Analysis of historical porous building materials by the NMR-MOUSE

Samples of sandstone with and without deposits of silicon oxide stone strengthener as well as samples of historical brick material were analyzed by transverse NMR relaxation and mercury intrusion porosimetry. Relaxation times and relaxation time distributions of the protons from the water saturated samples were measured by low-field NMR using homogeneous and inhomogeneous fields. The measurements in inhomogeneous fields were performed with two different NMR-MOUSE sensors, one with a field gradient of 2 T/m and the other with an average field gradient of about 20 T/m. In the sandstone samples the application of stone strengtheners was shown to result in a confinement of the large pores within the outer layer of a few millimeters depth. Depending on the ferromagnetic contamination of the brick samples, the relaxation time distributions can be affected. The agreement of T2 relaxation time distributions and pore size distributions from mercury intrusion porosimetry was found to be better for the NMR-MOUSE sensors than for the homogeneous field measurements. This is true even for different brick samples, unless the content in ferromagnetic particles is very strong.

Corpeptins, new bioactive lipodepsipeptides from cultures of Pseudomonas corrugata

The structure of the corpeptins, bioactive lipodepsipeptides produced in culture by Pseudomonas corrugata, the causal agent of tomato pith necrosis, has been determined. The combined use of FAB-mass spectrometry, NMR spectroscopy and chemical procedures has allowed us to assign the following primary structure to the peptide moiety: Dhb-Pro-Ala-Ala-Ala-Val-Val-Dhb-Hse-Val-alle-Dhp-Ala-Ala-Ala-Val-D hb-aThr-Ala-Dab-Ser-Ile with the terminal carboxy group closing a macrocyclic ring on the hydroxy group of the allo-threonine residue. The N-terminus is in turn acylated by 3-hydroxydecanoate in corpeptin A and by cis-3-hydroxy-5-dodecenoate in corpeptin B. Some preliminary data on the biological activity of corpeptins are included.

Structure-activity relationships in open ansa-chain rifamycin S derivatives as inhibitors of HIV-1 reverse transcriptase

Three types of open ansa-chain rifamycin S derivatives have been prepared: derivatives with the ansa-chain open at C(29) and the original dihydrofuranone ring; derivatives with the ansa-chain open at C(29) and a furane ring; derivatives with the ansa-chain at open NH-C(15). Only derivatives of the first type are weak inhibitors of HIV-1 reverse transcriptase (IC50 ca.300 microM) while derivatives of the two other types are inactive. It has been hypothesized that the active derivatives inhibit the viral enzyme interacting through the groups C(14)H3, C(13)H3, and C(1)O at the same site as the well-known inhibitors TIBO and Nevirapine. In particular C(13)H3 must be unhindered and in an appropriate position out of the plane containing the chromophore-rings. The open ansa-chain seems to play the role of a lipophylic substituent.

Novel bioactive lipodepsipeptides from Pseudomonas syringae: the pseudomycins

The covalent structure and most of the stereochemistry of the pseudomycins, bioactive metabolites of a transposon-generated mutant of a Pseudomonas syringae wild-type strain proposed for the biological control of Dutch elm disease, have been determined. While two pseudomycins are identical to the known syringopeptins 25-A and 25-B, pseudomycins A, B, C, C' are new lipodepsinonapeptides. For all of these the peptide moiety corresponds to L-Ser-D-Dab-L-Asp-L-Lys-L-Dab-L-aThr-Z-Dhb-L-Asp(3-OH) -L-Thr (4-Cl) with the terminal carboxyl group closing a macrocyclic ring on the OH group of the N-terminal Ser. This is in turn N-acylated by 3,4-dihydroxytetradecanoate in pseudomycin A, by 3-hydroxytetradecanoate in pseudomycin B, by 3,4-dihydroxyhexadecanoate in pseudomycin C, and by 3-hydroxyhexadecanoate in pseudomycin C'. Some preliminary data on the biological activity of pseudomycin A are reported.

