Unexplained acidosis of malnutrition: a study by ion-exchange chromatography/mass spectrometry.

Keto-acidosis is usually associated with uncontrolled diabetes and typically poses few diagnostic problems when presenting as hyperglycaemia, metabolic acidosis and a high anion gap. An emaciated patient suffering from Duchenne Muscular Dystrophy and volume depletion presented with acidosis of unknown origin. Preliminary investigations appeared to rule out lactic acidosis, diabetic keto-acidosis and acidosis due to base loss. We have previously reported a technique utilizing liquid chromatography coupled to mass spectrometry (LC-MS) which can be used to characterize the underlying aetiology of acidosis and applied it to ultrafiltrate derived from a blood sample taken from this patient. The anion profile obtained on the chromatogram showed elevated levels of acetoacetate and hydroxybutyrate but no evidence of lactic acidosis, nor was the profile typical of that seen in 'unexplained' acidosis. We concluded that the patient was suffering from keto-acidosis associated with starvation and dehydration, the biochemical features being obscured by both the patient's chronic malnutrition and minimal muscle mass. A combination of enteral feeding and rehydration led to prompt resolution of the patient's metabolic acidosis.

Amino acid and peptide conjugates of protoporphyrin: preparation and analysis by high-performance liquid chromatography, high-performance liquid chromatography/electrospray ionization mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Amino acid and peptide conjugates of protoporphyrin have been prepared by reacting protoporphyringen with cysteine, glutathione and peptides containing a free thiol group under acidic conditions. The conjugates were formed by the addition of the thioamino acids or peptides to the vinyl groups of protoporphyrin during the autoxidation of protoporphyinogen to protoporphyrin and is free-radical-mediated. The conjugates were separated by high-performance liquid chromatography (HPLC) and characterized by HPLC/electrospray ionization mass spectrometry (HPLC/ESI-MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). All the conjugates formed were diconjugates consisting of diastereoisomers.

Chemical and analytical aspects of areca nut.

A capillary zone electrophoretic (CZE) method for the rapid analysis of the major alkaloids (arecoline and guavacoline) in areca nut extract is described. Areca nuts were pulverized and then extracted with water by sonication in a water bath. After centrifugation, the supernatant was analysed on a fused-silica capillary with 100 mM ammonium acetate-acetic acid (pH 4.6) as the running buffer at a voltage of 20 kV and temperature of 30 degrees C. The method is applicable to the analysis of alkaloids in the nut, commercial preparations (pan masala) and in the saliva of areca nut chewers.

HPLC-electrospray mass spectrometry for the analysis of temoporfin-poly(ethylene glycol) conjugates.

The photodynamic therapeutic agent temoporfin, 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (m-THPC) conjugated with poly(ethylene glycol) 2000 (PEG), has been analysed by high performance liquid chromatography (HPLC), linked to electrospray ionisation mass spectrometry (ESI-MS). Sufficient separation of m-THPC-PEG 2000 oligomers was achieved, enabling determination of molecular mass. The use of ESI-MS alone could not achieve this, because of too great a complexity in the mass spectrum, resulting from the presence of four PEG 2000 side chains with a wide molecular mass distribution. The technique is applicable to similar PEG conjugated compounds.

Capillary zone electrophoresis/mass spectrometry of 5-aminolaevulinic acid and porphobilinogen.

