Determinants, consequences and potential solutions to poor adherence to anti-osteoporosis treatment: results of an expert group meeting organized by the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases (ESCEO) and the International Osteoporosis Foundation (IOF)

Many patients at increased risk of fractures do not take their medication appropriately, resulting in a substantial decrease in the benefits of drug therapy. Improving medication adherence is urgently needed but remains laborious, given the numerous and multidimensional reasons for non-adherence, suggesting the need for measurement-guided, multifactorial and individualized solutions.

INTRODUCTION

Poor adherence to medications is a major challenge in the treatment of osteoporosis. This paper aimed to provide an overview of the consequences, determinants and potential solutions to poor adherence and persistence to osteoporosis medication.

METHODS

A working group was organized by the European Society on Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal diseases (ESCEO) to review consequences, determinants and potential solutions to adherence and to make recommendations for practice and further research. A systematic literature review and a face-to-face experts meeting were undertaken.

RESULTS

Medication non-adherence is associated with increased risk of fractures, leading to a substantial decrease in the clinical and economic benefits of drug therapy. Reasons for non-adherence are numerous and multidimensional for each patient, depending on the interplay of multiple factors, suggesting the need for multifactorial and individualized solutions. Few interventions have been shown to improve adherence or persistence to osteoporosis treatment. Promising actions include patient education with counselling, adherence monitoring with feedback and dose simplification including flexible dosing regimen. Recommendations for practice and further research were also provided. To adequately manage adherence, it is important to (1) understand the problem (initiation, implementation and/or persistence), (2) to measure adherence and (3) to identify the reason of non-adherence and fix it.

CONCLUSION

These recommendations are intended for clinicians to manage adherence of their patients and to researchers and policy makers to design, facilitate and appropriately use adherence interventions.

Runaway electron imaging spectrometry (REIS) system

A portable Runaway Electron Imaging and Spectrometry System (REIS) was developed in ENEA-Frascati to measure synchrotron radiation spectra from in-flight runaway electrons in tokamaks. The REIS is a wide-angle optical system collecting simultaneously visible and infrared emission spectra using an incoherent bundle of fibers, in a spectral range that spans from 500 nm to 2500 nm, and visible images using a CCD color microcamera at a rate of 25 frames/s. The REIS system is supervised and managed using a dedicated LabVIEW program to acquire data simultaneously from three spectrometers every 20 ms (configurable down to 10 ms). An overview of the REIS architecture and acquisition system and resulting experimental data obtained in FTU are presented and discussed in this paper.

The course of asthma during pregnancy in a recent, multicase-control study on respiratory health

Background

Over the years it has been widely stated that approximately one-third of asthmatic women experience worsening of the disease during pregnancy. However, the literature has not been reviewed systematically and the meta-analytic reviews include old studies. This study aimed to examine whether the prevalence of worsening asthma during pregnancy is still consistent with prior estimate or it has been reduced.

Methods

A detailed Clinical Questionnaire on respiratory symptoms, medical history, medication, use of services, occupation, social status, home environment and lifestyle was administered to random samples of the Italian population in the frame of the Gene Environment Interactions in Respiratory Diseases (GEIRD) study. Only clinical data belong to 2.606 subjects that completed the clinical stage of the GEIRD study, were used for the present study.

Results

Out of 1.351 women, 284 self-reported asthma and 92 of them had at least one pregnancy. When we considered the asthma course during pregnancy, we found that 16 women worsened, 31 remained unchanged, 25 improved. Seven women had not the same course in the different pregnancies and 13 did not know. The starting age of ICS use almost overlaps with that of asthma onset in women with worsening asthma during pregnancy (19 years ± 1.4), unlike the other women who started to use ICS much later (30.3 years ± 12). In addition, the worsening of asthma was more frequent in women with an older age of onset of asthma (18 years ± 9 vs 13 years ± 10). Among women who completed the ACT during the clinical interview, the 50% of women who experienced worsening asthma during pregnancy (6/12) had an ACT score below 20.

Conclusion

Asthma was observed to worsen during pregnancy in a percentage much lower to that generally reported in all the previous studies. There is still room in clinical practice to further reduce worsening of asthma during pregnancy by improving asthma control, with a more structured approach to asthma education and management prepregnancy.

