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Biomedical subjects

M J Holmes

Publications and source records attributed to M J Holmes.

At least 37 records · Page 2Linked to original sources
PubMed1991

Strain dependent production of ciguatoxin precursors (gambiertoxins) by Gambierdiscus toxicus (Dinophyceae) in culture.

Thirteen strains of Gambierdiscus toxicus isolated from Queensland (Australia), Hawaii, French Polynesia and the Virgin Islands were mass cultured and extracted for ciguatoxin. A biodetrital sample containing wild G. toxicus collected from the Republic of Kiribati was also extracted for ciguatoxin. Ciguatoxin, as characterized from moray eels, was not detected in any of the strains examined. Two Queensland strains and the wild G. toxicus produced putative ciguatoxin precursors named gambiertoxins. These gambiertoxins were less polar than ciguatoxin but produced bioassay signs in mice and in-vitro responses in isolated guinea pig atria and vas deferens which were similar (but not identical) to those produced by ciguatoxin. The gambiertoxins from cultured cells were also shown to competitively inhibit the binding of [3H]brevetoxin-3 to rat brain membranes in a dose-dependent manner. The gambiertoxins were more potent than ciguatoxin (on a per mouse unit basis) at stimulating neural elements of guinea pig atria. The two culture strains produced similar amounts of gambiertoxins, even when grown in nutrient media made from different seawater containing different concentrations of nutrients. Changes in nutrient media did not induce the other strains of G. toxicus to produce gambiertoxins. The production of these ciguatoxin precursors appears to be limited to only certain genetic strains of G. toxicus, with the majority of strains not producing these toxins. We propose that ciguatera occurs when blooms of G. toxicus strains genetically capable of producing these ciguatoxin precursors enter the marine food chain. These toxins could then become oxidatively metabolized in fishes to the major polar ciguatoxin. Wild cells produced approximately 100-fold greater quantities of gambiertoxins per cell than did the two culture strains indicating that there is considerable potential for increased production of these ciguatoxin precursors from G. toxicus in culture.

Animals↗
PubMed1990

Toxicity of Australian and French polynesian strains of Gambierdiscus toxicus (Dinophyceae) grown in culture: characterization of a new type of maitotoxin.

Gambierdiscus toxicus strains isolated from Australia and French Polynesia were grown in modified f2 and f10 nutrient media and the cells extracted for ciguatoxin and maitotoxin. The high nutrient enrichment of f2 media induced aberrant cell morphology in both strains whereas the majority of cells grown in f10 media had the typical lenticular shape of wild G. toxicus cells. The Australian strain grew faster and produced greater cell densities than the French Polynesian strain. Different chromatographic types of maitotoxin were extracted from the two G. toxicus strains and purified to homogeneity using reverse-phase high-performance liquid chromatography. The toxins elicited similar bioassay signs in mice, but produced different death-time vs dose relationships. The maitotoxin extracted from the Australian strain eluted later on both straight-phase and reverse-phase chromatographic columns than did the maitotoxin extracted from the French Polynesian strain. The maitotoxin extracted from the French Polynesian strain was chromatographically identical to reference maitotoxin. For each strain no differences were found between maitotoxins extracted from cells grown in f2 or f10 media. Only one toxin was produced by each strain of G. toxicus. Ciguatoxin was not produced by either strain.

Animals↗
PubMed1990

A rabbit model for mucosal immunity in the bowel. II. Local cellular reactivity to virus infection.

An animal model was used to examine local and systemic cellular reactivity against virus infection of bowel mucosa. Firstly, existing techniques for extracting lymphoid cells from the dispersed populations of the bowel mucosa were adapted for use in rabbits and viable lymphocytes were isolated from the lapine ileal mucosa in numbers suitable for assay. Lamina propria lymphocytes (LPL) showed a strong blastogenic response to T-cell mitogens but intra-epithelial lymphocytes (IEL) responded poorly, even in the presence of splenic accessory cells. Next, chronically isolated ileal loops in rabbits were infected with parainfluenzavirus type 3 (PI-3) and isolates from the organized and dispersed lymphoid tissues associated with infected ileal mucosae and those from systemic lymphoid sites were used in in vitro assays of virus-specific lympho-proliferation. A T-cell-mediated immune response against PI-3 was mounted in lymphoid tissues associated with the infected loops, appearing first in loop Peyer's patches (PP) at Day 4 and in mesenteric lymph nodes (MLN) and lamina propriae at Day 7 after infection. The response in PP had waned by 21 days but was sustained in the other sites for at least 42 days. Epithelial lymphocytes were consistently anergic and there was no evidence of specific reactivity at systemic lymphoid sites or elsewhere in the bowel. Thus, a highly localized T-cell-mediated response was sustained, not only in organized lymphoid tissues but also in the bowel wall itself, following infection with a novel antigen.

