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Biomedical subjects

L Thomsen

Publications and source records attributed to L Thomsen.

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

Bile acids of marsupials. 2. Hepatic formation of vulpecholic acid (1 alpha,3 alpha,7 alpha-trihydroxy-5 beta-cholan-24-oic acid) from chenodeoxycholic acid in a marsupial, Trichosurus vulpecula (Lesson).

Free vulpecholic acid (1 alpha,3 alpha,7 alpha-trihydroxy-5 beta-cholan-24-oic) is the major biliary component of the Australian opossum (Trichosurus vulpecula), accompanied only by a few percent of its taurine conjugate. In order to exclude a microbial involvement in its formation (i.e., secondary origin) four sets of experiments were performed. It was found that a) the level of vulpecholic acid remained unchanged in the bile of opossums fed with neomycin and kanamycin for 7 days prior to bile collection; b) it also remained unchanged after long bile drainage; c) in opossums prepared with biliary cannula, intraportally injected [24-14C]chenodeoxycholic acid was transformed to [24-14C]vulpecholic acid; and d) in a similar experiment, the detectable transformation of [1 alpha,2 alpha-3H2]cholesterol to vulpecholic acid was observed. In experiment c) 28-66% of the administered radioactivity was secreted in 2 h in the form of free biliary vulpecholic and chenodeoxycholic acids. Only a trace amount of the corresponding taurine conjugates (approximately 0.4%) was formed. Moreover, rapidly declining specific radioactivity of the unconjugated chenodeoxycholic acid indicated its probable participation in the native formation of vulpecholic acid.

Animals↗
PubMed1990

The Na+/H+ exchange and H+ diffusion properties of human postmortem mucus: a comparison of gastric antral, gastric body, jejunal and ileal mucus.

The stomach and small intestine are areas of major electrolyte and solute transport. Mechanisms of transport in these areas have been widely studied and basic understanding is available. However, the mucus that lines the stomach and intestine is an important layer whose properties and functions in electrolyte and solute transport are not well understood. In this study we examined the Na+/H+ exchange of mucus from the stomach body and antrum, the jejunum, and the ileum. Mucus from the stomach body and antrum is a cation exchanger, a property that aids the net unidirectional flux of H+ ions from parietal cells to lumen. In the jejunum and ileum, mucus is an anion exchanger, which may be important in solute transport and absorption in the small bowel. In both the stomach and small bowel, proton movement is slow, which helps maintain the uphill pH gradient across gastric mucus and the downhill pH gradient across small intestinal mucus.

Anion Exchange Resins↗
PubMed1990

Tightly spiral shaped bacteria in the human stomach: another cause of active chronic gastritis?

Tightly spiral shaped Gram negative bacteria were seen in the gastric biopsies obtained from two patients undergoing gastroscopy. Active chronic gastritis was present in both patients and one patient also had gastric ulceration. Attempts to culture the organism by a number of methods were unsuccessful but positive urease results were obtained in both patients. Both patients were treated with colloidal bismuth subcitrate. Biopsies taken after treatment showed resolution of infection and histological gastritis. These results suggest that Helicobacter pylori is not the only organism associated with chronic active gastritis in man.

Adult↗
PubMed1989

Sucralfate interactions with gastric mucus.

Sucralfate protects the stomach against a number of experimental damaging agents and is efficacious in the treatment of peptic ulcer disease. It binds with acidity to the base of an ulcer to form a protective barrier. Sucralfate also enhances prostaglandin synthesis and release in the mucosa. In this study, the rat stomach was examined to determine sucralfate's interaction with gastric mucus. Mucus in the rat stomach forms a distinct and continuous blanket. In snap-frozen samples, pretreatment with phosphate-buffered saline as a control shows a layer of mucus of homogeneous structure thinner than the homogeneous layer after pretreatment with antibodies developed against rat gastric mucus. Pretreatment with the surface protective agent sucralfate shows some increase in the thickness of mucus with a thin dense sublayer adjacent to the epithelium and a less dense-appearing outer zone of variable thickness. Analysis of x-rays generated by the electron beam on windows of mucus and epithelium showed the expected gradients of sodium, potassium, chloride, and sulfur. The percentage of aluminum and sulfur in the mucus was higher in sucralfate-treated samples than in controls. Interaction between sucralfate and gastric mucus needs further investigation.

Animals↗
PubMed1989

Na+/H+ ion-exchange property of postmortem human gastric mucus. The effects of Campylobacter pylori infection and sucralfate.

The effect of Campylobacter pylori infection and sucralfate treatment on the ion-exchange property of human gastric mucus from 17 human postmortem stomachs was investigated in an in vitro chamber. Of the 10 stomachs not infected with C. pylori mucus from 4 stomachs had a 'normal' Na+/H+ exchange capacity, whereas 6 were without a Na+/H+ exchange capacity. The Na+/H+ exchange capacity of the seven stomachs infected with C. pylori was half that of the four 'normal' uninfected stomachs. Sucralfate significantly improved the Na+/H+ exchange capacity of mucus from C. pylori-infected stomachs and from the uninfected stomachs without Na+/H+ exchange. This study shows that impairment of the Na+/H+ exchange capacity of gastric mucus is associated with C. pylori infection and that sucralfate improves the Na+/H+ exchange capacity of gastric mucus.

Aged↗
PubMed1989

Ammonia produced by Campylobacter pylori neutralizes H+ moving through gastric mucus.

