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Die Nutzung von W��rme aus industriellen W��rmeprozessen wurde untersucht, um diese bei Bedarf als regenerative Energiequelle f��r Nah- und Fernw��rmeanwendungen zu nutzen. Zu diesem Zweck werden die folgenden Arbeiten durchgef��hrt: - Betrachtung von verschiedensten Reaktionsformen, welche f��r die TCS in Betracht gezogen werden k��nnen. Aufgrund dieser Vorauswahl werden die geeignet erscheinenden Reaktionssysteme in Hinblick auf deren Energiedichte und Gleichgewichtstemperatur quantifiziert und bewertet. - F��r das gew��hlte thermochemische Speichermaterial werden die vielversprechendsten Reaktorkonzepte in der Software "IpsePro" modelliert. Ein besonderes Augenmerk bei der Modellierung wird auf die Modularit��t gelegt, um in sp��terer Folge die Untersuchung unterschiedlichster TCSM zu erm��glichen. Aufgrund einer Sensitivit��tsanalyse mittels "IpsePro" kann ein geeignetes Reaktorkonzept identifiziert werden. - Um eine fundierte Aussage ��ber die Einsetzbarkeit des Reaktorkonzepts t��tigen zu k��nnen wird dieses Konzept mit verschiedenen Prozesskonfigurationen kombiniert. Da die Performance einer Prozesskonfiguration in nicht unwesentlicher Weise von den Prozessparametern und den Auswirkungen dieser auf das Gesamtsystem abh��ngen wird mittels einer Sensitivit��tsanalyse eine Bewertung durchgef��hrt. Die ausgew��hlte Prozesskonfiguration wird in weiterer Folge mittels einer Energie- und Exergieanalyse n��her betrachtet, um etwaige Verbesserungspotentiale aufzuzeigen. Au��erdem wird eine Analyse der verwendbaren Tr��gergase durchgef��hrt. - Aus technischer Sicht kann durch die vorhergehenden Punkte ein geeignetes System zur TCS gefunden werden. Auf Basis dieser Analyse wird die M��glichkeit untersucht das gew��hlte Gesamtkonzept mit einer m��glichen realen Anwendung zu verkn��pfen. In Folge dessen wird auch die ��konomische Komponente miteinbezogen und es kann dadurch eine fundierte Aussage ��ber die Einsetzbarkeit der thermochemischen Energiespeicherung get��tigt werden., In the context of this dissertation the thermochemical heat storage is analyzed to store waste heat from industrial processes. At a demand of heat the stored energy is released to supply a district heating network by renewable energy. For this purpose the following works are carried out: - Consideration of different forms of reactions for the thermochemical heat storage. Through a preselection it is possible to quantify and evaluate the best reaction systems with regard to the energy density and the equilibrium temperature. - Promising concepts are modeled for the selected thermochemical heat storage material by the Software -IpsePro-. Through the modular concept of the developed models in -IpsePro- it is possible to use these models for other huge changes in the program source of the -IpsePro- models. It is possible to identify a suitable reactor concept on the basis of sensitivity analysis through "IpsePro". - For profunde knowledge over the usability of the reactor concept it is necessary to combine this concept with different process configurations. A sensitivity analysis shows the influence of the process parameters in relation to the different process configurations to the efficiency of the whole process. The selected process configuration is considered through an energy and exergy analysis to identify possible improvements. The carrier gas which is necessary for the process is separately analyzed. As a result it is possible to identify the most suitable carrier gas for the process. - The previous works in this dissertation identify a suitable system from a technical perspective for the thermochemical heat storage. Based on this analysis the opportunity is proved to connect the selected overall concept to a realistic application. The investigation over the usability of the TCS concept is expanded through an economic anaylsis to find a wellgrounded statement over the applicability of the thermochemical energy storage.

