A mathematical model of optimized radioiodine-131 therapy of Graves' hyperthyroidism

Background

The current status of radioiodine-131 (RaI) dosimetry for Graves' hyperthyroidism is not clear. Recurrent hyperthyroidism and iatrogenic hypothyroidism are two problems which interact such that trying to solve one leads to exacerbation of the other. Optimized RaI therapy has therefore begun to be defined just in terms of early hypothyroidism (ablative therapy) as physicians have given up on reducing hypothyroidism.

Methods

Optimized therapy is evaluated both in terms of the greatest separation of cure rate from hypothyroidism rate (non-ablative therapy) or in terms of early hypothyroidism (ablative therapy) by mathematical modeling of outcome after radioiodine and critically discussing the three common methods of RaI dosing for Graves' disease.

Results

Cure follows a logarithmic relationship to activity administered or absorbed dose, while hypothyroidism follows a linear relationship. The effect of including or omitting factors in the calculation of the administered I–131 activity such as the measured thyroid uptake and effective half-life of RaI or giving extra compensation for gland size is discussed.

Conclusions

Very little benefit can be gained by employing complicated methods of RaI dose selection for non-ablative therapy since the standard activity model shows the best potential for cure and prolonged euthyroidism. For ablative therapy, a standard MBq/g dosing provides the best outcome in terms of cure and early hypothyroidism.     

Endoglin (CD105) and vascular endothelial growth factor as prognostic markers in colorectal cancer.

Endoglin (CD105) has been shown to be a more useful marker to identify proliferating endothelium involved in tumor angiogenesis than panendothelial markers such as CD31. We investigated endoglin and vascular endothelial growth factor expression as possible prognostic markers in colorectal cancer. Surgical specimens from 150 patients with resected colorectal carcinomas were immunostained for endoglin, CD31 and vascular endothelial growth factor. Colorectal carcinoma cases consisted of 50 cases without lymph node metastases, 50 cases with only lymph node metastases and 50 cases with liver metastases (38 cases also had positive lymph nodes). Positively stained microvessels were counted in densely vascular foci (hot spots) at x 400 fields in each specimen. For vascular endothelial growth factor, intensity of staining was scored on a three-tiered scale. Results were correlated with other prognostic parameters. Endoglin demonstrated significantly more proliferating neoplastic microvessels than CD31 (31+/-10 vs 19+/-8/0.15 mm2 field, P<0.001). Low vascular endothelial growth factor expression within tumor cells was seen in 49 (33%) and high expression in 101 cases (67%). There was a positive correlation of endoglin, CD31 counts and vascular endothelial growth factor overexpression with the presence of angiolymphatic invasion and lymph node metastases (P<0.05). Only endoglin counts correlated significantly with liver metastases and positive vascular pedicle lymph nodes (P<0.05), while vascular endothelial growth factor showed significant correlation with the depth of invasion (P<0.01). Endoglin, by staining higher numbers of the proliferating vessels in colon carcinoma, is a more specific and sensitive marker for tumor angiogenesis than the commonly used panendothelial markers. Endoglin staining also showed prognostic significance with positive correlation with angiolymphatic invasion and metastases to lymph nodes and liver.     

Identification and characterization of aquaporin-2 water channel mutations causing nephrogenic diabetes insipidus with partial vasopressin response

Congenital nephrogenic diabetes insipidus (NDI) is a rare disease caused most often by mutations in the vasopressin V2 receptor (AVPR2). We studied a family which included a female patient with NDI with symptoms dating from infancy. The patient responded to large doses of desmopressin (dDAVP) which decreased urine volume from 10 to 4 I/day. Neither the parents nor the three sisters were polyuric. The patient was found to be a compound heterozygote for two novel recessive point mutations in the aquaporin-2 (AQP2) gene: L22V in exon 1 and C181W in exon 3. Residue Cys181 in AQP2 is the site for inhibition of water permeation by mercurial compounds and is located near to the NPA motif conserved in all aquaporins. Osmotic water permeability (Pf) in Xenopus oocytes injected with cRNA encoding C181W-AQP2 was not increased over water control, while expression of L22V cRNA increased the Pf to approximately 60% of that for wild-type AQP2. Co-injection of the mutant cRNAs with the wild-type cRNA did not affect the function of the wild-type AQP2. Immunolocalization of AQP2-transfected CHO cells showed that the C181W mutant had an endoplasmic reticulum-like intracellular distribution, whereas L22V and wild-type AQP2 showed endosome and plasma membrane staining. Water permeability assays showed a high Pf in cells expressing wild-type and L22V AQP2. This study indicates that AQP2 mutations can confer partially responsive NDI.      