A capillary zone electrophoresis/electrospray ionisation mass spectrometry (CZE/ESI-MS) method has been developed for the separation and detection of 5-aminolaevulinic acid (ALA) and porphobilinogen (PBG). Capillaries were 70 cm long with an inner diameter of 75 micrometer and outer diameter of 375 micrometer. The buffer used was aqueous ammonium acetate (50mM, pH 5.2) with a co-axial 'make-up' flow of methanol/aqueous 0.1% formic acid (1:1 v/v) at a flowrate of 6 microL/min. A voltage of 20 kV was used for CZE and an ESI voltage of 3.5 kV. Full scan data was acquired over the range m/z 100-500 in positive ion mode, from which selected ion electropherograms were extracted; at m/z 132 for the protonated molecular ion of ALA and m/z 210 for the methylenepyrrolenine fragment ion of PBG. The protonated molecular ion of PBG, m/z 227, was found to be too facile to monitor, easily losing ammonia in the electrospray source and better sensitivity was achieved by monitoring the resulting fragment ion. The detection limits were circa 100 attomoles of ALA and 10 attomoles of PBG at a signal-to-noise ratio (S/N) better than 10, providing sufficient sensitivity for clinical use and offering advantages over existing techniques.

An inhibitor of the sodium pump obtained from human placenta.

BACKGROUND: Much effort has been expended in the search for an endogenous inhibitor of the cellular sodium/potassium pump, a compound of major physiological importance, which has been implicated in the mechanism of essential hypertension. Others have suggested that ouabain or an isomer of ouabain may be the endogenous pump inhibitor. Neonatal cord serum contains an inhibitor of the sodium pump; we attempted to isolate and characterise this substance from human placentas. METHODS: Homogenised placentas were dialysed and the resulting solutes were trapped on octadecylsilyl silica and then separated by high-performance liquid chromatography. Measurement of the activity of the sodium pump of human leucocytes was used to test each fraction for the presence of the inhibitor. FINDINGS: An inhibitor of the sodium pump was obtained by this technique in a mass spectrometrically pure form with a mass of 370 Da, an empirical formula of C24H34O3 and only one hydroxyl group. The characteristic fragmentation pattern observed in negative-ion mass spectrometry was compared with those of various model compounds; this comparison suggested that the active material was a dihydropyrone-substituted steroid. INTERPRETATION: These results suggest that a dihydropyrone-substituted steroid is an endogenous regulator of the sodium pump in humans and, presumably, other mammals. Proof of the endogenous origin will require the demonstration of a previously unrecognised biosynthetic pathway.

Infection rate in total hip arthroplasty as a function of air cleanliness and antibiotic prophylaxis. 10-year experience with 2,384 cementless Lord madreporic prostheses.

To separate the respective effects of sterile air and antibiotic prophylaxis in orthopedic surgery, the authors reviewed 2,384 cementless total hip replacements performed from 1975 to 1984 for incidence of deep sepsis. During this period, a conventionally ventilated room (100 particle-forming units (pfu)/m3) and a laminar vertical flow (1 pfu/m3) were alternately used, without significant difference in the sepsis rate. Beginning in 1979, a prophylactic antibiotic regimen was added, which from 1979 to 1984 reduced the incidence of deep sepsis from 2.78% to 0.52%. There was also a change in common infecting organisms, from sensitive to resistant strains, which is not an insignificant consequence.

Madreporique stemmed total hip replacement: five years' clinical experience.

Between February 1975 and December 1980, 1214 total hip arthroplasties were performed with a new type of rough surface implant. The results, pitfalls and complications are presented with special reference to the first 173 cases which have had a complete clinical and radiological follow up for at least five years. The indications for operations in both primary and revision arthroplasties are defined.

An uncemented total hip replacement: experimental study and review of 300 madreporique arthroplasties.

Mafreporique arthroplasty is not intended as a bustitute for acrylic cement stabilized arthroplasty but is available as an effective alternative. An experimental and clinical investigation including radiological analysis of 300 madreporique arthroplasties has convinced us of the reality and reliability of biological anchoring by endosteal osteogenesis. The madreporique method does not result in any local or general complications usually associated with the cement technique. Full weight-bearing is permitted at the same postoperative time as the cemented prosthesis. The results at early and interim follow-up periods compare favorably with cemented hip arthroplasties. Living bone that undergoes remodelling provides for long-term anchor of the prosthesis and eliminates the chemical intermediary which leads, more or less, with time to loosening of the implant in a significant number of cases.