It is generally accepted that functional dyspepsia is caused by heterogeneous pathogenetic factors. From the clinical point of view acid-related symptoms as heartburn, acid regurgitation and epigastric pain (acid-type) can be separated from general dyspeptic symptoms as predominant fullness, nausea/vomiting (dysmotility-type).In the present study, the influence of a four-week-treatment with ranitidine (twice 150/d, n = 346) in comparison with an antacid (40 mmol/d, n = 340) on the severity and course of symptoms in patients suffering from an acid-related functional dyspepsia was investigated.With ranitidine, acid-related as well as general dyspeptic symptoms disappeared in a significantly higher percentage after two and four weeks compared with antacid. Complete disappearance of symptoms was documented with ranitidine after two weeks in 37% and after four weeks in 66% compared with antacid in 13% and 30% respectively (p0.005). Patients with severe symptoms, history of ulcer and long-term dyspepsia and slight endoscopic changes in the upper gastrointestinal tract showed a significant faster and more distinct response. Both kinds of treatment were well tolerated.It is concluded that in acid-related functional dyspepsia ranitidine is superior to antacid in relieving symptoms. Therefore, a probative treatment with ranitidine up to four weeks is recommended as a practical therapeutic alternative in this syndrome.

We retrospectively investigated the efficacy of high dose omeprazole compared to a combined therapy of famotidine, pirenzepine and antacid for acute upper gastrointestinal hemorrhage (AUGIH) also adjuvant to endoscopic injection therapy if indicated. The clinical course of AUGIH was evaluated, if emergency endoscopy revealed lesions substantially dependent on intragastric acidity with respect to pathogenesis and/or healing (peptic ulcer, erosive gastroduodenitis, reflux-esophagitis, Mallory-Weiss tears) and patients either received a combined therapy of famotidine (20 mg i.v. every 12 hrs), pirenzepine (10 mg i.v. every 12 hrs) and antacid (control group: n = 96) or omeprazole (40 mg i.v. every 6 hrs; omeprazole group: n = 100). Rate of rebleeding was lower in the omeprazole group without reaching significance (12 vs. 21; p = 0.06). No difference was found for rates of operation (6 vs. 6; p = 0.94), death from bleeding (5 vs. 9; p = 0.22), transfusions ([mean +/- SD] 3.3 +/- 5.0 vs. 3.2 +/- 5.7; p = 0.51) and hospitalisation ([mean +/- SD] 26.8 +/- 12.1 vs. 27.8 +/- 16.0 days; p = 0.88). Considering prognostic risk factors (ageor = 65, actively bleeding lesion, initial state of shock) logistic regression showed that high dose omeprazole inhibited rebleeding (p = 0.01) but had no effect as regards surgery or mortality. Within two selected subgroups defined by additional criteria (no endoscopic treatment and anamnestic peptic lesion) omeprazole-treated cases showed lower rates of rebleeding (3/49 vs. 12/54, p " 0.02 and 3/44 vs. 13/48, p = 0.01 resp.) and death from bleeding (0/46 vs. 6/50, p = 0.03 and 0/43 vs. 5/45, p = 0.03 resp.).(ABSTRACT TRUNCATED AT 250 WORDS)

In a 8 week double-blind randomized multicenter trial in 159 patients with benign gastric ulcer the efficacy of hydrotalcite vs. ranitidine in expediting ulcer healing and in achieving pain relief was determined. 79 patients received hydrotalcite 1000 mg q.i.d. as tablets equalling a total neutralizing capacity of 111.2 mval and 80 patients received ranitidine (300 mg at night). Endoscopically controlled healing rates after 4 weeks of therapy amounted to 41.8% with hydrotalcite and 53.8% with ranitidine. After 8 weeks both regimen showed significant equivalent healing rates (hydrotalcite: 81.0%, ranitidine: 78.8%, p0.003). Ulcer pain decreased parallel in both groups. By the end of therapy 92.4% of the patients treated with hydrotalcite and 86.3% of those receiving ranitidine were free of pain. Incidence of helicobacter pylori in antral mucosal biopsies was not influenced by both treatments. We conclude that an 8-week treatment with low dose hydrotalcite therapy is as effective as ranitidine in healing benign gastric ulcers and achieving pain relief.

