Synthesis of FF-MAS from lithocholic acid.

An effective synthesis of 4,4 dimethyl-cholest-8,14,24-trien-3beta-ol (FF-MAS) from lithocholic acid is described, utilising a double oxidation and regioselective Wittig reaction as key steps.

Structural evidence for counter-current flow in proximal tubules versus pertitubular capillaries in the rat kidney. Evaluation of the counter-current mechanism between the proximal convoluted tubules and the peritubular capillaries in the rat nephron.

BACKGROUND: In spite of the very high exchange of water and solutes between the proximal tubules and the peritubular capillaries, very little is known about flow directions in these two interrelated structures. We therefore developed a morphological technique suitable for the quantitative evaluation of a counter-current system between the proximal convoluted tubules and the peritubular capillaries in rat renal cortex. METHODS: In male pentothal-anesthetized Wistar rats (body weight 200-250 g), India ink was injected into the aorta above the renal arteries, followed by instant freezing of the right kidney in isopentane at -165 degrees C, and subsequent freeze-substitution in alcohol. In microscopic slides from kidneys in which only 20-55% of the cortical peritubular capillary loops was filled with ink--representing the arterial end of the capillaries--and in which the proximal tubular segmentation could be identified in PAS-stained sections, the segments of the convoluted proximal tubules were quantitatively compared with regard to the presence of ink-stained and unstained peritubular capillaries in nephrons from the whole renal cortex. RESULTS: In the microscopic specimens of the five animals used both the loops from the first segment (P1) of the proximal convoluted tubule and those of the second segment (P2) were systematically packed closely together, the transitional segment (P1-2) being interposed between the groups. Around the loops of P1, 8%+/-2% of the capillaries was stained with India ink. In contrast, surrounding the P2 loops 67%+/-5% of the capillaries contained ink, significantly exceeding that for P1 (p<0.01). CONCLUSION: Throughout the rat renal cortex, the most proximal fraction of the peritubular capillaries surrounds the second segments of the proximal convoluted tubules, while the first tubular segments are surrounded by the more distal fraction of the peritubular capillaries. Consequently, the flows in the peritubular capillaries and in the proximal convoluted tubules in the rat renal cortex are systematically arranged as a counter-current system. This feature was previously identified only in superficial nephrons.

Meiosis-activating sterol promotes resumption of meiosis in mouse oocytes cultured in vitro in contrast to related oxysterols.

The sterol 4,4-dimethyl-5alpha-cholesta-8,14,24-trien-3beta-ol (FF-MAS [follicular-fluid meiosis-activating sterol]) from human follicular fluid has recently been identified as a compound that induces the resumption of meiosis. FF-MAS and various oxysterols have been reported to transactivate the orphan receptor LXRalpha. The objective was to determine the biological activity of synthetic FF-MAS on the resumption of meiosis and final maturation of mouse oocytes in vitro. In order to evaluate whether LXRalpha might mediate FF-MAS action on the oocyte, we compared the capability of various compounds to activate LXRalpha-dependent transcription and to induce resumption of meiosis in the oocyte assay. Ovaries were isolated from immature mice primed with FSH 48 h before collection. Naked oocytes (NkO) and cumulus enclosed oocytes (CEO) were isolated from follicles. The oocytes were cultured in two groups, NkO and CEO, respectively, in media containing either 3 mM hypoxanthine, 5 microM IBMX, or 0.100 mM dbcAMP to maintain the oocytes in the germinal vesicle stage. The resumption of meiosis was assessed by the frequency of germinal vesicle breakdown (GVBD) after 24 h of in vitro culture. FF-MAS overcame the meiotic inhibition by hypoxanthine in both the NkO group and CEO group in a dose-dependent manner within the concentration range 0.07-7 microM. FF-MAS displayed similar potency in all inhibitory agents used. Also, FF-MAS significantly increased the formation of polar bodies in both the CEO and NkO group. The oxysterols 22(R)-hydroxycholesterol (a potent ligand for the LXRalpha receptor), 16-hydroxycholesterol, 25-hydroxycholesterol, and 27-hydroxycholesterol, as well as cholesterol, were tested without any significant effect on maturation compared to that of controls. Oxysterols and FF-MAS were observed to activate LXRalpha. In conclusion, the results reported here clearly demonstrate that synthetic FF-MAS exclusively is capable of mediating resumption of meiosis in vitro in both NkO and CEO irrespective of the inhibitory substance used. In contrast, the oxysterols and cholesterol had no significant biological activity on this oocyte function, and consequently we found no correlation between LXRalpha activation and meiosis stimulation.

Effects of bromohomoibotenate on metabotropic glutamate receptors.