Auditory cortex involvement in emotional learning and memory

Emotional memories represent the core of human and animal life and drive future choices and behaviors. Early research involving brain lesion studies in animals lead to the idea that the auditory cortex participates in emotional learning by processing the sensory features of auditory stimuli paired with emotional consequences and by transmitting this information to the amygdala. Nevertheless, electrophysiological and imaging studies revealed that, following emotional experiences, the auditory cortex undergoes learning-induced changes that are highly specific, associative and long lasting. These studies suggested that the role played by the auditory cortex goes beyond stimulus elaboration and transmission. Here, we discuss three major perspectives created by these data. In particular, we analyze the possible roles of the auditory cortex in emotional learning, we examine the recruitment of the auditory cortex during early and late memory trace encoding, and finally we consider the functional interplay between the auditory cortex and subcortical nuclei, such as the amygdala, that process affective information. We conclude that, starting from the early phase of memory encoding, the auditory cortex has a more prominent role in emotional learning, through its connections with subcortical nuclei, than is typically acknowledged.

Pulmonary involvement in patients with Marfan Syndrome

AIM

Pulmonary involvement is not generally considered a main feature of Marfan syndrome, an autosomal connective tissue disorder caused by mutations in fibrillin 1. Thanks to the substantial progress in treatments, life expectation of these patients has been dramatically improved determining changes in different organ systems. The number of patients with pulmonary pathology may be higher than expected. Objective of the study was to evaluate the pulmonary involvement in all the patients referring to the largest Italian center for Marfan syndrome, assessing clinical examination and lung function tests.

METHODS

Clinical history, spirometry, lung volumes and diffusing capacity have been assessed in 64 patients of our national referral center.

RESULTS

None of the patients reported chronic respiratory symptoms. Fourteen percent reported a previous pneumothorax and 3 blebs and 45% had moderate to severe rib cage abnormalities. Twenty-three percent had cardiothoracic surgery. Two of the 19 patients with chest TC performed at our hospital were diagnosed with emphysema and were both non smoker; 7 had subpleural apical blebs. Only 37% of patients had normal lung function; 19% showed a restrictive pattern and 44% an obstructive pattern or an isolated diffusion impairment or an isolated hyperinflation. All patients with pneumothorax showed an obstructive pattern and diffusion impairment.

CONCLUSION

In the absence of early respiratory symptoms, pulmonary abnormalities should be detected and monitored before they aggravate. Particular attention should be paid to prevent pneumothorax. Our results support the importance of lung volume determination to identify patients in which pulmonary parenchyma require a careful chest CT evaluation.

What defines airflow obstruction in asthma?

Asthma guidelines from the Global Initiative for Asthma (GINA) and from the National Heart, Lung, and Blood Institute provide conflicting definitions of airflow obstruction, suggesting a fixed forced expiratory volume in 1 s (FEV(1))/forced vital capacity (FVC) cut-off point and the lower limit of normality (LLN), respectively. The LLN was recommended by the recent American Thoracic Society/European Respiratory Society guidelines on lung function testing. The problem in using fixed cut-off points is that they are set regardless of age and sex in an attempt to simplify diagnosis at the expense of misclassification. The sensitivity and specificity of fixed FEV(1)/FVC ratios of 0.70, 0.75 and 0.80 versus the LLN were evaluated in 815 subjects (aged 20-44 yrs) with a diagnosis of asthma within the framework of the European Community Respiratory Health Survey. In males, the 0.70 ratio showed 76.5% sensitivity and 100.0% specificity, the 0.75 ratio 100.0% sensitivity and 92.4% specificity, and the 0.80 ratio 100.0% sensitivity but 58.1% specificity. In females, the 0.70 ratio showed 57.3% sensitivity and 100.0% specificity, the 0.75 ratio 91.5% sensitivity and 95.9% specificity, and the 0.80 ratio 100.0% sensitivity but 72.9% specificity. The fixed cut-off points cause a lot of misidentification of airflow obstruction in young adults, with overestimation with the 0.80 ratio and underestimation with the 0.70 ratio. In conclusion, the GINA guidelines should change their criteria for defining airflow obstruction.

