Serum Aluminum Levels and Peritoneal Dialysis

Serum aluminum levels, significantly higher in dialysis patients than in normal subjects, were also found to be significantly higher in patients on PD than in those on HD. This could be related to a higher Al transport rate across membrane during PD than during HD. The easier contamination of PD dialysates and their acidic pH could account for this trend to a positive Al balance in PD.

On the basis of our observations, however, the significance of the serum aluminum level could be very low, since aluminemia does not seem to reflect the cumulative amount of Al ingested and might not readily help predict the risk of Al intoxication.

Non-A, Non-B Hepatitis and Anti-HCV Antibodies in Dialysis Patients

To define the prevalence of non-A, non-B hepatitis, antibodies to HCV were detected in 193 patients on renal replacement therapy (52 transplant and 141 hemodialysis patients) and in 50 staff members of a Nephrology Department. Unequivocal seroconversion was documented in 5 transplant (9.6%) and in 26 dialysis patients (18.4%). In the dialysis population, the prevalence of anti-HCV antibodies was evaluated in patients grouped according to the number of blood transfusions and to the different sections of dialytic treatment. The most striking findings were the marked differences in the prevalence of anti-HCV antibodies among patients treated in different sections (from 0% to 70%), and the presence of a significant increase in alanine-amino-transferase (ALT) concentrations in 14 anti-HCV negative patients. The results suggest that the diffusion of non-A, non-B hepatitis is mainly transfusion-related, with the possibility of significant environmental diffusion related to the violation of infection-control measures. The current immunoassay is probably unable to detect the actual frequency of the infection.

Red Blood Cell Volume Distribution Width (RDW) in Uraemic Patients on Chronic Haemodialysis

Red blood cell volume distribution width (RDW) was obtained with the Coulter counter in 60 haemodialysis patients and 55 normal individuals. RDW tended to be higher in the former and the degree of increase was to some extent correlated with the underlying nephropathy. Although RDW failed to correlate with conventional tests of iron status, it was observed that iron administration could produce a decrease toward normal in RDW and a parallel increase in haemoglobin when the initial RDW was increased. In contrast, the response to iron was negligible in the patients with normal RDW basally. It was concluded that high RDW is an acceptable indicator of iron deficiency in haemodialysis patients.

Clinical and Radiological Features of Bone Disease in Long-Term (15 or more years) Hemodialysis Patients

Fifteen patients on regular dialytic treatment for more than 15 years were given X-rays of the skull, spine, shoulders, wrists, pelvis and knees with the purpose of studying the principal skeletal and articular alterations due or not due to the uraemic status. Serum calcium, phosphorus, parathyroid hormone, alkaline phosphatase and basal aluminium were recorded. Osteopenia was evident in all the patients. Ten of whom (67%) showed alterations due to hyperparathyroidism. Nine patients presented the marks of dialysis spondyloarthropathy; in 14/15 cases geodes were present in the wrists, humeral heads or hip-joints; in ten patients there were multiple amyloid lesions. Two patients with serum basal aluminum above 100 μg/L showed the typical radiographic marks of osteomalacia. The majority of the long-term survivors showed multifactorial osteo-articular alterations resulting mainly from the combination of hyperparathyroidism and dialysis-related amyloidosis. The less frequent joint alterations were represented by arthrosis, enthesopathy and Chondrocalcinosis. Disability and decreased articular mobility resulted in being mainly due to amyloid osteo-arthropathy.

Managing data for the international, multicentre INTERGROWTH-21st Project

The INTERGROWTH-21(st) Project data management was structured incorporating both a centralised and decentralised system for the eight study centres, which all used the same database and standardised data collection instruments, manuals and processes. Each centre was responsible for the entry and validation of their country-specific data, which were entered onto a centralised system maintained by the Data Coordinating Unit in Oxford. A comprehensive data management system was designed to handle the very large volumes of data. It contained internal validations to prevent incorrect and inconsistent values being captured, and allowed online data entry by local Data Management Units, as well as real-time management of recruitment and data collection by the Data Coordinating Unit in Oxford. To maintain data integrity, only the Data Coordinating Unit in Oxford had access to all the eight centres' data, which were continually monitored. All queries identified were raised with the relevant local data manager for verification and correction, if necessary. The system automatically logged an audit trail of all updates to the database with the date and name of the person who made the changes. These rigorous processes ensured that the data collected in the INTERGROWTH-21(st) Project were of exceptionally high quality.

