Novel insights into actions of bisphosphonates on bone: differences in interactions with hydroxyapatite

Bisphosphonates are now the most widely used drugs for diseases associated with increased bone resorption, such as osteoporosis. Although bisphosphonates act directly on osteoclasts, and interfere with specific biochemical processes such as protein prenylation, their ability to adsorb to bone mineral also contributes to their potency and duration of action. The aim of the present study was to compare the binding affinities for hydroxyapatite (HAP) of 6 bisphosphonates currently used clinically and to determine the effects of these bisphosphonates on other mineral surface properties including zeta potential and interfacial tension. Affinity constants (K(L)) for the adsorption of bisphosphonates were calculated from kinetic studies on HAP crystal growth using a constant composition method at 37 degrees C and at physiological ionic strength (0.15 M). Under conditions likely to simulate bisphosphonate binding onto bone, there were significant differences in K(L) among the bisphosphonates for HAP growth (pH 7.4) with a rank order of zoledronate > alendronate > ibandronate > risedronate > etidronate > clodronate. The measurements of zeta potential show that the crystal surface is modified by the adsorption of bisphosphonates in a manner best explained by molecular charges related to the protonation of their side-chain moieties, with risedronate showing substantial differences from alendronate, ibandronate, and zoledronate. The studies of the solid/liquid interfacial properties show additional differences among the bisphosphonates that may influence their mechanisms for binding and inhibiting crystal growth and dissolution. The observed differences in kinetic binding affinities, HAP zeta potentials, and interfacial tension are likely to contribute to the biological properties of the various bisphosphonates. In particular, these binding properties may contribute to differences in uptake and persistence in bone and the reversibility of effects. These properties, therefore, have potential clinical implications that may be important in understanding differences among potent bisphosphonates, such as the apparently more prolonged duration of action of alendronate and zoledronate compared with the more readily reversible effects of etidronate and risedronate.

Risk factors for surgical site infection after elective resection of the colon and rectum: a single-center prospective study of 2,809 consecutive patients

OBJECTIVE

To identify the risk factors for surgical site infection (SSI) in patients undergoing elective resection of the colon and rectum.

SUMMARY BACKGROUND DATA

SSI causes a substantial number of deaths and complications. Determining risk factors for SSI may provide information on reducing complications and improving outcome.

METHODS

The authors performed a prospective study of 2,809 consecutive patients undergoing elective colorectal resection via laparotomy between February 1995 and December 1998 at a single institution. The outcome of interest was SSI, which was classified as being incisional or organ/space with or without clinical leakage. A likelihood ratio forward regression model was used to assess the independent association of variables with SSIs.

RESULTS

The overall SSI, incisional SSI, and organ/space SSI with and without clinical anastomotic leakage rates were 4.7%, 3%, 2%, and 0.8%, respectively. Risk factors for overall SSI were American Society of Anesthesiology (ASA) score 2 or 3 (odd ratio [OR] = 1.7), male gender (OR = 1.5), surgeons (OR = 1.3-3.3), types of operation (OR = 0.3-2.1), creation of ostomy (OR = 2.1), contaminated wound (OR = 2.9), use of drainage (OR = 1.6), and intra- or postoperative blood transfusion (1-3 units, OR = 5.3; >/=4 units, OR = 6.2). However, SSIs at specific sites differed from each other with respect to the risk factors. Among a variety of risk factors, only blood transfusion was consistently associated with a risk of SSI at any specific site.

CONCLUSIONS

In addition to ASA score and surgical wound class, blood transfusion, creation of ostomy, types of operation, use of drainage, sex, and surgeons were important in predicting SSIs after elective colorectal resection.

Plasma tumour necrosis factor-alpha and early carotid atherosclerosis in healthy middle-aged men

AIMS

Tumour necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine, which is implicated in some metabolic disorders and may play a role in the development of cardiovascular disease. We examined whether plasma TNF-alpha is related to established cardiovascular risk indicators, plasma levels of soluble cellular adhesion molecules and carotid artery intima-media thickness determined by ultrasound examination in a population-based cohort of 96 healthy 50-year-old men.

METHODS AND RESULTS

TNF-alpha and cellular adhesion molecules were measured with enzyme-linked immunosorbent assays. Plasma TNF-alpha concentration was associated with systolic and diastolic blood pressure, degrees of alimentary lipaemia, plasma very low density lipoprotein triglyceride, low density lipoprotein (LDL) cholesterol concentrations and peak LDL particle size. Two indices of insulin resistance as well as all soluble cellular adhesion molecules correlated positively with TNF-alpha. The plasma TNF-alpha concentration was associated with common carotid intima-media thickness in univariate analysis. In contrast, soluble E-selectin and postprandial triglycerides, but not TNF-alpha, were independent determinants of common carotid intima--media thickness.

