Growth factors and IL-17 in hereditary angioedema.

Hereditary angioedema (HAE) is a rare autosomal dominant disorder, due to C1-inhibitor deficiency, which causes episodic swellings of subcutaneous tissues, bowel walls and upper airways which are disabling and potentially life-threatening. We evaluated n = 17 patients with confirmed HAE diagnosis in basal and crisis state and n = 19 healthy subjects. The samples were tested for IL-17, FGFb, G-CSF and GM-CSF, using Bio-plex kit. Data analysis was performed via nonparametric Spearman's correlations and two sets of linear mixed models. When comparing HAE subjects during basal and crisis states, we found out significantly (i.e., p value <0.05) higher values in crisis states rather than in basal states for the three growth factors and cytokine IL-17. When comparing healthy subjects versus HAE patients at basal state, we found out significantly higher values in HAE subjects only for GM-CSF, FGFb and IL-17, but not for G-CSF. In HAE patients, there is a connection between IL-17 and growth factors. The low-grade inflammation in absence of attacks is demonstrated by constant higher amount of IL-17, FGFb and GM-CSF with respect to healthy patients. This could indicate that in this disease there is a level of activation that maintains the system in a "tick-over state," that can be activate by several stimuli that are able to induce a increase in inflammatory mediators during the acute attack.

Effects of ethanol on protein kinase C activity induced by filamentous actin.

Protein kinase C (PKC) can be activated by interaction with filamentous actin (F-actin) in the absence of membrane lipids (S.J. Slater, S.K. Milano, B.A. Stagliano, K.J. Gergich, J.P. Curry, F.J. Taddeo and C.D. Stubbs, Biochemistry 39 (2000) 271-280). Here, the effects of ethanol on the F-actin-induced activities of a panel of PKC isoforms consisting of 'conventional' (cPKC) alpha, betaI, gamma, 'novel' (nPKC) delta, epsilon and 'atypical' (aPKC) zeta were investigated using purified PKC and F-actin. Ethanol was found to inhibit the Ca2+- and phorbol ester-dependent activities of cPKCalpha and betaI, and the Ca2+- and phorbol ester-independent activity of cPKCgamma, whereas the activities of nPKCdelta, epsilon and aPKCzeta were unaffected. Although the activities of cPKCalpha and betaI induced by saturating levels of phorbol ester were inhibited by ethanol, the binding of these isozymes to F-actin was unaffected within the same phorbol ester concentration range. Conversely, within submaximal levels of phorbol ester, cPKCalpha and betaI activities were unaffected by ethanol whereas binding to F-actin was inhibited. The potency of the inhibition of F-actin-induced cPKCbetaI activity increased with n-alkanol chain length up to n-hexanol, after which it declined. The results indicate that PKC activities associated with F-actin, and therefore cellular processes involving the actin cytoskeleton, are potential targets for ethanol action. The effects of ethanol on these processes may differ according to the particular regulating PKC isoform, its intracellular localization and the presence of activators and cofactors.

MICE: a new active combination for non-small cell lung cancer.

We have treated 38 patients with stage III/IV non-small cell lung cancer with the following regimen: mitomycin-C = 6 mg/m2, ifosfamide = 3 g/m2, cisplatin = 75 mg/m2, vindesine = 3 mg/m2 (MICE), intravenously (i.v.) on day 1, every 3 weeks. Among 26 patients with stage IV disease, 15 obtained a partial remission (PR) (response rate = 57%, 95% confidence interval = 38-76), with a median time to disease progression and a median survival of 4.9 and 7.1 months, respectively. 6 out 7 patients with stage IIIA disease were documented as PR and 5 of them underwent radical surgery with two pathologically confirmed complete remissions. Overall toxicity was substantial but manageable: 3 patients had grade III/IV leucopenia (although 5 patients had neutropenic fever) whereas 13 patients experienced grade II/II anaemia. In conclusion we believe that MICE regimen is an interesting combination and warrants further evaluations both for palliation and in a neoadjuvant setting.

Rapid quantitative method for measuring phagocytosis of Leishmania promastigotes using a double radiolabelling method.

