Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We studied the dose requirements of thyroxine (T(4)) and serum concentrations of thyrotropin-stimulating hormone (TSH) and free T(4) in 16 pregnant women with primary hypothyroidism due to autoimmune thyroid disease (ATD, n = 11) or thyroidectomy (n = 5). All patients had been advised by their obstetricians to take prenatal vitamins enriched with iron ( approximately 90mg/tablet) and calcium ( approximately 200 mg/tablet), known to inhibit absorption of T(4). We asked patients to take their vitamins 4 hours after ingesting T(4) in the morning. The mean T(4) dose of 0.10 +/- 0.01 (mean +/- SEM, mg/d) during pregnancy did not differ significantly from that (0.09 +/- 0.005) before or after (0.10 +/- 0.01) pregnancy. Similarly, mean serum TSH of 2.7 +/- 0.28 mIU/L during pregnancy did not differ significantly from that before (2.2 +/- 0.47) or after (3.2 +/- 1.31) pregnancy. The mean serum free T(4) concentration during pregnancy (16 +/- 0.97 pmol/L) was significantly (P <.05) lower than that (22 +/- 1.5) before or after (23 +/- 2.2) pregnancy and similar to that observed with our free T(4) measurement technique in normal (healthy) pregnant women. We next examined the data separately in patients with ATD and thyroidectomy. The mean T(4) dose (0.08 +/- 0.009) and TSH (2.4 +/- 0.29) during pregnancy in 11 ATD patients did not differ appreciably from those before (T(4) dose, 0.08 +/- 0.0006; TSH, 2.7 +/- 0.54) or after (T(4) dose 0.09 +/- 0.0063; TSH, 4.1 +/- 1.91) pregnancy. Similarly, the mean T(4) dose (0.12 +/- 0.022, n = 5) during pregnancy in thyroidectomized patients was similar to that before (0.12 +/- 0.017, n = 3) or after (0.12 +/- 0.022) pregnancy. However, serum TSH increased significantly, albeit within the normal range, during pregnancy in thyroidectomized patients (3.2 +/- 0.62, n = 5 v 0.41 +/- 0.017, n = 3, P <.05) and it (1.3 +/- 0.60) decreased significantly (P <.05) after pregnancy. Our data suggest that (1) the dose requirement of T(4) does not change systematically in pregnancy in most hypothyroid women. There may occur a modest increase in T(4) dose requirement during pregnancy in some thyroidectomized patients; (2) diminished absorption of T(4), possibly related to ingestion of exogenous agents (eg, iron, calcium, vitamins), may have contributed to previous suggestions of substantial increased T(4) requirement in pregnancy; (3) ingestion of T(4) dose absorption-inhibiting agents some 4 hours away from T(4) markedly diminishes or obviates their effect in many patients. Although many hypothyroid patients may not require an adjustment in their T(4) dose during pregnancy, it is prudent to monitor all such patients carefully as the consequences of inadequate therapy may be very important.
 ...
PMID:Treatment of primary hypothyroidism during pregnancy: is there an increase in thyroxine dose requirement in pregnancy? 1252 72

Nanohybrid organo-inorgano clay mineral-polydimethylsiloxane (PDMS) membranes were prepared by the reaction of pure and/or modified natural clay minerals (Sepiolite and montmorillonite) with PDMS in hexane, followed by evaporation of the solvent at 70 degrees C. The membranes were characterized by means of XRD, SEM, ATD-TG and solid state (29)Si magic angle spinning (MAS) and cross-polarization (CP) CP/MAS NMR. The morphology of the membranes depends on the content loading of clay mineral. For low content, the membrane composition is homogeneous, with well dispersed nanoparticles of clay into the polymer matrix, whereas for higher clay content, the membranes are constituted also of a mixture of well dispersed nanoparticles into the polymer, but in the presence of agglomerations of small clay particles. Quantitative (29)Si MAS NMR demonstrated a strong correlation between the clay content of the membrane and the average length of the PDMS chain, indicating that the nanohybrid material is made of clay particles covalently linked to the PDMS structure. This is particularly the case for Sepiolite with has a high density of Q(2) silanol sites. The separation performances of the prepared membranes were tested for CO(2)/CH(4) and O(2)/N(2) mixtures. The observed separation factors showed an increase of the selectivity in the case of CO(2)/CH(4) in comparison with membranes made from PDMS alone under the same conditions.
 ...
PMID:Nanoporous polymer--clay hybrid membranes for gas separation. 2006 May 40