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Biomedical subjects

C L Bailey

Publications and source records attributed to C L Bailey.

At least 19 recordsLinked to original sources
PubMed2006

Aluminum chloride as a solid is not a strong Lewis acid.

Aluminum chloride is used extensively as Lewis acid catalyst in a variety of industrial processes, including Friedel-Crafts and Cl/F exchange reactions. There is a common misconception that pure AlCl3 is itself a Lewis acid. In the current study, we use experimental and computational methods to investigate the surface structure and catalytic properties of solid AlCl3. The catalytic activity of AlCl3 for two halide isomerization reactions is studied and compared with different AlF3 phases. It is shown that pure solid AlCl3 does not catalyze these reactions. The (001) surface of crystalline AlCl(3) is the natural cleavage plane and its structure is predicted via first principles calculations. The chlorine ions in the outermost layer of the material mask the Al3+ ions from the external gas phase. Hence, the experimentally found catalytic properties of pure solid AlCl3 are supported by the predicted surface structure of AlCl3.

Journal Article↗
PubMed2005

Composition and structure of the alpha-AlF3(0001) surface.

Strong Lewis acid catalysts are widely used in a variety of industrial processes including Cl/F exchange reactions. Aluminum fluorides (AlF3) have great potential for use in such reactions. Despite the importance of the surface in the catalytic process little is known about the detailed atomic scale structure of AlF3 surfaces. In the current study we employ state of the art surface thermodynamics calculations based on hybrid-exchange density functional theory to predict the composition and structure of the basal plane surface of alpha-AlF3 for the first time. We examine four possible terminations of the alpha-AlF3 (0001) surface and demonstrate that the surface is terminated by a layer containing two fluorine atoms per cell at all realistic fluorine partial pressures. The fluorine ions in the outermost layer of the material reconstruct to mask the Al3+ ion from the external gas phase and consequently we would expect this surface to be inactive as a Lewis acid catalyst in line with experimental observation.

Journal Article↗
PubMed2001

Upregulated TRP and enhanced capacitative Ca(2+) entry in human pulmonary artery myocytes during proliferation.

A rise in cytosolic Ca(2+) concentration ([Ca(2+)](cyt)) due to Ca(2+) release from intracellular Ca(2+) stores and Ca(2+) influx through plasmalemmal Ca(2+) channels plays a critical role in mitogen-mediated cell growth. Depletion of intracellular Ca(2+) stores triggers capacitative Ca(2+) entry (CCE), a mechanism involved in maintaining Ca(2+) influx and refilling intracellular Ca(2+) stores. Transient receptor potential (TRP) genes have been demonstrated to encode the store-operated Ca(2+) channels that are activated by Ca(2+) store depletion. In this study, we examined whether CCE, activity of store-operated Ca(2+) channels, and human TRP1 (hTRP1) expression are essential in human pulmonary arterial smooth muscle cell (PASMC) proliferation. Chelation of extracellular Ca(2+) and depletion of intracellularly stored Ca(2+) inhibited PASMC growth in media containing serum and growth factors. Resting [Ca(2+)](cyt) as well as the increases in [Ca(2+)](cyt) due to Ca(2+) release and CCE were all significantly greater in proliferating PASMC than in growth-arrested cells. Consistently, whole cell inward currents activated by depletion of intracellular Ca(2+) stores and the mRNA level of hTRP1 were much greater in proliferating PASMC than in growth-arrested cells. These results suggest that elevated [Ca(2+)](cyt) and intracellularly stored [Ca(2+)] play an important role in pulmonary vascular smooth muscle cell growth. CCE, potentially via hTRP1-encoded Ca(2+)-permeable channels, may be an important mechanism required to maintain the elevated [Ca(2+)](cyt) and stored [Ca(2+)] in human PASMC during proliferation.

Blood Proteins↗
PubMed2001

Function of the oblique hypaxial muscles in trotting dogs.