(S)-Bromohomoibotenic acid [(S)-BrHIbo] stereoselectively antagonized glutamate-stimulated phosphoinositide (PI) hydrolysis in baby hamster kidney (BHK) cells expressing mGluR1a in a competitive manner with an IC50 of 250 microM. However, (S)-BrHIbo did not inhibit (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid [(1S,3R)-ACPD]-induced PI hydrolysis in rat hippocampal slices (S)- or (R)-BrHIbo did not show any effects on forskolin-stimulated cAMP-formation in BHK cells expressing mGluR2 or mGluR4 but did displace [3H]2-amino-4-phosphonobutyrate ([3H]AP4) binding from rat corticalmembranes with high affinities (IC50 = 1.0 microM and 1.1 microM, respectively). These data suggest that (S)-BrHIbo may interest with multiple PI-coupled glutamate receptors, however, at concentrations that are several fold higher than for displacement of [3H]AP4 binding from rat cortical membranes.

Superiority of sandwich ELISA over competitive RIA for the estimation of ANP-270, an analogue of human atrial natriuretic factor.

ANP-270 is a 26 amino acid analogue of naturally occurring atrial natriuretic factor (ANF) which it was anticipated would be of value for the treatment of congestive heart failure and acute renal failure. Two sensitive assays--a radioimmunoassay (RIA) and a sandwich enzyme linked immunosorbent assay (ELISA)--were developed and validated for use in clinical investigations. The RIA utilized a single C terminal monoclonal antibody whereas two monoclonal antibodies directed against different epitopes were used for the ELISA. The two assays were comparable with respect to sensitivity and precision, but assay results obtained on samples from normal volunteers dosed intravenously with ANP-270 differed widely. Thus, in one volunteer the elimination half-life was estimated to be 123 min using RIA results but 6 min using the ELISA results. By reversed phase liquid chromatographic fractionation of plasma extracts followed by RIA and ELISA, these discrepancies were shown to be due to fragments of ANP-270 cross-reacting in the RIA but not in the ELISA. Consequently, the sandwich ELISA was the method of choice for estimating this compound in plasma.

Histamine-induced bronchoconstriction in conscious guinea pigs measured by strain-gauge transduction. A new method.

A new objective method for measuring histaminedihydrochloride-induced bronchoconstriction in conscious guinea pigs has been developed. The aim of the present work was to investigate whether identical results could be obtained when the clinical observation of conscious guinea pigs with symptoms of respiratory distress (bronchoconstriction) was compared to an objective measuring technique of this parameter. An evaluation of the repeatability of the method was made and the respiration frequence (fR) and histaminedihydrochloride challenge concentration were compared to see whether there was a correlation between the two. Consequently, an apparatus was built that allowed simultaneous recording of breathing pattern and clinical observation of the animal being challenged. The breathing pattern was recorded by a strain-gauge transducer, connected to a measuring bridge, and the curves obtained on a jet ink x-y writer were used for calculating changes in duration of expiratory phase (Te) and fR. During the attacks of histaminedihydrochloride-induced bronchoconstriction a significantly prolonged Te could be calculated from the respiration curves. A high degree of agreement was found between this objective measure and clinically observed respiratory distress. The repeatability of the method was comparable to that of corresponding methods used for histaminedihydrochloride challenge in man. No obvious correlation was found between changes in fR and histaminedihydrochloride challenge concentration.

Fine structure of neutrophils from turpentine-induced pleuritis in mice, simulating rheumatoid arthritis cells.

Pleural effusions were made by intrapleural turpentine installation in mice. The fine structure of inflammatory cells from the effusions was normal except for lipid inclusions. The same type of inclusion was previously found in neutrophils from pleural effusions in patients with tuberculous infection, rheumatoid disease, or carcinomatosis. The lipid inclusions observed in neutrophils from an irritative turpentine-induced pleurisy should be considered as "fatty change", and are structurally similar to the rheumatoid arthritis cells seen in patients with different diseases.

Carbamate ester prodrugs of dopaminergic compounds: synthesis, stability, and bioconversion.

