Using biorelevant dissolution to obtain IVIVC of solid dosage forms containing a poorly-soluble model compound

The usefulness of selected biorelevant dissolution media (BDM) to predict in vivo drug absorption was studied. Dissolution profiles of solid formulations of a poorly soluble model compound were compared in BDM simulating fasted and two levels of fed state. A non-physiologically relevant medium containing the cationic surfactant, cetrimide, was also investigated. All the media studied were capable of differentiating between the formulations employed, with formulation A consistently ranking high and formulations C and D ranking low. An in vivo dog study was carried out and an attempt was made to obtain a level A correlation between the plasma absorption curves and in vitro dissolution curves, using non-linear regression software. The in vitro-in vivo correlation (IVIVC) models developed indicated that fed state media (BDM 3) containing high levels of both bile salts (BS) and lipolysis products (LP) were best able to predict in vivo pharmacokinetic parameters (Cmax and AUC) with prediction errors lower than 10%. Overall, design and use of appropriate media for in vitro dissolution is extremely important. This study demonstrates the potential of physiologically relevant media containing both BS and LP for use in formulation and early drug development.     

Direct genotyping of single nucleotide polymorphisms in methyl metabolism genes using probe-free high-resolution melting analysis.

High-resolution melting (HRM) shows great promise for high-throughput, rapid genotyping of individual polymorphic loci. We have developed HRM assays for genotyping single nucleotide polymorphisms (SNP) in several key genes that are involved in methyl metabolism and may directly or indirectly affect the methylation status of the DNA. The SNPs are in the 5,10-methylenetetrahydrofolate reductase (MTHFR; C677T and A1298C), methionine synthetase (MTR; 5-methyltetrahydrofolate-homocysteine methyltransferase; A2756G), and DNA methyltransferase 3b (DNMT3b; C46359T and C31721T) loci. The choice of short amplicons led to greater melting temperature (Tm) differences between the two homozygous genotypes, which allowed accurate genotyping without the use of probes or spiking with control DNA. In the case of MTHFR, there is a second rarer SNP (rs4846051) close to the A1298C SNP that may result in inaccurate genotyping. We masked this second SNP by placing the primer over it and choosing a base at the polymorphic position that was equally mismatched to both alleles. The HRM assays were done on HRM capable real-time PCR machines rather than stand-alone HRM machines. Monitoring the amplification allows ready identification of samples that may give rise to aberrant melting curves because of PCR abnormalities. We show that samples amplifying markedly late can give rise to shifted melting curves without alteration of shapes and potentially lead to misclassification of genotypes. In conclusion, rapid and high-throughput SNP analysis can be done with probe-free HRM if sufficient attention is paid to amplicon design and quality control to omit aberrantly amplifying samples.     

Progression of Epididymal Maldevelopment Into Hamartoma-like Neoplasia in VHL Disease

Inactivation of the von Hippel-Lindau (VHL) gene and activation of the hypoxia-inducible factor (HIF) in susceptible cells precedes formation of tumorlets and frank tumor in the epididymis of male VHL patients. We performed detailed histologic and molecular pathologic analysis of tumor-free epididymal tissues from VHL patients to obtain further insight into early epididymal tumorigenesis. Four epididymides from two VHL patients were serially sectioned to allow for three-dimensional visualization of morphologic changes. Areas of interest were genetically analyzed by tissue microdissection, immunohistochemistry for HIF and markers for mesonephric differentiation, and in situ hybridization for HIF downstream target vascular endothelial growth factor. Structural analysis of the epididymides revealed marked deviations from the regular anatomic structure resulting from impaired organogenesis. Selected efferent ductules were represented by disorganized mesonephric cells, and the maldeveloped mesonephric material was VHL-deficient by allelic deletion analysis. Furthermore, we observed maldeveloped mesonephric material near cystic structures, which were also VHL-deficient and were apparent derivatives of maldeveloped material. Finally, a subset of VHL-deficient cells was structurally integrated in regular efferent ductules; proliferation of intraductular VHL-deficient cells manifests itself as papillary growth into the ductular lumen. Furthermore, we clarify that that there is a pathogenetic continuum between microscopic tumorlets and formation of tumor. In multiple locations, three-dimensional reconstruction revealed papillary growth to extend deeply into ductular lumina, indicative of progression into early hamartoma-like neoplasia. We conclude epididymal tumorigenesis in VHL disease to occur in two distinct sequential steps: maldevelopment of VHL-deficient mesonephric cells, followed by neoplastic papillary proliferation.     

Activity of cyclosporins as resistance modifiers in primary cultures of human haematological and solid tumours.

