Short note: the potential of umbilical cord blood to increase tissue oxygenation in adult respiratory distress syndrome

Umbilical blood, consisting mainly of fetal haemoglobin, has an increased oxygen affinity. Adult respiratory distress syndrome may be caused by any acute, diffuse, infiltrative lung lesion of diverse aetiologies and is characterized by severe arterial hypoxia. Mechanical ventilation with high FIO2 and elevated pressures is used to improve tissue oxygenation in these patients. Nevertheless, adult respiratory distress syndrome may be fatal. Our hypothesis suggests that transfusion of umbilical cord blood to adult respiratory distress syndrome patients may facilitate oxygen transport by increasing oxygen binding in the erythrocytes passing through the damaged lungs. The local hypoxia and the accompanied acidosis in the periphery may accelerate the oxygen unload to the tissues, thus augmenting overall oxygen delivery. Studies with animals and humans show that left-shifted oxyhaemoglobin dissociated curve confers a degree of adaptation to low-oxygen tension ambient. Umbilical cord blood is available in every hospital, and there are no contraindications to its use.

Focal epileptic episodes associated with hypoglycemia in children with diabetes

Focal neurological deficits associated with hypoglycemia have been well described in adults with diabetes. We could find only one report of the association between focal epileptic episodes and hypoglycemia in children with diabetes. We describe 3 patients with seven focal epileptic episodes associated with hypoglycemia.

Photodecomposition of 1,2,3,4- and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in water-alcohol media on a solid support

We used a hydrophobic solid support, octadecylsilylated silica gel (C18), packed in a quartz column as a reaction medium for the photolysis of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TCDD). When we exposed the column to a 450 W UV lamp, the adsorbed 1,2,3,4-TCDD or 2,3,7,8-TCDD in 10% 2-propanol/water decomposed completely in 20 minutes and 5 minutes, respectively. The large estimated partition coefficient of 1,2,3,4-TCDD in 10% 2-propanol/water (> 1000) indicates that on the C18 stationary phase, both the saturated hydrocarbon chains and the absorbed 2-propanol may act as proton donors and accelerate the photolysis. In direct sunlight, the adsorbed 1,2,3,4-TCDD in 10% 2-propanol/water decomposed much faster than in a nonaqueous solvent (50% 2-propanol/methanol). This solvent effect is advantageous for the practical use of the C18 photolysis process in aqueous waste treatment. We have demonstrated that complete C18 trapping with continuous photodecomposition of TCDD contained in an aqueous alcohol waste is possible.

The pharmacokinetics of 8-methoxypsoralen following i.v. administration in humans

1. 8-methoxypsoralen (8-MOP) is a naturally occurring photoreactive substance which, in the presence of u.v. light, forms covalent adducts with pyrimidine bases in nucleic acids. For many years, 8-MOP has been used in PUVA therapy for treatment of psoriasis. Recently, the drug has been found to inactivate effectively bacteria spiked into platelet concentrates. The purpose of this study was to determine the pharmacokinetics and safety of 8-MOP administered intravenously in the bactericidal dosage range. 2. Eighteen volunteers were divided into three treatment groups to receive, respectively, 5, 10, and 15 mg 8-MOP infused over 60 min. Frequent arterial samples were gathered, and the blood and plasma were assayed for 8-MOP concentration. The pharmacokinetic parameters were determined by moment and compartmental population analysis, the latter performed with the program NONMEM. Haemodynamics, ventilatory pattern, and subjective effects were recorded throughout the study. 3. The intravenously administered 8-MOP was well tolerated in all individuals, and no acute toxicity was observed. 4. The pharmacokinetics of 8-MOP were best described by a three-compartment mammillary model in which the volumes and clearances were proportional to weight. The mean pharmacokinetic parameters for the plasma concentrations were: V1 = 0.045 1 kg-1, V2 = 0.57 1 kg-1, V3 = 0.15 1 kg-1, CL1 (systemic) = 0.010 1 kg-1 min-1, CL2 = 0.0067 1 kg-1 min-1, CL3 = 0.012 1 kg-1 min-1. The mean pharmacokinetic parameters for the blood concentrations were: V1 = 0.061 1 kg-1, V2 = 1.15 1 kg-1, V3 = 0.21 1 kg-1, CL1 (systemic) = 0.015 1 kg-1 min-1, CL2 = 0.011 1 kg-1 min-1 and CL3 = 0.015 1 kg-1 min-1. 5. The plasma pharmacokinetic model described the observations with a median absolute error of 17%, and the blood pharmacokinetic model described the observations with a median absolute error of 18%. Analysis of the relative concentration of 8-MOP between plasma and red blood cells suggested concentration-dependent partitioning. 6. The addition of 7.5 mg 8-MOP to 300 ml platelet concentrate would produce bactericidal concentrations of 25 micrograms ml-1. Simulations based upon our data show that intravenous administration of 7.5 mg over 60 min would result in systemic concentrations of 8-MOP similar to those observed with conventional PUVA therapy. We conclude that the extensive safety history established in PUVA therapy will be applicable to this new application of 8-MOP.