Various carbamic acid esters (CAE) of a new class of dopaminergic drugs, 5-substituted 8-chloro-7-hydroxy-3-methyl-2,3,4,5- tetrahydro-1 H-3-benzazepines, were synthesized and evaluated as prodrug forms with the aim of protecting the parent phenols against first-pass metabolism following oral administration. Monosubstituted CAE were found to be highly unstable at pH 7.4 and 37 degrees C, the half-lives of hydrolysis being between 4 and 40 min. Plasma from various species catalyzed the hydrolysis of the carbamates. N,N-Disubstituted carbamates, on the other hand, were stable both in buffer and plasma solutions. They showed a very potent inhibition of butyrylcholinesterase (EC 3.1.1.8), but were less potent inhibitors of the specific erythrocyte acetylcholinesterase (EC 3.1.1.17). In vitro incubations of an N,N-dimethylsubstituted carbamate ester (10) with liver microsomes from mouse and rat showed an appreciable formation of the parent phenolic compound. This bioconversion is suggested to occur via an initial cytochrome P-450-catalyzed hydroxylation to give an N-hydroxymethyl derivative which spontaneously decomposes to the N-monomethylcarbamate. It is concluded that N,N-disubstituted carbamate esters may be potentially useful prodrugs for the 7-hydroxy-3-benzazepines, whereas N-monosubstituted carbamates appear to be too chemically and enzymatically labile.

Turpentine- and fibrin-induced pleuritis in nude mice. Histopathological, cellular and biochemical changes.

Turpentine was injected into the right pleural cavity of nude immune-incompetent mice, causing a temporary irritative exudative pleuritis. A transient occurrence of so-called rheumatoid arthritis cells was observed in the pleural fluid together with parallel characteristic biochemical changes. In similar experiments in nude mice, however, immunization followed by intrapleural application of bovine fibrin showed irritative "dry" pleuritis without the presence of rheumatoid arthritis cells. This is in contrast with previous results from similar experiments done using normal mice. The conclusion from the present experiments is that in nude immune-incompetent mice only the non-immunological, turpentine-induced pleuritis will generate cellular and biochemical changes typical of the rheumatoid disease in patients, while the fibrin-induced pleuritis fails to show similar changes. This suggests that the rheumatoid-like pleural changes described in the present experiments in nude mice have a non-immunological basis.

Rheumatoid arthritis cells and biochemical changes in turpentine-induced pleuritis in rabbits.

When turpentine was instilled into the right pleural cavity in rabbits a pleural effusion developed in half of the animals, with a low pH, low glucose concentration, high lactic dehydrogenase activity and the constant presence of rheumatoid arthritis cells in the affected pleural cavity. The biochemical values in the pleural fluid were significantly different from the values for normal pleural fluid obtained by a special microtechnique. These changes resulting from the experimentally induced, simple, irritative turpentine pleuritis are similar to the findings in the pleural effusion in human rheumatoid pleuritis; this implies that such changes are probably non-specific and without evidence of an immunological background.

Rheumatoid arthritis cells in experimental pleuritis in mice.

In mice immunized with bovine fibrin, the same antigen was applied to the pleural cavity. A granulomatous pleuritis appeared affecting both the visceral and the parietal pleura, especially located around the antigen particle. Rheumatoid arthritis (RA) cells were constantly found in the pleural cavity when pleural lesions were present. This immunological, granulomatous pleuritis is the first experimental model for the study of RA cell-positive types of pleurisy in humans.

Thoracoscopic, histological, and clinical findings in nine case of rheumatoid pleural effusion.

A characteristic thoracoscopic picture of a granular parietal pleural surface was found in nine patients with rheumatoid pleurisy. Characteristic changes could be identified histopathologically in material obtained by biopsy. The rheumatoid pleural effusion resolved within an average of 14 months and no serious complications developed after the pleurisy. It is concluded that in rheumatoid pleural effusion a positive diagnosis can be made by thoracoscopy, preferably supported by the identification of microscopic structural changes in the parietal pleura.

Correlation between distal nephron enzyme activity, structure and function in rats during lithium and lithium plus neuroleptic treatment.

The histochemical activities of nonspecific acid and alkaline phosphatases, NADH- and NADPH-tetrazolium reductases, alpha-glycerophosphate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase, lactate dehydrogenase and glucose-6-phosphate dehydrogenase were investigated in kidneys from rats treated with lithium and lithium plus neuroleptics. During the first 8 weeks of lithium treatment the activity of NADH-tetrazolium reductase, succinate dehydrogenase and alpha-glycerophosphate dehydrogenase activity in the collecting ducts increased. The other enzymes did not change. After 8 weeks of treatment no further changes in enzyme activity occurred. Withdrawal of lithium caused normalization of enzyme activity after 8 weeks. A decrease in concentration ability was found in parallel with the increase in enzyme activities (p less than 0.001). The changes in enzyme activity were not significantly correlated to morphological changes in the collecting ducts. Treatment with neuroleptics alone caused no change in enzyme activity. During combined lithium plus neuroleptic treatment the enzyme activities changed in a similar way as during lithium therapy, but the changes were less pronounced. In parallel, a less pronounced decrease in concentration ability was found during this treatment.

Functional and structural changes in the rat kidney by long-term lithium treatment.