[The institutional accreditation process in the Italian Regions of Emilia Romagna and Lazio: professional contents]

The problems related to the institutional accreditation of the structures of Nephrology, Dialysis and Transplantation has been dealt with in various documents of the Regional Scientific Societies and in Regional Legislative Decrees. Two of these documents are particularly important, one is a special experimental project by the city councillor office for Health Policies issued by the region of Lazio and the other drafted by the Regional Health Agency for the region of Emilia Romagna. What is special about these documents is the fact that nephrologists have actually participated in the drafting process and consequently great attention was given to the professional aspects of the specialised activity. The document issued by the region of Lazio tends to monitor - through criteria, indicators and standards - the various phases of health intervention in Nephrology, by following the different sectors of the process and health care areas identified by the Manual of Accreditation of the Italian Nephrology Society. The document of the region of Emilia Romagna, more complex and articulated, deals systematically with specific requirements (structural, technological, organisational), services, clinical competence and teaching, qualification of diagnostic and therapeutic processes and health care. The Italian Society of Nephrology has been asked to give an official evaluation of both documents. At this particularly uncertain stage, this approach is to be considered as being essential in maintaining consistent performance in the protection of the professional quality of the specialisation in Nephrology.

[Renal atheroembolic disease: evaluation of the efficacy of corticosteroid therapy]

BACKGROUND

Even though many organs may be involved and clinical manifestations are extremely variable, a sudden worsening of renal function after vascular surgery or invasive angiographic manoeuvres is a clue for the diagnosis of renal cholesterol crystal embolization. In rare cases the disease may also occur spontaneously during anticoagulant or thrombolytic therapy. Renal atheroembolism is becoming increasingly recognized as an important cause of renal failure particularly in elderly men, and is often associated with a bad outcome. To date there is no specific and proven useful treatment apart from a few anecdotal reports on the benefits of corticosteroids.

PATIENTS AND METHODS

We report a group of seven patients with cholesterol atheroembolic disease presenting acute renal failure; in six patients the disease appeared after coronary arteriography and PTCA performed in the last four months, and in one patient in an apparently spontaneous form. All the patients presented cutaneous lesions, livedo reticularis, purpuric rush, necrosis of the toes; laboratory data showed an increase of acute phase proteins and eosinophilia. Results. Treatment with prednisolone was begun at a dose of 40 mg/day i.v. for four days; the dose was reduced to prednisone 0.4-0.5 mg/kg/day for 1 week, than gradually reduced further and stopped within a month. Following therapy renal function rapidly improved; clinical symptoms of malaise and abdominal discomfort subsided, with amelioration of skin lesions and cyanosis of toes.

CONCLUSIONS

Despite the small number of patients studied, our experience suggests that corticosteroid treatment is an effective therapeutic option in cholesterol renal atheroembolic disease, especially in the more severe cases of acute renal failure.

Associations of squaric acid and its anions as multiform building blocks of hydrogen-bonded molecular crystals

Squaric acid, H(2)C(4)O(4) (H(2)SQ), is a completely flat diprotic acid that can crystallize as such, as well as in three different anionic forms, i.e. H(2)SQ.HSQ(-), HSQ(-) and SQ(2-). Its interest for crystal engineering studies arises from three notable factors: (i) its ability of donating and accepting hydrogen bonds strictly confined to the molecular plane; (ii) the remarkable strength of the O-H...O bonds it may form with itself which are either of resonance-assisted (RAHB) or negative-charge-assisted [(-)CAHB] types; (iii) the ease with which it may donate a proton to an aromatic base which, in turn, back-links to the anion by strong low-barrier N-H+...O(1/2-) charge-assisted hydrogen bonds. Analysis of all the structures so far known shows that, while H(2)SQ can only crystallize in an extended RAHB-linked planar arrangement and SQ(2-) tends to behave much as a monomeric dianion, the monoanion HSQ(-) displays a number of different supramolecular patterns that are classifiable as beta-chains, alpha-chains, alpha-dimers and alpha-tetramers. Partial protonation of these motifs leads to H(2)SQ.HSQ(-) anions whose supramolecular patterns include ribbons of dimerized beta-chains and chains of emiprotonated alpha-dimers. The topological similarities between the three-dimensional crystal chemistry of orthosilicic acid, H(4)SiO(4), and the two-dimensional one of squaric acid, H(2)C(4)O(4), are finally stressed.