In trotting dogs, the pattern of activity of the obliquely oriented hypaxial muscles is consistent with the possible functions of (i) stabilization against vertical accelerations that cause the trunk to sag in the sagittal plane and (ii) stabilization against forces that tend to shear the trunk in the sagittal plane. To test these hypotheses, we compared the amount of activity of the intercostal and abdominal oblique muscles (i) when dogs carried additional mass (8-15% of body mass) supported over the limb girdles versus supported mid-trunk (test of sagittal bounce), and (ii) when dogs trotted up versus down a 10 degrees slope (test of sagittal shear). In response to the loading manipulations, only the internal oblique muscle responded in a manner that was consistent with stabilization of the trunk against forces that cause the trunk to sag sagittally. In contrast, when the fore-aft forces were manipulated by running up- and downhill, all four of the monitored muscles changed their activity in a manner consistent with stabilization of the trunk against sagittal shearing. Specifically, muscles with a craniodorsal orientation (external oblique and external intercostal muscles) showed an increase in activity when the dogs ran downhill and a decrease when they ran uphill. Muscles with a cranioventral orientation (internal oblique and internal intercostal muscles) exhibited the opposite pattern: increased activity when the dogs ran uphill and decreased activity when they ran downhill. Changes in activity of two extrinsic appendicular muscles, the serratus ventralis and deep pectoralis, during uphill and downhill running were also consistent with the sagittal shearing hypothesis. In contrast, changes in the level of recruitment of the oblique hypaxial muscles were not consistent with stabilization of the trunk against torques that induce yaw at the girdles. Hence, we suggest that the oblique hypaxial muscles of trotting dogs act to stabilize the trunk against sagittal shearing torques induced by limb retraction (fore-aft acceleration) and protraction (fore-aft deceleration).

Animals↗
PubMed2000

Sustained membrane depolarization and pulmonary artery smooth muscle cell proliferation.

Pulmonary vasoconstriction and vascular medial hypertrophy greatly contribute to the elevated pulmonary vascular resistance in patients with pulmonary hypertension. A rise in cytosolic free Ca(2+) ([Ca(2+)](cyt)) in pulmonary artery smooth muscle cells (PASMC) triggers vasoconstriction and stimulates cell growth. Membrane potential (E(m)) regulates [Ca(2+)](cyt) by governing Ca(2+) influx through voltage-dependent Ca(2+) channels. Thus intracellular Ca(2+) may serve as a shared signal transduction element that leads to pulmonary vasoconstriction and vascular remodeling. In PASMC, activity of voltage-gated K(+) (Kv) channels regulates resting E(m). In this study, we investigated whether changes of Kv currents [I(K(V))], E(m), and [Ca(2+)](cyt) affect cell growth by comparing these parameters in proliferating and growth-arrested PASMC. Serum deprivation induced growth arrest of PASMC, whereas chelation of extracellular Ca(2+) abolished PASMC growth. Resting [Ca(2+)](cyt) was significantly higher, and resting E(m) was more depolarized, in proliferating PASMC than in growth-arrested cells. Consistently, whole cell I(K(V)) was significantly attenuated in PASMC during proliferation. Furthermore, E(m) depolarization significantly increased resting [Ca(2+)](cyt) and augmented agonist-mediated rises in [Ca(2+)](cyt) in the absence of extracellular Ca(2+). These results demonstrate that reduced I(K(V)), depolarized E(m), and elevated [Ca(2+)](cyt) may play a critical role in stimulating PASMC proliferation. Pulmonary vascular medial hypertrophy in patients with pulmonary hypertension may be partly caused by a membrane depolarization-mediated increase in [Ca(2+)](cyt) in PASMC.

Adenosine Triphosphate↗
PubMed2000

"High probability" perfusion lung scans in pulmonary venoocclusive disease.

"High-probability" ventilation/perfusion (V/Q) lung scans generally indicate proximal pulmonary arterial occlusion by thromboemboli or, rarely, other processes such as tumors, fibrosing mediastinitis, or vasculitis. In this report we describe three patients with high probability V/Q scans in whom pulmonary angiography failed to demonstrate arterial occlusion. All three patients were determined to have pulmonary venoocclusive disease (PVOD). In two patients, a tissue diagnosis of PVOD was made, in one case with explanted tissue taken after a successful heart-lung transplant and in the other case with tissue taken at autopsy. PVOD in the third patient was diagnosed with pulmonary venography. A potential explanation for the discrepancy between perfusion lung scan and pulmonary angiographic findings in PVOD is discussed.

