Height-based formulas for predicting intravascular length of tunnelled neck central venous catheter in paediatric population.

INTRODUCTION: Central venous catheter (CVC) placement is commonly performed in children. We aim to develop simple formulas to predict CVC intravascular length to minimise radiation exposure associated with the procedure. METHODS: 124 paediatric patients who received tunnelled neck CVCs and subsequent CT thorax at Hong Kong Children's Hospital from January 2020 to July 2022 were reviewed retrospectively. Formula development cohorts were subdivided by insertion sites-9 right external jugular vein (REJV), 41 right internal jugular vein (RIJV), 14 left external jugular vein (LEJV), 10 left internal jugular vein (LIJV). Using measurements from CT by two radiologists, formulas predicting the CVC intravascular length based on height and insertion sites were developed using a linear regression model. These formulas were tested with validation cohorts (10 randomly selected cases in REJV and RIJV groups respectively). Validation cohorts were not available for LEJV and LIJV groups due to small sample sizes. RESULT: The goodness-of-fit (R^2) of all formulas are above 0.8. In the validation cohorts, the REJV formula was predictive of intravascular CVC length within 1 cm in 70% of CVC with mean absolute difference of 0.63 cm (SD 0.48 cm), and the RIJV formula was predictive of intravascular CVC length within 1 cm in 80% of CVC with mean absolute difference of 0.67 cm (SD 0.53 cm). CONCLUSION: Intravascular CVC length can be estimated using simple formulas based on height and insertion sites. Further prospective validation of the LEJV and LIJV formulas is needed.

Multimodality imaging of developmental splenic anomalies: tips and pitfalls.

Anomalies in number and location may occur during splenic development. This review aims to offer a brief overview of splenic function and embryology and a detailed account of the imaging appearances using different imaging techniques of the normal spleen and various congenital splenic anomalies including (1) abnormal viscero-atrial situs, (2) splenogonadal fusion, (3) intrapancreatic accessory spleen, (4) wandering spleen, and (5) splenosis. Emphasis is placed on the salient features that help radiologists recognise important associations (e.g., asplenia/polysplenia in situs abnormalities), avoid diagnostic pitfalls (e.g., mistaking intrapancreatic accessory spleen as pancreatic neoplasms), and potential complications (e.g., acute torsion in wandering spleen). The correct identification of the said anomalies from more sinister causes, such as malignancies, are essential, where early intervention is necessary.

A comparison of aluminum levels in tea products from Hong Kong markets and in varieties of tea plants from Hong Kong and India.

This study project aimed to investigate the concentrations of aluminum (Al) in tea products available in Hong Kong markets. Tea samples consisting of 47 different tea bags and 28 samples of tea leaves were analysed for concentrations of Al. All tea samples released Al (0.70-5.93 mg L(-1)) during a standard infusion period. In comparison to the Joint FAO/WHO Provisional Tolerable Weekly Intake guideline of 7 mg Al kg(-1) body weight, it was concluded that tea made with these tea leaves will not impose adverse human health impacts. The relative effects of age, soil available Al, and genetic differences on the levels of Al accumulated by tea bushes were investigated. It was found that there was no definite trend between the amount of Al accumulated and the age of tea bushes. The soil available Al influenced the levels of Al in Camellia sinensis to a certain extent, but it was evident that the ability of different varieties of C. sinensis to accumulate Al was variable. C. sinensis accumulated Al in all stages of growth. Young seedlings had lower contents of Al while the mobility of Al within the tea bushes was high. In a manner typical of hyperaccumulators, Al was not retained in the roots, but was consistently transported to the shoots. Aluminum in the tea bush was distributed between the different parts in the following order: mature leaves>roots>branches>young leaves.

Aluminium and fluoride concentrations of three tea varieties growing at Lantau Island, Hong Kong.

The present project aims to investigate aluminium (Al) and fluoride (F) contents in teas (Camellia sinensis (L.) O. Kuntze). Three different commercial tea varieties: Assam variety and two China sub-varieties, a large leafed variety and small leafed variety, were collected in two tea gardens of Lantau Island tea plantation of Hong Kong. In general, high concentrations of Al and F were accumulated in the mature leaves (15.3 and of 2.07 g kg-1 respectively). Among the three varieties, 'the small leafed' variety exhibited the highest Al and F contents followed by the 'large leafed' variety whereas the Assam variety had the lowest Al and F concentrations in its tea bushes. Tea products from a plantation were also analysed and it was noted that black tea had higher Al and F concentrations than green tea. The amount of Al and F released into tea liquor was also tested and the results showed that higher concentrations of Al and F were released into tea liquor under repeated infusion method than continuous infusion method.

Aluminium and fluoride contents of tea, with emphasis on brick tea and their health implications.