Erythropoietin and cardiocirculatory condition in aged patients with chronic renal failure

BACKGROUND/AIM

The clearest benefit of recombinant human erythropoietin (rHuEPO) in end-stage renal disease is a substantial reduction in transfusion dependency and an improved quality of life. In this report, we describe the efficacy of weekly subcutaneous administration of rHuEPO in 11 elderly patients with anemia secondary to chronic renal failure.

METHODS

The role of rHuEPO therapy in increasing the patient's quality of life and in decreasing the hospitalization rates secondary to cardiac morbidity was verified in 11 elderly patients (age range between 66 and 85 years) with anemia due to chronic renal failure. The mean hemoglobin level at the beginning of the study was 8.2 +/- (SD) 0.7 g/dl, and the serum creatinine concentration was 4.8 +/- 1.36 mg/dl. The patients underwent baseline and annual echocardiography, in addition to an electrocardiogram.

RESULTS

Most patients experienced a partial regression of left ventricular hypertrophy, and no congestive heart failure was documented. The mean hemoglobin level during rHuEPO therapy increased to 11.3 +/- 1.2 g/dl, while the mean serum creatinine concentration did not change significantly.

CONCLUSIONS

Our results confirm that early anemia correction in aged chronic renal failure patients permits improvement of the quality of life, of exercise performance, and of cognitive functions. Reduced transfusion need and regression of left ventricular hypertrophy favor a minor incidence of cardiac morbidity and contribute to reduce health costs.

HBV-related cutaneous periarteritis nodosa in a patient 16 years after renal transplantation: efficacy of lamivudine

Cutaneous periarteritis nodosa (PAN) is a clinical feature characterized by chronic, benign course; its pathogenesis is unknown. In patients submitted to renal transplantation cutaneous PAN is a rare complication. We report a case of cutaneous PAN associated with the reappearance of hepatitis B antigen 16 years after kidney transplantation. A 44-year-old man underwent successful renal transplantation in June 1980. In December 1996 he presented multiple painful erythematous subcutaneous nodules on both legs. Skin lesion biopsy showed the presence of cutaneous PAN. Six months later laboratory data demonstrated the presence of HbsAg. HBeAg, HBcAb and detectable HBV-DNA serum by polymerase-chain-reaction (PCR) assay. Anti-HBs and anti-HBe proved negative. In July 1998 the laboratory tests showed an important increase of HBV-DNA (5.1 billion by Branched DNA), and so lamivudine (100 mg/day) was introduced. HBV-DNA became undetectable by PCR after 3 months of therapy. Seven months later a new skin biopsy was performed. The typical signs of PAN were no longer evident. As HBV infecion was demonstrated six months after the clinical appearance of the PAN, in a patient who was believed to be immune to the virus, it is possible that, in the early stages, the hepatitis B antigen title was methodologically indeterminable, but sufficient to form circulating immune complexes responsible for vasculitis primer. Lamivudine therapy resulted efficacious in favouring the regression of cutaneous PAN, but its long-term efficacy requires further evaluation as regards potential selection of drug resistant hepatitis B virus (HBV) mutants during treatment.

General rules for the packing of hydrogen-bonded crystals as derived from the analysis of squaric acid anions: aminoaromatic nitrogen base co-crystals

Preparation and single-crystal X-ray structure determination of three co-crystals of hydrogen squarate, HSQ(-), with 2-aminopyrimidine, 3-aminopyridine and 4-aminopyridine, and one of squarate, SQ(2-), with 8-aminoquinoline are reported. Their crystal packings are analyzed and discussed in terms of the intermolecular O--H...O, N--H...O/N and C--H...O hydrogen bonds formed. Although the fine details of the supramolecular architecture are barely rationalizable, the comparative analysis of the data makes it possible to suggest some simple rules that may be of general application for the packing of hydrogen-bonded crystals, i.e. Rule 1: 'All hydrogen-bond acceptors available in a molecule will be engaged in hydrogen bonding as far as there are available donors'; Rule 2: 'The hydrogen-bond acceptors will be saturated in order of decreasing strength of the hydrogen bonds formed'.

