High frequency immittance findings: Newborn versus six-week-old infants

This study aimed to compare the high frequency (1 kHz) tympanometry (HFT) and acoustic reflex (AR) measures obtained from infants at birth and at 6–7 weeks of age. HFT results and AR thresholds using a 2-kHz tone and broadband noise activators were obtained from 42 healthy full-term neonates (15 boys and 27 girls) at both test sessions, separated by six weeks. The results showed that the mean values of HFT test parameters and AR thresholds obtained at 6–7 weeks were generally greater than those obtained at birth. In particular, the differences in mean values of uncompensated admittance at 200 daPa, uncompensated peak admittance, uncompensated peak susceptance, peak-compensated static admittance, and AR thresholds with a 2 kHz tone and broadband noise were found to be statistically significant. The findings from this study suggest the need to have separate sets of normative HFT and AR data for infants at birth and 6–7 weeks.     

Screening for antihyperglycaemic activity in several local herbs of Malaysia

Screening of aqueous extract of Phyllantus niruri (PL), Zingiber zerumbet (ZG), Eurycoma longifolia (TA-a and TA-b) and Andrographis paniculata (AP) to determine their blood glucose lowering effect were conducted in normoglycaemic and Streptozotocin-induced hyperglycaemic rats. Significant reduction in blood glucose level at 52.90% was shown when hyperglycaemic rats were treated with 50 mg/kg body weight (BW) aqueous extract of AP. This effect is enhanced when freeze-dried material was used, where 6.25 mg/kg BW gave 61.81% reduction in blood glucose level. In the administration of TA-a and TA-b, positive results in hyperglyacaemic rats were only obtained when 150 mg/kg BW of the aqueous extract was used. No significant reduction in blood glucose level were shown in hyperglycaemic rats treated with PL and ZG at all concentrations used (50, 100 and 150 mg/kg BW). In normoglycaemic rats, no significant reduction was noted when all the same extracts were used.     

Measuring middle ear admittance in newborns using 1000 Hz tympanometry: a comparison of methodologies

The present study aimed to compare three measures to estimate middle ear admittance in neonates using 1000 Hz tympanometry. Data were obtained from 36 full-term newborns, aged between 24 and 123 hours, who passed a transient evoked otoacoustic emissions test and assessed using a Madsen Otoflex impedance meter. The results showed that the mean middle ear admittances obtained by compensating for the susceptance and conductance components at a pressure of 200 daPa and -400 daPa (Y(CC200) = 1.00 mmho and Y(CC-400) = 1.24 mmho, respectively) were significantly greater than that using the traditional baseline compensation method (Y(BC) = 0.65 mmho). Although Y(CC-400) has attained the highest mean value, it has the lowest test-retest reliability. Hence, the component compensation approach compensated at 200 daPa holds promise as an alternative method for estimating middle ear admittance in neonates. Further research to evaluate its test performance using clinical decision theory is required to determine its clinical significance.     

Spectral Hounsfield units: a new radiological concept

Objective  

Computed tomography (CT) uses radiographical density to depict different materials; although different elements have different absorption fingerprints across the range of diagnostic X-ray energies, this spectral absorption information is lost in conventional CT. The recent development of dual energy CT (DECT) allows extraction of this information to a useful but limited extent. However, the advent of new photon counting chips that have energy resolution capabilities has put multi-energy or spectral CT (SCT) on the clinical horizon.     

Probing simple structural modification of α-mangostin on its cholinesterase inhibition and cytotoxicity

α-Mangostin has been reported to possess a broad range of pharmacological effects including potent cholinesterase inhibition, but the development of α-mangostin as a potential lead compound is impeded by its toxicity. The present study investigated the impact of simple structural modification of α-mangostin on its cholinesterase inhibitory activities and toxicity toward neuroblastoma and liver cancer cells. The dialkylated derivatives retained good acetylcholinesterase (AChE) inhibitory activities with IC₅₀ values between 4.15 and 6.73 µM, but not butyrylcholinesterase (BChE) inhibitory activities, compared with α-mangostin, a dual inhibitor (IC₅₀: AChE, 2.48 µM; BChE, 5.87 µM). Dialkylation of α-mangostin produced AChE selective inhibitors that formed hydrophobic interactions at the active site of AChE. Interestingly, all four dialkylated derivatives of α-mangostin showed much lower cytotoxicity, being 6.4- to 9.0-fold and 3.8- to 5.5-fold less toxic than their parent compound on neuroblastoma and liver cancer cells, respectively. Likewise, their selectivity index was higher by 1.9- to 4.4-fold; in particular, A2 and A4 showed improved selectivity index compared with α-mangostin. Taken together, modification of the hydroxyl groups of α-mangostin at positions C-3 and C-6 greatly influenced its BChE inhibitory and cytotoxic but not its AChE inhibitory activities. These dialkylated derivatives are viable candidates for further structural modification and refinement, worthy in the search of new AChE inhibitors with higher safety margins.     

黄斑色素光学密度、中央黄斑厚度与体重指数的关系

目的：评估黄斑色素光学密度(MPOD)、中央黄斑厚度与体重指数(BMI)的关系。

方法：这是一项在单一机构中进行比较的横断面研究。本研究共纳入210名符合入选标准的志愿者。使用黄斑色素筛选剂II对受试者MPOD进行测量。使用SD Cirrus OCT测量中央黄斑厚度。记录所有眼MPOD和OCT信息。使用Microsoft^©Excel,SPSS和R进行数据分析。

结果：MPOD和中央黄斑厚度之间呈明显正相关(r=0.42, P<0.01)。同时,MPOD和BMI之间呈明显负相关(r=-0.23, P<0.01)。

结论：研究得出,MPOD和中央黄斑厚度之间呈明显正相关。还需要进一步研究中央凹的详细结构及其与MPOD的关系。研究发现了MPOD与BMI之间呈明显正相关,且得出BMI的降低可能会增加黄斑色素的密度,这有助于预防年龄相关性黄斑变性(ARMD)。