Variability in size distribution measurements obtained using multiple Andersen Mark II cascade impactors

PURPOSE: Andersen Mark II cascade impactors are commonly used for the testing of pharmaceutical aerosols. The reproducibility of size distribution measurements made with various Mark II impactors was assessed theoretically and experimentally. METHODS: Stage cutpoints were calculated for fourteen Mark II impactors based on jet diameter measurements for each stage. The calculated cutpoints were used to predict differences in size distributions measured with various Mark II impactors. Five impactors were exposed to an atomizer-generated oleic acid test aerosol to experimentally verify predicted differences in size distribution measurements among impactors. RESULTS: Stage cutpoints were calculated to vary by up to 0.45 micron for 'identical' stages of different Mark II impactors based on jet diameter measurements. The size distributions measured with various Mark II impactors were shown to be significantly different based on theoretical and experimental observations. For one particular experiment, the amount of material collected on Stage 6 ranged from 26.8 percent of the total sampled mass to 40.9 percent depending on which Mark II was used. Theoretical calculations predicted that the amount of material collected on Stage 6 would vary from 24.0 to 43.5 percent of the total sampled mass among impactors for this experiment. A Similarity Ratio, useful for interpreting the test results, was defined and discussed. CONCLUSIONS: Significant differences in stage cutpoints exist among Andersen Mark II impactors. These differences in stage cutpoints can result in large differences in size distribution measurements made with various Mark II impactors. By measuring jet diameters and calculating stage cutpoints, it is possible to predict the performance of a particular Mark II impactor.     

Thrombus distribution and changes in aneurysm size following endovascular aortic aneurysm repair

Microvascular lesions, also called varices or capillary ectasias, in contrast to vocal fold polyps with telangiectatic vessels, are relatively small lesions arising from the microcirculation of the vocal fold. Varices are most commonly seen in female professional vocalists and may be secondary to repetitive trauma, hormonal variations, or repeated inflammation. Microvascular lesions may either be asymptomatic or cause frank dysphonia by interrupting the normal vibratory pattern, mass, or closure of the vocal folds. They may also lead to vocal fold hemorrhage, scarring, or polyp formation. Laryngovideostroboscopy is the key in determining the functional significance of vocal fold varices. Management of patients with a varix includes medical therapy, speech therapy, and occasionally surgical vaporization. Indications for surgery are recurrent hemorrhage, enlargement of the varix, development of a mass in conjunction with the varix or hemorrhage, and unacceptable dysphonia after maximal medical and speech therapy due to a functionally significant varix.     

Plasma cholesteryl ester transfer protein activity in hyper- and hypothyroidism

Thyroid dysfunction is associated with multiple changes in lipoprotein metabolism, and we have determined the effects of thyroid dysfunction on plasma cholesteryl ester transfer protein (CETP) activity. CETP is a plasma protein that mediates the exchange of cholesteryl ester and triglyceride between plasma lipoproteins and plays an important role in high-density lipoprotein metabolism and in the reverse cholesterol transport pathway. Plasma CETP activity was assayed in 18 hyperthyroid and in 17 hypothyroid patients, before and after treatment, by measuring the transfer of cholesteryl esters from exogenous radiolabeled high-density lipoprotein to apolipoprotein B-containing lipoproteins. Plasma CETP activity was increased in hyperthyroid patients, compared with their matched controls (22.11 +/- 8.92% transferred/5 microL.4 h vs. 16.75 +/- 6.48, P < 0.05), whereas in hypothyroid patients, plasma CETP activity was decreased (11.14 +/- 4.84% transferred/5 microL.4 h vs. 17.26 +/- 7.13, P < 0.01). Plasma CETP activity decreased after treatment of thyrotoxicosis, although a significant change was observed, mainly in the severely thyrotoxic patients with free T4 > 100 pmol/L (n = 11, 25.61 +/- 8.12% transferred/5 microL.4 h vs. 21.71 +/- 7.84, P < 0.05). In the hypothyroid patients, there was a significant increase in plasma CETP activity after thyroxine replacement (11.14 +/- 4.84% transferred/5 microL.4 h vs. 15.46 +/- 6.71, P < 0.01). There was a strong positive correlation between log(free T4) and plasma CETP activity (r = 0.51, P < 0.001). In summary, both hyper- and hypothyroidism are associated with significant changes in plasma CETP activity, and these changes are corrected when the patients have been rendered euthyroid.     

N-substituted octahydro-4a-(3-hydroxyphenyl)-10a-methyl-benzo[g]isoquinolines are opioid receptor pure antagonists

N-Methyl- and N-phenylethyl-(+/-)-1,2,3,4,4a,5,10,10a- octahydro-4a-(3-hydroxyphenyl)-10a-methyl-benzo[g]isoquinolines (4 and 5, respectively) were found to be pure opioid antagonists. These compounds were shown to share many of the characteristics identified with the N-methyl- and N-phenylethyl trans-3,4-dimethyl-4-(3-hydroxyphenyl)piperidine (1 and 2, respectively) including N-substituent mediated potency and a lack of N-substituent mediated antagonism. These data suggest that compounds 4 and 5 and the N-substituted trans-3,4-dimethyl-4-(3-hydroxyphenyl)piperidines (1 and 2) may interact with opioid receptors similarly.     