A histochemical approach to the evaluation of the in vivo cytotoxicity of the nitrobutadienes (1E,3E)-1,4-bis(1-naphthyl)-2,3-dinitro-1,3-butadiene and methyl (2Z,4E)-2-methylsulfanyl-5-(1-naphthyl)-4-nitro-2,4-pentadienoate in mice liver and kidney

Two new molecules (1E,3E)-1,4-bis(1-naphthyl)-2,3-dinitro-1,3-butadiene (1-Naph-DNB) and (2Z,4E)-2-methylsulfanyl-5-(1-naphthyl)-4-nitro-2,4-pentadienoate (1-Naph-NMCB) in previous studies showed interesting antiproliferative activity in vitro. Furthermore, toxicological tests and histological analysis provided promising results, in particular for 1-Naph-NMCB that displayed lower toxic activity both in terms of lethal effect and tissue damage of the main organs. Finally, studies of the antitumour activity in vivo confirmed the efficacy of both molecules, though with some differences in tumour selectivity and levels of activity. In this investigation the activities of some specific enzymes, acid phosphatase (AcPase), alkaline phosphatase (AlkPase), catalase (Cat), succinic dehydrogenase (SDH), glucose-6-phosphatase (G6Pase) and K+ p-nitrophenyl phosphatase (K+ pNPPase) were studied in the liver and kidney as histopathological biomarkers, to assess the effects of the two compounds in organs generally involved in the metabolism and excretion of different drugs. As oxidative stress may also develop as a consequence of the toxic effect of chemicals, reactive oxygen species (ROS) production was evaluated by a histochemical method. The results indicated that some enzyme activities and ROS expression changed in a dose-related manner. Nevertheless, neither in the liver nor in the kidney were dramatic toxic effects evident. By contrast, the variations of some enzyme activities (AlkPase, AcPase, Cat, K+ pNPPase) were interpreted as possible defensive mechanisms for tolerating high dosage of the compounds.

Morphofunctional evidence of changes in principal and mitochondria-rich cells in the epidermis of the frog Rana kl. esculenta living in a polluted habitat

The epidermis of vertebrates is the body's principal barrier against environment and its possible contaminants. The presence of keratins, as well as specific detoxifying molecules or enzyme activities, in the various epidermis layers is believed to be involved in providing protection from harmful environmental influences. Anuran integument is poorly hornified and thus permeable to some endogenous and exogenous compounds and thus serves as a good bioindicator of overall environmental conditions. In the present investigation, we studied the epidermis of Rana kl. esculenta adult specimens collected at two different rice fields, relatively unpolluted and heavily polluted, respectively. Environmental pollution was assayed by chemical analysis performed on both sediments and animals. We evaluated the structural aspects of the epidermis at both light and electron microscopy levels and the pattern of keratinization by immunohistochemistry. Furthermore, we studied the activities of some enzymes (acid and alkaline phosphatase, nitric oxide synthase-related nicotinamide adenine dinucleotide phosphate dehydrogenase, glucose-6-phosphate dehydrogenase, catalase, nonspecific esterases, and succinic dehydrogenase) involved mainly in membrane transport, xenobiotics, and oxidative metabolism. Compared with controls, in polluted animals we found the following results: (1) an increase in pollutant levels (i.e., cadmium, mercury, and lead); (2) less keratinized superficial cells in the epidermis; and (3) changes in most enzyme activities in keratinocytes and mitochondria-rich cells (particularly glucose-6-phosphate dehydrogenase and esterases, both important to counteract oxidative and toxic stress). Taken as a whole, the present data indicate the morphofunctional plasticity of the frog epidermis in response to environmental contamination.

Hypertensive retinopathy revisited: some answers, more questions

Hypertension is associated with cardiovascular risk and systemic target organ damage. Retinopathy is considered one of the indicators of target organ damage. This review focuses on recent studies on hypertensive retinopathy and their implications for clinical care. Early recognition of hypertensive retinopathy signs remains an important step in the risk stratification of hypertensive patients.