Episodic changes of serum procollagen type I carboxy-terminal propeptide levels in fertile and postmenopausal women

The aim of the present study was to optimize the use of serum procollagen type I carboxy-terminal propeptide (PICP) as a possible marker of postmenopausal-376lted changes of bone metabolism. Postmenopausal (n = 20) and healthy fertile young (n = 4) women were studied after informed consent. The postmenopausal women were subdivided in 4 groups: (1) nontreated; (2) treated with estrogen-progestogen replacement therapy; (3) treated with calcitonin, or (4) with kidney or liver diseases. Blood samples were collected at 15-min time intervals for 4, 6 or 8 h. Serum concentration of PICP was measured by radioimmunoassay, in duplicate at two different dilutions. In postmenopausal women mean +/- SEM serum PICP levels were slightly but nonsignificantly higher than in fertile women. Serum PICP levels in estrogen-progestogen or calcitonin-treated women were significantly lower than in non-treated postmenopausal women. Episodic changes of circulating PICP level were observed in fertile and postmenopausal women. The pulses of serum PICP levels did not show significant differences among the groups of women studied. The present study showed that the measurement of serum PICP levels is a useful marker for investigating the changes of bone metabolism. In particular, low PICP levels in postmenopausal women under steroid hormone or calcitonin treatment in part reflect the changes of bone turnover. The pulses of serum PICP levels during a time interval suggest that collagen metabolism in women undergoes a rapid turnover.

Rifamycins as inhibitors of retroviral reverse transcriptase from M-MuLV, RAV-2, and HIV-1

29 Rifamycins were tested for inhibition of Reverse Transcriptase (RT) as potential anti HIV drugs. Two purified commercial enzymes from M-MuLV and RAV-2 were used. Anti-RT activity was also measured on a crude lysate of HIV-1. The results show that some derivatives have interesting levels of activity on isolated M-MuLV and RAV-2 RTs, while they are less active on the RT in the crude HIV-1 lysate. The active derivatives include oximes and hydrazones, alkylaminoderivatives, open ansa-chain derivatives and derivatives carrying a modified nucleoside.

Maternal hyperoxygenation in the treatment of intrauterine growth retardation

OBJECTIVE

In the current study the efficacy of maternal hyperoxygenation on growth-retarded fetuses was evaluated.

STUDY DESIGN

Thirty-six pregnant women with intrauterine growth retardation were studied. The patients were divided in oxygen-treated (n = 17) and untreated (n = 19) groups. Doppler analysis of the fetal circulation was performed on the arrival to the hospital, after 12 hours, and thereafter on alternate days until delivery. Fetal blood was sampled by cordocentesis for immediate blood gas analysis at entrance to the study and the day of delivery.

RESULTS

Significant improvement in Doppler flow patterns in treated patients were found when compared with untreated women. The Doppler variations were associated with complementary modifications in fetal blood gas. These differences resulted in a significant modification in perinatal mortality with an incidence of 29% and 68% (p less than 0.01) in treated and untreated groups, respectively.

CONCLUSION

Our data suggest a benefit of maternal hyperoxygenation in the treatment of fetal growth retardation.

The brain as a target organ of gonadal steroids

Gonadal steroids have many effects in the central nervous system. Through a feedback mechanism, they influence the synthesis and release of hypothalamic gonadotropin-releasing hormone (GnRH) and/or pituitary gonadotropic hormones (luteinizing hormone, LH, and follicle stimulating hormone, FSH). Endogenous opioid peptides (EOPs) represent one of the key factors modulating the activity of sex steroids on the hypothalamus-pituitary-gonadal (HPG) axis. In particular, these peptides control the secretion of LH by inhibiting the activity of the hypothalamic neurons which produce GnRH. The EOP effect is dependent on the steroid hormone milieu, as shown by different responses to naloxone administration, both in animals and in humans. For the naloxone-induced increase in LH secretion to occur, relatively high levels of sex steroids are required. In humans, LH release is absent before sexual maturation. In fertile women, naloxone administration increases LH levels in the luteal phase but not in the follicular phase. In the postmenopausal period, naloxone has no effect on LH release; estrogen/progestin therapy does restore the LH response.

