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     

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.      

Mutation of the p53 tumor suppressor gene in spontaneously occurring osteosarcomas of the dog

Inactivation of the p53 tumor suppressor gene has been implicated in the pathogenesis of numerous human cancers, including osteosarcomas. Appendicular osteosarcomas of the dog appear to be a good model for their human equivalent with regard to biologic behavior, epidemiology and histopathology. We individually screened exons 5-8 of the p53 gene for mutations in 15 canine appendicular osteosarcomas using 'Cold' SSCP to compare the role of this gene in human and canine osteosarcoma tumorigenesis. Seven of the tumors (47%) exhibited point mutations, with one tumor possessing two mutations within different exons. Of these, seven were missense mutations and the eighth was a 'silent' mutation potentially affecting the exon 6-7 splicing region. Five of the missense mutations were located in highly conserved regions IV and V, while another corresponded with the highly conserved codon 220 mutational hotspot located outside the conserved domains. The locations and types of mutations were nearly identical to those reported in human cancer. These findings provide strong evidence of the involvement of p53 mutations in the development of canine appendicular osteosarcomas. Canine osteosarcomas appear to be a promising model for their human equivalent on a clinical, pathologic, and molecular level.      

SOMATIC NEUROPATHY IN DIABETES MELLITUS

One hundred patients of Diabetes Mellitus (70 with and 30 without clinical somatic neuropathy) were studied to correlate clinical severity with the magnitude of nerve conduction abnormalities. Age range was 10-79 years (mean 49) with equal number of males and females. Incidence of neuropathy was more in patients over 40 years of age (60 out of 70 patients) with duration of disease over two years (78.33%). The grades of severity were mild in 22 (31.33%), moderate in 25 (35.71%) and severe in 23 (32.86%) patients. Nerve conduction studies were carried out in 48 (27 with and 21 without clinical neuropathy) patients, using the apparatus Dantec (Cantata TM). The nerves (median, peroneal and sural) were stimulated at two points and the recording of latency; amplitude (micro V) and motor and sensory nerve conduction velocities (m/s) were done under identical environmental conditions. Sensory nerve conduction velocity was more affected than motor velocity. In the 21 patients without clinical neuropathy, 14 showed abnormalities indicating early involvement of peripheral nerves. Reduction of motor nerve conduction velocity was more in patients with moderate and severe grades. The reduction was more in lower than in upper limbs. Nerve conduction abnormality helps in diagnosis in diabetic neuropathy even in preclinical state and correlates with severity, in clinical neuropathy.KEY WORDS: Diabetic neuropathy, Nerve conduction abnormality, Peripheral neuropathy     

Age has a profound effect on the incidence and significance of chromosome abnormalities in myeloma.

A simple high throughput micro-fluorescence in situ hybridisation technique (FISH) was used to detect chromosome 13 deletions (delta13), immunoglobulin heavy chain (IgH) rearrangements, t(11;14)(q13;q32), t(4;14)(p16;q32), t(14;16)(q23;q32), p53 loss, and numerical changes of chromosomes 3, 6, 7, 9, 10, 11 and 17 in 228 cases of multiple myeloma (MM), including 33 asymptomatic/smouldering MM (SMM). The patients were not part of a clinical trial and were from 30 different hospitals. In all, 98.4% of cases were abnormal, with 43% having IgH rearrangements and 42% Delta13. The low incidence of IgH rearrangements was due to a decrease in this finding with age (P = 0.001) and the relatively high proportion of elderly patients in our study population (41% >70 years old). The incidence of specific IgH translocations was t(4;14) 11%, t(11;14) 16% and t(14;16) 3%. Univariate statistical testing showed delta13 (P = 0.002), and t(14;16) (P = 0.005) to be associated with shorter survival. This effect was exaggerated for patient's aged 70 years or under but no effect on survival was seen for those over 70 years. In younger patients t(4;14) (P = 0.044) and p53 deletion (P < 0.001) were also significant poor prognostic indicators. Multivariate analysis showed delta13 and t(14;16) to be independent prognostic variables when considered with age and clinical parameters.