Direct demonstration of iron in a term placenta in two cases of beta-thalassemia

The aim of this study was to quantify iron in the placentas at the end of pregnancy in two patients suffering from beta-thalassemia and compare the data to that recorded from the placentas of healthy women. Iron was quantified in placental specimens taken after the delivery. The specimens were subjected to chemical treatments in order to remove extracellular iron and leave the intracellular iron intact. After coloration, each specimen was subjected to quantitative analysis of images in order to identify and quantify iron. Our results demonstrated that in beta-thalassemia there is an accumulation of iron in the outer basal cytoplasm of the epithelial cells of placental cotyledons.

GB virus C/hepatitis G virus exposure in Italian pediatric and young adult thalassemic patients

BACKGROUND

The aim was to estimate the prevalence and the persistence of GB virus C/hepatitis G virus (GBV-C/HGV) exposure markers in a group at high risk for transfusion-transmitted agents.

PATIENTS AND METHODS

Serum samples from 37 thalassemic patients were screened for GBV-C/HGV RNA by reverse transcription PCR (RT-PCR) and for antibodies to the envelope protein E2 of GBV-C/HGV (anti-E2).

RESULTS AND DISCUSSION

GBV-C/HGV RNA and anti-E2 were detected in 13 (35%) and 12 (32%) sera, respectively. Contemporary presence of both markers was found in one patient. GBV-C/HGV exposure was found in 24 patients (64.8%). Mean levels of liver enzymes were similar in both exposed and unexposed GBV-C/HGV groups. 33 out of 35 patients showed no change in GBV-C/HGV RNA and anti-E2 status in sera taken 6 months apart. The rate of persistent infection was 92.3% and the anti-E2 seroconversion rate was 23% for sera taken at least 6 months apart. The temporal overlap between anti-E2 seroconversion and loss of detectable GBV-C/HGV RNA may last more than 6 months.

[Laparoscopic appendectomy. Retrospective analysis of our experience compared with the literature]

BACKGROUND

The benefits of laparoscopic appendectomy (LA) remain controversial. This study reports a critical examination of our experience in a peripheral hospital.

METHODS

A total of 128 appendectomies have been performed since January 1996, of which 63 (49%) were laparoscopic. The patients included 52 (82.5%) females and 11 (17.5%) males with a mean age of 20.8 years (range 11-46). Emergency surgery was required in 6 cases (9.5%) and was elective in 57 (90.5%). Appendectomy was performed during another operation in 3 cases (laparoscopic cholecystectomy).

RESULTS

Mortality was nil. Morbidity was 1.7% (1 case). The index of conversion was 0%. Only one major complication occurred. This took the form of perforation of an ileal loop following accidental lesion during adhesiolysis. The intraoperative diagnosis was not confirmed in 12 (19%) cases: 9 ovarian cysts, 1 terminal ilieitis and 2 cases of acute salpingitis. In 10 cases (15%) surgery was associated with adhesiolysis, and in 6 cases (9.3%) the appendix was retrocecal. Mean operating time was 42 min (range 18-105 min). The mean hospitalisation was 3.3 days.

CONCLUSIONS

The authors emphasise the numerous advantages of laparoscopic techniques in their experience, including excellent cosmetic results, reduced PO pain, rapid functional recovery, lower incidence of adhesion, wound infection and laparocele, and more cost-effective when mechanical staplers are not used. Owing to the ability to explore the entire abdominal cavity, the main advantage of this technique consisted in a correct differential diagnostic balance, especially in young women of child-bearing age, between appendectomy and pathologies of the uterus and adnexa.

[Laparoscopic cholecystectomy. Our experience]

BACKGROUND

The many advantages and extreme versatility made laparoscopic cholecystectomy (L.C.) the gold standard for symptomatic cholelithiasis. The aim of this research is a retrospective analysis of personal experience with laparoscopic cholecystectomy in a peripheral hospital compared with the literature on the subject.

METHODS

Since June 1982, a total of 989 L.C. have been performed. The patients were: 691 (68.6%) women and 298 (29.4%) men with a mean age of 56 years (range 17-84). The indications were: 791 symptomatic cholelithiasis, 142 chronic cholecystitis, 45 empyema-hydrops and 11 adenomyomatosis.

