Isoprenaline reverses the slow force responses to a length change in isolated rabbit papillary muscle

An alteration in the length of isolated cardiac muscle produces an immediate change in twitch force, then a slow further change in the same direction. We have found that the slow changes in force in rabbit papillary muscles are blocked or reversed by the ß-agonist, isoprenaline (1 M). The abolition of the slow responses by isoprenaline was not due to saturation of the myofibrils with Ca²⁺, as the blockade continued if the extracellular [Ca²⁺] was reduced in the presence of isoprenaline so that twitch force was <50% maximal. Ryanodine (1 M) did not block the slow responses, suggesting that the sarcoplasmic reticulum does not mediate the responses. These results suggest that changes of intracellular [cAMP] may mediate, or at least modulate, the slow force responses to a length change in cardiac muscle.     

Unusual donor site reactions to calcium alginate dressings

Calcium alginate dressings have been used as the standard dressing for split skin donor sites at the Women's and Children's Hospital burn unit for the last 12 yr. This method has proven satisfactory with good haemostasis, reliable healing, low infection rate and is well accepted by the children and nursing staff.We have recently had 5 cases with the unusual and unexplained phenomenon of dermal calcification in the donor site following the use of two new varieties of calcium alginate dressing.     

Mild renal pelvic dilatation is not predictive of vesicoureteral reflux in children

Objective. To determine if mild renal pelvic dilatation at renal ultrasound (RUS) is a reliable sign of vesicoureteral reflux (VUR) at voiding cystourethrogram (VCUG) in children. Materials and methods. All patients less than 10 years of age who had RUS and VCUG on the same day during a 2-year period were identified in a computerized database. The appearance of the collecting system of each kidney was classified into two groups: group 0 – no dilatation (≤ 2-mm anteroposterior diameter of the renal pelvis) and group 1 – 3 to 10-mm AP diameter of the renal pelvis without caliectasis. VUR at VCUG was graded using the International Reflux Study Committee system. Results. Four hundred fifty-five patients (76 boys; 379 girls) with 910 kidneys were included. VUR occurred in 268 kidneys in 174 patients. There were 820 group 0 kidneys and 90 group 1 kidneys. Kidneys classified as group 1 (25.0 % had reflux) were no more likely to have reflux than were kidneys with nondistended (group 0) collecting systems (31.2 % had reflux). There was no statistical difference in the rate of reflux in patients with group 1 renal pelvic distention (39.2 % refluxed) and a normal collecting system (33.3 % refluxed) (P = 0.365). Conclusion. The frequency of vesicoureteral reflux in children with mild renal pelvic distention is not significantly different than in children with no distention. Therefore, mild dilatation of the renal pelvis should not be considered an indication for voiding cystourethrography. Received: 14 April 1997 Accepted: 24 July 1997     

Otoacoustic emissions as a screening test for hearing impairment in children recovering from acute bacterial meningitis

OBJECTIVES: To study the efficacy of otoacoustic emissions (OAEs) as a screening test for hearing impairment in children with acute bacterial meningitis. Hearing tests were performed before discharge from the hospital in an attempt to improve coverage and avoid delays in the diagnosis of postmeningitic hearing loss. METHODS: Children with bacterial meningitis were recruited from 21 centers. In the 48 hours before discharge from the hospital, all patients underwent a thorough audiologic assessment consisting of transient evoked OAEs, auditory brainstem responses (ABRs), otoscopy, and tympanometry. Hearing loss was defined as ABR threshold >/=30 dB. The results of OAE screening were compared with the gold standard of ABR threshold. RESULTS: Of 124 children recruited, we were able to perform both OAEs and ABRs on 110 children. Seven (6.3%) of the 110 children had ABR threshold >/=30 dB; 2 had sensorineural hearing loss and 5 had conductive hearing loss. At follow-up, hearing loss persisted in both cases of sensorineural hearing loss and no new cases were identified. All 7 children with hearing loss failed the OAE screening test. Ninety-four children with normal hearing thresholds passed the test, and 9 failed. Thus, the screening test had a sensitivity of 1.00 (95% confidence interval, 0.59 to 1.00), a specificity of 0.91 (0.85 to 0.97), a positive predictive value of 0. 44 (0.20 to 0.70), and a negative predictive value of 1.00 (0.96 to 1.00). CONCLUSIONS: OAE screening in children recovering from meningitis was found to be feasible and effective. The test was highly sensitive and reasonably specific. Inpatient OAE screening should allow early diagnosis of postmeningitic hearing loss and prompt auditory rehabilitation.     

Alcohol, ALDH2, and esophageal cancer: a meta-analysis which illustrates the potentials and limitations of a Mendelian randomization approach.

Mendelian randomization, the use of common polymorphisms as surrogates for measuring exposure levels in epidemiologic studies, provides one method of assessing the causal nature of some environmental exposures. This can be illustrated by looking at the association between the ALDH2 polymorphism and esophageal cancer. Alcohol drinking is considered a risk factor for esophageal cancer, and exposure to high levels of acetaldehyde, the principal metabolite of alcohol, may be responsible for the increased cancer risk. The ability to metabolize acetaldehyde is encoded by the ALDH2 gene, which is polymorphic in some populations. The ALDH2*2 allele produces an inactive protein subunit, which is unable to metabolize acetaldehyde. An individual's genotype at this locus may influence their esophageal cancer risk through two mechanisms, first through influencing alcohol intake and second through influencing acetaldehyde levels. We have carried out a meta-analysis of studies looking at the ALDH2 genotype and esophageal cancer and found that risk was reduced among *2*2 homozygotes [odds ratio (OR), 0.36; 95% confidence interval (95% CI), 0.16-0.80] and increased among heterozygotes (OR, 3.19; 95% CI, 1.86-5.47) relative to *1*1 homozygotes. This provides strong evidence that alcohol intake increases the risk of esophageal cancer and individuals whose genotype results in markedly lower intake, because they have an adverse reaction to alcohol are thus protected. This meta-analysis also provides evidence that acetaldehyde plays a carcinogenic role in esophageal cancer. The two different processes operating as a result of the ALDH2 genotype have implications for the interpretation of studies using the Mendelian randomization paradigm.