Syringopeptins, new phytotoxic lipodepsipeptides of Pseudomonas syringae pv. syringae

The primary structure of some new lipodepsipeptides named syringopeptins, produced by plant pathogenic strains of Pseudomonas syringae pv. syringae has been determined by a combination of chemical methods, 1H and 13C NMR spectroscopy and FAB mass spectrometry. Two syringomycin-producing strains afforded 3-hydroxydecanoyl-Dhb-Pro-Val-Val-Ala-Ala-Val-Val-Dhb-Ala-Val-Ala- Ala-Dhb-aThr-Ser-Ala-Dhb-Ala-Dab-Dab-Tyr, with Tyr acylating a Thr to form a macrolactone ring, and smaller amounts of the 3-hydroxydodecanoyl homologue. Evidence was obtained that a third syringomycin-producing strain and a syringotoxin-producing strain synthesize 3-hydroxydecanoyl-Dhb-Pro-Val-Ala-Ala-Val-Leu-Ala-Ala-Dhb-Val-Dhb- Ala-Val-Ala-Ala-Dhb-aThr-Ser-Ala-Val-Ala-Dab-Dab-Tyr, with Tyr and aThr forming again the macrolactone ring, and smaller amounts of the 3-hydroxydodecanoyl homologue.

Reduced spinal bone density in young women with amenorrhoea

To assess the influence of diminished oestrogen production on bone density, we studied 23 amenorrhoeic women and 20 controls (age range 16-29 years) divided into four groups: group 1: 6 patients with idopathic hypogonadotrophic hypogonadism with primary amenorrhoea (IHH); group 2: 5 patients with delayed puberty owing to thalassaemia major (TM); group 3: 12 patients with secondary hypothalamic amenorrhoea (HA); group 4: 20 women with normal menses (controls). Secondary sexual characteristics had developed in all except the women with TM. Groups 1 and 2 had never menstruated and group 3 had been amenorrhoeic for 6 months to 3 years. The control group was studied during the follicular phase of the cycle. None of the patients were taking oestrogens at the time of observation. Plasma concentrations were determined for 17 beta-oestradiol (E2), deidroepiandrosterone sulphate (DHEA-S), cortisol (F), prolactin (PRL), thyroid hormones (T3 and T4), and gonadotrophins (LH and FSH). Spinal bone mineral density (BMD g/cm2) was assessed by dual photon absorbiometry. BMD (mean +/- 1SD) was reduced in the patients (group 2: 0.920 +/- 0.95; group 1: 0.980 +/- 0.94; and group 3: 1.037 +/- 0.75) as compared with the controls (1.290 +/- 0.95) (P less than 0.01). In the three groups of patients, plasma E2 levels were lower than 50 pg/ml and were positively correlated with the BMD. As expected, plasma gonadotrophin levels were highly and significantly reduced (P less than 0.01) in the patients, compared with that of the controls. These results suggest that reduced spinal BMD in hypogonadic women may be related to the lack of oestrogenic influence on bone metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidermal growth factor and transferrin receptor expression in human embryonic and fetal epidermal cells

Epidermal growth factor receptors (EGFR) and transferrin receptors (TFR) are known to be involved in cell proliferation and to be expressed in normal human epidermis. To date little is known about EGFR and TRF expression in human skin during embryonic and fetal development. In the present work, we studied skin specimens from 30 aborted embryos and fetuses ranging from 7 to 31 weeks estimated gestational age. Monoclonal antibodies to EGFR and TFR were applied on frozen skin sections using an amplification biotin-streptavidin-fluorescein technique. TFR was faintly expressed on epidermal basal cells throughout embryonic and fetal development, as it is in adult epidermis. Up to week 12, EGFR was uniformly expressed on cells of the basal, intermediate and periderm cell layers. From the midfetal period onwards, the suprabasal cell layers showed a decreased staining compared with the basal layer. During the third trimester the cornified cell layer was completely negative. The hair germ and heir peg cells were positive. Later, the outer root sheath and hair bulb remained labelled, with less staining of the hair cone. The sebaceous and eccrine sweat glands were also labelled. These results suggest that in embryonic and fetal epidermis, TFR expression is not correlated with cellular proliferation, whereas EGFR appear to be associated with proliferating and undifferentiated cells.