Prevalence of infected patients and understaffing have a role in hepatitis C virus transmission in dialysis

To assess hepatitis C virus (HCV) incidence rates and identify determinants of infection among hemodialysis patients, a multicenter study was conducted in 58 units in ITALY: An initial seroprevalence survey was conducted among 3,492 patients already on hemodialysis therapy as of January 1997 and among an additional 434 patients who began dialysis up to January 1998. HCV antibodies were assessed by third-generation enzyme immunoassays. Patients testing seronegative at baseline were enrolled into a 1-year incidence study with serological follow-up at 6 and 12 months. For patients who seroconverted, an HCV RNA assay was performed on stored baseline samples to confirm new infection. A nested case-control study was subsequently performed to investigate potential risk factors. For each incident case, three controls negative for both HCV antibodies and HCV RNA were randomly selected. At enrollment, HCV seroprevalence was 30.0%. During follow-up, 23 new HCV cases were documented, with a cumulative incidence of 9.5 cases/1,000 patient-years. By logistic regression analysis, an increased risk for HCV infection emerged for patients attending the dialysis units with a high prevalence of HCV-infected patients at baseline (odds ratio [OR], 4.6) and for those attending units with a low personnel-patient ratio (OR, 5.4). Among extradialysis factors, a history of surgical intervention in the previous 6 months (OR, 16.7) significantly increased HCV risk. These findings suggest that the combination of understaffing and a high level of infected patients in the dialysis setting increases the risk for HCV nosocomial transmission. This is likely related to an increased likelihood for breaks in infection control measures.

Can thermodynamic measurements of receptor binding yield information on drug affinity and efficacy?

The present commentary surveys the methods for obtaining the thermodynamic parameters of the drug-receptor binding equilibrium, DeltaG degrees, DeltaH degrees, DeltaS degrees, and DeltaC degrees (p) (standard free energy, enthalpy, entropy, and heat capacity, respectively). Moreover, it reviews the available thermodynamic data for the binding of agonists and antagonists to several G-protein coupled receptors (GPCRs) and ligand-gated ion channel receptors (LGICRs). In particular, thermodynamic data for five GPCRs (beta-adrenergic, adenosine A(1), adenosine A(2A), dopamine D(2), and 5-HT(1A)) and four LGICRs (glycine, GABA(A), 5-HT(3), and nicotinic) have been collected and analyzed. Among these receptor systems, seven (three GPCRs and all LGICRs) show "thermodynamic agonist-antagonist discrimination": when the agonist binding to a given receptor is entropy-driven, the binding of its antagonist is enthalpy-driven, or vice versa. A scatter plot of all entropy versus enthalpy values of the database gives a regression line with the equation TDeltaS degrees (kJ mol(-1); T = 298.15 K) = 40.3 (+/- 0.7) + 1.00 (+/-0.01) DeltaH degrees (kJ mol(-1)); N = 184; r = 0.981; P < 0.0001 - which is of the form DeltaH degrees = beta. DeltaS degrees, revealing the presence of the "enthalpy-entropy compensation" phenomenon. This means that any decrease of binding enthalpy is compensated for by a parallel decrease of binding entropy, and vice versa, in such a manner that affinity constant values (K(A)) of drug-receptor equilibrium (DeltaG degrees = -RT ln K(A) = DeltaH degrees - TDeltaS degrees ) cannot be greater than 10(11) M(-1). According to the most recent hypotheses concerning drug-receptor interaction mechanisms, these thermodynamic phenomena appear to be a consequence of the rearrangement of solvent molecules that occurs during the binding.