We determined the capacity and the profile of prostaglandin synthesis in the antral mucosa of patients with erosive (n = 43) or non-erosive (n = 24) Type B gastritis in comparison with normal controls (n = 24). Prostaglandin synthesis was measured by the incorporation of 14C-labelled arachidonic acid into cyclooxygenase products in mucosal homogenate. There was no significant difference between controls and patients with antral gastritis. Furthermore, there was no correlation of the prostaglandin synthesis with helicobacter colonisation or with the degree of inflammation. In another group of 15 patients there was a 17% increased synthesizing capacity nearby the erosions, compared to a non-erosive area (p = 0.05). In these patients with chronic Type B gastritis the treatment with an antacid (Maalox 70, 4 x 10 ml) for 4 weeks did not affect the synthesizing capacity or the profile of mucosal prostaglandin synthesis.

Bile acids are a factor in the pathogenesis of peptic lesions of the mucosa. The introduction in the literature of the term type C gastritis reflects the recognition of this fact. It is possible that antacids develop their effect not merely via the neutralization of hydrochloric acid, but, to an appreciable extent, through the adsorption of toxic substances. Since antacids often elevate the gastric pH only slightly, we investigated bile acid binding not only as a function of dose, but also at low pH values. The aim of the study was, in a follow-on to previous studies of a layer-lattice antacid to describe the characteristics of an antacid of the mixed type (aluminium-magnesium hydroxide + smectite). Already at neutral pH, Gelofalk manifests a high level of bile acid absorption, which increases further at low pH values. The high bile acid absorption capacity of Gelofalk shows no correlation with decreasing bile acid polarity; the dose-dependency is lower at high than at low pH levels. This indicates that bile acid absorption by Gelofalk must, at least in part, involve other mechanisms than those operative in the case of pure layer-lattice antacids.

In a randomized, multicenter, double-blind study involving a total of 97 patients, the effectiveness and tolerance of Gelofalk, a new type of antacid combination comprising smectite--a natural alum earth, the specific molecular structure of which permits it to bind aggressive substances particularly well--aluminium hydroxide and magnesium hydroxide were investigated in comparison with a commercially available aluminium hydroxide antacid used by patients with gastritis, esophagitis and functional upper abdominal complaints over a treatment period of 4 weeks. The buffering capacity of a daily dose of Gelofalk was 135 mval, in the case of the reference antacid 210 mval. In terms of pain relief, reduction of accompanying symptoms, and endoscopic healing properties, Gelofalk proved very effective. Because of its particular properties, the preparation proved significantly superior to an aluminium hydroxide suspension in the case of most test parameters, in particular pain relief, onset of effect and heartburn. Gelofalk was very well tolerated; constipation or diarrhea occurred in only 2 cases each.

Acid Suppression Profile of Hydrotalcite in Man. In this randomized, double blind, placebo-controlled cross-over study, the effect of hydrotalcite (CAS 12304-65-3, Talcid), 2 tablets qid (neutralizing capacity 122 mmol) on intragastric 24-h acidity was investigated. 12 healthy male and female volunteers were administered hydrotalcite, 2 tablets qid, or placebo on 2 study days, in each case at 10, 15, 20 and 23 h. Daytime (8-22 h) and nighttime (23-7 h) intragastric H+ concentrations (mmol/l) were significantly reduced by hydrotalcite compared with placebo. The following inhibiton rates were obtained: daytime 37.4%, nighttime 31.5% (p less than 0.05). During the 2-h periods immediately after oral application of hydrotalcite or placebo inhibition rates of up to 65% were observed. These results suggest that hydrotalcite may have also antiulcer activity like other antacids which are used in the treatment of peptic ulcer disease in low daily neutralizing capacities (120-280 mmol/die).

