Identification of mutations in regions corresponding to the two putative nucleotide (ATP)-binding folds of the cystic fibrosis gene.

Additional mutations in the cystic fibrosis (CF) gene were identified in the regions corresponding to the two putative nucleotide (ATP)-binding folds (NBFs) of the predicted polypeptide. The patient cohort included 46 Canadian CF families with well-characterized DNA marker haplotypes spanning the disease locus and several other families from Israel. Eleven mutations were found in the first NBF, 2 were found in the second NBF, but none was found in the R-domain. Seven of the mutations were of the missense type affecting some of the highly conserved amino acid residues in the first NBF; 3 were nonsense mutations; 2 would probably affect mRNA splicing; 2 corresponded to small deletions, including another 3-base-pair deletion different from the major mutation (delta F508), which could account for 70% of the CF chromosomes in the population. Nine of these mutations accounted for 12 of the 31 non-delta F508 CF chromosomes in the Canadian families. The highly heterogeneous nature of the remaining CF mutations provides important insights into the structure and function of the protein, but it also suggests that DNA-based genetic screening for CF carrier status will not be straightforward.     

Na(+)-H+ antiport activity in skin fibroblasts from blacks and whites

The predisposition of black people to salt (NaCl)-sensitive essential hypertension may relate to racial differences in cellular Na+ metabolism. This tenet was investigated by examining the Na(+)-H+ antiport in serially passed skin fibroblasts from blacks and whites. Na(+)-dependent stimulation of the Na(+)-H+ antiport by cellular acidification resulted in a greater maximal velocity (Vmax) (mean +/- SEM) of this transport system in quiescent fibroblasts from blacks than fibroblasts from whites; the Vmax for recovery from cellular pH (pHi) of 6.6 was 5.84 +/- 0.50 versus 4.39 +/- 0.34 mmol H+/l X 20 seconds for blacks and whites, respectively (p less than 0.05). Although the Na+ concentration producing 50% stimulation of the Na(+)-H+ antiport for blacks (35.1 +/- 5.7 mM) was greater than for whites (24.1 +/- 3.5 mM), this difference was not statistically significant. No racial differences were observed in the Hill coefficient (n, 1.35 +/- 0.21 for blacks and 1.46 +/- 0.28 for whites). Compared with whites, cells from blacks exhibited a greater response to cytoplasmic acidification over the range of pHi values 6.20-6.60, as exhibited by an augmented rate of recovery in the pHi. These differences were not due to different basal pHi values or cellular buffering capacities, which were similar for blacks and whites. Na(+)-H+ antiport activity was not correlated with family history of hypertension. Increased activity of the Na(+)-H+ antiport in fibroblasts from blacks was confirmed without cellular acidification by stimulating quiescent cells with 10% human serum. This study demonstrates innate racial differences in cellular membrane Na(+)-H+ antiport activity.     

Promoter hypermethylation of mismatch repair genes, hMLH1 and hMSH2 in oral squamous cell carcinoma

Objectives:  Major risk factors of oral squamous cell carcinoma (OSCC) are environmental and can lead to DNA mutagenesis. Mismatch repair (MMR) system functions to repair small DNA lesions, which can be targeted for promoter hypermethylation. We therefore wanted to test whether hypermethylation of MMR genes ( hMLH1, hMSH2 ) could contribute to oral carcinogenesis by correlating the information to patient clinical data.
Methods:  Genomic DNA was extracted from 28 OSCC and six normal oral epithelium samples. The methylation status of the two MMR genes was assessed using Methylation Specific PCR after DNA modification with sodium bisulfite. Serial sections of the same tissues were immunostained with antibodies against hMLH1 and hMSH2 protein.
Results:  Promoter hypermethylation was observed in 14/28 OSCC cases. Remarkably, 100% of patients with multiple oral malignancies showed hypermethylation in hMLH1 or hMSH2 compared with 31.5% of single tumor patients. In 10 cancer cases, expression of the hMLH1 and hMSH2 genes by immunostaining showed reduced or absence of expression of one of the genes, although some did not reflect the methylation status.
Conclusions:  Hypermethylation of hMLH1 and hMSH2 might play a role in oral carcinogenesis and may be correlated with a tendency to develop multiple oral malignancies.     