Fatal sepsis from Vibrio vulnificus in a hemodialyzed patient

Vibrio vulnificus, a particularly virulent halophilic vibrio, has been isolated from the blood and skin necrotic lesion of a hemodialyzed patient with sepsis. The patient has had exposure of the skin to seawater. Various chronic conditions including renal failure have a great risk for developing septicemia due to V vulnificus. It is necessary to inform persons with liver diseases or immunocompromising conditions of hazards associated with the consumption of undercooked seafood and seawater exposure.

Clinical characteristics associated to atrial fibrillation in chronic hemodialysis patients

BACKGROUND

Atrial fibrillation (AF) is the most common sustained arrhythmia diagnosed in non-uremic patients and its prevalence increases in older subjects, however, information concerning AF in dialysis patients is scarce. Therefore, we carried out a prospective cross-sectional study from September 1996 to December 1996 in order to evaluate the prevalence and some of the clinical characteristics associated to AF in hemodialysis (HD) patients.

SUBJECTS AND METHODS

316 HD patients (age 63 +/- 12 years, dialysis duration 69 +/- 71 months) treated in three different hospital-based units were studied. Standard 12-lead electrocardiograms (ECGs) carried out in the interdialytic day during the study period were reviewed. Data concerning age, history of ischemic heart disease (IHD), cerebrovascular disease (CVD), peripheral vascular disease (PVD), presence of diabetes, smoking history and antihypertensive therapy were collected. Systolic and diastolic blood pressure, fasting cholesterol and triglycerides, albumin and hemoglobin were also derived from the clinical records. Performance status was assessed by Karnofsky index (Ki).

RESULTS

74 patients (23.4%) had persistent AF, i.e. presence of AF in all (at least two) ECGs performed in the study time. Patients with AF were older (age 69 +/- 10 vs 62 +/- 12 years, p < 0.001), had lower Ki (54 +/- 20 vs 68 +/- 17, p < 0.01), cholesterol (182 +/- 46 vs 198 +/- 52 mg/dl, p < 0.01) and albumin (3.9 +/- 0.5 vs 4.1 +/- 0.5 g/dl, p < 0.001) compared to those with no AF. Prevalence of IHD (44.5% vs 19%, p < 0.05) and PVD (23% vs 11%, p < 0.05) was higher among AF patients. Logistic regression analysis showed that IHD (p < 0.001) and Ki (p < 0.01) were independently associated to AF.

CONCLUSION

We conclude that AF is a frequent arrhythmia in HD patients treated in hospital-based dialysis units, especially in those with low performance status. It appears to be associated to the atherosclerotic damage of coronary arterial tree. Prospective studies are necessary to assess whether it could contribute to cardiovascular morbidity and mortality in end-stage renal disease.

Urinary glycosaminoglycans in recurrent urinary tract infections in kidney transplant patients

Glycosaminoglycans have generalized antibacterial anti-adherent activity, and cooperate with secretory immunoglobulin-A in anti-infection defense mechanisms of the urinary tract. Cyclosporin A modulates T-lymphocytes and fibroblast functions. In this report we analyze urinary glycosaminoglycans and secretory immunoglobulin-A in renal transplant patients with recurrent urinary tract infections treated with cyclosporin. The results show a significant decrease of total glycosaminoglycans and secretory immunoglobulin-A in recurrent urinary tract infections which is unrelated to cyclosporin treatment. The data support the hypothesis that recurrent urinary tract infections may be the consequence of a genetic pathology rather than cyclosporin-induced alterations.

Kaposi's sarcoma in renal transplant recipients: pathogenetic relation between the reduced density of Langerhans cells and cyclosporin-A therapy

Patients treated with immunosuppressive drugs can develop cancers. The authors present two cases of Kaposi's sarcoma in kidney transplant patients who had been treated with azathioprine, steroids and cyclosporin-A; during this treatment the Langerhans cells decreased and Kaposi's sarcoma appeared. Discontinuation or reduction of the dosage of cyclosporin-A led to complete regression of the illness, and the Langerhans cells reappeared. We suggest that cyclosporin-A damages the immunological function of the epidermal Langerhans cells, and that this is the primary factor in the development of Kaposi's sarcoma.