Tea plant takes up a large quantity of aluminium (Al) and fluoride (F) from acidic soils. It has been known that fluorosis can be developed for people who consume a large quantity of tea made from brick tea, a low quality tea consisting mainly of old tea leaves in China. In addition, it has been claimed that Alzheimer's disease (AD) is linked with the Al content in the human brain. Therefore, the high Al content in tea, especially brick tea is also a concern. This article reviews the basis background on tea including classification, growth conditions, types of tea leaves and their production, and processing of tea. Special emphasis is made on the transfer of Al and F from soil to tea plant and then to tea liquor. Health implications of drinking a large quantity of tea liquor especially those made from brick tea are discussed. Recommendations are suggested to reduce the uptake of these two elements by tea plant, and lower their contents in tea products.

Pharmacokinetics of sarafloxacin in pigs and broilers following intravenous, intramuscular, and oral single-dose applications.

Pharmacokinetics of sarafloxacin, a fluoroquinolone antibiotic, was determined in pigs and broilers after intravenous (i.v.), intramuscular (i.m.), or oral (p.o.) administration at a single dose of 5 (pigs) or 10 mg/kg (broilers). Plasma concentration profiles were analysed by a noncompartmental pharmacokinetic method. Following i.v., i.m. and p.o. doses, the elimination half-lives (t1/2beta) were 3.37 +/- 0.46, 4.66 +/- 1.34, 7.20 +/- 1.92 (pigs) and 2.53 +/- 0.82, 6.81 +/- 2.04, 3.89 +/- 1.19 h (broilers), respectively. After i.m. and p.o. doses, bioavailabilities (F) were 81.8 +/- 9.8 and 42.6 +/- 8.2% (pigs) and 72.1 +/- 8.1 and 59.6 +/- 13.8% (broilers), respectively. Steady-state distribution volumes (Vd(ss)) of 1.92 +/- 0.27 and 3.40 +/- 1.26 L/kg and total body clearances (ClB) of 0.51 +/- 0.03 and 1.20 +/- 0.20 L/kg/h were determined in pigs and broilers, respectively. Areas under the curve (AUC), mean residence times (MRT), and mean absorption times (MAT) were also determined. Sarafloxacin was demonstrated to be more rapidly absorbed, more extensively distributed, and more quickly eliminated in broilers than in pigs. Based on the single-dose pharmacokinetic parameters determined, multiple dosage regimens were recommended as: a dosage of 10 mg/kg given intramuscularly every 12 h in pigs, or administered orally every 8 h in broilers, can maintain effective plasma concentrations with bacteria infections, in which MIC90 are <0.25 microg/mL.

An internet-based learning portfolio in resident education: the KOALA multicentre programme.

CONTEXT AND OBJECTIVES: To describe the Computerized Obstetrics and Gynecology Automated Learning Anaalysis (KOALAtrade mark), a multicentre, Internet-based learning portfolio and to determine its effects on residents' perception of their self-directed learning abilities. METHODS: The KOALA programme allows residents to record their obstetrical, surgical, ultrasound, and ambulatory patient encounters and to document critical incidents of learning or elements of surprise that arose during these encounters. By prompting the student to reflect on these learning experiences, KOALA encourages residents to articulate questions which can be directly pursued through hypertext links to evidence-based literature. Four Canadian residency training programmes participated in the pilot project, from February to May 1997, using a dynamic relational database with a central server. All participants completed the Self-directed Learning Readiness Scale and a learning habits questionnaire. The impact of the KOALA programme on residents' perception of their self-directed learning abilities was measured by comparing KOALA-naive schools (schools 2, 3, and 4) with school 1 (exposed to the KOALA prototype for 1 year). Ordered variables were compared using the Mann-Whitney U test and continuous variables with the Student t test (statistical significance P < 0. 05). RESULTS: During the study period, 7049 patient and 1460 critical incidents of learning were recorded by 41 residents in the four participating universities. Residents at the exposed school (school 1) had a significantly higher perception of their self-directed learning (P < 0.05) and believed their future learning was less likely to be from continuing medical education (P < 0.028), textbooks (P < 0.04), and didactic lectures (P < 0.011) and would be derived from a learning portfolio with online resources. CONCLUSION: This Internet-based, multi-user, multicentre learning portfolio has a significant effect on residents' perception of their self-directed learning abilities.

Neurodevelopmental outcome after antenatal diagnosis of posterior fossa abnormalities.