A double radiolabelling method is described for the measurement of phagocytosis of Leishmania major promastigotes in cultures of murine resident peritoneal macrophages. L. major promastigotes were radiolabelled during exponential growth in RPMI supplemented with [125I]5-iodo-2-deoxyuridine. They were used to infect sodium [51Cr]chromate-labelled macrophages. Phagocytosis was evaluated by measuring the radioactivity of the 125IUdR-labelled parasites detectable inside 51Cr-labelled macrophages by a Beckmann gamma 5500 counting system. This was able to count simultaneously, in two different windows the radioactivity of (a) the parasites and (b) the cells. The technique compares favorably with the conventional light microscopic technique and appears to be more sensitive, totally objective, and easy to use for the rapid analysis of multiple samples. Furthermore, the double radiometric method permits a more precise distinction between adherent and engulfed organisms than does the microscopic assay.

Studies on the role of 5-HT1A autoreceptors and alpha 1-adrenoceptors in the inhibition of 5-HT release--I. BMY7378 and prazosin.

UNLABELLED: The present study utilized in vivo microdialysis to investigate the importance of 5-HT1A autoreceptors and alpha 1-adrenoceptors in the decreased 5-HT release obtained following administration of the mixed 5-HT1A autoreceptor partial agonist/alpha 1-adrenoceptor antagonist BMY7378, the selective 5-HT1A receptor agonist 8-OH-DPAT and the alpha 1-adrenoceptor antagonist prazosin. BMY7378 (0.25 mg/kg, s.c.), 8-OH-DPAT (0.025 mg/kg, s.c.) and prazosin (0.1-1.0 mg/kg, s.c.) all suppressed ventral hippocampal 5-HT efflux. The BMY7378- and 8-OH-DPAT-induced inhibition of 5-HT release were reversed by a 40 min pre-treatment with either (+/-)pindolol (8 mg/kg, s.c.) or WAY-100635 (0.3 mg/kg, s.c.), to block 5-HT1A autoreceptors. Neitehr of these antagonists altered the prazosin-induced (0.3 mg/kg, s.c.) 5-HT disease. THE RESULTS: (i) confirm that both an alpha 1-adrenoceptor antagonist (prazosin) and 5-HT1A autoreceptor stimulants (BMY7378 and 8-OH-DPAT) may reduce cerebral 5-HT release; (ii) support that the BMY7378-induced decrease in 5-HT release results from 5-HT1A autoreceptor agonism, rather than alpha 1-adrenoceptor blockade; and (iii) argue against "physiological" antagonism (i.e. via blockade of beta-adrenoceptors, 5-HT1B receptors or some other mechanism) as an explanation for the reversal by pindolol of 5-HT1A autoreceptor agonist-induced suppression of 5-HT release. These data support the usefulness of pindolol, as well as the more specific compound WAY-100635, to block 5-HT1A autoreceptors.

Synthesis, structure-activity relationships, and pharmacological profile of 9-amino-4-oxo-1-phenyl-3,4,6,7-tetrahydro[1,4]diazepino[6, 7,1-hi]indoles: discovery of potent, selective phosphodiesterase type 4 inhibitors.

The synthesis, structure-activity relationships, and biological properties of a novel series of potent and selective phosphodiesterase type 4 (PDE4) inhibitors are described. These new aminodiazepinoindoles displayed in vitro PDE4 activity with submicromolar IC(50) values and PDE4 selectivity vs PDE1, -3, and -5. Specifically, one compound (CI-1044, 10e) provided efficient in vitro inhibition of TNFalpha release from hPBMC and hWB with IC(50) values of 0.34 and 0.84 microM, respectively. This compound was found to exhibit potent in vivo activity in antigen-induced eosinophil recruitment in Brown-Norway rats (ED(50) = 3.2 mg/kg po) and in production of TNFalpha in Wistar rats (ED(50) = 2.8 mg/kg po). No emetic side effects at therapeutic doses were observed in ferrets.

Effects of chemically modified tetracyclines (CMTs) in sensitive, multidrug resistant and apoptosis resistant leukaemia cell lines.