RESULTS

No postoperative death have been observed and the conversion rate was of 24 cases (2.3%). The main complications were 3 cases of injury of the biliary tract and 2 cases of postoperative bleeding (1 from cystic artery and 1 from the umbilical wound). Minor complications observed were 12 cases (1.2%) of infections of the umbilical wound and 3 cases of umbilical hernia (0.3%). The elevation of stasis index was observed in 3 cases which solved spontaneously. The length of stay was 2 days in 957 cases (97%), 8 days in 24 cases and 4-5 days in 8 (0.7%).

CONCLUSIONS

No major trochar's lesions occurred, contrary to the percentages quoted in the literature (0.02%-0.9%). The selective use of the open technique and of the multiuse conic section trocar in the "closed" technique is suggested. The 3 cases of bile duct lesions did not occur during the training period, contrary to what quoted in the literature. In personal opinion, a careful surgical technique with a good Calot's triangle preparation, is necessary to prevent these inconveniences. Parietal complications (umbilical wound infections and laparocele) even if lesser than in the laparotomy technique, can be reduced by using the endobag and suturing the abdominal fascia of the 10 mm trocars. Moreover, the use of a systematic subhepatic drainage during the first 24 postoperative hours is suggested, since it can be useful to reveal possible bleeding.

[The correlation between morphology, electrolytic content and risk factors in breast cysts]

Many studies on the biochemical composition of the liquid aspirated from breast cysts have identified three types of cysts: type I (apocrine) cysts, with a high concentration of K+ and low levels of Na+ and C1-; type II (transudate) cysts, with an electrolytic content similar to that of plasma and high Na+ levels and, finally, type III cysts, with intermediate characteristics. The literature data appear to indicate that the women with type I cysts are at higher risk for breast cancer. The authors report the results of a study carried out on 143 women from October, 1991, through October, 1994, in the Radiology Department of the University of Bologna, to investigate the correlations between some risk factors for breast cancer, the characteristics of cyst fluid and the morphology of the cysts after pneumocystography. Of 186 cysts, 104 (55.9%) were type I, 49 (26.4%) were type II, and 33 (17.7%) were type III. Among the risk factors we considered, only the premenopausal state (41 to 45 years of age) exhibited a statistically significant correlation with the presence of type I cysts. The morphological study of the cysts after pneumocystography showed a surprisingly high correlation between the honeycomb pattern and type I cysts. The constant correlation between cyst morphology and electrolytic content may allow the easy identification of the subgroups of patients eligible for a closer follow-up.

Anion-induced dynamic behavior of apical water channels in vasopressin-sensitive epithelia exposed to mercury

We showed recently that, in toad skins preexposed to Hg, water permeability is high in SO4-Ringer and low in Cl-Ringer. This anion effect was further investigated in Hg-treated skins and bladders of toads (Bufo marinus) in a variety of experimental conditions, including glutaraldehyde fixation and stimulation by vasopressin (VP) or isoproterenol (IP). In fixed bladders either unstimulated or stimulated with VP, net water flow (Jw) in SO4-Ringer [Jw (SO4)] was always significantly higher than Jw in Cl [Jw (Cl)]; the same applies to fixed toad skins, either unstimulated or stimulated with IP. In unfixed isolated toad epidermis challenged with IP before Hg exposure, Jw(SO4)/Jw(Cl) >> 1 approaching the ratio Jw (maximally stimulated)/Jw (basal). Therefore, anion-induced Jw changes were present whether Hg acted on epithelial water channels exocytosed by Hg itself or by hydrosomotic agents and suggest a switching between open and closed configurations of the channel protein. This anion effect was not abolished by glutaraldehyde and might be correlated with changes in intracellular chloride.

