Antithrombins Wibble and Wobble (T85M/K): archetypal conformational diseases with in vivo latent-transition, thrombosis, and heparin activation

The inherent variability of conformational diseases is demonstrated by two families with different mutations of the same conserved aminoacid in antithrombin. Threonine 85 underlies the opening of the main beta-sheet of the molecule and its replacement, by the polar lysine, in antithrombin Wobble, resulted in a plasma deficiency of antithrombin with an uncharacteristically severe onset of thrombosis at 10 years of age, whereas the replacement of the same residue by a nonpolar methionine, antithrombin Wibble, gave near-normal levels of plasma antithrombin and more typical adult thromboembolic disease. Isolated antithrombin Wibble had a decreased thermal stability (Tm 56.2, normal 57.6 degreesC) but was fully stabilized by the heparin pentasaccharide (Tm 71.8, normal 71.0 degreesC), indicating that the prime abnormality is a laxity in the transition of the main sheet of the molecule from the 5- to 6-stranded form, as was confirmed by the ready conversion of antithrombin Wibble to the 6-stranded latent form on incubation. That this transition can occur in vivo was shown by the finding of nearly 10% of the proband's plasma antithrombin in the latent form and also, surprisingly, of small but definitive amounts of latent antithrombin in normal plasma. The latent transition will be predictably accelerated not only by gross mutations, as with antithrombin Wobble, to give severe episodic thrombosis, but also by milder mutations, as with antithrombin Wibble, to trigger thrombosis in the presence of other predisposing factors, including the conformational stress imposed by the raised body temperatures of fevers. Both antithrombin variants had an exceptional (25-fold) increase in heparin affinity and this, together with an increased inhibitory activity against factor Xa, provides evidence of the direct linkage of A-sheet opening to the conformational basis of heparin binding and activation.     

Follicular and Hurthle cell carcinomas of the thyroid: a comparative study

University of Texas M. D. Anderson Cancer Center cases filed as Hurthle cell and follicular carcinoma were reviewed. Requirements for including a case in the study were that the diagnosis of Hurthle cell or follicular carcinoma be confirmed, that histologic material and clinical information be adequate, and that there be at least 9 years of follow-up. The study group included 18 cases of Hurthle cell carcinoma and 33 cases of follicular carcinoma. Ten of the Hurthle cell carcinomas had extrathyroid invasion, three had intrathyroid invasion, and five were encapsulated (i.e., they had intracapsular invasion only). In the follicular carcinoma group, 5 tumors had extrathyroid invasion, 14 had intrathyroid invasion, and 14 were encapsulated. When the cases were stratified according to extent of invasion in this manner, there was no statistically significant difference in rate of local recurrence, rate of metastasis (either regional lymph node or distant), or patient survival between Hurthle cell carcinoma and follicular carcinoma. Other variables including patient age and sex, treatment differences, tumor size, vascular invasion, predominant growth pattern (follicular versus solid-trabecular), nuclear size and pleomorphism, mitotic rate, and tumor necrosis did not provide significant additional prognostic information. Metastases of both Hurthle cell and follicular carcinoma were mostly distant and predominantly involved bone and lung. Behavioral differences between Hurthle cell and follicular carcinoma that were not statistically significant included a higher rate of local recurrence in Hurthle cell carcinoma with intrathyroid invasion, more frequent occurrence of regional lymph node metastasis in Hurthle cell carcinoma with extrathyroid invasion, and absence of distant metastasis and death caused by tumor in encapsulated Hurthle cell carcinoma. Five follicular carcinomas and one Hurthle cell carcinoma appeared to have arisen within an adenoma.     

Quantitative analysis of microvascular changes in diffuse astrocytic neoplasms with increasing grade of malignancy

BACKGROUND: Despite concerns about its prevalence and ramifications, harassment has not been well quantified among physicians. Previous published studies have been small, have surveyed only 1 site or a convenience sample, and have suffered from selection bias. METHODS: Our database is the Women Physicians' Health Study, a large (4501 respondents; response rate, 59%), nationally distributed questionnaire study. We analyzed responses concerning gender-based and sexual harassment. RESULTS: Overall, 47.7% of women physicians reported ever experiencing gender-based harassment, and 36.9% reported sexual harassment. Harassment was more common while in medical school (31% of gender-based and 20% for sexual harassment) or during internship, residency, or fellowship (29% for gender-based and 19% for sexual harassment) than in practice (25% for gender-based and 11% for sexual harassment). Respondents more likely to report gender-based harassment were physicians who were now divorced or separated and those specializing in historically male specialties, whereas those of Asian and other (nonwhite, nonblack, non-Asian, non-Hispanic) ethnicity, those living in the East, and those self-characterized as politically very conservative were less likely to report gender-based harassment. Being younger, born in the United States, or divorced or separated were correlated with reporting ever experiencing sexual harassment; those who were Asian or who were currently working in group or government settings were less likely to report it. Those who felt in control of their work environments, were satisfied with their careers, and would choose again to become physicians reported lower prevalences of ever experiencing harassment. Those with histories of depression or suicide attempts were more likely to report ever having been harassed. CONCLUSIONS: Women physicians commonly perceive that they have been harassed. Experiences of and sensitivity to harassment differ among individuals, and there may be substantial professional and personal consequences of harassment. Since reported rates of sexual harassment are higher among younger physicians, the situation may not be improving.     