Recently discovered chemically modified tetracyclines (CMTs) have shown in vitro and in vivo anti-proliferative and anti-tumour activities. Here, we evaluated in vitro the anti-proliferative and apoptotic activity of six different dedimethylamino chemically modified tetracyclines (CMT-1, CMT-3, CMT-5, CMT-6, CMT-7 and CMT-8) in sensitive and multidrug resistant myeloid leukaemia cells (HL60 and HL60R) in vitro. Three of these compounds (CMT-5, CMT-6, CMT-7) showed low cytotoxic activity both in sensitive and in resistant cells, CMT-3 was endowed with a high anti-proliferative activity only in sensitive cells and was moderately effective as apoptosis inducing agent, with an activity similar to that shown by doxycycline. On the contrary, CMT-1 and CMT-8 were very effective as programmed cell death inducing agents. The apoptotic pathway activated by these compounds involved the activation of caspases, especially caspase-9 and, for CMT-1, also the activation of FAS: Interestingly CMT-8, but not CMT-1, was able to induce apoptosis in multidrug resistant HL60R and in Fas-ligand resistant HUT78B1 cell lines. These properties, together with others previously described (e.g. anti-metastatic and anti-osteolytic activities), suggest that CMT-8 may have important applications in the clinical management of cancer. The comparative analysis of structure-activity relationship of CMT-8 and doxycycline suggests that the C-5 hydroxy moiety may play an important role in conferring activity in multidrug resistant cells. These findings appear to support the hypothesis that CMT-8 may represent an interesting lead for the development of a new class of potent apoptosis inducer agents active in multidrug resistant and Fas-ligand resistant malignancies.

Effect of partially modified retro-inverso analogues derived from C-reactive protein on the induction of nitric oxide synthesis in peritoneal macrophages.

1. The ability of three modified tetrapeptides, representing fragments of the C-reactive protein (CRP) sequence and stabilized in the first peptide bond by retro-inverso modification, to affect the secretion of nitric oxide (NO) was studied in macrophages of BALB/c mice. 2. These tetrapeptides, resembling the aminoacid sequence of tuftsin (CRP 1, H-gThr-(R,S)mLys-Pro-Leu-OH, ITF 1192; CRP II, H-gGly-(R, S)mLys-Pro-Arg-OH, ITF 1127; CRP III, H-gThr-(R,S)mLys-Pro-Gln-OH. ITF 1193), were able to induce NO synthesis by peritoneal macrophages in a dose-dependent manner; the most stimulating dose was 1000 ng ml-1 for CRP II and 100 ng ml-1 for CRP I and CRP III. NO synthesis was not strictly dependent on lipopolysaccharide (LPS) activation. 3. The enhanced effect of retro-inverso CRP-related analogues on the expression of iNOS (inducible NO synthase) was confirmed by higher levels of iNOS activity in the cytosol and by the increase in iNOS protein, as evaluated by Western blot analysis, in macrophages stimulated by CPR compared with untreated ones. 4. The production of NO by retro-inverso CRP-peptide analogues was significantly inhibited by dexamethasone (20 microM), NG-monomethyl-L-arginine (L-NMMA) (500 microM) and pyrrolidine dithiocarbamate (PDTC) (100 microM). 5. Retro-inverso CRP-peptide analogues stimulated macrophages to produce high levels of interleukin-1 (IL-1) and tumour necrosis factor-alpha (TNF-alpha) in the presence of LPS. 6. Retro-inverso CRP-peptide analogues stimulated NO synthesis by the enhancement of endogenously produced IL-1 and TNF-alpha, as the treatment of peritoneal macrophages with LPS in the presence of neutralizing anti-IL-1 and anti-TNF monoclonal antibodies (mAbs) reduced retro-inverso analogue-induced NO secretion. Data indicate a predominant role for IL-1 alpha in the induction of NO secretion by retro-inverso analogues. 7. These results suggest that retro-inverso CRP derived analogues act as costimulators of NO and cytokine synthesis in macrophages. The mechanisms by which they cause iNOS induction appear to be strongly dependent on the activation of nuclear factor-kappa B (NF-kappa B).

Histopathological grading of response to induction chemotherapy in non-small cell lung cancer: a preliminary study.

Management of locally advanced NSCLC is controversial. Induction chemotherapy followed by surgery has become an accepted approach for Stage III disease. However, the clinical assessment of the efficacy of preoperative treatment is inaccurate. We propose a four-grade histopathological evaluation of the response to chemotherapy based on the analysis of 20 evaluable cases and compared with clinical outcome. Follow-up ranged from 12 to 68 months. Correlation between different grading of necrosis and survival is statistically significant. Based on these preliminary results, we suggest that grading of response is a valid parameter to evaluate standard regimens and novel drug associations in larger trials.

Synthesis and sulfatase inhibitory activities of non-steroidal estrone sulfatase inhibitors.