Reciprocal effect of Waardenburg syndrome mutations on DNA binding by the Pax-3 paired domain and homeodomain

The Pax-3 protein contains two DNA-binding domains, a paired domain and a homeodomain. Mutations in Pax-3 cause Waardenburg syndrome (WS) in humans and the mouse Splotch (Sp) phenotype. In the Sp-delayed mouse, a mutation in the Pax-3 paired domain (G9R) abrogates the DNA-binding activity of both the paired domain and the homeodomain, suggesting that they may functionally interact. To investigate this possibility further, we have analyzed the DNA-binding properties of additional point mutants in the Pax-3 paired domain and homeodomain that occur in WS patients (F12L, N14H, G15S, P17L, R23L, G48A, S51F and G66D in the paired domain, V47F and R53G in the homeodomain), the Pax-1 un mutation (G15A) and a substitution associated with Peters' anomaly in the PAX-6 gene (R23G). Within the paired domain, seven of 10 mutations were found to abrogate DNA-binding by the paired domain. Remarkably, these seven mutations also affected DNA binding by the homeodomain, causing either a complete loss (P17L and G66D), a reduction (R23G, R23L, G15S and G15A) or an increase in DNA-binding activity (N14H). In addition, the effect of paired domain mutations occurred at the level of monomer formation by the homeodomain, while the dimerization potential of this domain seemed unaffected in mutants where it could be analyzed. Furthermore, while both homeodomain mutations were found to abolish DNA binding by this domain, the R53G mutation also abrogated DNA binding by the paired domain. The important observation that independent mutations in either domain can affect DNA binding by the other in the intact Pax- 3 protein strongly suggests that the two domains are not functionally independent but bind DNA through cooperative interactions. Modeling the deleterlous mutations on the three-dimensional structure of the paired domain of Drosophila Prd shows that these mutations cluster at the DNA interface, thus suggesting that a series of DNA contacts are essential for DNA binding by both the paired domain and the homeodomain of Pax-3.      

PREVALENCE OF MICROALBUMINURIA IN NON-INSULIN-DEPENDENT DIABETES MELLITUS

The prevalence of microalbuminuria was assessed in 50 patients of non-insulin dependent diabetes mellitus. The mean age of patients was 52.1 ± 11.6 years and the duration of diabetes was 8.3 ± 6.8 years. Twenty (40%) patients had microalbuminuria. Microalbuminuria was more common in patients with a longer duration of diabetes (more than 5 years), a poor glycaemic control, and higher systolic blood pressure.KEY WORDS: Microalbuminuria, Diabetes mellitus, Diabetic nephropathy, Chronic renal failure     

In vitro combination treatment with perifosine and UCN-01 demonstrates synergism against prostate (PC-3) and lung (A549) epithelial adenocarcinoma cell lines.

PURPOSE: Antineoplastic agents often achieve antitumor activity at the expense of close to unacceptable toxicity. One potential avenue to improve therapeutic index might combine agents targeting distinct components of the same growth regulatory pathway. This might lead to more complete modulation of the target pathway at concentrations lower than those associated with limiting adventitious toxicities from either agent alone. The protein kinase antagonist UCN-01 is currently used in Phase I/II trials and has recently been demonstrated to inhibit potently PDK1. We have recently documented that the alkylphospholipid perifosine potently also inhibits Akt kinase (PKB) activation by interfering with membrane localization of Akt. This leads to the hypothesis that these two agents might act synergistically through distinct mechanisms in the PI3K/Akt proliferation and survival-related signaling pathway. EXPERIMENTAL DESIGN: The synergistic effects of UCN-01 and perifosine, on two cell lines (A-549 and PC-3), were examined using various long-term in vitro assays for cell growth, cell cycle distribution, clonogenicity, survival morphology, and apoptosis. Along with Western blotting experiments were performed to determine whether this synergistic combination of two drugs has significant effect on their downstream targets and on biochemical markers of apoptosis. RESULTS: After 72 h, perifosine at concentrations of 1.5 and 10 microM UCN-01 at 40 and 250 nM did not significantly affect the growth of PC-3 and A459 cells, respectively. However, in combination at the same respective individual concentrations (1.5 microM and 40 nM of perifosine and UCN-01, respectively, in PC-3 cells and 10 microM perifosine and 0.25 microM UCN-01 in the somewhat more resistant A549 cells), virtually complete growth inhibition of both the cell lines resulted. Supra-additive inhibition of growth was also demonstrated in independent clonogenic assays. Mechanistic studies in cell culture models suggest enhanced depletion of the S-phase population in cells treated by the combination. This correlated with enhanced inactivation of Akt along with activation of caspases 3 and 9 and poly(ADP-ribose) polymerase cleavage. Evidence of synergy was formally demonstrated and occurred across a wide range of drug concentrations and was largely independent of the order or sequence of drug addition. CONCLUSIONS: As the concentrations of UCN-01 and perifosine causing synergistic inhibition of cell growth are clinically achievable without prominent toxicity, these data support the development of clinical studies with this combination.     