Bile acid adsorption may be one therapeutical mechanism of antacids. Little is known about the effect of pH and amount of antacid on bile acid adsorption. Therefore we carried out the following investigations using a lattice [correction of lettuce] layer antacid as a model substance. 5 ml of "quasi-natural reflux milieu" were mixed with 0.5, 1 or 2 ml of hydrotalcite and adjusted to pH 3, 5 or 7. The highest total bile acid adsorption was found at pH 3, the degree of bile acid adsorption correlated with bile acid lipophilicity, i.e. the most lipophilic and toxic bile acids are adsorbed best. High adsorption of lipophilic and particularly toxic bile acids even at low gastric pH may help to explain the good therapeutic effect of low-dose antacids in gastric ulcer.

In this randomised double-blind cross-over study the gastroduodenal tolerability of buffered acetylsalicylic acid (ASS) (Aspalox = 325 mg ASS plus 300 mg magnesium aluminium hydroxide) daily has been compared with unbuffered ASS (325 mg) daily in 12 healthy volunteers using upper Gl-endoscopy. The treatment period lasted 14 days: endoscopic controls were performed at entry and repeated at day 14. At day 0 the mean endoscopic score averaged 0.8 +/- 0.1 in both groups (MW +/- SEM). One tablet Aspalox daily induced marked gastroduodenal damage at day 14 (6.5 +/- 1.5). The median lesion score rose from 1.0 (day 0) to 7.0 at day 14. Unbuffered ASS evoked almost identical gastroduodenal injuries at day 14 (7.5 +/- 1.8). The corresponding median values were 1.0 (day 0) and 7.0 at day 14. Our data suggest, that the amount of buffering in the Aspalox preparation is not sufficient enough to protect human gastroduodenal mucosa against low dose acetylsalicylic acid.

Report is given concerning a clinical study on 15 healthy volunteers who received 4 x 10 ml/die Maalox 70 or placebo. The influence on the serum electrolytes calcium, magnesium, aluminium, and the phosphate concentration has been determined by daily monitoring. Furthermore the renal elimination rates for calcium, magnesium, aluminium, and phosphate as well as urine pH, and osmolality have been determined. The quality of stools of the volunteers was monitored. The results were proved statistically. The study led to the following results: The drug has been tolerated subjectively. The stool quality and quantity of the subjects did not change. Magnesium- and aluminium concentration in serum shifted to higher concentrations. At the same time the renal magnesium- and aluminium excretion increased, and the phosphate elimination decreased. This shifting was within the physiological limits, so that relevant clinical side effects could not be observed. All other parameters did not change.

4 weeks treatment of healthy volunteers with Magaldrate (Al-Mg-containing antacid) is followed by an increase of basal serum gastrin, and a decrease of the antral G-cell density. Gastric acid secretion remained unchanged. In contrast, during maintenance therapy of duodenal ulcer patients with 400 mg cimetidine an increase of the postprandial gastrin output can be observed after 12 months treatment, whereas basal serum gastrin, antral G-cell density and gastric acid secretion remained unchanged. These results suggest that the effects observed during antacid treatment can not be related to an increase in gastric pH and may rather reflect a pH independent direct action of Magaldrate on the antral G-cell.

The neutralizing capacity of pentaaluminum-decamagnesiumhentriacontahydroxide-bis(sulfate)-hydrate (magaldrate, Riopan), a stable Al-Mg-hydroxide mono-substance, determined by a modification of the method described in literature, surpasses the efficacy index (mval divided by g) of various commercial antacids. These results coincide with the findings of other workers. The intragastric pH is rapidly and consistently raised to a value between 3 and 5 which is not exceeded (no acid rebound). Due to this fact, pepsin is inactivated and finally adsorbed by magaldrate. Moreover, magaldrate binds a considerable amount of substances contained in duodeno-gastric reflux, such as bile acids and lysolecithin (aggressors in case of gastritis, peptic ulcer, stress ulcer, peptic esophagitis).