The semiautomated fluorimetric microculture cytotoxicity assay (FMCA) was used for evaluation of the ability of cyclosporin A (CsA) and its novel non-immunosuppressive derivative SDZ PSC 833 (PSC) to modify the response to doxorubicin or vincristine in vitro in different haematological and solid human tumour types. Primary cultures of 322 tumour samples were analysed. Both cyclosporins showed resistance-modifying activity in all haematological tumours tested, and in solid tumours activity was observed in ovarian carcinoma and childhood tumours. Little or no effect was found in the remaining tumour types, including breast, renal and adrenal cortical carcinomas and adult sarcomas. In most of the responsive cases the interaction between the modifier and the cytotoxic drug was synergistic. There was a tendency to higher activity in samples from previously treated patients, and an inverse relationship between degree of cytotoxic drug resistance and resistance-modifying activity was noted. No difference in potency between CsA and PSC could be discerned. The results indicate differential in vitro resistance-modifying activity of the cyclosporins depending on tumour type. The results also suggest that treatment with resistance modifiers should be considered also for primary therapy of drug-sensitive tumours. Drug resistance assays such as the FMCA may become useful in preclinical evaluation of resistance modifiers.     

Risk factors for development of dehydration in young children with acute watery diarrhoea: a case-control study

In a case-control study to understand the risk factors for development of life-threatening dehydration, a total of 379 children comprising 243 cases (moderate or severe dehydration) and 136 controls (non or mild dehydration) up to 2 years of age suffering from acute watery diarrhoea were studied. By univariate analysis, the presence of vibrios in stool, withdrawal of breast feeding during diarrhoea, not giving fluids, including oral rehydration solution (ORS), during diarrhoea, frequent purging (> 8/ day), vomiting (> 2/day) and undernutrition were identified as risk factors. However, by multivariate analysis after controlling for confounders, withdrawal of breast feeding during diarrhoea (odds ratio (OR) = 6.8, p < 0.00001) and not giving ORS during diarrhoea (OR = 2.1, p < 0.006) were identified as significant risk factors. The confounding variables which also contributed significantly to increasing the risk were age (≤ 12 months; OR = 2.7, p = 0.001), frequent purging (> 8/day; OR = 4.1, p < 0.00001), vomiting (> 2/day; OR = 2.4, p = 0.001) and severe undernutrition (%median <60 weight-for-age of Indian Academy of Paediatrics classification; OR = 3.1, p = 0.001). We feel that these findings will be useful for Global and National Diarrhoeal Diseases Control Programmes for formulating intervention strategies for preventing death due to diarrhoeal dehydration.     

Implications of human papillomavirus type for survival in cervical squamous cell carcinoma

In a Swedish series of 107 invasive squamous carcinomas of the cervix, DNA extraction from paraffin-embedded material was successful in 97 cases. The prevalence of human papillomavirus (HPV) in this material was 86.6%, as determined by polymerase chain reaction (PCR) using both consensus and type-specific primers. HPV type 16 was most common (42.3%; other types were 31 (12.3%), 18 (9.3%) and 33 (10.3%). Seventeen cases (17.3%) were positive for the consensus primers only and were regarded as HPV of unknown type. There was no significant difference in corrected survival between patients with HPV-positive or -negative tumors. In the HPV-positive group, patients with tumors containing HPV 33 or HPV 18 had a significantly poorer prognosis than patients with tumors containing other types of HPV DNA (relative hazard 3.18, 95% confidence interval 1.37–7.39, P = 0.007), implying a prognostic significance of HPV type.     

Schneiderian papillomas of the nasal septum

Summary A case of Schneiderian papilloma of the nasal septum is presented. The condition is rare, as indicated by a review of previously published cases. The clinical course of the lesion suggests that it behaves like Schneiderian papillomas elsewhere in the nasal cavity and paranasal sinuses. The need for aggressive surgical management and careful follow-up is emphasized.     

Squamous odontogenic tumour: review of the literature and a new case

Squamous odontogenic tumour (SOT) is a rare benign odontogenic neoplasm, apparently arising from rests of Malassez. It was first described in 1975 and since then only 17 cases have been recorded in the literature. A new, not previously reported, characteristic case of SOT is presented in connection with a review of the literature. It is concluded that the lesion occurs with equal frequency in the maxilla and mandible and now and then multifocally. Maxillary lesions seem to grow more aggressively than do mandibular ones. The symptoms are modest. SOT has a characteristic pathologic picture which differs decisively from ameloblastoma and which, in connection with its benign nature, warrants the classification of SOT. Although most cases have been treated by conservative surgical therapy without recurrence, there are cases, especially in the maxilla with diffuse lesions, which have required en bloc resection or hemimaxillectomy. The diagnostic problems are stressed and recommendations are made for the pathologist and the surgeon to pay attention to this rare but benign tumour.