Animals↗
PubMed1988

Rabbit model for mucosal immunity in the bowel: I. Establishment of virus-infected ileal loops.

An animal model was designed for use in studies of initial cellular immune responses to virus infection of the intestinal mucosa. The animal chosen was the New Zealand White rabbit and the mucosal site the subterminal ileum, isolated in a Thirty-Vella loop. The antigen used was parainfluenzavirus type 3, which would normally be destroyed by bile salts if ingested. Loops approximately 20 cm in length, each containing at least one Peyer's patch, were exteriorised through left paramedian stomata. Atrophic changes began to appear in the loops by 7 days, but no observable diminution in their associated lymphoid tissues was evident. The genesis of parainfluenzavirus type 3 infection in the loops was monitored by assay of sequential loop washings for infectious virus and in fluorescent antibody studies of cells from infected loop epithelia. Infectious virus was recovered for up to 13 days after inoculation and specific intracytoplasmic immunofluorescence was detected in loop epithelial cells. There was little serological evidence of systemic spread of the virus. A localised cellular immune response against parainfluenzavirus type 3 was mounted in the lymphoid tissues associated with the infected loops by day 14, but was not detected in systemic lymphoid tissues. No reactivity was detected in rabbits given inactivated virus via their loops or in those receiving infectious virus intravenously. This model appears to be capable of generating mucosal cellular responses to infection and may therefore be suitable for further studies in this field.

Animals↗
PubMed1987

An improved method for recovery of secretory immunoglobulins and lymphocytes from the nasal mucosa.

The difficulty of obtaining adequate specimens for assay has severely restricted in vivo investigations of local immune responses in humans. Washing the posterior nasopharynx for an extended period using chilled saline to stimulate serous secretions has improved yields of both secretory immunoglobulins and functionally competent immunocytes. The proportions of T- and B-cells found in such washings appear to differ from those found in blood.

Alkaline Phosphatase↗
PubMed1987

Drug effects on a novel model of connective tissue breakdown.

Production of a granulomatous tissue adjacent to cartilage implants in subcutaneous tissues of mice by prior wrapping of cartilage with cotton, induces matrix depletion and a rise in serum levels of the acute phase protein haptoglobin. The granulomatous reaction to cotton could be inhibited partially, following treatment of mice with indomethacin, dexamethasone and cyclophosphamide but only the latter two reduced cartilage matrix loss. D-penicillamine was inactive. Regarding the acute phase response, dexamethasone and D-penicillamine appeared to lower and indomethacin and cyclophosphamide to elevate, serum levels of haptoglobin, but these effects were not statistically significant.

Animals↗
PubMed1987

Cartilage damage by a granulomatous reaction in a murine species.

The encapsulation of intact rat femoral head cartilage or discs of bovine nasal cartilage with cotton-gauze before implantation in the subcutaneous tissues of mice, results in an accelerated loss of cartilage proteoglycan. Loss of proteoglycan from bovine nasal cartilage occurred later than rat femoral head cartilage, but eventually brought about complete dissolution of the cartilage. Freeze-thaw killing of bovine nasal cartilage did not alter the amount of proteoglycan lost. Destruction of both femoral and nasal cartilage was related to the mass of cotton implanted and to the growth of connective tissue within the implanted cotton. Mice previously implanted with femoral head cartilage were able to show enhanced degradation to new implants; this was even greater if the original implants were encapsulated with cotton. Presoaking of cotton-cartilage implants with the non-specific irritant, carrageenan inhibited the breakdown of cartilage. Autoradiographs of 35sulphate pulsed femoral cartilage following implantation with cotton showed reduced incorporation of radiolabel by chondrocytes.

Animals↗
PubMed1986

Antibody dependent cellular cytotoxicity against coronavirus 229E-infected cells.

An antibody dependent cellular cytotoxic (ADCC) reaction was elicited using human mixed lymphocyte cultures against coronavirus 229E-infected C-16 cells. The response was assayed in microtitre plates by radioactive chromium release. Optimal killing of target cells was achieved using cells labelled 22 h after infection. A prozone was present and the optimal dilution of sera was invariably 1:200. The majority (70%) of sera tested gave a positive ADCC response. These included all sera judged positive by ELISA, but also some which were judged negative. Two experiments using purified IgG from serum which was ADCC and ELISA positive suggested that the response is mediated by an IgG antibody and that the prozone is due to a separate serum component.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1984

A critical review of urban pediatric trauma.

