nose-only exposure system for inhalation exposures of rodents to large particles.

A large-particle exposure system for small animals was designed, constructed and evaluated. The system was designed by incorporating a fluidized bed aerosol generator (FBG) and a nose-only exposure device to accommodate 40 small animals into a single unit. The system has four levels of exposure ports, each level having ten exposure ports radially positioned around the aerosol delivery components of the system. The aerosol generator produces aerosols that travel to the top of the system then downwards in order to be drawn past each animal's nose via vacuum ports immediately above the exposure ports. Nearly monodisperse polystyrene latex aerosols with nominal sizes of 3.0, 9.0 and 15.0 micron were generated as dry powders in an FBG with an inside diameter of 5 cm. During 60-min test runs, average aerosol mass concentrations up to 37 mg/m3 were achieved with less than 10% variation in mass concentration distribution throughout the unit.

Administration, Inhalation↗
PubMed1987

Polycystic ovarian disease: US features in 104 patients.

Ultrasonographic (US) study was performed in 25 healthy women and 104 patients with polycystic ovarian disease (PCOD). Although the average size of ovaries in the PCOD patients was much larger than that of the healthy women, 29.7% of ovaries in the PCOD patients were normal in size. The shapes of the ovaries (roundness index) in PCOD patients were not different from those of the healthy women. There was no significant correlation between the size and shape of the ovaries. Bilaterally enlarged, globular-shaped ovaries were rare and usually asymmetric in size. The most important feature of PCOD on US scans is the bilaterally increased numbers of developing follicles (0.5-0.8 cm in size), usually more than five in each ovary. Although maturing follicles (1.5-2.9 cm) are much rarer in PCOD patients (13.5%) than in healthy women (36%), the incidences of follicular cysts (greater than 3 cm) was about the same in both.

Adolescent↗
PubMed1986

Computed tomography and ultrasonography of the hemophilic pseudotumor and their use in surgical planning.

Twenty-one hemophilic pseudotumors in 17 patients were evaluated radiologically to facilitate surgical planning. Plain radiography, angiography, intravenous urography, computerized tomography (CT), and ultrasonography (U/S) were the modalities used. CT proved to be the most efficient method in the detection of bone destruction and soft tissue lesions including additional daughter cysts. The combination of CT, intravenous urography, and angiography were used in pelvic pseudotumors, and that of CT and angiography for extremity pseudotumors, to determine the proper surgical approaches to the lesions. As a non-ionizing technique, U/S was usually preferable in visualizing soft tissue masses and, in sequential studies, to evaluate progress or recurrence of the lesion.

Adult↗
PubMed1986

Crossed fused renal ectopia: sonographic diagnosis.

Five cases of crossed fused renal ectopia, all confirmed by either computed tomographic scan or intravenous urography, were diagnosed sonographically. The sonographic appearance of this entity consists of a characteristic anterior and/or posterior notch, difference in orientation of the 2 collecting systems in the fused kidneys, and absence of a kidney in the contralateral renal fossa, or elsewhere in the body, such as the pelvis. The inability to diagnose this condition correctly may lead to the misdiagnosis of a renal mass or infiltrative disease occupying the contralateral renal fossa. Computed tomographic scans will also identify the anomaly.

Adult↗