Effects of brain renin-angiotensin on cardiovascular function and saline intake in awake dogs

Initial studies were undertaken to investigate the effects of prolonged administration of angiotensin II (AII), 1 micrograms twice daily, via the lateral ventricles to mongrel dogs on arterial blood pressure and to determine if sodium intake was essential for the development of hypertension. Increasing AII levels in the cerebrospinal fluid for a prolonged period of time produced a sustained hypertensive state only in those dogs in which the daily intake of sodium was increased. The hypertension appeared to be due to an increase in total peripheral resistance. Central administration of AII increased both fluid intake and urine output. In order to assess the hemodynamic effects of increasing endogenous brain AII, renin was injected in doses of 0.025, 0.05, 0.1 and 0.3 units (from porcine kidney) into the lateral ventricles of chronically instrumented awake dogs. Hemodynamic variables were recorded prior to and one and 2 h after the central administration of renin. Renin produced a dose-dependent increase in mean arterial pressure with no significant change in heart rate or carotid, coronary and renal blood flow velocities. Chronic intraventricular administration of renin, 0.15 units twice daily to awake instrumented dogs receiving saline as the drinking fluid, markedly increased the daily intake of saline and increased diastolic and systolic blood pressure without increasing heart rate or carotid, coronary or renal blood flow velocities. There appears to be a direct significant relationship between the increase in mean blood pressure due to the intraventricular administration of renin and the volume of saline consumed.     

Analysis of molecular deletions with cDNA probes in patients with Duchenne and Becker muscular dystrophies

In the course of a systematic survey of DMD and BMD patients with intronic probes and with cDNA probes covering three-fourths of the coding sequence, 45 molecular deletions within the DMD gene were investigated. Forty-two percent of the breakpoints were located in the intronic sequence containing probe P20, whereas the other deletions were widespread around the more proximal part of the gene. Most of the BMD deletions were in the P20 region. Pulsed field gel electrophoresis was used to determine the size of some deletions and allowed us to estimate the physical distance between the intronic probes JBir and P20. The reading frame was checked in 11 cases with proximal deletions and found to be disrupted in 6 of 7 DMD patients, in 1 intermediate case, and, unexpectedly, in 3 BMD patients.     

The molecular basis for Duchenne versus Becker muscular dystrophy: Correlation of severity with type of deletion

About 60% of both Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) is due to deletions of the dystrophin gene. For cases with a deletion mutation, the "reading frame" hypothesis predicts that BMD patients produce a semifunctional, internally deleted dystrophin protein, whereas DMD patients produce a severely truncated protein that would be unstable. To test the validity of this theory, we analyzed 258 independent deletions at the DMD/BMD locus. The correlation between phenotype and type of deletion mutation is in agreement with the "reading frame" theory in 92% of cases and is of diagnostic and prognostic significance. The distribution and frequency of deletions spanning the entire locus suggests that many "in-frame" deletions of the dystrophin gene are not detected because the individuals bearing them are either asymptomatic or exhibit non-DMD/non-BMD clinical features.     

Seven novel Tay-Sachs mutations detected by chemical mismatch cleavage of PCR-amplified cDNA fragments.

Total RNA was isolated from cultured fibroblasts from 12 unrelated patients with Tay-Sachs disease, an autosomal recessive disorder due to beta-hexosaminidase A deficiency. beta-Hexosaminidase mRNA was amplified by cDNA-PCR in four overlapping segments spanning the entire coding sequence. In two patients, abnormal size cDNA-PCR fragments in which exons were removed resulted from splicing mutations that were characterized at the genomic DNA level: both were G to A transitions, at the first position of intron 2 and at the fifth position of intron 4. Five other mutations have been identified by cDNA-PCR chemical mismatch analysis and direct sequencing of an amplified fragment containing the mismatch site. One missense mutation alters the codon for Ser210 to Phe in exon 6 and the other one alters the codon for Arg504 to Cys in exon 13. A 3-bp deletion results in the deletion of a phenylalanine residue in exon 8. Two nonsense mutations in exon 3 (Arg137 to stop) and in exon 11 (Arg393 to stop) are associated with a marked decrease of mRNA abundance, probably because they result in mRNA instability. Three of the six single base mutations involve the conversion of a CpG dinucleotide in the sense strand to TpG. These results demonstrate the extreme molecular heterogeneity of mutations causing Tay-Sachs disease. The procedure described in this paper allows the rapid detection of any type of mutation, except those impairing the promoter function. Applicable even to patients with splicing or nonsense mutations and very low mRNA abundance, it has therefore a potentially broad application in human genetics, for both diagnostic and fundamental purposes.     

Prognostic factors and survival in metastatic breast cancer: A single institution experience

Background

The current retrospective study aims to identify some determinants of survival in metastatic breast cancer.

Methods

The study concerned 332 patients with synchronous (SM) or metachronous (MM) metastatic breast cancer treated between January 2000 and December 2007. Statistical comparison between subgroups of patients concerning survival was carried out employing log-rank test for the invariable analysis and Cox model for the multivariable analysis. Factors included: age group (≤50 years vs. >50; ≤70 years vs. >70; ≤35 years vs. >35), menopausal status, presentation of metastatic disease (SM vs. MM), disease free interval (DFI) (≤24 months vs. >24 months; ≤60 months vs. >60 months), performance status at diagnosis of metastatic disease (PS) (0–1 vs. >1), hormone receptors (HR), number of metastatic sites (1 site vs. >1), nature of the metastatic site (visceral vs. non visceral), first line therapy, surgery of the primary tumor (SPT), locoregional radiotherapy (LRRT) and use or not of bisphosphonates.

Results

Overall survival at 5 years was 12%. Positive prognostic factors in univariate analysis were: age ≤ 70 years, hormono-dependence of the tumor, good PS (PS 0–1), less than two metastatic sites, no visceral metastases, DFI ≥ 24 months, SPT or LRRT. In multivariate analysis, favorable independent prognostic factors included: good PS (PS 0–1), absence of visceral metastases (liver, lung, brain) and age ≤ 70 years.

Conclusion

Many of the prognostic factors in metastatic breast cancer found in our study are known in the literature but some of them, like the application of locoregional treatment (radiotherapy or surgery) and the use of bisphosphonates, need to be further investigated in randomized clinical trials.     

MeCP2 deficiency is associated with impaired microtubule stability

Rett syndrome (RTT) is a neurodevelopmental disorder caused by MECP2 mutations. Previous studies performed on Mecp2-deficient brain showed striking changes in neuronal maturation. We recently showed that MeCP2 deficiency affects microtubule (MT) dynamics in RTT astrocytes. Here, we analyze MT stability in primary fibroblast cultures from patients with RTT syndrome and identify a significant decrease in stability compared to controls. Furthermore, we found that MT stability was reduced both in cells expressing the mutant or the wild-type allele in RTT fibroblasts, suggesting that mutated cells could damage wild-type ones through a non-cell-autonomous pathway. These results suggest that MeCP2 has a stabilizing role on MT dynamics and that its deficiency could lead to impaired MT stability that may explain in part the dendritic abnormalities observed in RTT brains.