Optimal intravenous dosing strategies for sedatives and analgesics in the intensive care unit

Achieving and maintaining adequate levels of analgesia and sedation in critically ill patients is a fundamental part of ICU care. Understanding the clinical pharmacology of commonly used sedative agents (e.g., midazolam, lorazepam, and propofol) and opioids (e.g., fentanyl and morphine) enables clinicians to best dose these drugs to the desired clinical effect while minimizing the risk of excessive sedation and cardiopulmonary depression. This has significant safety and cost implications for patient care in the ICU. Simulations of plasma concentrations of these medications when administered to ICU patients provide useful insight into the clinical pharmacology of these agents. A number of points should be made with regards to the interpretation of these predicted plasma concentrations, however. First, it is important to remember that PK parameters for most of these agents, with the exception of midazolam and propofol, were derived from bolus or short-term infusions administered to healthy patients, and that the PK parameters for lorazepam, fentanyl, and morphine when administered as long-term infusions to critically ill patients may vary dramatically from these initial estimates. Specifically, their volumes of distribution and elimination half-lives may prove to be significantly larger and longer, respectively, when administered to patients in the ICU. This pharmacokinetic variability may result in even longer emergence times than predicted herein following discontinuation of continuous infusions of these agents. Until similar studies in ICU patients are performed for lorazepam, fentanyl, and morphine, the clinical pharmacology of these agents in ICU patients remains uncertain. Additionally, midazolam and morphine both have active metabolites that can accumulate in critically ill patients receiving long-term infusions. These metabolites add significantly to the sedative effects of the primary compound. Other drugs with sedative effects given concurrently with any of these agents (i.e., psychotropic agents, epidural opioids, etc.) may also contribute to the sedative effects of these drugs. These studies do not account for the development of tolerance (which can occur with both benzodiazepines and opioids) or changing kinetic profiles within an individual patient over time (i.e., due to changes in volume of distribution, protein binding, or clearance). Finally, there is a high degree of interpatient variability among critically ill patients, and medication dosing must be tailored to individual patients' needs (i.e., one dose does not fit all patients). Given the uncertainty of resulting plasma concentrations with long-term administration of these medications, the best ways to achieve and maintain optimal levels of sedation and analgesia while minimizing the risk of oversedation and side effects are to (1) initiate sedation in an incremental fashion until the desired level of sedation is achieved, then periodically (i.e., once a day) titrate the infusion rate of sedative-hypnotics and opioids downward until the patient begins to emerge from the sedative effects of these drugs; and finally gradually increase the infusion rate until the desired level of sedation is once again achieved; and (2) consider the use of a sedation scale to standardize the level of sedation to be maintained (see Table 3). The use of such a scale enables physicians to communicate to nursing staff the specific level of sedation to be achieved and maintained in an individual patient (i.e., titrate the midazolam infusion between 0 to 5 mg/hr to maintain a sedation score of 2-3; call MD for inadequate sedation, respiratory depression, or hypotension). Achieving optimal sedation and analgesia of patients in the ICU requires not only that the choice of medication(s) be appropriate for the clinical setting but also that there are specific clinical endpoints for the agents used (i.e., light versus deep sedation, continuous versus intermittent sedation, sedation with

IL-13 results in differential regulation of the complement proteins C3 and factor B in tumour necrosis factor (TNF)-stimulated fibroblasts