Bumetanide-sensitive sodium-22 transport in vascular smooth muscle cell of the spontaneously hypertensive rat

The effect of bumetanide, a known probe of Na+, K+ cotransport, on 22Na+ uptake and washout was examined in serially passed cultured vascular smooth muscle cells of spontaneously hypertensive rats (SHR), Wistar-Kyoto rats (WKY), and Wistar rats. In Ca2+-deficient medium, the drug exerted the greatest effect on 22Na+ washout in vascular smooth muscle cells from SHR and the least effect on cells from WKY. The respective mean values for the apparent bumetanide-sensitive 22Na+ washout rate constants (Ke; X 10(-2)/min) were 7.2, 4.3, and 1.7 for cells from SHR, WKY, and Wistar rats. In both 1 mM Ca2+ and Ca2+-deficient medium, in the presence of 1 mM ouabain, vascular smooth muscle cells from SHR had the highest plateau phase of 22Na+ uptake among the three cell preparations. All cells exhibited higher 22Na+ uptake in Ca2+-deficient medium than in 1 mM Ca2+ medium. Under this condition, bumetanide caused an additional rise in steady state 22Na+ uptake that was most pronounced in cells from SHR (21.3% versus 16.6% for Wistar rats and 4.8% for WKY). This finding indicates that a quantitatively greater inhibition of washout than of the uptake component of the bumetanide-sensitive 22Na+ transport occurs in Ca2+-deficient medium. It is concluded that, in Ca2+-deficient medium, the bumetanide-sensitive 22Na+ washout is higher in vascular smooth muscle cells of SHR than in those of normotensive controls and that this phenomenon reflects a higher Na+ turnover in vascular smooth muscle cell in the hypertensive rat strain.     

Chemo-immunotherapy in patients with metastatic melanoma using sequential treatment with dacarbazine and recombinant human interleukin-2: evaluation of hematologic and immunologic parameters and correlation with clinical response.

We have treated 18 patients with metastatic malignant melanoma (MM) with high-dose IL-2 administered by continuous iv infusion in combination with dacarbazine (DTIC), and correlated the clinical response with various hematologic and immunologic parameters. Two regimens differing in the sequence of treatment were employed, and 1-6 treatment cycles were given, depending on patient response. Two patients had a complete response (CR, 46+m, 14m), two patients a partial response (PR, 16m,6m), one a minimal response and four had a stable disease lasting 2-7 months, thus the response rate (CR+PR) was 22%. None of the following parameters, tested prior to initiation of the therapy and 1-2 days after termination of each course of IL-2, correlated with the clinical response: WBC counts (total and differential), levels of blood CD4 and CD8 T cells, NK cells, monocytes and B cells, production of IL-1 and IL-1 inhibitor by monocytes, responsiveness to 3 mitogens, NK/LAK cell activity, and serum levels of IL-1 alpha, IL-2, soluble IL-2 receptor, and TNF alpha. The only prognostic parameter was the greater increase in the level of IL-2 receptor (Tac)-bearing lymphocytes in the responding patients after 1-3 cycles of IL-2. The data suggests that non-specific immune parameters have no prognostic value for patients undergoing IL-2-based immunotherapy.     

Persistent Erectile Dysfunction Following Radical Prostatectomy: The Association between Nerve-Sparing Status and the Prevalence and Chronology of Venous Leak

IntroductionFailure to recover erectile function after radical prostatectomy (RP) may result from venous leak as a sequela of neuropraxia-induced erectile tissue damage. Venous leak portends a poor prognosis for erections recovery as well as phosphodiesterase type 5 inhibitor (PDE5i) response.AimsTo define the impact of RP nerve-sparing status on venous leak prevalence and chronology.MethodsStudy population: men who underwent RP for localized prostate cancer, had functional erections prior to RP, developed postoperative erectile dysfunction (ED), had a Doppler ultrasonography within 6 months of RP, and did not receive any ED treatment for the first 6 months after RP other than on-demand PDE5i.Main Outcome MeasuresVenous leak prevalence and erectile function recovery at different time-points.ResultsData on 142 patients were analyzed, mean age: 58 ± 16 years. Sixty percent had bilateral nerve-sparing (BNS) surgery, 20% unilateral nerve-sparing (UNS) surgery, and 20% non-nerve-sparing (NNS) surgery. Eleven percent and 21% had venous leak by 3 and 6 months, respectively. Venous leak prevalence by 6 months was 7%, 11%, and 75% for BNS, UNS, and NNS surgery (P < 0.001). Mean end-diastolic velocity was 1.8, 2.1, and 7.2 cm/second for the three groups (P < 0.01). The only patients developing venous leak prior to 3 months were NNS patients, one-third of NNS-associated venous leak occurring before this time-point. At 18 months, the proportion of men having return of unassisted erections was 49%, 42%, and 7% with mean erectile function domain scores of 21, 18, and 12, and PDE5i response rates were 72%, 64%, and 12% for the three groups, respectively.ConclusionsNerve-sparing status impacts heavily upon the prevalence and the chronology of venous leak development post-RP. NNS RP is associated with early development of venous leak, increased prevalence of venous leak, and reduction in return of natural erections. Tal R, Valenzuela R, Aviv N, Parker M, Waters WB, Flanigan RC, and Mulhall JP. Persistent erectile dysfunction following radical prostatectomy: The association between nerve-sparing status and the prevalence and chronology of venous leak. J Sex Med 2009;6:2813–2819.