Structure of syringotoxin, a bioactive metabolite of Pseudomonas syringae pv. syringae

The covalent structure of syringotoxin, a bioactive metabolite of Pseudomonas syringae pv. syringae isolates, pathogenic on various species of citrus trees, has been deduced from 1D and 2D 1H- and 13C-NMR spectra combined with extensive FAB-MS data and results of some chemical reactions. Similarly to syringomicins and syringostatins, produced by other plant pathogenic strains of P. syringae pv. syringae, syringotoxin is a lipodepsinonapeptide. Its peptide moiety corresponds to Ser-Dab-Gly-Hse-Orn-aThr-Dhb-(3-OH)Asp-(4-Cl)Thr with the terminal carboxy group closing a macrocyclic ring on the OH group of the N-terminal Ser, which in turn is N-acetylated by 3-hydroxytetradecanoic acid.

[Ovarian cancer and pregnancy. Description of a clinical case]

A case of conservatively treated ovarian cancer in pregnancy is presented. Careful diagnosis is proposed and above all personalisation of each individual case so as not to use the customary, easy radical surgery.

[Transvesical cesarean section]

On the basis of a clinical case the authors report the technique of laparotomic transvesical incision for cesarean section, which, nevertheless, has limited and special indications.

The structure of syringomycins A1, E and G

By a combination of 1D and 2D 1H- and 13C-NMR, FAB-MS, and chemical and enzymatic reactions carried out at the milligram level, it has been demonstrated that syringomycin E, the major phytotoxic antibiotic produced by Pseudomonas syringae pv. syringae, is a new lipodepsipeptide. Its amino acid sequence is Ser-Ser-Dab-Dab-Arg-Phe-Dhb-4(Cl)Thr-3(OH)Asp with the beta-carboxy group of the C-terminal residue closing a macrocyclic ring on the OH group of the N-terminal Ser, which in turn is N-acylated by 3-hydroxydodecanoic acid. Syringomycins A1 and G, two other metabolites of the same bacterium, differ from syringomycin E only in their fatty acid moieties corresponding, respectively, to 3-hydroxydecanoic and 3-hydroxytetradecanoic acid.

Intra-uterine growth retardation is associated with increased levels of magnesium in amniotic fluid

Magnesium (Mg) and zinc (Zn) levels were measured in amniotic fluid of 30 normal pregnancies between the 16th and the 42nd week of amenorrhea and in 15 cases of intra-uterine growth retardation (IUGR) at 30-38th week of pregnancy. While Zn levels were stable throughout physiological pregnancy, the Mg concentration decreased progressively from 1.09 +/- 0.31 mg/100 ml (mean +/- SD) at the end of the second trimester to 0.75 +/- 0.20 (p less than 0.02) at term. In the case of IUGR, Mg levels (1.22 +/- 0.28) were higher than in controls (0.89 +/- 0.27, p less than 0.01) matched for gestational age. No differences in Zn levels were found between the two groups. Although the mechanisms leading to Mg accumulation in the amniotic fluid of growth-retarded fetuses remain unknown, these data support the role played by Mg in fetal growth.

Plasma and amniotic fluid immunoreactive neuropeptide-Y level changes during pregnancy, labor, and at parturition

This study was designed to determine the presence of and possible changes in plasma and amniotic fluid immunoreactive neuropeptide-Y (irNPY) levels in pregnant women during gestation and at parturition. We studied 127 healthy pregnant and 12 nonpregnant women. The peptide was extracted from plasma or amniotic fluid with a propanolformic acid mixture and measured by RIA. The mean plasma irNPY concentration in 15 pregnant women during the first trimester of gestation was 129 +/- 12 (+/- SE) pmol/L, compared to 40 +/- 8 pmol/L in nonpregnant women (p less than 0.01). The mean values were 144 +/- 13 and 156 +/- 24 pmol/L, respectively, in 15 pregnant women during the second trimester and 33 women during the third trimester. These values did not differ from that during the first trimester. Amniotic fluid irNPY levels were similar to those in plasma and did not vary among the 3 groups of women studied during the various trimesters of gestation. During labor, plasma irNPY levels progressively increased, reaching the highest levels at the most advanced stages of cervical dilatation (greater than 8 cm, 351 +/- 38 pmol/L) and at the time of vaginal delivery (416 +/- 73 pmol/L). Plasma irNPY levels then decreased significantly 2 h after vaginal delivery. The amniotic fluid irNPY levels in women during the early or late stages of labor were similar. Moreover, plasma and amniotic fluid irNPY levels at the time of elective cesarean section also were similar. These results indicate that pregnant women have high plasma and amniotic fluid irNPY levels and that the stress of labor results in a further increase in plasma levels, suggesting a possible role of NPY in human pregnancy and parturition.