Adult↗
PubMed1998

The malignant potential of small cystic ovarian tumors in women over 50 years of age.

OBJECTIVE: The aim of this study was to determine the risk of malignancy in cystic ovarian tumors < 10 cm in diameter in asymptomatic postmenopausal women or women >or =50 years of age. METHODS: All cystic ovarian tumors detected by transvaginal sonography screening in asymptomatic postmenopausal women or women > or =50 years of age were evaluated with respect to size and morphology. Histology was recorded on all tumors removed surgically. Follow-up data were available both on patients undergoing surgery and on those who elected to be followed without operative intervention. RESULTS: Unilocular cystic tumors were detected in 256 of 7705 patients (3.3%). All tumors were < 10 cm in diameter and 90% were < 5 cm in diameter. One hundred twenty-five of these cysts (49%) resolved spontaneously within 60 days and 131 (51%) persisted. Forty-five patients with persisting ovarian cysts underwent operative removal of these tumors. Thirty-two patients had ovarian serous cystadenomas, and the remainder had a variety of benign lesions. There were no cases of ovarian carcinoma in this group. Eighty-six patients with unilocular cystic ovarian tumors were followed at 3- to 6-month intervals without surgery, and none have developed ovarian cancer. Complex cystic ovarian tumors were detected in 250 patients (3.2%). All tumors were < 10 cm in diameter and 89% were < 5 cm in diameter. One hundred thirty-five (55%) resolved spontaneously within 60 days, and 115 (45%) persisted. One hundred fourteen of these patients underwent operative tumor removal. Seven patients had ovarian carcinoma, 1 had primary peritoneal cancer, and 1 had metastatic breast cancer to the ovary. CONCLUSION: Unilocular ovarian cysts < 10 cm in diameter in asymptomatic postmenopausal women or women > or =50 years of age are associated with minimal risk for ovarian cancer. In contrast, complex ovarian cysts with wall abnormalities or solid areas are associated with a significant risk for malignancy. These data are important in determining optimal strategies for operative intervention in these patients.

Aged↗
PubMed1996

Lymph node metastases and prognosis in patients with stage IA2 cervical cancer.

Ninety-four patients with squamous cell carcinoma invading the cervical stroma to a depth of >3.0-5.0 mm with 7 mm or less in horizontal spread (FIGO Stage IA2) were evaluated. Depth and lateral extent of stromal invasion were verified using an ocular micrometer. Cell type and lymph vascular space invasion (LVSI) were recorded in each case. Patients were treated primarily by radical hysterectomy with pelvic lymphadenectomy, and those with lymph node metastases were offered postoperative radiation. Following treatment, patients were seen at 3-month intervals for 2 years, and every 6 months thereafter. The mean duration of follow-up was 6.9 years (range 0.4-23.5 years). Seven of 94 patients (7.4%) had lymph node metastases. Five patients had 1 positive node, 1 patient had 2 positive nodes, and 1 patient had 3 positive nodes. Five patients developed recurrent cancer and 4 died of disease. LVSI was present in 31 cases (33%). Tumor recurrence was significantly increased in patients with positive LVSI (9.7% vs 3.2%). The 5-year survival rate of patients with LVSI was 89% vs 98% in patients without this finding (P = 0.058). The 5-year survival rate of all Stage IA2 cervical cancer patients was 95%. Patients with Stage IA2 cervical cancer have a significant risk of lymph node metastases and should be treated by radical hysterectomy with pelvic lymphadenectomy. LVSI is an important prognostic variable in these patients and should be recorded in all cases.

Adult↗
PubMed1994

Nd:YAG laser excision of a giant gingival pyogenic granuloma of pregnancy.