Across the surface of the stomach mucosa exist large electrolytic concentration differences. While the pH value of the mucosa cells remains very constant within the range of 7.0 to 7.2, the pH value of the stomach fluctuates between 1 and 5. The differences in concentration of H-ions and other ions on both sides of the mucosa membrane result in an electrical voltage. Measurement of this voltage permits inferences to be made about the integrity of the mucosa cells. The electrical voltage and its changes can be measured and evaluated using a model developed in our institute++. Previously, there existed no studies comparing the irritation on the human stomach of solutions of Euphylline(R) and Theophylline. Now, using the ++aforementioned model, we have performed such a study by examining the gastric transmural potential difference changes in nine (9) healthy subjects receiving Euphylline(R), Theophylline, and Ethylendiamin dihydrochloride in a cross-over design. Additionally, we have attempted to clarify if it is possible to suppress the irritation caused by Theophylline with Riopan(R). The investigation led to the following results: 1) The gastric irritation caused by Euphylline(R) solution is statistically smaller than that caused by Theophylline solution; 2) The Ethylendiamin dihydrochloride solution caused a minor irritation smaller than that of Euphylline(R) solution; and 3) A pretreatment with Riopan(R) reduced the irritation of the Theophylline solution.

Across the surface of the stomach mucosa exist large electrolytic concentration differences. While the pH value of the mucosa cells remains very constant within the range of 7.0 to 7.2, the pH value of the stomach fluctuates between 1 and 5. The differences in concentration of H-ions and other ions on both sides of the mucosa membrane result in an electrical voltage. Measurement of this voltage permits inferences to be made about the integrity of the mucosa cells. The electrical voltage and its changes can be measured and evaluated using a model developed in our Institut. Previously, there existed no studies comparing the irritation on the human stomach of solutions of Euphyllin and Theophylline. Now, using the forementioned model, we have performed such a study by examining the gastric transmural potential difference changes in nine (9) healthy subjects receiving Euphylline, Theophylline, and Ethylendiamin dihydrochloride in a cross-over design. Additionally, we have attempted to clarify if it is possible to suppress the irritation caused by Theophylline with Riopan. The investigation led to the following results: 1) The gastric irritation caused by Euphylline solution is statistically smaller than that caused by Theophylline solution. 2) The Ethylendiamin-dihydrochloride solution caused a minor irritation smaller than that of the Euphylline solution. 3) A pretreatment with Riopan reduced the irritation of the Theophylline solution.

Antacids are relative simply assembled salts and salt-like compounds which neutralize acids. This neutralization reactions lead to several products (other salts, water, and possibly carbondioxid), resulting in steps, like hydrolysis and precipitations of insoluble compounds. When antacids containing aluminum are neutralized in the presence of organic acids, peptones, and polypeptides, there is a marked loss in their neutralizing capacity and neutralization rate.

Side effects of antacid therapy are dose dependant and compound related. High dose antacid intake may lead to fluid retention in the body depending on the sodium content of the different antacid preparations. Sodium bicarbonate ingestion provokes metabolic alkalosis and alkaliuria, the "nonsystemic calcium and magnesium containing antacids" cause these changes too, but to a lower degree. Urinary pH elevation favours the precipitation of calcium and magnesium salts, predisposing to renal stone formation. In patients with renal insufficiency the calcium and magnesium absorption may lead rapidly to toxic serum concentrations. Calcium and magnesium containing acids may provoke an acid rebound, which is clinically not relevant following magnesium-hydroxide-ingestion. Phosphorus depletion is an important side effect of aluminum hydroxide intake. The phosphorus depletion syndrome combined with skeletal demineralisation and osteomalacia may occur. As well as calcium and magnesium cations the tribasic aluminum will be absorbed from the gut in small amounts. In patients with renal insufficiency aluminum deposition in the brain grey matter following Al(OH)3 ingestion will occur and seems to be a co-factor for the development of a dialysis encephalopathy syndrome. The clinical relevance of aluminum absorption from gut in patients with normal renal function is unknown until now.