We aimed to show that Campylobacter pylori infection increases the concentration of ammonia in the gastric mucus and alters the movement of H+ through the mucus. Mucus from uninfected and C. pylori-infected stomachs was collected at postmortem. Ammonia was measured enzymatically. The ammonia concentration in C. pylori-infected mucus was fourfold greater than in uninfected mucus. H+ movement experiments were carried out using an in vitro chamber, in which a layer of mucus separated a 0.1 M HCl solution from distilled H2O. The change in pH of the distilled H2O was measured over 30 min. A drop in pH was measured for uninfected mucus. A slight rise in pH was measured for C. pylori-infected mucus. We conclude that C. pylori infection is associated with reduced H+ movement through mucus and that this may be due to increased ammonia concentration within mucus.

Ammonia↗
PubMed1988

Distribution of Campylobacter pylori in the human stomach obtained at postmortem.

The distribution of Campylobacter pylori, its prevalence, and its relationship to gastritis and urease activity have been studied in 54 postmortem stomachs. Infection was confirmed by finding C. pylori in a Gram-stained smear of gastric mucus harvested from the entire stomach. Eight tissue specimens were obtained from predetermined sites from each stomach and examined for histologic gastritis and urease activity. Thirty-seven per cent of stomachs were infected, and of these 80% had widespread histologic gastritis. The detection of urease activity provided information on the distribution of the organism and had a high correlation with histologic gastritis. The organism is capable of infecting any area of the stomach. Infection is common and is more prevalent in Polynesian subjects (60%) than in Caucasians (19%).

Adolescent↗
PubMed1988

Na+/H+ ion-exchange property of postmortem human gastric mucus.

The Na+/H+ ion-exchange property of human gastric mucus and its relationship to age has been studied. Mucus was collected from 40 postmortem human stomachs (age range, 21-83 years) within 24 h of traumatic death. Twenty-one stomachs (age range, 21-76 years) were free of Campylobacter pylori infection and histologic gastritis. Mucus from these stomachs was consistently a cation exchanger at pH 6 in an in vitro system. The cation-exchange capacity of mucus from seven stomachs within the age range 55-70 years was 50% less than the cation-exchange capacity of mucus from eight stomachs within the age range 20-35 years. This study shows that human gastric mucus at pH 6 is a cation exchanger and that the ion-exchange capacity decreases with age.

Adult↗
PubMed1987

Cerebral blood flow and metabolism during controlled hypotension with sodium-nitroprusside and general anaesthesia for total hip replacement a.m. Charnley.

Cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) were studied during hypotension induced with sodium nitroprusside (SNP) in 10 patients undergoing total hip replacement a.m. Charnley. Cerebral blood flow was measured using an injection of xenon-133 into an arm vein. The decay curve was detected by five scintillation counters placed over each hemisphere and analysed with the Novo 10a cerebrograph. Blood samples were drawn from the radial artery and the jugular venous bulb to calculate the CMRO2. In the group as a whole, there were significant decreases in mean arterial pressure and in cerebrovascular resistance. There were no significant changes, in either CBF or CMRO2 in the group as a whole, but there were substantial individual differences. In conclusion, the use of SNP-induced hypotension for extracranial surgery should be used only in patients monitored closely.

Aged↗
PubMed1987

Mucosal defences and gastroduodenal disease.

Peptic ulcer disease occurs when there is an imbalance between aggressive factors and mucosal resistance. Mucus plays a key role in mucosal resistance. The mucus layer is relatively resistant to peptic digestion, it provides a layer through which there is a movement of hydrogen ions from the parietal cell to the lumen but a resistance to back-diffusion of hydrogen ions in the opposite direction. It maintains a pH gradient by 'sequestering' secreted bicarbonate and by its resistance to H+ back-diffusion. Colloidal bismuth subcitrate (De-Nol) binds to mucus to stabilize the mucous layer and increase the resistance to back-diffusion of hydrogen ions without significantly modifying the ion-exchange properties of mucus.

Adult↗
PubMed1985

Activity of mono- and biarticular leg muscles during sprint running.

A cinematographic recording of the movements of the lower limbs together with simultaneous emg tracings from nine lower limb muscles were obtained from two male track sprinters during three phases of a 100 m sprint run. The extensor muscles of the hip joint were found to be the primary movers by acceleration of the body's center of gravity (C.G.) during the ground phase of the running cycle. The extensors of the knee joint were also important in this, but to a minor extent, while the plantar flexors of the ankle joint showed the least contribution. The biarticular muscles functioned in a way different from the monoarticular muscles in the sense that they perform eccentric work during the flight and recovery phases and concentric work during the whole ground phase (support), whereas the monoarticular muscles are restricted first to eccentric work and then to concentric work during the ground phase. Furthermore, the biarticular muscles show variation (and rate of variation) in muscle length to a larger extent than the monoarticular muscles. Paradoxical muscle actions appear to take place around the knee joint, where the hamstring muscles, m. gastrocnemius, m. vastus laterialis and m. vastus medialis act as synergists by extending the knee joint during the last part of the ground phase.

Ankle↗
PubMed1985

Inactivation of interferon by serum and synovial fluids.

The stability of interferons-alpha, -beta, and -gamma (IFN) in serum and synovial fluids were compared. Interferon-beta was the least stable interferon species, losing at least 75% of its activity during incubation in samples of both serum and synovial fluid. Interferon-alpha was the most stable IFN, but interferon-gamma under these conditions approached the stability of the alpha species. The inactivation of IFN-beta was found due to dialyzable factors and hence not classical antibodies.

Arthritis, Rheumatoid↗