A 19-year-old Hispanic nullipara experienced the rapid growth of an oral lesion on the right lower gingiva which she had first noticed at 29 weeks gestation. The lesion interfered with oral hygiene and eating. At surgery, the lesion measured 3.5 x 2.5 x 2.0 cm. Biopsy confirmed a pyogenic granuloma ("granuloma gravidarum"). Panorex films showed no bony invasion. The lesion was excised using the Nd:YAG laser under general anesthesia when the patient had reached 36 3/7 weeks gestation. We chose the Nd:YAG laser over the CO2 laser for the removal of this very vascular lesion, because of its superior coagulation characteristics. This technique results in removal of the lesion with less danger of bleeding than with any other surgical technique. The patient did well postoperatively, delivered a healthy 3,884 g infant at 40 6/7 weeks gestation, and has had no recurrence after 15 months of follow-up.

Adult↗
PubMed1993

Management of advanced juvenile granulosa cell tumor of the ovary.

Juvenile granulosa cell tumor of the ovary occurs most frequently in young women and children. Ten percent of cases present during pregnancy. The majority of tumors are in FIGO Stage I and have a favorable prognosis. The prognosis of higher stage tumors, however, is generally less favorable. We report the long-term, disease-free survival of a patient with FIGO Stage III juvenile granulosa cell tumor of the ovary. We believe this to be the first report of a successful pregnancy following "MAC" chemotherapy for this particular malignancy.

Adolescent↗
PubMed1993

Primary breast cancer of the vulva.

Supernumerary breasts on the vulva are a rare occurrence. There have been 26 cases previously reported and only 4 case reports of primary mammary carcinoma of the vulva. This is the fifth case report of mammary carcinoma of the vulva and the second report using tamoxifen for adjuvant treatment.

Aged↗
PubMed1992

An immunocytochemical study of the distribution of Rift Valley fever virus in the mosquito Culex pipiens.

The dissemination of Rift Valley fever (RVF) virus in females of the epidemic vector Culex pipiens was studied immunocytochemically. Among orally infected specimens, viral antigen was detected in all major midgut regions, although individuals varied with respect to which regions were infected. Among specimens with disseminated infections (infections beyond the midgut epithelium), antigen was detected in most tissues, including those of the nervous and endocrine systems. However, no antigen was found in the ovarian follicular epithelia, oocytes/nurse cells, or female accessory gland. A viral dissemination index (DI) based on several tissues was determined for each orally infected specimen and used to estimate the extent of viral dissemination in the hemocoel. Plots of DI values as a function of time after ingestion of an infectious blood meal indicated that dissemination was sporadic, and that once virus escapes from the midgut, its spread to other tissues is rapid. The most common sequence of tissue/organ infection following escape of virus from the midgut epithelium appears to be as follows: intussuscepted foregut, fat body, salivary glands and thoracic ganglia, epidermis, and ommatidia of the compound eyes. Reduced fecundity and survival identified in other studies of RVF virus-infected Cx. pipiens are probably explainable on the basis of extensive tissue and organ infection resulting in an overall energy drain. Infection of regulatory tissues and organs such as the ganglia of the central nervous system, neurosecretory cells, and the corpora allata may also have detrimental effects on the overall functioning of a mosquito, even in the absence of widespread infection.

Animals↗
PubMed1991

Laboratory biology of Hyalomma truncatum (Acari: Ixodidae).

The life cycle of Hyalomma truncatum Koch (Acari: Ixodidae) required an average of 108 d at 26 +/- 1 degree C. 92-96% RH, and a 12:12 (L:D) photoperiod to complete. Mean weights of unfed larvae, nymphs, and females were 0.02, 0.19, and 11.1 mg, respectively. Weight of larvae, nymphs, and females increased 20-, 91-, and 48-fold, respectively, as a result of feeding on guinea pigs. All stages exhibited host-seeking behavior less than 1 d after emergence. The mean (+/- SE) feeding period of larvae, nymphs, and adults was 3.8 (+/- 0.1), 7.7 (+/- 0.3), and 8.3 (+/- 0.3) d, respectively. Larvae and nymphs molted an average of 11.0 (+/- 0.3), and 30.7 (+/- 0.2) d after engorgement, respectively. The female/male sex ratio, as determined from emerged adults, was 1.4:1. Oviposition started an average of 11.9 (+/- 0.8) d after engorgement, and a mean of 6.701 eggs per female was deposited. A total of only 48% of the eggs enclosed after a mean incubation of 35 (+/- 1.1) d. Females converted 56% of their engorged weight into eggs and produced an average of 12,614 (+/- 2.0) eggs/g of engorged body weight. On the first day of oviposition, an egg less than 24 h old weighed an average of 44.8 (+/- 1.5) micrograms. Egg weight was significantly (P less than 0.01) lower during peak egg production (days 2-8 after onset of oviposition) than during reduced egg production (days 14-20 after onset of oviposition).