Posterior fossa abnormalities are sonographically diagnosable in the fetus. Anomalies of this region include Dandy-Walker malformation, enlarged cisterna magna, and arachnoid cyst. Despite prenatal diagnosis, the uncertainties related to natural history and neurodevelopmental outcome in survivors make patient counseling difficult. The purposes of this study were to determine the accuracy of prenatal diagnosis of these lesions and elucidate long-term neurodevelopmental outcome in survivors in prenatally diagnosed posterior fossa abnormalities. Fifteen cases of posterior fossa abnormalities were reviewed. Antenatal diagnoses of Dandy-Walker malformation was made in 13 of these cases, arachnoid cyst in one case, and enlarged cisterna magna in one case. Hydrocephalus was present in 66% of patients. The sonographic diagnosis was concordant with the pathologic or neonatal radiologic diagnosis in 13 of 15 cases. Seven fetuses (47%) exhibited additional cranial or extracranial anomalies. A karyotypic abnormality (trisomy 18) was found in one of 15 cases of posterior fossa abnormalities. Neurodevelopmental delay was present in 80% of survivors with follow-up study to 4 years of age. Prenatal diagnosis of posterior fossa abnormalities is highly accurate, yet the differential diagnosis can be challenging. Cognitive and psychomotor developmental delays remain commonplace despite early diagnosis and treatment. The approach with families in cases of prenatal diagnosis of posterior fossa abnormalities should include a search for additional central nervous system and extra-central nervous system anomalies in the fetus and counseling of parents regarding potential adverse outcome for survivors.

Perinephric abscess mimicking fulminant hepatic failure.

We describe a female diabetic patient who presented with features suggestive of hepatobiliary disease and who exhibited clinical signs of fulminant hepatic failure. Identification and drainage of a right perinephric abscess resulted in prompt resolution of both the physical signs and biochemical indices of liver disease. Infection remote from the hepatobiliary tree can mimic fulminant hepatic failure, and recognition of this unusual presentation of infection is important if dangerous delay in diagnosis and treatment is to be avoided.

Pharmacokinetic-pharmacodynamic modelling of meperidine in goats (II): Modelling.

Simultaneous pharmacokinetic-pharmacodynamic (PK-PD) models of meperidine in goats were established by utilizing the P3 wave of the cerebral evoked potentials as an analgesic measurement. An effect compartment linked to the central compartment was postulated in the models. The hypothetical drug amount in the effect compartment was related to the observed analgesia through the Hill equation. After intramuscular (i.m., n = 16) and intravenous (i.v., n = 13) dosing (5 mg/kg), the elimination rate constants of meperidine in the effect compartment (Ke0) were 0.3744 +/- 0.2546 and 0.1123 +/- 0.0428 min-1, drug concentrations in the effect compartment generating half maximal analgesia (EC(50)) were 0.70 +/- 0.33 and 0.41 +/- 0.26 microgram/ml, the maximal effects (Emax) were 89.63 +/- 15.63 and 85.92 +/- 9.64%, and the Hill coefficients (S) were 2.61 +/- 1.21 and 2.37 +/- 1.15, respectively. Ke0 and EC(50) with i.m. dosing were significantly greater than with i.v. injection. However, administration route had no influence on S, Emax and the total amount of effect (AUE). The predicted peak effect (Emax) of 64.44 +/- 14.64 and 66.02 +/- 11.51% were achieved at 14.7 +/- 7.4 and 8.5 +/- 2.2 min after i.m. and i.v. dosing, respectively. Peak analgesia appeared much later than peak plasma concentration, but simultaneously with peak CSF level both after i.m. and i.v. dosing. An obvious hysteresis was demonstrated between plasma concentration and analgesic effect. This study demonstrates that meperidine analgesia can be predicted using a PK-PD model, but not by PK data alone. Both i.m. and i.v. administration routes were evaluated kinetically and dynamically.

Pharmacokinetic-pharmacodynamic modelling of meperidine in goats (I): Pharmacokinetics.