Differential interaction of coagulation factor VIII and factor V with protein chaperones calnexin and calreticulin

Factor VIII (FVIII) and factor V (FV) are homologous coagulation cofactors sharing a similar domain organization (A1-A2-B-A3-C1-C2) and are both extensively glycosylated within their B-domains. In mammalian cell expression systems, compared with FV, the FVIII primary translation product is inefficiently transported out of the endoplasmic reticulum. Here we show that FVIII is degraded within the cell by a lactacystin-inhibitable pathway, implicating the cytosolic 20 S proteasome machinery. Protein chaperones calnexin (CNX) and calreticulin (CRT) preferentially interact with glycoproteins containing monoglucosylated N-linked oligosaccharides and are proposed to traffic proteins through degradative and/or secretory pathways. Utilizing co-immunoprecipitation assays, intracellular FVIII was detected in association with CNX maximally within 30 min to 1 h following synthesis, whereas FV could not be detected in association with CNX. In contrast, both FVIII and FV displayed interaction with CRT during transit through the secretory pathway. B-domain deleted FVIII significantly reduced the CNX and CRT interaction, indicating the B-domain may represent a primary CNX and CRT interaction site. In the presence of inhibitors of glucose trimming, the interactions of FVIII with CNX, and of FVIII and FV with CRT, were significantly reduced whereas the secretion of FVIII, and not FV, was inhibited. In addition, transfection in a glucosidase I-deficient Chinese hamster ovary cell line (Lec23) demonstrated that both degradation and secretion of FVIII were inhibited, with little effect on the secretion of FV. These results support that CNX and CRT binding, mediated at least in part by the B-domain of FVIII, is required for efficient FVIII degradation and secretion. In contrast, FV does not require CNX interaction for efficient secretion. The results suggest a unique requirement for carbohydrate processing and molecular chaperone interactions that may limit the productive secretion of FVIII.     

Current trends in the detection and management of carotid body tumors

PURPOSE: Because the natural history of carotid body tumors is believed to be unpredictable, immediate surgical removal has been recommended. The present study reviews our experience in the diagnosis and treatment of these uncommon lesions. METHODS: The medical records of patients who appeared for treatment with carotid body tumors between 1981 and 1997 were reviewed. Patients demographics, mode of presentation, imaging and treatment modalities, Shamblin classification, and neurologic complications (stroke, cranial nerve injuries) were analyzed. RESULTS: Over the past 16 years, 31 patients with 32 carotid body tumors have been evaluated, with an average follow-up of 3.2 years. The patients were arbitrarily classified into two groups on the basis of the mode of detection. Seventy percent (23 of 32) of the tumors discovered on clinical or self-examination were classified as Group 1; 28% (9 of 32) of the tumors detected during duplex scanning for carotid artery disease (8) or MRI (1) were classified as Group 2. The mean size of chemodectomas found on palpation (4.3 +/- 1.7 cm) was larger than that of those detected by duplex ultrasound (2.7 +/- 1.0 cm; p < 0.05, by paired t test). Preoperative embolization was successfully performed in 5 of 6 instances of large tumors; the remaining patient suffered a procedure-related stroke. Thirty-one carotid body tumors were resected. In one case, the tumor was felt by the primary surgeon to be too small (0.9 x 0.7 cm on duplex scan) to warrant immediate excision; this patient is being followed by periodic duplex scanning. Five neurologic complications were noted in Group 1, one after preoperative embolization and four after surgery. One cranial nerve injury occurred in Group 2. One patient had a large recurrent chemodectoma with clinical evidence of metastatic disease. CONCLUSION: The increasing use of sophisticated imaging modalities may allow earlier discovery of carotid body tumors before they can be clinically detected. Resection of carotid body tumors of all sizes in appropriate surgical candidates remains the standard of care. Unfortunately, resection of even small tumors is associated with a low but constant incidence of neurologic complications.     

H-cadherin expression inhibits in vitro invasiveness and tumor formation in vivo

H-cadherin is a newly characterized cadherin molecule whose expression is decreased in a variety of human carcinoma cells, suggesting that it may play a role in maintaining normal cellular phenotype. To investigate how re-expression of H-cadherin could influence the malignant phenotype of human breast carcinoma cells in vivo, we transfected both control and H-cadherin expression vectors into human breast cancer cells (MDAMB435), which do not express H-cadherin constitutively. We found that invasiveness of these cells could be prevented by transfection with H-cadherin. We also compared the ability of control- and H-cadherin-transfected cells to induce subcutaneous tumors after injection into mammary fat pads of nude mice. Our results show that H-cadherin transfection produced a marked inhibition of tumor growth and modified the morphology of tumor cells: tumors from mice injected with control cells were significantly larger and contained larger cells having a higher degree of pleomorphism than those of tumors generated from carcinoma cells expressing H-cadherin. Altogether, these results indicate that H-cadherin expression antagonizes tumor growth in nude mice, presumably by enhancing cell-cell association in a tissue environment. These findings strongly suggest that H-cadherin could provide a possible target for corrective gene therapy against breast cancer.     

Metabolism to a response pathway selective retinoid ligand during axial pattern formation

We report identification of 9-cis-4-oxo-retinoic acid (9-cis-4-oxo-RA) as an in vivo retinoid metabolite in Xenopus embryos. 9-Cis-4-oxo-RA bound receptors (RARs) alpha, beta, and gamma as well as retinoid X receptors (RXRs) alpha, beta, and gamma in vitro. However, this retinoid displayed differential RXR activation depending on the response pathway used. Although it failed to activate RXRs in RXR homodimers, it activated RXRs and RARs synergistically in RAR-RXR heterodimers. 9-Cis-4-oxo-RA thus acted as a dimer-specific agonist. Considering that RAR-RXR heterodimers are major functional units involved in transducing retinoid signals during embryogenesis and that 9-cis-4-oxo-RA displayed high potency for modulating axial pattern formation in Xenopus, metabolism to 9-cis-4-oxo-RA may provide a mechanism to target retinoid action to this and other RAR-RXR heterodimer-mediated processes.