Animals↗
PubMed1991

Venezuelan equine encephalomyelitis virus infection in and transmission by the tick Amblyomma cajennense (Arachnida: Ixodidae).

To assess a possible role of ticks as the maintenance host for epizootic strains of Venezuelan equine encephalomyelitis (VEE) virus, laboratory experiments were conducted to determine if ticks could become infected, maintain, and transmit the virus. Larval and nymphal Amblyomma cajennense (F.) and larval Dermacentor nitens Neumann ticks were exposed to epizootic VEE virus (Trinidad donkey strain) by allowing them to feed on viremic guinea pigs (strain 13). In A. cajennense, transstadial transmission was observed from larvae to nymphs and adults. Horizontal viral transmission to a mammalian host was accomplished by nymphs. Infection rates in nymphs and adults were 2% (42/2,750) and 4% (9/244), respectively, afer ingestion of virus as larvae. Virus was detected in A. cajennense adult ticks for up to 171 d after infection in the larval stage. A cajennense, exposed as nymphs, ingested virus but did not become infected (0/164 after 10 d after taking an infective bloodmeal). No virus was detected in D. nitens 7 d after exposure. These findings suggest that A. cajennense potentially could be involved in an interepizootic maintenance cycle of epizootic VEE viral strains.

Animals↗
PubMed1990

Replication of Crimean-Congo hemorrhagic fever virus in four species of ixodid ticks (Acari) infected experimentally.

The vector potentials of Hyalomma dromedarii Koch, H. impeltatum Schulze & Schlottke, H. truncatum Koch, and Rhipicephalus appendiculatus Neumann for Crimean-Congo hemorrhagic fever (CCHF) virus (IbAr 10200) were evaluated by intracoelomic inoculation. All three Hyalomma species became infected; infection rates ranged between 80 and 100% at 7-14 d after inoculation, and viral titers increased in unfed specimens almost 100 times above inoculation levels within the first week following infection. Only 40% of the R. appendiculatus became infected, and viral titers of unfed specimens increased less than 10 times above inoculation levels. The virus persisted to 153 d in unfed H. impeltatum. Viral titers were significantly higher in female than in male H. dromedarii, H. impeltatum, H. truncatum, and R. appendiculatus after blood feeding. Blood feeding had little effect on the viral titers of male Hyalomma species. However, the percentage of female and male ticks from which virus was recovered was significantly higher from fed ticks compared with unfed ticks. No virological evidence of transovarial transmission was found in greater than 78,000 first-generation progeny (larvae, nymphs, and adults) of inoculated female H. dromedarii, H. impeltatum, H. truncatum, and R. appendiculatus. All species transmitted CCHF virus to guinea pigs when allowed to feed at both 6 and 21 d after inoculation.

Animals↗
PubMed1990

Application of polar-orbiting, meteorological satellite data to detect flooding of Rift Valley Fever virus vector mosquito habitats in Kenya.

Measurements of green-leaf vegetation dynamics recorded by the advanced very high resolution radiometer instruments onboard National Oceanic and Atmospheric Administration satellites 7 and 9 were used to derive ground moisture and rainfall patterns in Kenya and monitor resultant flooding of mosquito larval habitats (dambos) likely to support Rift Valley Fever virus vector mosquitoes (Aedes and Culex spp.). Satellite-derived data from mid-1981 to December 1988 have been analysed with corresponding rainfall, flooding and vector population data as they relate to Rift Valley Fever virus ecology. Single (7 x 7 km) and multiple grid-cell image analysis (200 x 300 km) in small localized areas and large geographical regions, respectively, of vegetation data were used to quantify the potential for flooding of mosquito breeding habitats. The ability to detect accurately parameters, such as ground moisture, that determine flooding could provide local officials with sufficient warning to allow for implementation of specific mosquito control measures before a disease outbreak.

Animals↗