Accidents are the leading single cause of childhood mortality in the United States. While prevention plays a major role in reducing morbidity and mortality, improvement in all aspects of management is a crucial goal. This study was designed to critically evaluate the prevalence and significant features of childhood injuries as experienced at Cook County Children's Hospital, including the transport system utilized. During a 2-year period (1 April 1979 to 31 March 1981) 719 pediatric patients with trauma were admitted to our institution. Forty-six per cent had lacerations, fractures, or wringer injuries serious enough to warrant hospitalization; 35% had isolated head injuries; and 10% had multiple injuries. Gunshot wounds, straddle injuries, and stab wounds formed the bulk of the rest. Forty-one patients were directly admitted to the intensive care unit with serious injuries, half of whom were transferred after initial care (or no care) from an outlying hospital with an average transport time of 4 hours. Four of the transferred patients died within 24 hours and three had serious sequelae. A review of their injuries showed that early, aggressive, and coordinated management would have significantly reduced the morbidity and mortality. There were no deaths and only one serious sequela in the patients brought directly to our institution. A detailed presentation of the direct correlation between improved survival and early initiation of specialized care to these traumatized children is discussed.

Adolescent↗
PubMed1981

The extraction of lymphoid cells from the human nasopharynx.

No criteria exist at present for judging the quality, extent, specificity, immunological memory or degree of functional autonomy of the local mucosal immune response in humans owing to difficulty in obtaining suitable specimens for assay. This paper offers a simple, practical, atraumatic technique for the extraction of viable lymphoid cells from the human nasopharyngeal mucosa together with some preliminary figures on the numbers of cells obtained and lymphocyte responses to mitogenic stimuli. The technique is based on the collection of nasal washings with chilled saline and sufficient lymphoid cells have been collected by this method to make multiple in vitro cultures. Cultures have been maintained for over 5 days and significant blastogenic responses have been recorded suggesting that the luminal cells retain some degree of functional competence.

Adult↗
PubMed1978

Flow and composition of renal hilar lymph during volume expansion and saline diuresis.

Volume expansion of 5-10% body weight in dogs was achieved by infusion of 0.9%, 1.2% or 0.4% saline. The average diuretic response for each group was 9.9 +/- 2.1, 5.5 +/- 0.6 and 3.3 +/- 0.9 (mean +/- S.E.) ml/hr/kg respectively. Flow from single hilar lymphatics increased by an average of 150%, there being no significant difference between the groups. A significant (p less than 0.02) positive correlation was found between the increase in hilar lymph flow and thoracic duct lymph flow. No correlation was found between hilar lymph flow and the extent of the diuresis. Control hilar lymph contained higher concentrations of Na+ (L/P = 1.05) and C1- (L/P = 1.12) (p less than 0.001) and lower concentrations of glucose (L/P = 0.86) (P LESS than 0.001) than did simultaneous plasma. The electrolyte lymph-to-plasma differences were maintained despite increases or decreases in plasma concentrations. The results indicate that changes in hilar lymph flow are related to volume expansion rather than to the diuresis, and that the processes responsible for lymph-to-plasma compositional differences are relatively unaffected by changes in plasma levels.

Animals↗
PubMed1977

Neuronal transport in salamander nerves and its blockade by colchicine.

Neuronal transport and the effects of colchicine on it has been studied in salamander spinal nerves. Cholinesterase (ChE) accumulation above the cut region of a nerve at 12.5 degrees C was shown to depend upon two processes. One caused a transient increase which declined to zero by 24 h; the other was explained by axoplasmic transport. At 22 degrees C the transient change was not observed, but the rate of accumulation attributable to transport increased. The Q10 for this transport over the range 12.5 degrees C--22 degrees C is approximately three. The ChE accumulation in the sensory component of the mixed nerve was about equal to that in the motor. The rate of fast axoplasmic transport of labeled leucine was 56 mm/day at 22 degrees C; if ChE moves at the same rate, then only 7% of the total enzyme is carried by fast axoplasmic transport. The transport of ChE was reduced by at least 50% when nerves were bathed in a 75 mM solution of colchicine for 30 min; this treatment is known not to cause subsequent degeneration of these nerves. The rate of slow flow of labeled material after bathing the nerve trunk in tritiated colchicine was found to be approximately 0.5 mm/day.