Aluminum toxicity is becoming more and more evident as a complication of maintenance dialysis treatment. The aluminum contamination of the dialysate bath solution no longer plays an important role. The main source of aluminum overloading turns out to be the ingestion of aluminum-containing antacids as phosphate binders in the impaired renal aluminum excretion. In 19 dialysis patients an antacid poor in aluminum (Magaldrate) was compared with one rich in aluminum (compound M 70). The serum concentrations of aluminum, magnesium, phosphorus and calcium were investigated over a period of 14 days. After M 70 the aluminum and magnesium levels were markedly more elevated than after Magaldrate. Calcium remained unchanged with both compounds. Phosphorus was diminished only by M 70. The results of this short term study on dialysis patients are also important for patients with normal renal function, in particular in cases of uncontrolled long term treatment with antacids rich in aluminum.

In ten patients in heart failure for which they were on long-term administration of digitoxin, the influence of aluminium-magnesium hydroxide gel (Maaloxan) on steady-state digitoxin plasma concentration and renal glycoside excretion was studied. Compared with control values before antacid medication (13.6 +/- 4.4 ng/ml), the administration of 20 ml aluminium-magnesium hydroxide gel three or four times daily for several weeks caused no significant change in digitoxin plasma levels (15.1 +/- 4.9 ng/ml). Daily renal glycoside excretion, as a further measure of bioavailability of digitoxin, was also unchanged by the antacid. Therapeutic plasma concentrations of digitoxin are not influenced by antacids which contain aluminium-magnesium hydroxide, at least not if the antacid is taken 1-2 hours after the digitoxin dose.

The direct correlation between the dosage of magnesium in antacids and the appearance of partly massive diarrheas in ulcus-patients known from literature could be confirmed. The clinically relevant dosage of antacids of 420 mval NK/day, divided in six individual dosages, resulted in diarrheas from the second to fourth day in 32 percent of the test persons when antacid A with a high content of magnesium was administered. There was no hint for a constipating effect of Solugastril gel at these high dosages (= 12 individual doses). Indeed the application of an Al-Ca-antacid may result in a slight fecal impaction, however, at the same time also to an increase of stool frequency, which is similar to that obtained with antacid B having a lower content of magnesium. The antacid can be regarded as neutral concerning stool frequency and consistency in the majority of test persons. From all four tested antacids the triple-combination (Al, Mg, Ca), showed the least important deviations from the preceding norms concerning stool frequency and consistency. The triple-combination shows an absolutely neutral stool behaviour. Serum electrolytes remained in the normal range with the Al-Ca- and the Al-Mg-Ca-antacid; whereas after application of antacid. A with high magnesium content, important increases of magnesium could be observed after seven days already, which were also dealt with in the literature.

In the last years the importance of the evaluation of antacid compounds according to their neutralizing capacity decreased. Clinical investigations have shown that antacid mixtures of aluminum-magnesium hydroxide healed gastric an duodenal ulcers (neutralizing capacity 100-150 mmol/day) as well as H2 receptor antagonists and better than a placebo. By this the necessary daily dosage could be reduced essentially. This paper presents studies showing that lattice like structured antacids (e.g. Magaldrate) healed gastric and duodenal ulcers (neutralizing capacity 100-350 mmol/day) as well as Ranitidine (150 mg b.d.). Maintenance therapy should be evaluated critically because sufficient data are not available and mineral metabolism is changed significantly by extremely small dosages of aluminium-magnesium hydroxide antacids even in patients with normal kidney function.