Proopiomelanocortin-related peptides and methionine enkephalin in human follicular fluid: changes during the menstrual cycle

Several studies indicate the presence of different pituitary hormones or neuropeptides in ovarian follicular fluid from various species. Recently our group showed that the ovarian follicular fluid of health women contains two of the endogenous opioid peptides, beta-endorphin and methionine enkephalin, in concentrations that are tenfold to twentyfold higher than in circulating plasma. The presence of immunoreactive beta-lipotropin was also shown. The aim of the present study was to evaluate whether adrenocorticotropic hormone, which in pituitary cells is synthesized from proopiomelanocortin such as beta-endorphin and beta-lipotropin, is also present in follicular fluid and the possible changes of proopiomelanocortin-related peptides during the menstrual cycle. Concentrations of beta-endorphin, methionine enkephalin, adrenocorticotropic hormone, and beta-lipotropin were measured in 60 healthy menstruating women at different periods of the menstrual cycle (20 during the follicular, 22 in the preovulatory days, and 18 during the luteal phase). Thirteen women participated in an in vitro fertilization program and thus received clomiphene citrate (100 mg/day from the fifth to the ninth day) plus 5000 IU human chorionic gonadotropin before starting the program. All samples were collected at laparoscopy under general anesthesia. In another eight patients fluid was collected from follicular cysts. Peptides were extracted on octadodecasilyl silica columns with 80% methanol in 0.5 mol/L acetic acid. The identity of follicular fluid beta-endorphin, methionine enkephalin, adrenocorticotropic hormone, and beta-lipotropin and standard peptides was demonstrated with high-pressure liquid chromatography. Peptide concentrations were measured in extracts by radioimmunoassays either directly by (methionine enkephalin and adrenocorticotropic hormone) or after (beta-endorphin and beta-lipotropin) gel filtration on Sephadex G-75. The concentrations of methionine enkephalin, adrenocorticotropic hormone, and beta-lipotropin were similar in the different periods of the cycle. Conversely, beta-endorphin concentrations were significantly higher in preovulatory days than in the other periods; no differences were evident between spontaneous and stimulated cycles. These results indicate that proopiomelanocortin-related peptides are present in the follicular fluid and that beta-endorphin concentrations change during the menstrual cycle, with the highest values occurring in the preovulatory follicle.

[Ileal occlusion associated with ascites following delivery]

An ascite complicated an acute ileal obstruction in the immediate post-partum period. The basal hormonal condition and a pharmacological treatment with synthetic oxytocin have to be considered as important etiological factors.

Human remains of Homo sapiens neanderthalensis from the pleistocene deposit of Santa [corrected] Croce Cave, Bisceglie (Apulia), Italy

The paper deals with a Neanderthal human femur, recovered during excavations in Santa [corrected] Croce Cave, Bisceglie. The cave also yielded Mousterian lithic industry and fauna indicating a paleoclimate condition with dry-warm tendency and savannah landscape. Metrical, morphometrical, and morphological analysis, and the comparison with Neanderthal specimens show that the femur belonged to an adult individual. It particularly shows great affinities with the analogous specimens from La Ferrassie 1 and 2, Spy 2, and Fond de Forêt, which are similar in size and, above all, show similar archaic morphological traits.

Prostaglandin-induced mid-pregnancy abortion increases plasma and amniotic fluid levels of beta-lipotropin and beta-endorphin