Efficacy of Zoladex LA (goserelin) in the treatment of girls with central precocious or early puberty

OBJECTIVE: To assess the efficacy of a longer acting preparation of the gonadotrophin releasing hormone (GnRH) analogue goserelin (Zoladex LA, 10.8 mg) in 12 girls with central precocious or early puberty. METHODS: Two girls started treatment de novo; the remainder had been on suppressive treatment for a median duration of 1.5 (range, 0.2-5.6) years. Assessment comprising auxology, pubertal staging, and pelvic ultrasound examination was carried out at weeks 0, 4, 8, 10, and 12 (first cycle) and weeks 8, 10, and 12 (second cycle) to evaluate the required injection frequency. Thereafter, assessment was performed on the day of injection. Zoladex LA was given every 12 weeks unless pubertal progression occurred. RESULTS: Satisfactory control was achieved in eight patients using this regimen, and three patients required more frequent injections. One girl was removed from the study because of clinical progression and extreme mood swings. No serious adverse effects occurred. Mean height velocity during the study period was 4.5 cm/year (range, 3.1-6.6) compared with 6.5 cm/year (range, 3.8-9.6) before treatment in nine patients for whom data were available. CONCLUSIONS: Zoladex LA was effective in controlling precocious puberty in girls when given at intervals of 9-12 weeks and it is recommended that an initial assessment is made eight weeks after beginning treatment.     

Beta2 integrin/ICAM-1 adhesion molecule interactions in cutaneous inflammation and tumor promotion

The beta2 integrin (CD 18/CD 11 a, b, c) family of proteins mediate adherence of leukocytes to vascular endothelium and the associated ligand, intercellular adhesion molecule-1 (ICAM-1; CD 54), interacts with beta2 integrin proteins to allow transendothelial migration of leukocytes into sites of inflammation. The present study examines the function of these proteins in a murine model of acute cutaneous inflammation induced following topical application of 12-O- tetradecanoylphorbol-13-acetate (TPA) to the dorsal epidermis of SENCAR mice and in a model of skin multistage carcinogenesis. At 24 h following topical application of TPA to the dorsal epidermis of mice, dermal leukocytes expressed higher levels of beta2 integrin protein compared with the lower levels of beta2 integrin protein expression by peripheral blood leukocytes. ICAM-1 protein was localized to epidermal keratinocytes and vascular endothelium in TPA-treated skin and to proliferating papilloma cells. Intravenous (i.v.) injection of either 50 microg anti-beta2 integrin antibody alone or in combination with anti-ICAM-1 antibody significantly inhibited both TPA-stimulated neutrophil infiltration into the dermis (P < 0.001) and myeloperoxidase (MPO) activity (P < 0.03 anti-beta2 integrin antibody; P < 0.01 anti- beta2 integrin + ICAM-1 adhesion molecule antibodies), but had no effect on TPA-induced epidermal hyperplasia. In addition, injection of either anti-ICAM-1 adhesion molecule antibody alone (P < 0.004) or in combination with anti-beta2 integrin antibody (P < 0.001) significantly inhibited TPA-induced production of 7,8-dihydroxy-2'-deoxyguanosine (8- OHdG) immunoreactive proteins by epidermal keratinocytes. Beta2 integrin/ICAM-1 adhesion molecules work in concert to regulate migration, retention and functional activation of leukocytes within the dermis during TPA-induced skin inflammation and within stromal tissue of papillomas that form during multi-stage carcinogenesis. Agents that inhibit these receptor/ligand interactions may be useful in defining the roles of specific cell populations in cutaneous inflammation and multistage carcinogenesis and may also have potential as anti-promoting and anti-progression agents.