About one-third of breast cancers are classified as estrogen-dependent breast cancers. In the past 10 years, numerous reports have suggested the importance of estrone sulfate and estrone sulfatase in regulating the supply of estrogens to these cancers. Estrone sulfatase inhibitors may thus prove to be useful for the treatment of these diseases. Several research groups have reported the development of estrone sulfatase inhibitors, and estrone-3-O-sulfamate has been shown to be the most potent sulfatase inhibitor. However, a recent report indicated that estrone may be released during the inactivation of sulfatase by estrone-3-O-sulfamate and rendered the inhibitor to be estrogenic. Therefore, there is a need for a potent non-steroidal sulfatase inhibitor that is metabolically stable, more selective, and lacking estrogenic activity. We developed a series of (p-O-sulfamoyl)-N-alkanoyl tyramines, and they proved to be potent estrone sulfatase inhibitors. Using human placental microsome as the enzyme source, the best inhibitor in this series, compound 18, has an IC50 of 55.8 nM. Another potent inhibitor in this series, compound 17, exhibited time-dependent inactivation of sulfatase when incubated at various concentrations (0.2-1.0 microM) of the inhibitor. Estrone sulfate partially blocked the inactivation of the enzyme by the compound, indicating that the compound inactivated sulfatase at the active site. The irreversible nature of the enzyme-inhibitor interaction was supported by irreversibility studies. Thus, (p-O-sulfamoyl)-N-alkanoyl tyramines represent a new series of non-steroidal estrone sulfatase inhibitor.

Diaphragmatic and abdominal muscle activity during coughing in the decerebrate cat.

We studied electrical activity of the phrenic and abdominal nerves and from the diaphragm and abdominal muscles during coughing elicited by stimulation of the superior laryngeal nerves (SLN) in decerebrate spontaneously breathing cats. This activity was compared with that observed after partial and complete paralysis. During coughing, the duration, rate of rise, and amplitude of inspiratory discharge increased concomitantly with activity of the rectus abdominis and external, but not internal, oblique muscle. After end-inspiration, the abdominal muscles discharged with one or more bursts. Similar patterns of activity were observed in phrenic and abdominal nerves during SLN-induced coughing, first in spontaneously breathing and then in paralyzed, ventilated cats. The paralyzed, ventilated decerebrate cat provides a powerful experimental model for studying coughing.

Multi-phase expiratory inhibition of phrenic motoneurons in the decerebrate cat.

We studied the membrane potential changes of 11 phrenic motoneurons (PMs), located in the C5 portion of the cervical spinal cord, in decerebrate, paralyzed and artificially ventilated cats. Intracellular chloride iontophoresis into PMs could reverse the waves of inhibitory postsynaptic potentials (IPSPs) causing membrane hyperpolarization during expiration. In all PMs, we revealed, in addition to the previously described late expiratory augmenting wave of IPSPs, an early expiratory decrementing wave of IPSPs. Moreover, in three PMs, recorded in two cats exhibiting slow respiratory rhythms, an additional wave of IPSPs was interposed between the early and late ones. The possible origins and roles of these three different waves of inhibition are discussed.

Discharge patterns of phrenic motoneurons during fictive coughing and vomiting in decerebrate cats.

In decerebrate, paralyzed, and ventilated cats, we recorded the activity of 100 spontaneously active phrenic motor axons during the increased phrenic discharges characteristic of fictive vomiting (FV) and coughing (FC). During control respiratory cycles, approximately one-half the neurons were recruited in the first decile of inspiration; recruitment continued throughout inspiration. During FV, the duration of phrenic discharge was halved; 20 of 26 motoneurons studied were recruited in the first decile of the burst. During FC, recruitment times did not change compared with control, although the duration of the phrenic burst doubled. Discharge frequencies increased and recruitment order of phrenic motoneurons was virtually unaffected during FC and FV. Limited recruitment of previously inactive neurons in the filaments from which we recorded was found during FV and FC. During FV, 1 previously inactive motoneuron was recruited in 16 filaments containing 25 spontaneously active motor axons. During FC, 3 new motoneurons were recruited in addition to the 64 already active in 35 filaments. Recruitment during FV and FC was absent even when recording from filaments known, on the basis of antidromic activation, to contain inactive motor axons. During FV, 10 of 26 motoneurons began their discharges with doublets (interspike interval < 10 ms); doublets occurred in only 4 of 67 motoneurons during FC. Already active phrenic motoneurons contributed to the intense phrenic activity associated with both respiratory (coughing) and nonrespiratory (vomiting) behavior by increases in discharge frequency, earlier recruitment, and doublets; the contribution of previously quiescent motoneurons remains uncertain.