CONCLUSION

The plasma TNF-alpha concentration is associated with degrees of early atherosclerosis and correlates with metabolic and cellular perturbations that are considered important for the vascular process.

Alimentary lipemia, postprandial triglyceride-rich lipoproteins, and common carotid intima-media thickness in healthy, middle-aged men

BACKGROUND

Alimentary lipemia has been associated with coronary heart disease and common carotid artery intima-media thickness (IMT). This study was designed to investigate the relations of subclasses of postprandial triglyceride-rich lipoproteins (TRLs) with IMT.

METHODS AND RESULTS

Ninety-six healthy 50-year-old men with an apolipoprotein (apo) E3/E3 genotype underwent an oral fat tolerance test and B-mode carotid ultrasound examination. The apo B-48 and apo B-100 contents of each fraction of TRLs were determined as a measure of chylomicron remnant and VLDL particle concentrations. In the fasting state, LDL cholesterol (P<0.05) and basal proinsulin (P<0. 05) were significantly related to IMT, whereas HDL cholesterol, plasma triglycerides, and insulin were not. In the postprandial state, plasma triglycerides at 1 to 4 hours (P<0.01 at 2 hours), total triglyceride area under the curve (AUC) (P<0.05), incremental triglyceride AUC (P<0.01), and the large VLDL (Sf 60 to 400 apo B-100) concentration at 3 hours (P<0.05) were significantly related to IMT. Multivariate analyses showed that plasma triglycerides at 2 hours, LDL cholesterol, and basal proinsulin were consistently and independently related to IMT when cumulative tobacco consumption, alcohol intake, waist-to-hip circumference ratio, and systolic blood pressure were included as confounders.

CONCLUSIONS

These results provide further evidence for postprandial triglyceridemia as an independent risk factor for early atherosclerosis and also suggest that the postprandial triglyceridemia is a better predictor of IMT than particle concentrations of individual TRLs.

Anti-colony-stimulating factor-1 antibody staining in primary breast adenocarcinomas correlates with marked inflammatory cell infiltrates and prognosis

BACKGROUND

Clinical studies have shown that a marked lymphoplasmocytic reaction in breast tumors is associated with poor prognosis. Such findings raise the possibility that an inflammatory cell reaction might be a tumor-induced response that tends to promote tumor growth.

PURPOSE

We assessed the expression of colony-stimulating factor-1 (CSF-1) as well as the prevalence of specific tumor-infiltrating lymphocytes and monocytes in breast tumors.

METHODS

Tissue sections were obtained from archival paraffin blocks from 196 breast cancer patients. Seventy-eight percent of the women had been treated by mastectomy and 22% by lumpectomy. Median age of the patients was 54 years, and median follow-up was 7.3 years. Immunohistochemical and in situ hybridization techniques were used to characterize the specimens.

RESULTS

Markedly high numbers of CD45RO-positive T- and L26-positive B-cell infiltrates were found in 13% and 17% of the tissue specimens, respectively. CSF-1 receptor-positive monocytes were detected in 48% and CD68-positive monocytes in 90% of the tumors. In turn, tumors with large fractions of CD68-positive monocytes also showed CSF-1 receptor-positive monocytes (P < .0001). CSF-1 was expressed significantly in 74% of the tumors and the CSF-1 receptor in more than 50% of the tumors. Tumors with high percentages of CSF-1 expressing cells also had marked monocyte infiltrates (P = .035). The presence of marked CD45RO-positive T-cell infiltrates and apparent nuclear staining of CSF-1 in tumor cells were associated with the more frequent occurrence of metastases (P = .02 and P = .04, respectively) and with poor survival (P = .02 and P = .03, respectively).

CONCLUSIONS

Large numbers of CD45RO-positive (activated memory but noncytotoxic) T cells as well as a predominant nuclear staining pattern for CSF-1 are associated with a poor outcome in breast cancer patients.

IMPLICATIONS

Nuclear retention of CSF-1 could reflect CSF-1 turnover and function in tumor cells, but new approaches are needed to establish the significance of these observations. Secreted CSF-1 appears to cause monocyte recruitment and activation, thereby modulating immune functions and potentially the expression of the CD45RO phenotype in T cells.

The relation of obesity throughout life to carotid intima-media thickness in adulthood: the Bogalusa Heart Study

OBJECTIVE

Although obese children are at increased risk for coronary heart disease in later life, it is not clear if this association results from the persistence of childhood obesity into adulthood. We examined the relation of adiposity at various ages to the carotid intima-media thickness (IMT) at age 35 y.

DESIGN

Prior to the determination of IMT by B-mode ultrasound, subjects (203 men, 310 women) had, on average, six measurements of body mass index (BMI) and triceps skinfold thickness (TSF) between the ages of 4 and 35 y. Mixed regression models for longitudinal data were used to assess the relation of these characteristics to adult IMT.