The continuous and progressive rise of beta-endorphin (B-EP), beta-lipotropin (B-LPH) and cortisol plasma levels during labor in term-pregnant women represents one of the most relevant maternal hormonal responses to the stress of parturition. The aim of the present study was to evaluate the changes of these hormones, both in plasma and amniotic fluid (except cortisol), in a group of pregnant women undergoing prostaglandin-induced therapeutic abortion at the 2nd trimester of pregnancy. B-EP, B-LPH and cortisol were measured by radioimmunoassay. Both plasma and amniotic fluid samples were purified through extraction and chromatography (Sephadex G-75 columns). The prostaglandin derivative, 16-phenoxy-PGE2-methylsulfonylamide (sulprostone, Schering, Berlin) (500 micrograms, i.m., every 4 h), caused a rapid and significant rise of plasma B-EP, B-LPH and cortisol levels in all subjects. The relative increase of the 3 hormones was less relevant after the 2nd and absent after the 3rd injection of PGE2. The amniotic fluid concentrations of B-EP and B-LPH were also raised 2 h after the 1st injection. These data indicate that sulprostone-induced abortion activates both maternal and fetoplacental release of opioids independently of the trend of uterine contractions. The pattern of pro-opiomelanocortin-related labor differs from spontaneous labor and can probably be linked to a direct effect of the drug.

Met-enkephalin enhances follicle-stimulating hormone-dependent progesterone production from cultured granulosa cells

beta-Endorphin (beta-EP) and methionine-enkephalin (Met-Enk) have been detected in human follicular fluid in concentrations several times higher than those in plasma. These data stimulated us to study the possible physiological role of ovarian opioids. We, therefore, determined the effects of both beta-EP and Met-Enk, alone or in combination with naloxone, on FSH-induced progesterone (P) secretion by cultured granulosa cells. Granulosa cells were collected from follicular fluid recovered at laparoscopy in seven superovulated women. The cells were preincubated with RPMI-1640 medium containing 20% fetal calf serum in 5% CO2 for 48 h, followed by the addition of 100 mU purified FSH and the various test substances for 48 more h. beta-EP (10 nM to 1 pM) had no effect on P secretion either alone or in combination with FSH and/or naloxone. Micro- to picomolar amounts of Met-Enk increased FSH-induced P secretion up to 186.9 +/- 35.1% (+/- SEM). Met-Enk had no affect in the absence of FSH, and its action was significantly blunted by the concomitant addition of 10(-5) M naloxone. These data provide evidence for a dose-dependent naloxone-reversible synergistic action of Met-Enk and FSH on P secretion by cultured granulosa cells. This finding supports the hypothesis of the existence of an ovarian opioid system.

Beta-endorphin and met-enkephalin in peritoneal and ovarian follicular fluids of fertile and postmenopausal women

Immunoreactive (IR) beta-endorphin (beta-EP) and met-enkephalin (MET-ENK) have been found in peritoneal fluid (PF) and ovarian follicular fluid (FF). Gel chromatography also revealed the presence of coeluting IR beta-lipotropin and gamma-lipotropin. IR beta-EP and IR MET-ENK levels in healthy menstruating women were from 10 to 40 times higher than those present in circulating plasma, which indicated a possible local production. The highest concentrations of IR beta-EP in FF were found in the largest follicles, whereas in the PF they correlated with the luteal period of the menstrual cycle and with progesterone concentrations. No relevant changes in IR MET-ENK were detected in the FF or in the PF in relation to the phase of the menstrual cycle. In postmenopausal women, the concentrations of the two IR opioid peptides were undetectable in both fluids.

Chemical modifications of the aliphatic bridge of ansamycins. 3. Synthesis and activity of 21-epi-rifamycin S

Rifamycins inhibit bacterial DNA-dependent RNA polymerase through the formation of non-covalent bonds by the oxygenated groups at C(1), C(8), C(21), and C(23). These must be unhindered and underivatized, with the antibiotic in a proper overall molecular conformation. The present study shows that contrary to previous conclusions the availability of the hydroxyl group at C(21) is not as important as that of the other three groups. In support of this is the observation that 21-epi-rifamycin S is partially active, both on the isolated DNA-dependent RNA polymerase and on some Gram-positive bacterial strains.