Mercury blockage of apical water channels in toad skin (Bufo marinus)

1. Net water flow (Jw) was continuously monitored across the abdominal skin of the toad Bufo marinus by means of a volumetric, automatic technique. Jw was either averaged over periods of 2 min or taken cumulatively (10 or 30 min periods). 2. The state of high water permeability induced by vasopressin or isoprenaline was reversed (88-89% inhibition of delta Jw after 1 h) by the addition of 10(-3) M HgCl2 (or CH3ClHg) to the external bathing medium. Similarly, pre-exposure of the skins to Hg2+, totally blocked the induction of the hydrosmotic response to the same agents. By itself, Hg2+ exerted only a minor (26%) stimulation of basal Jw. 3. There was a sigmoidal dose-response relationship between the reduction of the hydrosmotic effect of vasopressin (VP) and the concentration of Hg2+ in the external medium, with a half-maximal effect at 1.2 x 10(-4) M HgCl2. 4. Total replacement of Na+ by K+, Rb+ or Cs+ in the Ringer solution, caused a VP-like, hydrosmotic effect that was reversed, or prevented, by exposure to Hg2+ in a manner indistinguishable from that previously seen with vasopressin or isoprenaline. 5. The data point to the presence of a Hg(2+)-sensitive apical water pathway in stimulated epithelia, very probably constituted by water channels similar to those reported in red blood cells, amphibian bladder and mammalian kidney tubules.

Effects of anions and/or cell volume on the permeance of an apical water pathway induced by Hg in toad skin epithelium

Hg compounds block membrane transport units behaving as water channels. Here we show that Hg induces an apical water pathway in toad skins pretreated with 10(-3) M CH3ClHg or HgCl2, added to the outer bathing medium. Washing with SO4-Ringer caused a several-fold increase in net water flow (Jw) and osmotic permeability coefficient (Pf) that was reversed by re-exposure to Cl- or NO3-Ringer and mimicked by gluconate-Ringer. These Pf changes could be elicited repeatedly and were present if, and only if, anion replacements took place in the inner bathing solution. Such inner polarity was related to the anion permeability of the epidermal basolateral membrane: impermeant anions (SO4, gluconate) increased Pf; permeant anions (Cl, NO3) did not change basal Pf but reversed the high Pf induced by impermeant anions. Hg induced the appearance of aggregates that persisted despite repeated washings of the skins during 4-5 h, and whether Pf was high (SO4-Ringer) or low (Cl-Ringer) before skin fixation. The Hg-induced apical water pathway in toad skin appears to be a unique model for studying the interplay between cell volume, cell ionic composition and water permeability.

The growth response of the green alga Chlorella vulgaris to combined divalent cation exposure

Using the growth response of the green alga Chlorella vulgaris as a model system, the effects of combinations of the environmentally active cations Cd, Co, and Cu were evaluated. The 96-h static EC50 for these cations to C. vulgaris were, respectively, 0.89 microM, 9.0 microM, and 2.8 microM, yielding a toxicity series such that Cd > Cu > Co. The cation combinations of Cd + Cu, and Cu + Co acted synergistically, while Cd + Co, and the tri-metallic combination Cd + Cu + Co resulted in antagonistic interactions. Examination of these toxic combinations at 24, 48, 72, and 96 h indicate that the cellular response is not a uniform one. Failure of energy dispersive X-ray spectrophotometric analysis to demonstrate any intracellular incorporation of these cations (except for a weak cytoplasmic Cu peak at the 8.0 KEV position) suggests that the toxic actions of these cations at EC50 concentrations are exerted at the level of the plasma membrane.

The effects of pH on the growth of Chlorella vulgaris and its interactions with cadmium toxicity

The effects of pH alone, and in combination with exposure to 0.89 microM cadmium, on the growth response of the green alga Chlorella vulgaris were evaluated. Acidic (3.0-6.2) and alkaline (8.3-9.0) pH values retarded the growth of this alga. Optimal growth occurred when the pH of the medium was adjusted to values of 7.5 and 8.0. When the cells were exposed to pH adjusted medium plus the presence of 0.89 microM Cd, a value known to reduce population growth by 50% at the control pH of 6.9, the affects were additive at the acidic (3.0-5.0) pH ranges. At alkaline pH values of 8.3-9.0 all toxicity responses could be explained by pH adjustment alone, indicating that additional cadmium toxicity was absent. At pH values of 7.5 and 8.0, cadmium toxicity was mitigated against, and resultant growth at pH 8.0 was at the same enhanced rate as this pH without cadmium.