Observations made during intragastric titration studies performed with antacids that have an identical neutralizing capacity but differ in their chemical compositions suggested that aluminum hydroxide loses a large portion of its neutralizing capacity when applied postprandially. To further elucidate the mechanism involved in-vitro studies were performed whereby the reactivity of magnesium hydroxide, aluminum hydroxide, and calcium carbonate was estimated either in aliquots of 10 ml of water or 10 ml of 5% oxo solution. The effectively available neutralizing capacity of the respective antacids was measured for the pH range of 1 to 5. The results revealed that magnesium hydroxide as well as calcium carbonate can fully react with acid whereby their theoretically available neutralizing capacity is fully available for the pH of 1 to 4.5, this in water as well as in 5% oxo solution. In contrast, aluminum hydroxide loses a large proportion of the theoretically available neutralizing capacity already in water but especially in oxo solution in a pH dependent manner. The loss far exceeds that calculated when one takes into account the pKa dependent hydrolysis of aluminum hydroxide. This loss of reactivity increased from 20% at pH 1 in a near linear fashion up to above 80% at pH 3.5. A food induced decrease of aluminum hydroxide solubility as well as stabilisation of the macromolecular aluminum hydroxide complexes through anions and organic acids are likely to be responsible for this loss of reactivity.

The usefulness of antacids in peptic ulcer disease is based on their ability to neutralize secreted gastric acid and to inhibit pepsin activity. The neutralizing capacity (expressed as mval of neutralized hydrochloric acid at a given pH) of different antacids depends upon their chemical composition. To achieve adequate neutralization of stimulated gastric acid secretion antacids have to be taken one and three hours after a meal in a dosage neutralizing 40-80 mval of acid. So far antacids have not been shown to be more effective in relieving ulcer symptoms than placebo. On the contrary an adequate antacid regimen will promote the healing of both gastric and duodenal ulcers in outpatients. Furthermore antacid prophylaxis will reduce the occurrence of acute gastrointestinal bleeding in critically ill patients.

A decreased PG E2 content in gastric mucosa of humans receiving a longterm antirheumatic therapy has been reported to be partially reversed after a one week treatment with an antacid (Reimann et al., Fortschr Med 102 [1984], 25-26). Therefore the effect of an Aspirin treatment of healthy volunteers with or without an antacid on the prostaglandin synthesis in gastric or duodenal mucosa was investigated. 14C-labelled arachidonic acid was used as substrate during in vitro incubation of the mucosal homogenate for determination of the endogenous formation of prostaglandins. Aspirin suppressed the total prostaglandin synthesis to less than 10% of control after one week treatment. The addition of a high dose antacid did not influence this inhibition, and no significant effect on the prostaglandin profile was detectable. It is concluded that antacids do not influence the suppression of the endogenous prostaglandin synthesis by NOSAC's, however another effect, eg a prolonged stability of PG E2 in a less acidic environment is more likely.

After reviewing the hypotheses about the pathogenesis of asbestos-induced malignant tumours we report about experimental data on animals. A high incidence of tumours (most of them mesotheliomas) was induced in rats by intraperitoneal injection of fibrous dusts (chrysotile, palygorscite, crocidolite, glass fibres, nemalite). Treatment with 8 types of granular dusts led though applicating a high dosage (50--100 mg) to neoplasms in only a small percentage of animals. After intraperitoneal application of 2 mg of chrysotile, crocidolite or glass fibres a tumour incidence in a range from 16% to 38% was observed and fibrous reaction was slight. 100 mg of milled chrysotile with relative short fibres (99.8% less than 5 mum, 99.5% less than 3 mum) caused no asbestosis, nevertheless tumours developed in 32% of the rats. Intraperitoneal injection of fibrous dusts also induced mesotheliomas in mice, however not in Syrian hamsters and guinea pigs. Our results point out that the fibrous shape of asbestos dust causes its carcinogenic effect and that furthermore other fibrous dusts can also lead to tumours. Prerequisites are an adequate measure of the fibres and their constancy in the tissue. For these two parameters no exact dates exist. It is estimated that a fibre with a diameter less than 1 mum and a length less than 3 mum exert a cancerogenic effect. Furthermore, a sequence of other factors has an importance for the dose-effect relationship of fibrous dusts. Material of the fibres plays a role in so far it defines the effect producing amount of fibres. The relevance of the results of animal experiments to man is discussed especially with regard to the cancerogenic effect of glass fibres.