A study of structure-activity relationships in 4-deoxypyrido[1',2'-1,2]imidazo[5,4-c]rifamycin SV derivatives by electron spectroscopy for chemical analysis and 1H NMR

A new class of rifamycins, 4-deoxypyrido[1',2'-1,2]imidazo[5,4-c]rifamycin SV derivatives, has been synthesized. They are potent antibacterial agents and are not absorbed at the gastrointestinal level and can therefore probably be used as antibacterial intestinal disinfectants. From the present X-ray, electron spectroscopy for chemical analysis, and 1H NMR study, it appears that this peculiar pharmacokinetic behavior is mainly to be attributed to the fact that the pyridoimidazo system exists in these compounds in a mesomeric betaine form, bearing one positively and one negatively charged nitrogen. If it is assumed that rifamycins are generally absorbed by passive diffusion, the presence of the two oppositely charged nitrogens, together with the presence of the phenolic hydroxyls, means that these molecules are ionized at all pH values encountered along the gastrointestinal tract, which thus prevents their absorption. These molecules also display a strong tendency to self-associate both in solution and in the solid state, and the increase in molecular size may also play a role in preventing their absorption.

The synthesis of 4-deoxypyrido[1',2'-1,2]imidazo[5,4-c]rifamycin SV derivatives

Two series of new semisynthetic rifamycin SV derivatives have been prepared. One of them bears a quaternary ammonium salt at C3 (1-5), and the other a pyridoimidazo system condensed at C3 and C4 (6-11). While compounds 1-5 had poor antibacterial activity in vitro, compounds 6-11 were found to be highly active in vitro but poorly absorbed in vivo. They could thus have potential as agents in the therapy of intestinal infections. The synthesis and the 1H NMR structure determination of these new compounds are reported.

Metabolites of microorganisms. 229. Absolute configuration of naphthomycin A determined by X-ray analysis and chemical degradation

The relative and absolute configurations of naphthomycin A were elucidated by an X-ray structural analysis of a methylation product, 25-O-methylnaphthomycin A iminomethyl ether. The absolute configuration was confirmed by degradation (O3, NaBH4) to (S)-butane-1,2,4-triol.

X-ray crystal structure of 4-deoxy-3'-bromopyrido(1',2'-1,2)imidazo(5,4-c)rifamycin S

This paper reports the determination of the X-ray molecular structure of 4-deoxy-3'-bromopyrido[1',2'-1,2]imidazo[5,4-c]rifamycin S, carried out in order to unequivocally define the general structure of a new series of rifamycin SV derivatives, which are potent antibacterial agents, and are not absorbed at the gastroenteric level. They have been prepared by Alfa Farmaceutici, Bologna, by condensing 2-aminopyridine derivatives to 3-bromorifamycin S. The solid state X-ray study has confirmed the structure proposed on the basis of 1H NMR studies in solution. It has also shown that the newly formed pyridoimidazo system is in a mesomeric betaine form, the pyrido nitrogen being positively charged and the imidazo nitrogen being negatively charged. This feature is believed responsible for the pharmacokinetic behavior of these new drugs, one of which, denoted either as rifamycin L 105 or rifaximin, is actually under clinical trial as a topical intestinal disinfectant.

1H n.m.r. of the DNA-dependent RNA polymerase from Escherichia coli

The (1)H n.m.r. study of the DNA-dependent RNA polymerase from Escherichia coli has revealed that the holoenzyme (betabeta'alpha(2)sigma) displays two mobile regions: one, observable also in the core enzyme (betabeta'alpha(2)), is characterized by basic amino acids and its appearance and form depend on ionic strength; the other, specific to the holoenzyme, is characterized by threonine residues and its appearance does not depend on ionic strength.

Structure-activity relationships in the ansamycins. Molecular structure and activity of 3-carbomethoxy rifamycin S

The X-ray and NMR structural study of 3-carbomethoxy rifamycin S5 was undertaken in order to determine whether its low antimicrobial activity was related to a conformation of the molecule which was unfavorable for interaction with bacterial DNA-dependent RNA polymerase. However, the molecule assumes a conformation similar to that of the active rifamycins. Indeed the compound was found to be active on the isolated enzyme, so that its low activity on whole bacteria has to be attributed to factors affecting its penetration through the bacterial cell wall.

Camptomelic syndrome. A rare type of congenital dwarfism associated with skeletal and other abnormalities

Three cases of the rare camptomelic syndrome are presented observed within fourteen months at the Mangiagalli University Clinic, Milan. The radiographic appearances and clinical characteristics are described, and compared with the thirty five cases in the literature. The differential diagnosis is discussed and the possibility of diagnosing this malformation prenatally is suggested.