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Biomedical subjects

G R Gray

Publications and source records attributed to G R Gray.

At least 19 recordsLinked to original sources
PubMed1992

Studies of model compounds for the analysis of ester-containing polysaccharides by the reductive-cleavage method.

The four O-propionyl regioisomers of methyl tri-O-methyl-alpha-D-glucopyranoside and the 2- and 3-O-propionyl regioisomers of methyl tri-O-methyl-beta-D-glucopyranoside were subjected to reductive cleavage in the presence of Et3SiH and Me3SiOSO2CF3, BF3.Et2O, or Me3SiOSO2Me-BF3.Et2O. The O-propionyl group was stable when either Me3SiOSO2CF3 or BF3.Et2O was the catalyst, but was slowly reduced to the (1-propyl) ether when Me3SiOSO2Me-BF3.Et2O was the catalyst. Reductive cleavages catalyzed by Me3SiOSO2CF3 were complete in 6 h, those catalyzed by BF3.Et2O required at least 24 h, and those catalyzed by Me3SiOSO2Me-BF3.Et2O required 30 min or less. In the alpha-series, the rate of reductive cleavage decreased in the order 6-O-propionyl greater than 4-O-propionyl greater than 3-O-propionyl much greater than 2-O-propionyl. The reductive cleavage of beta anomers was faster than that of the corresponding alpha anomers. This effect was particularly striking for the alpha and beta anomers of the 2-O-propionyl regioisomer, as would be expected on the basis of a participation reaction.

Carbohydrate Conformation↗
PubMed1992

Analysis of Macrocystis pyrifera and Pseudomonas aeruginosa alginic acids by the reductive-cleavage method.

Permethylated alginic acids comprised of 4-linked D-mannopyranosyluronic acid and 4-linked L-gulopyranosyluronic acid residues undergo reductive cleavage to yield, after acetylation, methyl 3-O-acetyl-2,6-anhydro-4,5-di-O-methyl-D-mannonate (2b) and methyl 3-O-acetyl-2,6-anhydro-4,5-di-O-methyl-D-gluconate (3b) as major products. Small amounts (ca. 13%) of ring-contracted products, namely methyl 2-O-acetyl-3,6-anhydro-4,5-di-O-methyl-D-mannonate (9) and methyl 2-O-acetyl-3,6-anhydro-4,5-di-O-methyl-D-gluconate (10), were also observed in these experiments. These results are in marked contrast to previous results on the reductive cleavage of 4-linked D-glucopyranosyluronic acid residues, wherein the ring-contracted product was formed exclusively. Formation of the ring-contracted products could be completely eliminated by reduction (LiAlH4) of ester groups in the permethylated alginic acid prior to reductive cleavage. In the latter experiments, 4,6-di-O-acetyl-1,5-anhydro-2,3-di-O-methyl-D-mannitol (5b) and 4,6-di-O-acetyl-1,5-anhydro-2,3-di-O-methyl-L-gulitol (6b) were the sole products of reductive cleavage of the 4-linked ManA and 4-linked GulA residues, respectively. However, in the previous experiments it was noted that low yields of permethylated alginic acids were obtained and that extensive depolymerization occurred under methylation conditions. Depolymerization could be avoided and higher yields of permethylated polysaccharides could be obtained, by reduction of the carboxyl groups of the alginic acids prior to methylation. Reductive cleavage of the latter polysaccharides yielded the products expected from 4-linked D-mannopyranosyl and 4-linked L-gulopyranosyl residues, namely 4-O-acetyl-1,5-anhydro-2,3,6-tri-O-methyl-D-mannitol (13b) and 4-O-acetyl-1,5-anhydro-2,3,6-tri-O-methyl-L-gulitol (14b), respectively. Using the latter analytical strategy, it was established that the Macrocystis pyrifera alginate was comprised of 60% 4-linked ManA and 40% 4-linked GulA residues, whereas the Pseudomonas aeruginosa alginate was comprised of 80% 4-linked ManA and 20% 4-linked GulA residues.

Alginates↗
PubMed1992

Spontaneous remission of multilobated non-Hodgkin lymphoma.

A 67-year-old previously well man was admitted with hypercalcemia after a 7-day history of fever, night sweats, and back pain. The blood showed 5% multilobated lymphoid cells. A multilobated non-Hodgkin lymphoma associated with marked reticulin fibrosis was diagnosed on a bone marrow biopsy. During the next 7 days, in the absence of specific therapy, his symptoms disappeared. Three weeks after admission his biochemical abnormalities had resolved and after 9 weeks his bone marrow examination was normal. He remains in clinical and laboratory remission 16 months after presentation.

