Limited beta2-adrenoceptor haplotypes display different agonist mediated airway responses in asthmatics.

BACKGROUND: In vitro and some in vivo studies suggested that genetic haplotypes may have an impact on beta2-agonist mediated airway responses in asthmatics. Due to strong linkage disequilibrium the single nucleotide polymorphisms (SNPs) in the beta2-adrenoceptor gene result in only a limited number of haplotypes. We intended to evaluate the impact of beta2-adrenoceptor haplotypes on beta2-agonist mediated airway responses and the development of tolerance in mild to moderate asthmatics. METHODS: Patients were genotyped for the part of the beta2-adrenoceptor gene with a known bearing on receptor function and regulation. Cumulative dose response curves of fenoterol versus PD20 methacholine and FEV1 were constructed after 2 week treatment periods with either terbutaline or placebo in a double blind, randomised and cross-over design. Analysis of the dose response curves was based on a repeated measurement analysis of covariance. RESULTS: In our study population comprising 45 asthmatic patients, we found three limited allelic haplotypes, resulting in six different genotypes. Our data support the existence of differences between these six genotypes both in the shape of the dose response relationship of the beta2-adrenoceptor agonist fenoterol as well as in the propensity to develop tolerance for these effects by pre-treatment with terbutaline. However, this could only be substantiated for the endpoint PD20 methacholine. CONCLUSION: Between beta2-adrenoceptor genotypes differences exist both in baseline beta2-agonist induced airway responses as well as in the propensity to develop tolerance during maintenance beta2-agonist therapy. The net differences after two weeks of therapy are, however, of magnitudes that are unlikely to be of clinical significance.

Gastrointestinal toxicity and its relation to dose distributions in the anorectal region of prostate cancer patients treated with radiotherapy.

PURPOSE: To study the correlations between the dose distributions in the anorectal region and late GI symptoms in patients treated for localized prostate carcinoma. METHODS AND MATERIALS: Data from a randomized study were analyzed. In this trial, patients were treated with either rectangular or conformal fields with a dose of 66 Gy. Data concerning GI symptoms were collected from questionnaires of 197 patients. The distributions of the anorectal region were projected on maps, and the dose parameters were calculated. The incidences of complaints were studied as a function of the dose-area parameters and clinical parameters, using a proportional hazard regression model. Finally, we tested a series of dose parameters originating from different parts of the anorectal region. RESULTS: Analyzing the total region, only a statistically significant dose-area effect relation for bleeding was found (p < 0.01). Defining subareas, we found effect relations for bleeding, soiling, fecal incontinence, and mucus loss. For bleeding and mucus loss, the strongest correlation was found for the dose received by the upper 70-80% of the anorectal region (p < 0.01). For soiling and fecal incontinence, we found the strongest association with the dose to the lower 40-50% (p < 0.05). CONCLUSION: We found evidence that complaints originate from specific regions of the irradiated lower GI tract. Bleeding and mucus loss are probably related to irradiation of the upper part of the rectum. Soiling and fecal incontinence are more likely related to the dose to the anal canal and the lower part of the rectum.

Impact of volume and location of irradiated rectum wall on rectal blood loss after radiotherapy of prostate cancer.

PURPOSE: To identify dose-volume parameters related to late rectal bleeding after radiotherapy for prostate cancer. MATERIALS AND METHODS: Clinical complication data from a randomized trial were collected and linked to the individual dose-volume data. In this trial, patients with prostate cancer were treated with either conventional (with rectangular fields) or three-dimensional conformal radiotherapy to a dose of 66 Gy. Patient complaints, including rectal blood loss, were collected for 199 patients, using questionnaires. Absolute and relative dose-volume histograms (DVHs) of the rectal wall (with and without the anal region) were calculated with and without rectal filling. A proportional hazard regression (PHR) model was applied to estimate the probability of any rectal blood loss within 3 years, as a function of several DVH parameters. In a multivariable analysis, dose-volume parameters were tested together with patient- and treatment-related parameters (age, smoking, diabetes, cardiovascular disease, tumor stage, neo-adjuvant androgen deprivation, conformal vs. conventional and rectal bleeding during treatment). RESULTS: The estimated incidence of any and moderate/severe rectal bleeding at 3 years was 33% and 8%, respectively. Differences between the conventional and conformal technique were small and not significant. The analysis of relative DVHs of the rectal wall (with and without the anal region), showed significant (p < 0.01) relations between the irradiated volume and the probability of rectal blood loss within 3 years for dose levels between 25 Gy and 60 Gy. This relationship was shown in subgroups defined by dose-volume cutoff points as well as in the PHR model, in which a continuously rising risk was seen with increasing volumes. For absolute DVHs and DVHs of the rectum including filling, less or no significant results were observed. The most significant volume-effect relation (p = 0.002) was found at 60 Gy for the rectum wall excluding the anal region. The probability of rectal bleeding increased from 10% to 63% when the irradiated rectum volume at 60 Gy increased from 25% to 100%. Other factors. including age, smoking, diabetes, cardiovascular disease, tumor stage, neo-adjuvant androgen deprivation, conformal vs. conventional, rectal bleeding during treatment, rectum length. and whole rectum volume. did not have a significant effect in the multivariable analysis. When controlling for the volumes at 60 Gy, the volumes at lower dose levels (25-55 Gy) were no longer significant (p = 0.5). CONCLUSIONS: For any rectal bleeding within 3 years, an overall incidence of 33% was observed for patients treated to 66 Gy. For this endpoint, a volume-effect relation was found for DVH parameters of the relative rectal wall volume. This relationship appeared to be most significant for the rectum without the anal region and for the higher dose levels (50-60 Gy).