Danazol for systemic lupus erythematosus with refractory autoimmune thrombocytopenia or Evans' syndrome

OBJECTIVE: To determine the efficacy of danazol for refractory autoimmune thrombocytopenia or Evans' syndrome complicating systemic lupus erythematosus (SLE). METHODS: We studied 16 consecutive patients with SLE and corticosteroid refractory autoimmune thrombocytopenia; 3 patients had coexisting autoimmune hemolysis (Evans' syndrome). Five patients had undergone splenectomy. Danazol was commenced at 200 mg/day, and increased stepwise (maximum 1200 mg/day) until benefit or toxicity was observed. After remission the danazol dose was gradually reduced to 200-400 mg/day. RESULTS: All 16 patients achieved a complete remission (platelet count >100 x 10(9)/l, hematocrit >39%) 2 months after starting danazol (range 6 weeks-8 months). Remission persisted during continued danazol therapy (mean followup 18.2 months, range 2-49 months). One patient with Evans' syndrome required discontinuation of danazol because of jaundice and biopsy proven minimal hepatic necrosis: hemolysis recurred after discontinuation of danazol. CONCLUSION: Danazol is effective for the treatment of autoimmune thrombocytopenia or Evans' syndrome complicating SLE irrespective of splenectomy status. Longer followup will be needed to determine whether the remission persists after withdrawal of danazol.     

Effects of acute and chronic morphine on rotational behavior in nigral-lesioned rats

Stimulation of mu-opioid receptors located on dopaminergic neurons in the striatum and the nucleus accumbens increases dopamine release, which may account for some of the behavioral effects of morphine. In this study, we examined the effects of acute and chronic morphine treatment on rotational behavior in rats with unilateral 6-hydroxydopamine dopamine (6-OHDA)-induced lesions of the nigrostriatal pathway. Rats receiving morphine acutely (0.3-10 mg/kg) did not show a significant bias toward contralateral or ipsilateral turning. Mini osmotic pumps dispensing morphine continuously (20-24 mg/kg/day) were implanted s.c. in these animals. This treatment induced tolerance to the behavioral depression produced by the highest dose of morphine (10 mg/kg) when it was given acutely. A slight but significant increase in ipsilateral turning occurred over the range of morphine doses examined. The effects of morphine on rotational behavior are slight, and do not correlate well with the reported increase in locomotor activity or extraneural dopamine in the striatum that are produced by doses of morphine similar to the ones tested in this study.     

Effect of alcohol consumption on adult and aged bone: composition, morphology, and hormone levels of a rat animal model

To determine the effect of life-long alcohol consumption on the adult and aged rat model, 4-week-old, female Sprague-Dawley rats were divided into three diet groups. Alcohol-treated animals were fed a modified Lieber-DeCarli diet ad libitum containing 35% ethanol-derived calories, whereas the pair-fed animals (weight-matched to ethanol rats) received an isocaloric liquid diet in which maltose-dextrin substituted calories supplied by ethanol. Chow animals were fed a standard rat chow ad libitum. Proximal tibiae (primarily cancellous bone) and femora (primarily cortical bone) were removed for analysis after 3, 6, 9, 12, or 18 months on the diets. Serum was collected for analysis of calcium levels, the calcium regulating hormones; parathyroid hormone, 25-hydroxyvitamin D, calcitonin, corticosterone, estradiol, testosterone, and IGF-1. Creatinine, SGOT/AST, and SGPT/ALT levels were measured to determine kidney and liver integrity. Previous studies, with young animals, showed that chronic alcohol consumption during the age of bone development reduced bone density and bone mass in both cortical and cancellous bone. The present study demonstrates that these reductions last throughout life, whereas morphological values, such as length and diameter, attain control levels. Calcium regulating hormones and sex hormones are essentially normal and do not appear to be the primary causative agent for adult alcohol-induced osteopenia, but it appears to be due to a more direct effect of alcohol on bone cells.     

Functional modulation of P2X2 receptors by cyclic AMP-dependent protein kinase

It is generally believed that protein phosphorylation is an important mechanism through which the functions of voltage- and ligand-gated channels are modulated. The intracellular carboxyl terminus of P2X2 receptor contains several consensus phosphorylation sites for cyclic AMP (cAMP)-dependent protein kinase (PKA) and protein kinase C (PKC), suggesting that the function of the P2X2 purinoceptor could be regulated by the protein phosphorylation. Whole-cell voltage-clamp recording was used to record ATP-evoked cationic currents from human embryonic kidney (HEK) 293 cells stably transfected with the cDNA encoding the rat P2X2 receptor. Dialyzing HEK 293 cells with phorbol 12-myristate 13-acetate, a PKC activator, failed to affect the amplitude and kinetics of the ATP-induced cationic current. The role of PKA phosphorylation in modulating the function of the P2X2 receptor was investigated by internally perfusing HEK 293 cells with 8-bromo-cAMP or the purified catalytic subunit of PKA. Both 8-bromo-cAMP and PKA catalytic subunit caused a reduction in the magnitude of the ATP-activated current without affecting the inactivation kinetics and the value of reversal potential. Site-directed mutagenesis was also performed to replace the intracellular PKA consensus phosphorylation site (Ser431) with a cysteine residue. In HEK 293 cells expressing (S431C) mutant P2X2 receptors, intracellular perfusion of 8-bromo-cAMP or purified PKA catalytic subunit did not affect the amplitude of the ATP-evoked current. These results suggest that as with other ligand-gated ion channels, protein phosphorylation by PKA could play an important role in regulating the function of the P2X2 receptor and ATP-mediated physiological effects in the nervous system.     

A two-component interpretation of the far infrared dielectric loss in liquid methyl chloroform

A possible interpretation of the so-called Poley absorption in polar liquids is that it is due to overlapping contributions from liquid- lattice bands together with a contribution from an inertially “rolled-off” Debye absorption. We propose a test involving the inertially similar but electrically very different molecules methyl chloroform and carbon tetrachloride. This test gives results which offer plausible support for the two-component interpretation.