Aged↗
PubMed1992

Socio-cognitive skills as a determinant of life satisfaction in aged persons.

The purpose of this study was to explore the viability of a revised model of elderly life satisfaction, specifically evaluating the contribution of socio-cognitive skills. The role of such skills in relation to life satisfaction among aged persons has not been explored in research to date. Pilot data gathered from 60 community-living aged individuals indicated that numerous variables (e.g., subjective/objective health, education, financial satisfaction, role participation, subjective integration) significantly correlated with life satisfaction. However, the combined effects of two variables, persons' feelings of loneliness and isolation from their families and a measure of socio-cognitive skill, accounted for 49 percent of the variability in elderly life satisfaction. The effects of each on life satisfaction were unique however. Implications of these data and possible interventions for increasing elderly persons' life satisfaction are discussed.

Aged↗
PubMed1991

In vitro stimulation of immune functions by lipids derived from macrophages exposed to bacterial peptidoglycan.

It has previously been established that the processing of Bacillus subtilis cell walls by the macrophage-like cell line RAW264 leads to the formation of peptidoglycolipids containing glycopeptides of bacterial origin. In view of the immunologic activities associated with lipophilic muramyl peptide derivatives, lipid extracts derived from macrophages exposed to bacterial cell walls were assayed for mitogenicity. The crude lipid extract derived from RAW264 cells exposed to bacterial cell walls gave a strong mitogenic response when delivered as liposomes to murine splenocytes, whereas lipids derived from macrophages not exposed to bacterial cell walls did not give a mitogenic response. Fractionation of the RAW264 lipids into neutral lipids, glycolipids, and phospholipids demonstrated that mitogenicity was associated primarily with the phospholipid fraction and thus correlated with the presence of the aforementioned peptidoglycolipids. Mitogenicity was specific to the lipids derived from macrophages exposed to bacterial cell walls and was not observed in lipids derived from macrophages that had either been nonspecifically activated by exposure to Con A or had been allowed to phagocytize latex beads. The mitogenic response was found to be dependent on the presence of macrophages in the splenocyte population and to, at least in part, involve macrophage activation.

Animals↗
PubMed1991

Analysis of a pyruvic acid acetal-containing polysaccharide by the reductive-cleavage method.

The applicability of the reductive-cleavage method to the analysis of polysaccharides bearing pyruvic acid acetals has been demonstrated. Direct reductive cleavage of fully methylated gum xanthan yielded the expected products, including 1,5-anhydro-4,6-O-[(S)-1-methoxycarbonylethylidene]-2,3-di-O-methy l-D- mannitol. The latter product was not observed when reductive cleavage was performed subsequent to reduction of ester groups in the fully methylated polysaccharide and mild hydrolysis to remove pyruvic acid acetal substituents. Instead, the latter experiment yielded 1,5-anhydro-2,3-di-O-methyl-D-mannitol, establishing the presence in the polysaccharide of terminal (nonreducing) D-mannopyranosyl groups bearing 4,6-O-(1-carboxyethylidene) substituents. The products of reductive cleavage were characterized, where appropriate, by comparison of the gas chromatographic retention times and chemical ionization- and electron ionization-mass spectra of their acetates to those of authentic standards. Alternatively, the products of reductive cleavage could be characterized without resort to comparison with authentic standards by analysis of the 1H-n.m.r. spectra of their benzoates, which were obtained in pure form by high-performance liquid chromatography. By either method of product characterization, this two-step procedure of analysis reveals the presence of pyruvic-acetal residues in polysaccharides and establishes both the identity of the sugar residue to which they are attached and their positions of attachment.

Carbohydrate Sequence↗
PubMed1991

Synthesis and mass spectra of 4-O-acetyl-1,5-anhydro-2,3,6-tri-O -(methoxycarbonylmethyl)-D-glucitol and the positional isomers of 4- O-acetyl-1,5-anhydro-di-O-(methoxycarbonylmethyl)-O-methyl-D-glucitol and 4-O-acetyl-1,5-anhydro-O-(methoxycarbonylmethyl)-di-O-methyl-D-glucitol .

Reductive cleavage of fully methylated, partially O-carboxymethylated cellulose had previously been shown to produce 4-O-acetyl-1,5-anhydro-2,3,6-tri-O-methyl-, -2-O-(methoxycarbonylmethyl)-3,6-di-O-methyl-, -3-O-(methoxycarbonylmethyl)-2,6-di-O-methyl-, -6-O-(methoxycarbonylmethyl)-2,3-di-O-methyl-, -2,3-di-O-(methoxycarbonylmethyl)-6-O-methyl-, -2,6-di-O-(methoxycarbonylmethyl)-3-O-methyl-, -3,6-di-O-(methoxycarbonylmethyl)-2-O-methyl-, and -2,3,6-tri-O-(methoxycarbonylmethyl)-D-glucitol. Described herein is the independent synthesis of these derivatives, except for the first, which had been reported. In addition, their 1H-n.m.r. spectra, chemical-ionization (NH3) mass spectra, and electronionization mass spectra are tabulated.

