Plasma exchange (PE) was associated with clinical improvement in 63% of patients at 6 months. Early initiation of PE and improvement at discharge were predictors of this response. Twelve patients (48%) who did not improve early did so during follow-up.

In patients with motor complete SCI, we were able to define three different neuropathophysiological patterns that are associated with bowel function abnormalities and clinical complaints; this might be of help when designing therapeutic strategies.

Routes t o hydroxychlorin derivatives of two distinct categories (nuclear hydroxy substituent; sidechain hydroxy substituent) are developed. Such substances, covering a range of amphiphilic character depending on the number of hydroxy groups, are seen as potential sensitisers for photodynamic therapy. Osmylation of octaethylporphyrin gives the dihydroxyoctaethylchlorin 2 and the tetrahydroxybacteriochlorin 3. Pinacol-pinacolone rearrangement of 2 gives the octaethyl-poxochlorin 4, borohydride reduction of which gives the secondary alcohol 6. This is converted via the bromochlorin 7 (prepared using 50% HBr/HOAc at room temperature) into a series of ethers, including those, 10, 11, 12, derived from glycerol, D-glucose, and D-mannitol respectively. Alkylation of these unprotected polyols with the highly hindered bromide 7 occurs preferentially at the primary alcohol functions in each case. Some of these hydroxychlorins are found in animal assays to be highly effective sensitisers of tumour photonecrosis. In this respect the most effective compounds in each category are the most highly hydroxylated. However, the D-glucose derivative 11 proves also to be an effective sensitiser of skin and muscle, i.e. it does not show the selectivity shown by 5,10,15,20-tetra(m-hydroxypheny1)chlorin.

Cleavage of nickel(I1) octaethyl-2,3-dihydroxychlorin 3 with lead tetraacetate gives the novel octaethyl-2,3-secochlorin-2,3-dione system as its nickel(I1) complex 4, which on treatment with base cyclises to a novel homoporphyrinone structure 5; electronic spectra are presented: 4 and 5 are seen as representing chromophores that may arise in chlorophyll catabolism.The catabolic fate of chlorophyll has received increasing attention recently. [1][2][3] Although in the form of metalloporphyrins, a small fraction persists in sedimentary organic deposits, most of it must be destroyed during senescence. On chemical grounds the major reactive sites (shown in 1) of chlorophyll a are expected to be (a) C-132, a pseudobenzylic acidic (p-keto ester) position; ( b ) the metal-x system, readily oxidised and readily demetallated; (c) the ring A-C-3 vinyl system; ( d ) the unsubstituted meso positions (C-5,10,20-electrophilic substitution, addition); and the tertiary pseudobenzylic C-17 and C-18 positions. Adams4 postulated (Scheme 1) that radical reactions at the 17 and 18 positions could lead to cleavage of the 17-18 bond to give the secochlorindione (A). We now describe this dione in a model system, which may allow this chromophore to be recognised should it occur naturally.Osmylation of octaethylporphyrin gave the dihydroxychlorin 2 . 5 Attempted cleavage of the glycol function of this gave complex mixtures, but the nickel(I1) complex 3 reacted smoothly with lead tetraacetate in anhydrous benzene (20 "C, 15 min) to give 76% of the secochlorindione 4 as tiny green needles, C36H&&i02 (elemental analysis, accurately measured M+). The electronic spectrum (Fig. 1) showed strong broad bands at 444 nm ( E 49 000) and 648 nm ( E 13 300), while in the IR the conjugated carbonyl groups appeared as a single band at Y 1676 cm-1 (KBr). In the 1H NMR spectrum the meso signals at 6 9.03 (s) and 6 8.17 (s) showed marginal changes compared with the corresponding singlets (6 9.12, 8.25) in the spectrum of the precursor 3. The structure 4 was confirmed by X-ray crystal analysis.6 In the crystal the carbonyl groups point in opposite directions: thus the C-2 carbonyl group, for instance, lies in a plane (C-1, C-2, C-2', 0) which makes a dihedral angle of 62" to the mean plane determined by C-1, C-2, C-20 and N-21. As a consequence, the two hydrogens of each methylene group adjacent to a carbonyl are inequivalent, and in the 1H NMR spectrum appear as double quartets at 6 2.04 and 2.75.