Amiloride inhibits the vasopressin-induced increase in epithelial water permeability

The vasopressin (VP)-induced increase in water permeability in high-resistance, amphibian epithelia is not altered by the abolition of net Na+ flux caused by amiloride added to the apical bathing medium. In this work we looked at the effects on water transport of amiloride added to the serosal medium at a concentration (10(-3) M) known to inhibit Na+/H+ exchange. In urinary bladders of Bufo marinus, amiloride partially blocked the hydrosmotic response to VP. A similar inhibition was found with cyclic adenosine 5'-monophosphate (cAMP) or serosal hypertonicity. We hypothesized that this effect of amiloride could be due to an inhibition of Na+/H+ and/or Na+/Ca2+ antiporters present in the epithelial basolateral membrane and looked at the effects of the diuretic in Na(+)-free media. A similar degree of inhibition of water flow was still found, thus showing that amiloride acts on a cell target other than the antiporters. In toad skin, amiloride did not inhibit the hydrosmotic response to VP and to isoproterenol; however the response to high K+ was significantly reduced. Among the amiloride cell targets described so far, adenylate cyclase and protein kinase A appear to be the best candidates to explain the inhibition of the hydrosmotic response reported here. Direct measurements of intracellular cAMP are needed however to substantiate this hypothesis.

Forskolin mimics the hydrosmotic action of vasopressin in the urinary bladder of toads Bufo marinus

Net water flow JW was measured across the urinary bladder of toads Bufo marinus and averaged over periods of 1 min by means of a volumetric, automatic technique. The diterpene forskolin, an activator of adenylate cyclase bypassing the hormonal receptor subunit, induced a rapid, reversible, dose-dependent increase in osmotic water permeability, Pf, very similar to that induced by vasopressin. At 1.1 microM, forskolin induced a half-maximal response. At 5 microM forskolin caused a near maximal response and Pf increased from 1.66 +/- 0.15 to 66.6 +/- 2.99 microns s-1. In bladders pre-exposed to 5 microM-forskolin, further significant increases in Pf were obtained by their subsequent exposure to vasopressin, cyclic AMP, theophylline or serosal hypertonicity. The similarity of the forskolin and vasopressin actions was further demonstrated by the finding that substances causing enhancement (quercetin) or inhibition (trifluoperazine, vanadate, silver, cobalt, manganese and Ca2+-free Ringer solution) of the vasopressin response, induced parallel changes in the forskolin response. Three agents, however, induced dissimilar effects on vasopressin and forskolin: high K+ potentiated vasopressin but inhibited forskolin; methohexital and diamide inhibited vasopressin but had no effect on forskolin. The forskolin-induced hydrosmotic response can be viewed as a new criterion for ascertaining the messenger role of cycle AMP in the the hydrosmotic effect of vasopressin.

High [K+] alters the stimulus-hydrosmotic response coupling in toad bladder

Substitution of K+ for Na+ in the Ringer solution bathing the inner surface of toad urinary bladders (Bufo marinus) had no effect on basal water permeability but significantly altered the stimulus-hydrosmotic response of this epithelium. In chloride-Ringer, high [K+] increased the hydrosmotic responses to submaximal stimulations induced by vasopressin or exogenous cAMP, while the responses to theophylline or serosal hypertonicity were decreased. In sulfate-Ringer, all these responses were enhanced but for that induced by serosal hypertonicity which was actually diminished. As a step towards determining if Ca2+ might mediate the K+-induced effects on water flow, experiments were conducted either in the presence of a Ca2+ "antagonist" (cobalt) or in nominally Ca2+-free Ringer. In both conditions the hydrosmotic effects of vasopressin and cAMP were markedly reduced. The results raise the possibility that a transient Ca2+ influx through voltage-sensitive, Co2+-blockade Ca2+ channels may play a role in the stimulus-hydrosmotic response of toad urinary bladder.