Raphe 5-HT1A autoreceptors, but not postsynaptic 5-HT1A receptors or beta-adrenoceptors, restrain the citalopram-induced increase in extracellular 5-hydroxytryptamine in vivo.

In vivo microdialysis in rat ventral hippocampus was used (i) to verify the importance of 5-HT1A autoreceptors in the raphe as targets for drugs that enhance the citalopram-induced elevation of forebrain 5-hydroxytryptamine (5-HT), and (ii) to further examine the specificity of (-)-penbutolol in this regard. The selective 5-HT1A receptor antagonist WAY100635 (s.c., or intra-raphe) or the mixed 5-HT1A/1B/beta-adrenoceptor antagonist (-)-penbutolol (s.c.), potentiated the citalopram-induced 5-HT rise, whereas local "reverse' dialysis of WAY100635 into the ventral hippocampus did not. Furthermore, the (-)-penbutolol-induced augmentation proved stereoselective and not mediated by beta-adrenoceptors (no effect of s.c. (+)-penbutolol, or beta 1- and beta 2-adrenoceptor blockers (betaxolol, ICI118.551)). These data provide direct evidence that increased stimulation of 5-HT1A autoreceptors in the midbrain raphe impedes the effect of citalopram on forebrain extracellular 5-HT, whereas neither postsynaptic 5-HT1A receptors nor beta-adrenoceptors appear to be involved.

Protein kinase C activation and anti-amnesic effect of acetyl-L-carnitine: in vitro and in vivo studies.

Drugs belonging to different chemical classes having the ability to improve behavioral performance in animal learning and memory tests may share the common ability to stimulate protein kinase C activity in rat brain cortex. In vitro acetyl-L-carnitine (100 nM) promoted in rat brain cortex slices a significant increase in particulate activity associated with lower soluble protein kinase C activity and produced a direct stimulation of the enzyme in both the cortex and hippocampus. In vivo a significant increase in particulate protein kinase C activity was observed in the group of rats treated with 60 mg/kg acetyl-L-carnitine, a dose shown to be effective in improving the cognitive deficits induced by scopolamine in the Morris maze test. The results suggest that acetyl-L-carnitine increases particulate protein kinase C activity in the cortex both in vitro and in vivo. This effect in the in vivo experiments seems to be observed only with doses that are effective in improving the performance of rats in a spatial learning task.

Tetracycline inhibits the nitric oxide synthase activity induced by endotoxin in cultured murine macrophages.

Here we investigate the effects of tetracycline base and of a semi-synthetic tetracycline derivative, doxycycline, on the induction of inducible nitric oxide synthase and, hence, on the production of nitric oxide (NO) by lipopolysaccharide in J774 macrophage cultured in vitro. The treatment of J774 line with tetracycline base (6.25-250 microM) or doxycycline (5-50 microM) dose-dependently decreased the lipopolysaccharide-stimulated (1 microg/ml) inducible NO synthase activity and, consequently, nitrite formation. For instance, the inhibition was 70% for tetracycline base at 250 microM and 68% for doxycycline at 50 microM. The inhibitory effect of tetracyclines was due neither to a reduction in the viability of the cells, studied as colorimetric 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide (MTT) reduction assay, nor to an indiscriminate inhibition of total protein synthesis, but to a specific decrease in inducible NO synthase protein content in the cells, as attested by the significant reduction of the expression of inducible NO synthase, assayed by sodium-dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot. However, no effect of tetracyclines on inducible NO synthase mRNA accumulation could be demonstrated in lipopolysaccharide-stimulated macrophage line, suggesting that the inhibitory effect of tetracyclines on NO synthesis involves post-transcriptional events. The reduction in lipopolysaccharide-stimulated nitrite accumulation produced by tetracyclines was significantly less when they were applied 6 h after lipopolysaccharide and absent 12 h after lipopolysaccharide, indicating that tetracyclines modify an early event in inducible NO synthase activation operating after mRNA transcription. The findings presented in this study indicate that the modulation of NO synthesis is another possible pathway by which tetracyclines may function as anti-inflammatory compounds.