A double blind placebo controlled trial was conducted to compare the effect of two antacid brands (liquid and tablet form) on fasting and postprandial intragastric pH. In 9 healthy volunteers intragastric pH was continuously recorded by solid state memory on 6 occasions. 40 mmol of each antacid was given one hour before and after a standardized meal. The time during which pH was below 3.5 during the first hour following each medication was, in the fasting state, 56.7 +/- 2.1 min. with placebo tablets, 30.7 +/- 8.0 min. (p 0.05) with magaldrate tablets, 26.6 +/- 8.0 min. (p less than 0.01) with Al-Mg-hydroxide tablets, 46.1 +/- 6.1 min. with placebo liquid, 18.4 +/- 5.2 min. (p less than 0.01) with magaldrate liquid, and 21.5 +/- 6.2 min. (p less than 0.01) with Al-Mg-hydroxide liquid. Postprandially the respective periods of time were 48.3 +/- 4.9 min. with placebo tablets, 45.4 +/- 4.6 min. (n.s.) with magaldrate tablets, 48.9 +/- 5.6 min. (n.s.) with Al-Mg-hydroxide tablets, 46.7 +/- 7.9 min. with placebo liquid, 26.6 +/- 9.3 min. (p less than 0.05) with magaldrate liquid, and 28.0 +/- 7.1 min. (p less than 0.05) with Al-Mg-hydroxide liquid. Both tested brands were equally effective. With regard to pH activity, both tested forms were more effective in fasting state than postprandially; tablets showed no measureable activity postprandially and were less effective than the liquid form. The usefulness of the usual medication of low-dosed antacids, one hour postprandially, is open to doubt.

In a multi-centre double-blind (double-dummy) trial the effectiveness of low-dose antacid gel (6 X 12 ml/d; neutralisation capacity 120 mmol) was compared with that of a standard dose of cimetidine (1 g/d) in the curative treatment of gastric ulcer. Antacid gel was given to 65 patients, cimetidine to 60. Diagnosis was confirmed by endoscopic biopsy, which was also employed in a serial follow-up. After 4 weeks antacid gel and cimetidine produced cures in 43% and 52%, respectively; after 8 weeks 76% and 89%, respectively, the difference between the two methods not being statistically significant. There was also no statistically significant difference with regard to ulcer pain. In one case each in the antacid and cimetidine groups, the treatment had to be stopped because of side effects. Diarrhoea was more common on cimetidine than on antacid gel. It is concluded that both low-dose antacids gels and cimetidine are suitable in the treatment of gastric ulcers.

Gastric acid secretion and gastric emptying rate was measured using double marker method and continuous titration of a liquid peptone test meal. Titration rate was significantly reduced by 30 ml of an aluminiumhydroxide- and magnesiumhydroxide containing antacid compound (Maalox). Acidity of gastric contents was reduced over a period of 48.4 +/- 9.1 min (mean +/- SD; endpoint of titration pH 5.5) and 77.6 +/- 2.0 min (pH 3.5) (p less than 0.05). The histamine H2-receptor blocker Ranitidine (0.25 mg/kg b.w.) and the antimuscarinic agent Pirenzepine reduced titrable gastric acid secretion in a similar range, as far as the observation period of 90 min is concerned. Biosorbin MCT, a formula diet, stimulated gastric acid secretion half the amount of gastric acid secretion stimulated by the peptone meal. Gastric emptying rate was significantly reduced by formula diet, but not by either of the other compounds.

The effect of the antacid magaldrate on intragastric pH behaviour was investigated in 9 medical intensive care patients. During the 24-hour test period 10 ml of this complex preparation induced pH increases to values between 6 and 7 when it was administered every two hours. However, three-hourly administration of 15 ml magaldrate did not result in a sufficient intragastric pH increase. Thus relatively small volumes of magaldrate are sufficient to neutralize gastric acid of these intensive care patients effectively.