The relation between functional and structural renal changes induced by lithium was studied in rats during long-term treatment and after withdrawal of lithium. Administration of LiCl in the diet for up to 21 weeks caused marked polyuria associated with a significant lowering of renal concentrating ability assessed by dehydration and vasopressin tests. Plasma creatinine and plasma urea were not significantly changed by the treatment. Upon withdrawal of lithium water intake and concentrating ability were normalized within 4--8 weeks. Lithium caused focal light microscopic changes in the distal convoluted tubule and the collecting duct, consisting of nuclear and cellular polymorphism and, after prolonged treatment, dilatation of tubular lumens with tubular cell atrophy. These changes appeared later than the concentrating defect and persisted when lithium was withdrawn after prolonged treatment. No significant correlation was found between the degree of tubular changes and water intake or concentrating ability. It is concluded that the reversible diabetes insipidus induced by lithium in rats cannot be explained directly by the light microscopical changes observed in the distal part of the nephron, although the structural changes may be secondary to the polyuric state induced by lithium.

Reversible changes in small infarcts of the rabbit kidney.

Infarcts of the rabbit kidney were experimentally induced in 22 animals by selective left renal arteriography using the genuine foreign bodies present in the contrast media and catheters as damaging agents. Three days later the infarcts were macroscopically located and measured at laparotomy. Three weeks later the infarcts were macroscopically and microscopically investigated. Small infarcts (below 5 mm diameter) now were rendered grossly invisible, and no fibrous scarring of the infarcted area was present. Histologically, the changes varied from slight atrophy to total lack of microscopical parenchymal changes. Greater infarcts (above 5 mm in diameter) showed traditional cicatricial changes, the degree of scarring being dependent of the initial size of the infarct. Thus the small infarcts were found to be able to regenerate and revascularize.

Effects of lithium and neuroleptics and combinations of the two on renal function and structure in rats.

The effects of 8 weeks of treatment with lithium and neuroleptics, alone and combined, on renal concentrating ability and morphology were studied in rats. LiCl was administered in the diet and neuroleptics were given as one daily dose: haloperidol 1 mg/kg, chlorpromazine 15 mg/kg, and perphenazine 4 mg/kg. Plasma lithium levels were about 1 mmol/l, and the area under the plasma concentration curve was not statistically different in the control and neuroleptic groups. Rats treated with lithium developed marked polyuria which was less in rats receiving neuroleptics concomitantly. After 8 weeks, rats treated with lithium alone showed marked impairment of renal concentrating ability and moderate degree of structural renal changes. Neuroleptics alone had no effect on concentrating ability or renal morphology, nor did they aggravate the changes caused by lithium. In fact, neuroleptics seemed to improve the concentrating ability in rats treated with lithium. It is concluded that in rats high doses of neuroleptics do not potentiate lithium-induced functional and structural renal changes.

Pleural granulocytes with cytoplasmic inclusions from patients with malignant lung tumours and mesothelioma.

Granulocytes with cytoplasmic inclusions (RA = Rheumatoid Arthritis cells) have previously been found in pleural effusions of rheumatoid and tuberculous origin. We now report the finding of RA-cells in effusions from patients suffering from bronchogenic carcinomas of the squamous-cell type and malignant mesothelioma. Such cells occurred only rarely in other types of primary or secondary lung tumour.

Reye's syndrome in a child on long-term salicylate medication.

A case of Reye's syndrome in a four-year-old child on long-term salicylate medication for rheumatoid arthritis is reported. Severe fatty changes of the liver, lipid vacuolation in the renal proximal tubules, and severe brain oedema were the prominent postmortem findings. Symptoms of a trivial infection and vomiting just before death added to the resemblance of this case to Reye's syndrome.

Sequelae of intrinsic foreign-body contamination during selective renal angiography in rabbits.

The significance of foreign-body contamination of contrast media, flushing solutions, and angiographic equipment was investigated by selective renal angiography in 32 rabbits. Infarction caused by foreign bodies introduced by the angiographic procedure was frequently demonstrated. As a particulate matter is also injected during human angiography, its effects should be carefully sought.

Structural changes and ability to release renin in auto- and allo-transplants of mouse submaxillary glands.

In mice having a high renin content in the submaxillary glands allo- and autotransplantation of the gland showed identical histological changes of the tissue, comprising disappearance of acini and intercalated ducts as well as a reduction in the number and size of granules in the granulated ducts. No structural signs of rejection were found. Adenomas, possibly originating in the granulated ducts, were frequently present in the transplanted glands. The renin content of autotransplanted glands was invariably much higher than in allotransplants, and after noradrenaline injection renin was released only from autotransplants, never from allotransplants. Blockade of the renin system was accordingly followed by a decrease in blood pressure only in mice with autotransplants.