IL-13, like IL-4, a product of activated T cells, has multiple biological actions, primarily on B cells and monocytes. The purpose of the present study was to compare the effects of IL-13 with those of IL-4 on the synthesis of complement proteins in fibroblasts. Dermal fibroblasts were developed from skin biopsies. Confluent monolayers were stimulated with the relevant cytokine or combinations of cytokines and biosynthetically labelled with 35S-methionine. The specific proteins were analysed using immunoprecipitation and SDS-PAGE. Addition of IL-13 to fibroblast cultures treated with TNF-alpha resulted in a dose-dependent increase in C3 protein biosynthesis and a concomitant down-regulation of factor B protein biosynthesis. In TNF-stimulated fibroblasts, the addition of IL-13, 100 ng/ml, induced a 2.45-fold increase in the synthesis of C3, while in the same cells under identical conditions the synthesis of factor B was only 42% of the level without IL-13. Similar effects of IL-13 were noted on IL-1-treated fibroblasts. These effects were specific for C3 and factor B, and no alteration of the constitutive or TNF-induced synthesis of C1s or C1 inhibitor proteins was observed. IL-13 altered the synthesis of C3 and factor B proteins also in fibroblasts stimulated with interferon-gamma (IFN-gamma) in addition to TNF, in the same direction as it did in cells stimulated with TNF alone. IL-13 has similar effects to those of IL-4 on the synthesis of C and factor B in TNF- and IL-1-stimulated fibroblasts. The observed effects of IL-13 are IL-4-independent, as anti-IL-4 antibody abrogates IL-4-induced effects, but has no effect on IL-13-induced responses. This interaction between different cytokines on the synthesis of proinflammatory and immunoregulatory proteins may have significance, particularly at local sites of inflammation, and may affect the synthesis of complement proteins in inflamed joint as in rheumatoid arthritis.

Lipid profile with paternal history of coronary heart disease before age 40

Serum lipids were measured in children and their parents from 40 families in which the father had a myocardial infarction or coronary heart disease (CHD) before age 40 years. The relationship between physical activity and serum lipid concentrations in the children was also evaluated. Twenty six men had one or more abnormal lipid value (in mmol/l): total venous cholesterol (TVC) > 6.24, triglycerides < 2.55, low density lipoprotein cholesterol (LDL-C) > 4.42, or high density lipoprotein cholesterol (HDL-C) < 0.91. There were 15 spouses with significant hyperlipidaemia (values above). In the 107 children examined, TVC mean (SD) was 4.68 (1.17), triglycerides 1.4 (0.8), LDL-C 3.0 (1.0), and HDL-C 1.18 (0.28). Altogether 42% of the children had significant hyperlipidaemia. No significant correlation was found between the degree of physical activity of the children and their LDL-C and TVC concentrations. However, a significant positive correlation was found between the degree of physical activity and HDL-C and a significant negative one with triglyceride concentrations. It is concluded that screening the progeny of young CHD patients is highly productive in identifying young people at excessive risk for future CHD. The data also suggest that promoting high degrees of activity among these children may have a positive influence on risk factors for adult onset CHD.

CT of renal densities caused by intravenous infusion of antibiotics

OBJECTIVE

Patients treated with intravenous antibiotics were seen to have increased attenuation of the renal collecting system on CT scan of the abdomen. To detect whether this was related to certain antibiotics, we undertook a prospective study on patients being treated for sepsis while receiving intravenous antibiotics. In addition, we also tested antibiotics administered to rabbits.

MATERIALS AND METHODS

Fourteen patients were tested with cefazolin, gentamicin, cefotaxime, vancomycin, amoxicillin and clavulanic acid (Augmentin), and metronidazole. Ten groups of rabbits received these drugs by intravenous injection. Computed tomography scan of the kidneys was performed prior to and 2 h after intravenous injection of antibiotics. Fourteen patients who underwent CT scan of the abdomen and were treated by intravenous antibiotics were scanned without contrast agent injection.

RESULTS

According to our results, cefazolin, cefotaxime, and gentamicin seemed to be the most potent antibiotics in inducing increased attenuation of the collecting system. This effect was synergistic when a combination of drugs was used.

CONCLUSION

The elucidation of the potential increase in attenuation of the collecting system by antibiotics in normally functioning kidneys should help to eliminate confusion with other pathologies such as medullary sponge kidney.

BAEP studies in children with attention deficit disorder

Brainstem auditory evoked potentials (BAEPs) were performed on 114 children with attention deficit disorder (ADD). Prolonged latencies of waves III and V and longer brainstem transmission time interval of waves I-III and I-V were observed in the study group compared with normal controls. A significant asymmetry of wave III latency between the ears was found in children with ADD, but not observed in the control group. The authors conclude that children with ADD have brainstem dysfunction. BAEPs, an objective electrophysiological test, may contribute to the diagnosis of ADD, distinguishing these children from the normal population.