Hysteresis and scanning behavior of mesoporous molecular sieves

Sorption hysteresis is a widely studied phenomenon whose predicted behavior is well documented and researched. On the other hand, there is much less known about the region that lies between sorption isotherms, believed to be a metastable region. Scanning curves are a way of understanding the mechanism of hysteresis and a tool for hysteresis model validation. Scanning curves were produced for mesoporous materials: SBA-15 and MCM-41 for N(2) sorption at 77 K and Ar sorption at 87 K. A limited set of different scanning behaviors is identified. Like most hysteresis theories, it was found that a single model for scanning behavior cannot be extended to all materials under the same or different experimental conditions. Two behaviors are consistent with recent theories and simulations; however, several are not. The implications as to the characterization of pore dimensions and structure are discussed.

The incidence of transient neurologic symptoms (TNS) after spinal anaesthesia in patients undergoing surgery in the supine position. Hyperbaric lidocaine 5% versus hyperbaric bupivacaine 0.5%

BACKGROUND

The incidence of TNS after spinal anaesthesia is a problem. Especially the use of hyperbaric lidocaine in patients placed in the lithotomy position during surgery has been associated with a high incidence of TNS. The present study was performed to investigate whether TNS is present more frequently in patients undergoing surgery in the supine position with use of hyperbaric lidocaine compared with hyperbaric bupivacaine.

METHOD

Seventy patients were included and randomised to receive either hyperbaric lidocaine or hyperbaric bupivacaine. All patients were contacted on the first and third postoperative days by an anaesthesiologist blinded to the local anaesthetic used. The patients were asked about symptoms of TNS, pain not associated with the operation area, and asked to grade the complaints after a verbal analogue score from 0 to 10.

RESULTS

We found a total of ten patients who showed signs of TNS. There were nine patients in the lidocaine group (26%) who showed signs of TNS compared to only one patient in the bupivacaine group (3%) (P<0.01). The average score of TNS complaints was 3.5. A total of 13 patients (19%) complained of back pain. There were no significant differences with regard to which local anaesthetic was used. The average score of back pain was 3.3.

CONCLUSION

TNS is a significant problem in patients having spinal anaesthesia with hyperbaric lidocaine compared to hyperbaric bupivacaine, both in the supine position. For day-case surgery, TNS would start after dismissal from hospital. The use of hyperbaric lidocaine is therefore questionable, even though these problems are of an order that the majority of patients would still choose spinal anaesthesia for future operations.

Purification and 1H NMR spectroscopic characterization of phase II metabolites of tolfenamic acid

Tolfenamic acid, an anti-inflammatory drug (NSAID), is metabolized in vivo to form several oxidative metabolites which are all conjugated with beta-D-glucuronic acid. In this study, the metabolites of tolfenamic acid were identified by 1H nuclear magnetic resonance (NMR) spectroscopy in urine samples obtained on days 7 to 10 from a human volunteer after oral administration of 200 mg of the drug three times per day (steady-state plasma concentration). The metabolites of tolfenamic acid were initially concentrated by preparative solid phase extraction (PSPE) chromatography, thereby removing the endogenous polar compounds that are present in the urine. The individual metabolites were purified by preparative high performance liquid chromatography (HPLC) and then identified using 1H NMR. Both one- and two-dimensional NMR experiments were performed to identify the phase II metabolites of tolfenamic acid; the study shows the applicability of 1H NMR for the identification of drug metabolites in biological fluids. In addition to NMR analysis, two metabolites were also identified by mass spectrometry (MS). The glucuronides of the following parent compounds, N-(2-methyl-3-chlorophenyl)-anthranilic acid (T), N-(2-hydroxymethyl-3-chlorophenyl)-anthranilic acid (1), N-(2-hydroxymethyl-3-chloro-4-hydroxyphenyl)-anthranilic acid (2), N-(2-formyl-3-chlorophenyl) anthranilic acid (3), N-(2-methyl-3-chloro-4-hydroxyphenyl)-anthranilic acid (4), N-(2-methyl-3-chloro-5-hydroxyphenyl)-anthranilic acid (5), N-(2-carboxy-3-chlorophenyl)-anthranilic acid (6), N-(2-hydroxymethyl-3-chlorophenyl)-4-hydroxy-anthranilic acid (7), N-(2-methyl-3-chlorophenyl)-5-hydroxy-anthranilic acid (8), N-(2-methyl-3-chloro-4-metoxyphenyl)-anthranilic acid (9), N-(2-methyl-3-chlorophenyl)-4-hydroxy-anthranilic acid (10), and N-(2-methyl-4-hydroxyphenyl)-anthranilic acid (11) were identified. The phase II metabolites (5-11) had not previously been identified in urine from humans administered tolfenamic acid. The phase I metabolites of the glucuronides 7, 8, 10, and 11 were identified here for the first time. An HPLC method was developed that simultaneously separates all the phase II metabolites identified as well as some phase I metabolites in urine samples obtained after intake of tolfenamic acid.

Problems of adjustment reported among a group of heroin addicts

Many reports in the literature concerning the heroin addict and his addiction have been related to psychological tests and the personality and behavior among addicts. However, studies have not cited his adjustment problems. Forty-seven narcotic addicts were surveyed to determine their adjustment difficulties by an administration of the Mooney Problem Checklist. The results indicate that the most difficult areas of adjustment were related to personality, self-improvement, the home and family, and occupation. It was concluded that among these participating narcotic addicts, four areas were noted as frequent problems while five additional areas were reported as less of an adjustment difficulty.