Influence of heat and moisture exchanger respiratory load on transcutaneous oxygenation in laryngectomized individuals: a randomized crossover study.

BACKGROUND: High-resistance heat and moisture exchangers (HMEs) have been reported to increase transcutaneous oxygenation (tcpO(2)) values in laryngectomized individuals and to negatively influence patient compliance. The goal of the present study was to validate earlier published results on short-term transcutaneous oxygenation changes by high-resistance HMEs. METHODS: We conducted a randomized crossover study, monitoring the influence of an HME on tcpO(2) over a 2-hour time interval in 20 subjects. RESULTS: No evidence of an immediate HME effect (95% CI: -14.9-13.3 mm Hg, p = .91), or a time-dependent HME effect (95% CI: -.121 - .172 mm Hg/minute, p = .74), on tcpO(2) was found. After fitting the statistical model without time dependency, again no evidence of HME presence was seen (95% CI: -.5 mm Hg - 3.6 mm Hg, p = .15). CONCLUSION: In contrast to earlier suggestions, there is no evidence of increased tcpO(2) levels by high-resistance HMEs in laryngectomized individuals. Thus, using such HMEs has no added clinical value in this respect.

New insight into rectal function in pediatric defecation disorders: disturbed rectal compliance is an essential mechanism in pediatric constipation.

OBJECTIVE: To evaluate rectal sensitivity in patients with pediatric constipation (PC) and nonretentive fecal soiling (FNRFS) using pressure-controlled distention (barostat). STUDY DESIGN: Thresholds for rectal sensitivity (first sensation, urge to defecate, and pain), and rectal compliance were determined using a barostat. RESULTS: A total of 69 patients with PC (50 males; mean age, 10.9 +/- 2.2 years) and 19 patients with FNRFS (15 males; mean age, 10.0 +/- 1.9 years) were compared with 22 healthy volunteers (HVs) (11 males; mean age, 12.7 +/- 2.6 years). Sensitivity thresholds were not significantly different among the 3 groups. Rectal compliance was increased in 58% of the patients with PC (P < .0001 vs HVs). Rectal compliance did not differ between patients with FNRFS and HVs. Children with PC with abnormal rectal function required significantly larger rectal volumes at urge to defecate. CONCLUSIONS: Increased compliance is the most prominent feature in patients with PC. Because of higher compliance in these children, larger stool volumes are required to reach the intrarectal pressure of the urge to defecate. Children with FNRFS have normal rectal function.

Isolated limb perfusion prolongs the limb recurrence-free interval after several episodes of excisional surgery for locoregional recurrent melanoma.

BACKGROUND: The influence of isolated limb perfusion (ILP) on the limb recurrence-free interval (LRFI) and the number of lesions per recurrence was studied for patients with frequently recurring regional in-transit metastases previously managed by excisional surgery. METHODS: All 43 patients who had their first ILP for a third or further limb recurrence were selected from our computer database of 451 patients who underwent therapeutic ILP for recurrent extremity melanoma in our centers. Eighteen patients had resectable and 25 had locally unresectable lesions at the time of ILP. The patients had a total of 269 intervals between treatment of their primary melanoma and last recurrence or last follow-up. Median follow-up was 35 months (interquartile range, 14-64 months). RESULTS: The median LRFI decreases over time from primary melanoma to the third or further recurrence for which ILP was performed (P < 0.001). The median LRFI is 4.7 times longer (95% confidence interval [CI], 2.8-7.9; P < 0.001) after ILP in comparison with the last interval before ILP. Patients with resectable lesions have a median LRFI that is 5.9 times longer (95% CI, 2.7-13; P < 0.001). In all patients, the number of lesions increases by 22% per recurrence number (95% CI, 10%-35%; P = 0.02). At the same recurrence number, patients before ILP have a 2.6-fold higher (95% CI, 1.6-4.5) mean number of lesions than do patients after ILP (P < 0.001). CONCLUSIONS: ILP lengthens the LRFI and decreases the number of lesions per recurrence significantly in patients with repeatedly recurrent limb melanoma. Therefore, ILP could be a valuable adjunct to excisional surgery for in-transit metastases in these patients whose LRFIs tend to shorten over time.