Animals↗
PubMed1977

Morphology of the intrarenal lymphatic system. Capsular and hilar communications.

Recent functional evidence has indicated that ureteric obstruction for three or more days in dogs causes a diversion of renal lymph from the hilar to the capsular system. The present study was concerned with the structural correlate of this functional evidence, having special reference to communications between the two systems. Within three days of ureteric occlusion the capsular lymphatic system became dilated. On histological examination two types of tributaries were found. One (termed a perforating lymphatic) served as a primary pathway for superficial cortical lymph from the subcapsular plexus, and penetrated the capsule either alone or in company with a small vein. The other (termed a communicating lymphatic) was closely associated with the occasional penetrating interlobular blood vessel which traversed the capsule to ramify in the perirenal tissue. Approximately 60% of the penetrating arteries in eight dog kidneys had associated communicating lymphatics. On the renal surface the perforating and communicating lymphatics formed the primary collecting vessels of the capsular system. Within the renal substance the communicating lymphatics were directly continuous with lymphatics which surrounded the interlobular blood vessels and which have been shown to drain into the hilar network. Thus the communicating lymphatics formed direct connections between the hilar and capsular systems. It was concluded that these communications, although dilated by hydronephrosis, existed under control conditions. Functionally they are probably of importance only under special circumstances when intrarenal lymph may be diverted from one to the other system.

Animals↗
PubMed1977

Effect of hypotonic volume expansion with water diuresis on renal lymph.

Water diuresis was induced in dogs, under chloralose anesthesia, by hypotonic volume expansion of 5 to 10% body weight. The average diuretic response was 12.5 ml/hr/kg body weight with a urine osmolality of 175 mOsm/L. Renal hilar lymph flow and thoracic duct lymph flow increased significantly by an average of 125% and 150% respectively. The Na concentration in plasma and lymph fell by approximately 7.0 mEq/L whereas that for Cl was relatively unaffected. Control lymph to plasma ratios of approximately 1.050 for Na and 1.130 for Cl were not significantly altered even when plasma concentrations fell significantly. Urea, glucose and K concentrations were little affected. The results are consistent with the hypothesis that renal hilar lymph reflects in part the composition of the outer medullary interstitium which is directly influenced by the electrolyte pump in the ascending thick limb of Henle.

Animals↗
PubMed1977

Influence of protein content upon the electrolyte composition of lymph and plasma.

The concentration of Na+ and Cl' is higher in renal hilar lymph (HL) than in arterial (P) or renal venous plasma or thoracic duct lymph (TDL). The purpose of the present study was to test the theory that this is the consequence of differences in protein content of lymph and plasma rather than a reflection of renal function. Samples of P, HL and TDL were obtained from dogs and analysed for Na+, Cl', K+ and Ca++. The samples were then centrifuged through an ultrafiltration membrane to remove the protein and reanalysed for electrolyte content. Ca++ concentrations were reduced by 30-40% in the (protein-free) filtrate. This was attributed to protein binding. Na+ and Cl' concentrations were raised minimally (2.0 mEq/L and 5.0 mEq/L respectively) in protein-free filtrate of plasma, but not in protein-free filtrate of lymph. It was concluded that the relative protein concentration in lymph and plasma are not an important influence on Na+ and Cl' concentrations.

Animals↗
PubMed1976

Studies of experimental rhinovirus type 2 infections in polar isolation and in England.

After five months of total isolation a wintering party of seventeen British Antarctic Survey (BAS) personnel was inoculated under double blind concitions with placebo, or rhinovirus type 2 which had been propagated in tissue culture. The clinical and virological responses of these subjects were compared with those of volunteers in England who received a similar dose of the same strain. The virus used was apparently partly attenuated for man; at the dosage used its effects in England were similar to a smaller dose of an unattenuated strain, but in the Antarctic it caused relatively severe infections. Both the symptoms and the laboratory evidence of virus infection appeared to be more pronounced in the BAS subjects than in the volunteers in England who received the same challenge. In the former group the infection readily spread to those who were originally given placebo. In the BAS subjects serum antibody titres were well maintained during the isolation period but a significant fall in nasal immunoglobulin concentration was recorded during the 5 months of isolation after the virus challenge. Possible mechanisms for the increased sensitivity to rhinovirus of subjects who have been totally isolated in a small closed community are discussed.

Adult↗