Isomerism↗
PubMed1991

Early endoscopic sphincterotomy for retained bile duct stones after gallbladder surgery.

Endoscopic sphincterotomy (ES) was performed in 36 patients (age range 33-88 years; median 63 years) with retained bile duct stones after cholecystectomy (32 patients) or cholecystostomy (4 patients). The median time interval between surgery and ES was 28 days (range 10-216 days). At the time of ES, 23 patients had a T-tube in situ. Clearance of the bile duct was achieved by T-tube irrigation in 15 patients, and by basket or balloon extraction in seven patients. Spontaneous clearance of the duct after ES occurred in 12 patients, while two patients required widening of the sphincterotomy to allow successful basket extraction. Complications occurred in four patients (11%). Two patients sustained significant haemorrhage from the ES site and subsequently died. One patient developed mild acute pancreatitis while another had persisting cholangitis before and after ES. Both of these patients recovered with conservative management. While ES performed soon after gallbladder surgery allows for early bile duct clearance, the small but significant risk of potentially lethal haemorrhage suggests that its use should be reserved for patients in whom other non-operative methods have failed or are inappropriate.

Adult↗
PubMed1991

Prostaglandins in the treatment of reflux oesophagitis: double-blind placebo controlled clinical trial.

The efficacy of the prostaglandin analogue, rioprostil, in the treatment of reflux oesophagitis has been assessed in a double-blind, randomized, placebo-controlled trial of 25 patients with endoscopic and histological evidence of reflux oesophagitis. At the beginning and end of the study, endoscopic appearances were graded 0-4 (0 = no oesophagitis, 4 = severe oesophagitis) and the symptoms of heartburn, regurgitation, pain and dysphagia were each graded 0-3 (0 = none, 3 = severe). Fourteen patients received rioprostil, 300 micrograms twice daily, and 11 patients received identically marked placebo for a period of 12 weeks. At the end of the study there were no significant differences between the groups in mean (s.d.) endoscopic grading (rioprostil 2.4 (1.3); placebo 1.9 (0.9)) and mean (s.d.) cumulative symptom score (rioprostil 2.5 (3.1); placebo 2.6 (1.5)). Five patients in the rioprostil group reported diarrhoea. Rioprostil had no significant benefit over placebo in the treatment of reflux oesophagitis.

Double-Blind Method↗
PubMed1979

Structures of the homologous series of monoalkene mycolic acids from Mycobacterium smegmatis.

The positions of localization of the single carbon-carbon double bond in homologs of C series mycolic acids from Mycobacterium smegmatis have been established by 1) combined ammonia chemical ionization mass spectrometry/gas-liquid chromatography of aldehyde ozonolysis products, and 2) high resolution electron impact mass spectral analysis of vicinal glycol derivatives as their trimethylsilyl ethers. These studies have revealed that each homolog is a mixture of two isomers differing in double bond location. In each of the three homologs examined, approximately equal amounts of two isomers were present as follows: (formula: see text).

Alkenes↗
PubMed1979

Acetylated methylmannose polysaccharide of Streptomyces griseus. Locations of the acetyl groups.

The positions of esterification of the 4 to 5 acetyl residues in the acetylated methylmannose-containing polysaccharide from Streptomyces griseus have been established by the methyl replacement technique, wherein ester substituents are specifically replaced with methyl ether substituents. The newly incorporated methyl groups were distinguished from 3-O-methyl groups by the use of polysaccharide containing radioactively labeled endogenous methyl groups. The positions of methyl group localization were established by a proton magnetic resonance study of the intact methyl-replaced polysaccharide combined with an analysis of the constituent monosaccharides by gas-liquid chromatography-electron impact mass spectrometry of their alditol acetate derivatives. These studies demonstrate that the acetyl groups are located at position 6 of approximately half of the 10 contiguous alpha(1 leads to 4)-linked 3-O-methyl-D-mannose residues. Purification of the polysaccharide was accomplished by an added step involving affinity chromatography on a column containing immobilized palmitoyl residues. The affinity of the polysaccharide for this long chain lipid suggests that its plays a role similar to the methylmannose-containing polysaccharide of Mycobacterium smegmatis in its regulation of the bacterium's fatty acid synthetase.