[Causes and risks of hyperlipidemia during dialysis and after renal transplantation]

The most widely studied hyperlipidemies in patients affected by renal insufficiency or subsequent to kidney transplant present phenotype IIa, IIb or IV. The lipidic alteration most frequently observed in chronic renal insufficiency and/or dialytic treatment is represented by hypertrigliceridemia as a result of: 1) altered VLDL metabolism; 2) reduced activity of lecithin cholesterol acyltransferase (LCAT); 3) decrease in Apo-A1 and HDL3. Furthermore, marked anomalies in lipoprotein Lp (a) have been reported in hemodialysis. In patients undergoing peritoneal dialysis, hyperlipidemia arises from both an anomalous retrograde absorption of glucose and protein dispersion. Following kidney transplant the most frequent hyperlipidemia is hypercholesterolemia, consequent to immunosuppressive treatment (mainly steroids and cyclosporin). The documented significant increase of cardiovascular risk in the presence of hyperlipidemia points to the need for a clearer etiopathogenic definition of this anomaly, as well as the necessity to find an efficacious pharmacological treatment.

Binding thermodynamics at the human neuronal nicotine receptor

The thermodynamic parameters deltaGo (standard free energy), deltaHo (standard enthalpy) and deltaSo (standard entropy) of the binding equilibrium of eleven ligands (six agonists and five antagonists) to the neuronal nicotinic receptor were determined by affinity measurements carried out on human thalamus membranes at six different temperatures (0, 10, 20, 25, 30, 35 degrees) and deltaG vs. T plot analysis. Affinity constants were obtained by saturation experiments for [3H]-cytisine, a ganglionic nicotinic agonist, or its displacement in inhibition assays for the other compounds. The deltaG vs T plots appeared to be reasonably linear in the full temperature range for most of the compounds investigated (equilibrium heat capacity change,deltaCo(p) approximately 0), with the exception of the three agonists cytisine, nicotine and methylcarbachol (deltaCo(p) of the order of -720 / -1610 J mol(-1) K(-1)). Thermodynamic parameters were in the range -53.3 < or =deltaHo < or = -28.9 kJ mol(-1) and -41 < or = deltaSo < or = 69 J mol(-1) K(-1) for agonists, and 8.7 < or = deltaHo < or = 68.2 kJ mol(-1) and 99 < or = deltaSo < or = 311 J mol(-1) K(-1) for antagonists, indicating that agonistic binding was both enthalpy- and entropy-driven, while antagonistic binding was totally entropy-driven. Agonists and antagonists were, therefore, thermodynamically discriminated. Experimental results were discussed with particular regard to the following points: 1) reasons why membrane receptors displayed unusually low values of deltaCo(p); 2) possible reasons for the phenomenon of thermodynamic discrimination between agonists and antagonists particularly in connection with ligand-gated ion channel receptors; and 3) the origin of the recurrent phenomenon of enthalpy-entropy compensation which has been observed for neuronal nicotinic receptor ligands as well as for all membrane receptors studied thus far.

Receptor binding thermodynamics as a tool for linking drug efficacy and affinity

Determination of drug-receptor binding constants (association, KA, or dissociation, KD = l/KA) by radiochemical specific binding assays has proved to be an invaluable tool for screening of potential active drugs. Simple determination of KA (or KD) values makes it possible, however, to calculate the standard free energy delta G degree = -RTln KA = RTln KD (T = 298.15 K) of the binding equilibrium but not that of its two components as defined by the Gibbs equation delta G degree = delta H degree - T delta S degree, where delta H degree and delta S degree are the equilibrium standard enthalpy and entropy, respectively. This incomplete knowledge is highly inconvenient from a pure thermodynamic point of view as delta H degree and delta S degree carry much information on the details of the drug-receptor interaction and the interplay of both reaction partners with the solvent. In recent times it has been shown that the relative delta H degree and delta S degree magnitudes can often give a simple 'in vitro' way for discriminating 'the effect', that is the manner in which the drug interferes with the signal transduction pathways. This particular effect, called 'thermodynamic discrimination', results from the fact that binding of antagonists may be enthalpy-driven and that of agonists entropy-driven, or vice versa. The first case of thermodynamic discrimination was reported for the beta-adrenergic G-protein coupled receptor (GPCR) and only recently has it been confirmed for adenosine A1 and A2a receptors. Only very recently has the binding thermodynamics of ligand-gated ion channel receptors (LGICR) been investigated and data for four receptors have been reported showing that all of them are thermodynamically discriminated. While it seems difficult at present to find a reasonable explanation for the thermodynamic discrimination phenomenon in GPCR, some hypotheses can be suggested for LGICR. Since global delta H degree and delta S degree values of the binding process are expected to be heavily affected by rearrangements occurring in the solvent, thermodynamic discrimination in LGICR is at least logically understandable admitting that the observed delta H degree (and then delta S degree) values are determined by both specific binding and abrupt variation of water-accessible receptor surfaces consequent to the setting up of the channel opening.