Plasma and cerebrospinal fluid (CSF) pharmacokinetics of meperidine were investigated after intramuscular (i.m.) or intravenous (i.v.) administration at a dose of 5 mg/kg in adult goats. After i.m. dosing, the plasma profile was best described by a one-compartment open model. In healthy (n = 16) and post-operative (n = 16) goats, the parameters were, respectively: tmax 8.3 +/- 3.9 and 9.2 +/- 5.5 min, Vd 2.763 +/- 1.231 and 3.929 +/- 2.101 l/kg, Clb 0.125 +/- 0.036 and 0.087 +/- 0.025 l/kg/min, Ke 0.0563 +/- 0.0358 and 0.0271 +/- 0.0136 min-1. The plasma profile was best fitted by a two-compartment open model following i.v. injection. In this case, the parameters for healthy (n = 7) and post-operative (n = 13) goats were, respectively: Vd 5.212 +/- 1.992 and 5.085 +/- 2.288 l/kg, Clb 0.096 +/- 0.028 and 0.075 +/- 0.026 l/kg/min, beta 0.0211 +/- 0.0093 and 0.0160 +/- 0.0052 min-1. There were, however, a few individuals with a prolonged elimination phase. Bioavailability of i.m. meperidine was 66.5 +/- 15.8% in healthy (n = 6) goats, but much higher in postoperative (n = 10) ones at 94.6 +/- 30.0%. Meperidine diffused into and out of CSF according to a first-order rate process. The time-course of CSF drug concentration was simulated by a biexponential function. CSF kinetic parameters of i.m. meperidine for healthy (n = 7) and postoperative (n = 13) goats were: elimination rate constant (K(ef)) 0.0269 +/- 0.0131 and 0.0305 +/- 0.0177 min-1, peak CSF concentration time (Tmaxf) 15.9 +/- 5.0 and 17.0 +/- 6.9 min. For the i.v. dosed healthy (n = 6) and postoperative (n = 8) animals, K(ef) was 0.0408 +/- 0.0107, 0.0414 +/- 0.0123 min-1 and Tmaxf was 10.0 +/- 5.0 and 7.7 +/- 2.5 min, respectively. It was demonstrated that an obviously lower peak concentration can be reached significantly later in CSF than in plasma, and the kinetic behaviour of meperidine in plasma is different from that in the CSF, indicating meperidine analgesia might not be predicted by simple extrapolation from the kinetic data.

Pharmacokinetics of sulfadimidine and its N4-acetyl metabolite in healthy and diseased rabbits infected with Pasteurella multocida.

The pharmacokinetics of sulfadimidine (SDM) and its N4-acetyl metabolite (N4SDM) were investigated after intravenous bolus injection of a single dose (200 mg/kg) of SDM in normal and diseased New Zealand white rabbits. The apparent distribution volume at steady state, total body clearance and elimination half-life of SDM in normal animals were 0.7 +/- 0.3 l/kg, 0.57 +/- 0.24 l/kg/h and 1.6 +/- 1.3 h, respectively. Of the administered dose, 62.1% was metabolized by N4-acetylation, and 12.7 +/- 1.1 and 2.8 +/- 1.8% of the dose was excreted as free drug by the kidney and gastrointestinal tract, respectively. The 'apparent' formation and elimination half-lives of N4SDM were 0.6 +/- 0.4 and 2.2 +/- 1.1 h, respectively. The metabolite was eliminated mainly by excretion through the kidney. There was no significant effect of acute pasteurellosis on the pharmacokinetics of either SDM or N4SDM in rabbits.

Effects of experimentally induced Streptococcus suis infection on the pharmacokinetics of penicillin G in pigs.

The pharmacokinetics of potassium penicillin G were studied in both healthy (n = 8) and experimentally Streptococcus-suis-infected (n = 6) pigs following intramuscular administration (15,000 iu/kg). Streptococcus-suis infection was induced artificially in young cross-bred pigs by subcutaneous inoculation with 9 x 10(8) to 10(9) colony-forming units of S. suis. The rectal temperature of infected pigs was significantly increased (P less than 0.01) before penicillin G injection and this was maintained for 8 h after the drug was given. Other clinical symptoms were also present. The serum concentration-time data for penicillin were found to fit a one-compartment open model with first-order absorption in the two groups of pigs. Significant changes were not observed between healthy and diseased pigs in following parameters: A, Ka, Ke and Tmax. However, in diseased pigs, significant increases (P less than 0.01) were found in Vd and ClB, and significant decreases (P less than 0.01) in Cmax and AUC occurred. The increased body clearance (ClB) and greater apparent volume of distribution (Vd) of penicillin G could partly explain why the serum values of the drug were much lower in diseased pigs than in healthy pigs.

Dose-response effects of atropine on thermal stimulus-response relationships in asthma.

To determine how cholinergic blockade modifies the stimulus-response relationships to thermal provocations, we had seven asthmatics perform increasing levels of eucapnic hyperventilation of subfreezing air (-10.6 +/- 1.9 degrees C) after pretreatment with aerosols of saline and atropine in doses of 0.25, 0.5, 1.0, 3.0, and 6.0 mg. Testing was performed on 5 separate days with both placebo and a single dose of drug. In control experiments, increasing ventilation produced a progressive decrease in the 1-s forced expiratory volume in a stimulus-response fashion. There were no significant differences between any placebo study. Atropine pretreatment did not abolish the obstructive response to airway cooling at any dose but, rather, shifted the stimulus-response curve to the right, so that the effects of muscarinic blockade could be overcome by increasing the stimulus. There were no significant differences between the results observed with 0.25 or 6 mg of atropine. These data demonstrate that cholinergic mechanisms play, at best, a very minor role in exercise-induced bronchospasm and offer a unifying explanation for the disparate findings in the literature regarding antimuscarinic agents in this condition.