Acetylation↗
PubMed1979

Intralesional immunotherapy of malignant melanoma with mycobacterium smegmatis cell wall skeleton combined with trehalose dimycolate (P3).

The clinical efficacy of intralesional immunotherapy utilizing Mycobacterium smegmatis cell wall skeleton (CWS) and trehalose dimycolate attached to oil droplets was investigated in 15 patients with advanced malignant melanoma. Patients received 300 microgram to 1050 microgram of the CWS combined with one-half that amount of trehalose dimycolate every 1 to 2 weeks for a total of 8 treatments. Therapy was continued if regression of injected lesions only occurred. Therapy was discontinued if regression of noninjected disease also occurred. Six of the 15 patients had regression of at least one injected lesion. Four of these 6 patients also had regression of noninjected disease lasting 4+, 6, 16 and 18+ months. Response was highly related to immune status. Six (83%) of 7 patients who reacted to one of a battery of skin tests responded. All 8 patients who did not react to skin tests failed to respond to therapy. There was no correlation of response with sex, prior therapy, disease-free interval or presence of visceral disease. Mycobacterial CWS and trehalose dimycolate is an effective immunotherapeutic agent. Additional studies of purified immunoadjuvants are warranted.

Cell Wall↗
PubMed1979

Structural and immunochemical characterization of the acidic arabinomannan of Mycobacterium smegmatis.

A serologically active, acidic arabinomannan has been isolated from Mycobacterium smegmatis. The polysaccharide contains approximately 56 arabinosyl and 11 mannosyl residues, and 2 phosphate, 6 monoesterified succinate, and 4 ether-linked lactate groups. After saponification to remove succinyl groups, the polysaccharide can be separated into phosphorylated (55%) and nonphosphorylated (45%) forms, the former containing a little more arabinose and a little less mannose than the latter. The structures of these polysaccharides were investigated by 1H- and 13C-n.m.r. spectroscopy and methylation analysis, before and after selective cleavage of furanosyl linkages. The phosphorylated and nonphosphorylated forms of the polysaccharide were found to have similar, if not identical, structures. The main structural feature of the polysaccharides is the presence of chains of contiguous arabinofuranosyl residues linked alpha-(1 leads to 5). These chains are attached at 0-4 of arabinopyranosyl residues that are present in a core region of the polysaccharide that also contains mannopyranosyl residues. Immunochemical studies demonstrated that the polysaccharide is an effective, precipitating antigen with antisera from rabbits immunized with cell walls or heat-killed cells of M. smegmatis. The polysaccharide is, however, more effective as a precipitating antigen after removal of the succinate groups, and completely ineffective after removal of arabinofuranosyl residues. The polysaccharide therefore contains an important antigen in common with the arabinogalactan lipopolysaccharide of the cell wall of the bacterium, i.e., chains of contiguous alpha-(1 leads to 5)-linked arabinofuranosyl residues.

Animals↗
PubMed1978

Hemoglobinopathies in a hospital population in Vancouver.

A number of varieties of thalassemia were found to be common in the Vancouver area and in other parts of British Columbia. Of 3117 patients whose blood samples were studied by hemoglobin electrophoresis at the Vancouver General Hospital between Jan 1, 1965 and June 30,1977, 813 had the beta-thalassemia trait, 18 had homozygous beta-thalassemia, 97 had alpha-thalassemia trait, 24 had hemoglobin H disease and 14 had miscellaneous variants. Eight patients had interactions of beta-thalassemia with hemoglobin S,C, D, O arab or Vancouver, and one patient had alpha thalassemia associated with hemoglobin Constant Spring. Twelve other variants were noted. They included hemoglobins B2, E, Q, GHsi Tsou, J Bangkok, British Columbia, KOLN, Lepore, Rampa, Tacoma, St. Claude and an unidentified alpha-chain variant.

Adolescent↗
PubMed1978

Mycolic acids. A reinvestigation.

Mycolic acids derived from the cell walls of Mycobacterium bovis BCG, Mycobacterium bovis Bovinus I, Mycobacterium smegmatis, and Mycobacterium tuberculosis H37Rv have been fractionated as their p-bromophenacyl esters by a two-step high performance liquid chromatographic procedure: 1) adsorption chromatography on 10-micrometer particle size silica gel, and 2) reverse phase partition chromatography on a 10-micrometer particle size support containing a C18 bonded phase. This procedure has resulted in the isolation of approximately 24 mycolic acids from each bacterium (very likely homologs of various mycolate types) instead of the two to four that have previously been described. The implication of these results on the previously determined structures of these fatty acids is discussed.

Molecular Weight↗