Intermolecular N-H...O Hydrogen Bonding Assisted by Resonance. II. Self Assembly of Hydrogen-Bonded Secondary Enaminones in Supramolecular Catemers

The crystal structures of 15 compounds containing the 2-en-3-amino-1-one heterodienic system and forming intermolecular N—H...O hydrogen bonds assisted by resonance (RAHB) are reported: (1) 3-phenylamino-2-cyclohexen-1-one; (2) 3-(4-methoxyphenylamino)-2-cyclohexen-1-one; (3) 3-(4-chlorophenylamino)-2-cyclohexen-1-one; (4) 3-(4-methoxyphenylamino)-2-methyl-2-cyclohexen-1-one; (5) 3-(4-methoxyphenylamino)-5-methyl-2-cyclohexen-1-one; (6) 3-isopropylamino-5,5-dimethyl-2-cyclohexen-1-one; (7) 3-phenylamino-5,5-dimethyl-2-cyclohexen-1-one; (8) 3-(3-methoxyphenylamino)-5,5-dimethyl-2-cyclohexen-1-one; (9) N,N-3-aza-pentane-1,5-bis[1-(3-oxo-5,5-dimethyl-1-cyclohexenyl)]; (10) 3-phenylamino-6,6-dimethyl-2-cyclohexen-1-one; (11) 3-(2-methoxyphenylamino)-6,6-dimethyl-2-cyclohexen-1-one; (12) 3-(3-chlorophenylamino)-6,6-dimethyl-2-cyclohexen-1-one; (13) 3-(4-chlorophenylamino)-6,6-dimethyl-2-cyclohexen-1-one; (14) 1-(4-chlorophenyl)-4-(4-chlorophenylamino)-6-methyl-2-pyridone; (15) 3-(4-chlorophenylamino)-5-phenyl-2-cyclopenten-1,4-dione. All compounds form intermolecular N—H...O=C hydrogen bonds assisted by resonance connecting the heteroconjugated enaminonic groups in infinite chains. Chain morphologies are analyzed to find out crystal engineering rules able to predict and interpret the crystal packing. Simple secondary enaminones [i.e. (1)–(13) together with a number of structures retrieved from the Cambridge Structural Database] are found to form hydrogen bonds having π-delocalizations, as characterized by a C=O bond-length average of 1.239 ± 0.004 Å, and hydrogen-bond strengths, represented by the N...O average distance of 2.86 ± 0.05 Å, very similar to those previously found for amides. Enaminones, however, can be easily substituted by chemical groups able to influence both π-conjugations and N...O hydrogen-bond distances. Some substituted enaminones, retrieved from the literature, display, in fact, N...O hydrogen-bond distances as short as 2.627 Å and large π-delocalizations with C=O double-bond distances as long as 1.285 Å. These effects appear to be associated with (a) the presence of further π-conjugated systems involving the C=O and NH groups of the enaminone moiety or (b) the transformation of the enaminone carbonyl group in an amidic function.