Flavonoids and hepatic cyclic monophosphates in liver injury

Among the large spectrum of pharmacological activities of flavonoids, play an important role the recently investigated properties involving the arachidonic acid metabolism. In order to clarify the mechanisms of "cytoprotection" of the 3-palmitoyl-(+)-catechin (Palm-cat), a new flavonoid compound (C31 H44 O7) we have studied in experimental hepatitis of the rat, induced by Galactosamine (Ga1N) and E. coli 055:B 5 endotoxin (LPS), hepatic cAMP and cGMP, transaminases, bilirubin and endotoxemia. The Palm-cat significantly increases cyclic-GMP levels in the liver, whereas reduces or slightly modifies the cAMP. Transaminases and bilirubin values increase both in controls and flavonoid treated rats. The flavonoid significantly decreases the frequency of endotoxemia. These effects suggest that RES and hepatocytes functions, immune and inflammatory response can be affected in liver disease by flavonoids via cyclic nucleotides regulation.

Correlation between water flow and intramembrane particle aggregates in toad epidermis

In abdominal skins of toads (Bufo marinus) challenged with either vasopressin or isoproterenol, the stimulation of transepithelial water flow was accompanied by the appearance of intramembrane particle (IMP) aggregates. These aggregates were found only in the apical plasma membrane of granular cells of the first-reacting cell layer. The effect of vasopressin varied in magnitude and could be selectively blocked by preincubation of the skins with methohexital. This barbiturate also prevented the appearance of IMP aggregates. Preexposure with propranolol had a similar effect in skins challenged with isoproterenol. Linear regression analysis of net water flow vs. the percentage surface occupied by IMP aggregates showed a significant (P less than 0.001) correlation, which applied to data obtained in six different experimental conditions, i.e., vasopressin or isoproterenol alone and either of these agents in combination with methohexital or propranolol. The results reported here in a nonurinary epithelium (toad epidermis) suggest that the appearance of IMP aggregates is a general response in epithelia undergoing adenosine 3',5'-cyclic monophosphate-mediated changes in water permeability.

Cellular and membrane events involved in the K-induced increase in water permeability of toad skin

Exposure of the inner surface of toad skin (Bufo marinus) to high [K+] resulted in a marked (up to 7-fold) increase in water permeability (Pf) that was more marked in KC1-Ringer than in K2SO4-Ringer. Although high [K+] did not elicit a maximal increase in Pf, it blunted the hydrosmotic responses to vasopressin, isoproterenol and cAMP. Both "post-cAMP" inhibitors of stimulated water flow, such as diamide and vanadate, and "pre-cAMP" inhibitors, such as methohexital and propranolol, markedly reduced the K response, while exposure to Ca2+-free, KC1-Ringer did not inhibit water flow. Intramembrane particle aggregates, similar to those induced by cAMP-mediated hydrosmotic agents, were seen in the apical membrane of granular cells, just beneath the stratum corneum, in skins exposed to KC1. Available evidence indicates that cAMP might mediate, at least partially, the hydrosmotic effect of high [K+]. In contrast, a role of voltage-dependent Ca2+ channels, described in other cell systems depolarized with K, was not apparent in toad skin.

Osmotic water flow across the abdominal skin of the toad bufo marinus: effect of vasopressin and isoprenaline

1. Net water flow J(w), was measured across the abdominal skin of the toad Bufo marinus with a volumetric, automatic technique that allows for averaging J(w) over time intervals as short as 1 sec.2. Basal J(w) was very stable and corresponded to a coefficient of osmotic flow, L(PD), of ca. 15 x 10(-7) cm sec(-1) atm(-1) (or to an osmotic water permeability coefficient, P(f), of 20 mum sec(-1)).3. Both vasopressin and the beta-adrenergic agonist, isoprenaline, triggered high hydrosmotic responses that could lead to P(f) values exceeding 250 mum sec(-1). The effect of isoprenaline was very reproducible while that of vasopressin varied considerably.4. Methohexital and propranolol selectively inhibited the hydrosmotic effects of vasopressin and isoprenaline, respectively, whereas amiloride and ouabain had no effect.5. Mutual inhibition was found between vasopressin and isoprenaline in skins very sensitive to vasopressin. In less sensitive skins isoprenaline further increased J(w) despite exposure of the epithelia to supramaximal concentrations of vasopressin.6. Differential reactivity to vasopressin was found between the skin and the bladder taken from the same toad. In some instances, the bladder responded normally to vasopressin while the skin was totally unresponsive, suggesting the presence of osmoregulatory mechanisms exerting a local modulation of the vasopressin action in different target epithelia of the same animal.