Brainstem neurons with projecting axons to both phrenic and abdominal motor nuclei: a double fluorescent labeling study in the cat.

The distribution of retrogradely doubly labeled brainstem neurons were analyzed in the cat after injection of two different fluorescent markers into the phrenic and abdominal motor nuclei. Diamidino Yellow (DY) was first injected either ipsilaterally or bilaterally into the ventral horn of lumbar spinal cord, and then Fast Blue (FB) into the right ventral horn of cervical spinal cord. Doubly labeled neurons were mainly found in the caudal ventrolateral medulla (retroambiguus region), in the dorsomedial and dorsolateral regions of the nucleus of the tractus solitarius (NTS) and in the raphe nuclei. In addition, doubly labeled neurons were found in the parabrachial and Kölliker-Fuse nuclei. Our results give anatomical evidence that pontine and medullary neurons are the source of a common pathway to both phrenic and abdominal motor nuclei. These neurons might be involved in strain efforts for expulsion such as vomiting or defecation.

Long-term acetyl-L-carnitine preserves spatial learning in the senescent rat.

1. Untreated rats of different ages and old rats chronically treated with Acetyl-1-carnitine were subjected to the spatial learning task. 2. For this test, a circular pool filled with milk-opacified water was used. The animals were to reach an escape platform with the aid of visible environmental cues. 3. The experimental results indicated a clear-cut deterioration of the old animal's acquisition ability of a spatial learning task. 4. The long-term treatment (8 months) with Acetyl-1-carnitine was found to antagonize such a deterioration.

Anti-inflammatory effects of chemically modified tetracyclines by the inhibition of nitric oxide and interleukin-12 synthesis in J774 cell line.

We investigated the effects of chemically modified tetracyclines (CMTs) on the production of nitric oxide (NO) and on the synthesis of some cytokines: tumour necrosis factor alpha (TNF-alpha), interleukin(IL)-10 and IL-12 in lipopolysaccharide (LPS)-treated J774 cell line. Furthermore, we studied the ability of these drugs to modify the viability in LPS-stimulated J774 macrophages. CMTs decreased, in a dose-dependent manner, inducible NO synthase (iNOS) activity and, consequently, nitrite formation in J774 cultures. The CMT-induced decrease in NO production is due to the inhibition of enzyme activity rather than to a direct effect on enzyme expression. The absence of the inhibition in mRNA accumulation indicates that the inhibiting activity is mainly post-transcriptional. CMTs were unable to modulate TNF-alpha and IL-10 synthesis and they were not effective in modifying the transcription of relative mRNA in J774 macrophages. On the contrary, IL-12 mRNA expression was significantly increased by CMT-1 and CMT-8 with LPS activation. Since IL-12 protein secretion was inhibited by CMTs, these compounds interfere in the blocking of post-transcriptional events. The studies on cell viability showed that various CMTs induced a dose-dependent decrease in J774 macrophage viability. The cytotoxic activity was present even though NO production was inhibited by CMTs. These compounds appear to be able to activate apoptosis in aNO-independent way. Altogether, these results indicate that CMTs can exert anti-inflammatory effects by inhibiting NO synthesis, and they are able to modify cell viability by exerting a strong apoptotic activity.

Structure-activity relationship studies of the amide functionality in (p-O-sulfamoyl)-N-alkanoyl tyramines as estrone sulfatase inhibitors.

Recently, we reported the synthesis and biomedical studies of a series of (p-O-sulfamoyl)-N-alkanoyl tyramines as nonsteroidal estrone sulfatase inhibitors. One of the most potent inhibitors in this series is (p-O-sulfamoyl)-N-tridecanoyl tyramine 1 with an 1C50 value of 61.3 nM. In this study, we synthesized four analogs of 1 (compounds 2-5) to investigate the structure-activity relationships of the amide functionality in (p-O-sulfamoyl)-N-tridecanoyl tyramine. Replacement of the amide functionality in 1 with an ethylene moiety to form the alkyl analog 5 resulted in complete loss of sulfatase inhibitory activity (IC50 of 61.3 nM vs. > 20 microM). The keto, hydroxy, and ester analogs (inhibitors 2-4) are 8-15 times less in affinity to the sulfatase than inhibitor 1. However, their inhibitory activities are significantly higher than the alkyl analog 5. The results suggest that the amide functionality is favorable for sulfatase inhibitory activity and that there may be a hydrogen bonding component to the enzyme interaction in this region.