Stereochemistry of serotonin receptor ligands from crystallographic data. Crystal structures of NAN-190.HBr, 1-phenylbiguanide, MDL 72222 and mianserin.HCl and selectivity criteria towards 5-HT1, 5-HT2, and 5-HT3 receptor subtypes

The crystal and molecular structures of the following serotoninergic drugs have been determined: (1) 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl]piperazine hydrobromide hemihydrate (NAN-190.HBr), C23H28N3O3+.Br-.1/2H2O, M(r) = 483.42, monoclinic, C2/c, a = 21.916 (4), b = 15.207 (2), c = 14.052 (2) A, beta = 101.56 (1) degree, V = 4588 (1) A3, Z = 8, Dx = 1.40 Mgm-3, lambda (Mo K alpha) = 0.71069 A, mu = 1.823 mm-1, F(000) = 2008, T = 295 K, R = 0.035 for 2617 observed reflections; (2) N-phenylimidocarbonimidic diamide (1-phenylbiguanide), C8H11N5, M(r) = 177.21, monoclinic, P2(1)/c, a = 9.781 (2), b = 35.040(5), c = 11.000 (2) A, beta = 97.72(1) degree, V = 3736(1)A3, Z = 16, Dx = 1.26 Mg m-3, lambda (Mo K alpha) = 0.71069 A, mu = 0.084 mm-1, F(000) = 1504, T = 295 K, R = 0.070 for 3407 observed reflections; (3) 8-methyl-8-azabicyclo[3.2.1]oct-3yl 3,5-dicholorobenzoate (MDL 72222), C15H17Cl2NO2, M(r) = 314.21, triclinic, P1, alpha = 8.480 (3), b = 9.840 (3), c = 10.158 (4) A, alpha = 90.04 (3), beta = 111.77 (3), gamma = 105.07(3) degrees, V = 755.6(5) A3, Z = 2, Dx = 1.38 Mg m-3, lambda(Mo K alpha) = 0.71069 A, mu = 0.430 mm-1, F(000) = 328, T = 295 K, R = 0.070 for 1685 observed reflections; (4) 1, 2, 3, 4, 10, 14b-hexahydro-2-methyldibenzo[c.f]pyrizino[1, 2-alpha]azepine hydrochloride (mianserin. HCl), C18H21N2+. Cl-, M(r) = 300.83, monoclinic, P2(1)/a, a = 9.014 (2), b = 14.917 (2), c = 12.412 (2) A, beta = 108.84 (1) degree, V = 1579.5 (5) A3, Z = 4, Dx = 1.26 Mg m-3, lambda(Mo K alpha) = 0.71069 A, mu = 0.237 mm-1, F(000) = 640, T = 295 K, R = 0.063 for 1493 observed reflections. A systematic structural analysis of the present compounds and others known to interact with the 5-HT1, 5-HT2 and 5-HT3 receptors allows to identify their similarities with the endogenous ligand serotonin (5-HT) and the stereochemical differences which determine selectivity for the various receptor subtypes. The pharmacophoric feature for 5-HT receptor binding is identified in a constant-length vector linking an aromatic ring with a protonated nitrogen, while specific affinities for receptorial subtypes and the nature of the effect appear to be modulated by the dimensions of the substituents at nitrogen.

The determination of plasma transferrin receptor as good index of erythropoietic activity in renal anemia and after renal transplantation

Both the plasma determinations of erythropoietic (EPO) and transferrin receptor (TfR) would provide a good characterization of anemia especially when mixed erythron disorders underlie, such as in renal failure. Immunologic assays of EPO and TfR, as well as standard hematologic determinations (hematocrit, reticulocyte count, serum iron, transferrin, ferritin) were performed in patients with chronic renal failure (CRF), in regular dialysis treatment (RDT) and in transplanted (TX) patients. In nonanemic TX patients both EPO and TfR ranged normally, whereas in anemic TX ones (Hct < 40%) both values were increased suggesting the physiologic response both of the kidney and of the erythron to decreased red cell mass. In transitory posttransplant erythrocytosis the increased values of TfR, with normal EPO values, would hypothesize a defective feedback to EPO release. Both EPO and TfR values were found increased in TX patients with adult polycystic kidney disease with persistent erythrocytosis (Hct > 50%), thus confirming previous observations. In CRF and RDT patients, all anemic, both EPO and TfR were normal, even though significantly low with respect to the degree of anemia. In RDT seriously anemic patients, the administration of recombinant human EPO induced different patterns of bone marrow response. We conclude that the determination of TfR would provide further information on renal anemia since the receptor increase mostly preceded the rise of Hct, evidencing those patients who will not have an effective bone marrow response to the therapy.