RESULTS

Overall, adult IMT was associated with levels of both BMI and TSF (P<0.001), with the magnitudes of the associations with childhood adiposity comparable to those with adult levels of BMI and TSF. Furthermore, adult obesity modified the association between childhood adiposity and IMT: high IMT levels were seen only among overweight (BMI > or =95th percentile) children who became obese (BMI > or =30 kg/m2) adults (P<0.01 for linear trend). In contrast, IMT levels were not elevated among (1) overweight children who were not obese in adulthood, or among (2) thinner children who became obese adults.

CONCLUSIONS

These results emphasize the adverse, cumulative effects of childhood-onset obesity that persists into adulthood. Since many overweight children become obese adults, the prevention of childhood obesity should be emphasized.

Effects of nitric oxide on human and canine prostates

OBJECTIVES

To determine whether nitric oxide (NO) is a mediator of prostatic smooth muscle activity.

METHODS

Pharmacologic experiments using electrical field stimulation (EFS) were performed on strips of human and canine prostate.

RESULTS

EFS alone elicited frequency-dependent contractions in preparations of human and canine prostates. The greatest contractile activity was achieved at 30 Hz. In the presence of 10(-5) M guanethidine (GUA) and 2 x 10(-6) M atropine (ATR), EFS elicited relaxation of canine prostate strips relative to baseline tension. A weak biphasic response consisting of initial relaxation and subsequent contraction relative to baseline tension was observed in the human prostate strips exposed to similar conditions. The smooth muscle activity observed in the presence of GUA plus ATR was attributed to nonadrenergic, noncholinergic (NANC) nerve transmission. 10(-4) M L-NG-nitroarginine methylester (NAME) significantly increased EFS-elicited NANC smooth muscle activity both in human and canine prostates. L-arginine, 10(-2) M, reversed the effect of L-NAME in human and canine prostates. Sodium nitroprusside, 10(-4) M, a donor of NO, caused relaxation of both human and canine prostates. The mean magnitude of the relaxant response/cross-sectional area in human prostate (2.64 +/- 0.4 g/cm2) was significantly greater than in the canine prostate (1.09 +/- 0.17 g/cm2) (P < 0.005).

CONCLUSIONS

These results provide compelling evidence that NO plays a role in mediating contractile function of human and canine prostates.

Recombinant respiratory syncytial viruses with deletions in the NS1, NS2, SH, and M2-2 genes are attenuated in vitro and in vivo

Respiratory syncytial virus (RSV) encodes several proteins that lack well-defined functions; these include NS1, NS2, SH, and M2-2. Previous work has demonstrated that NS2, SH, and M2-2 can each be deleted from RSV genome and thus are considered as accessory proteins. To determine whether RSV can replicate efficiently when two or more transcriptional units are deleted, we removed NS1, NS2, SH, and M2-2 genes individually and in different combinations from an infectious cDNA clone derived from human RSV A2 strain. The following six mutants with two or more genes deleted were obtained: DeltaNS1NS2, DeltaM2-2SH, DeltaM2-2NS2, DeltaSHNS1, DeltaSHNS2, and DeltaSHNS1NS2. Deletion of M2-2 together with NS1 was detrimental to RSV replication. It was not possible to obtain a recombinant RSV when all four genes were deleted. All of the double and triple deletion mutants exhibited reduced replication and small plaque morphology in vitro. Replication of these deletion mutants was more reduced in HEp-2 cells than in Vero cells. Among the 10 single and multiple gene deletion mutants obtained, DeltaM2-2NS2 was most attenuated. DeltaM2-2NS2 formed barely visible plaques in HEp-2 cells and had a reduction of titer of 3 log(10) compared with the wild-type recombinant RSV in infected HEp-2 cells. When inoculated intranasally into cotton rats, all of the deletion mutants were attenuated in the respiratory tract. Our data indicated that the NS1, NS2, SH, and M2-2 proteins, although dispensable for virus replication in vitro, provide auxiliary functions for efficient RSV replication.

Baseline reproducibility of B-mode ultrasonic measurement of carotid artery intima-media thickness: the European Lacidipine Study on Atherosclerosis (ELSA)

BACKGROUND AND OBJECTIVE

The European Lacidipine Study of Atherosclerosis (ELSA) is a prospective, randomized, double-blind, multi-national interventional trial to determine the effect of four-year treatment using the calcium antagonist lacidipine versus the beta-blocker atenolol on the progression of carotid atherosclerosis in 2259 asymptomatic hypertensive patients. B-mode ultrasound is used to measure the primary and secondary endpoints including the mean maximum intima-media thickness (IMT) of the carotid bifurcations and the common carotid arteries (CBM(max)), the mean maximum IMT of 12 standard carotid sites (M(max)) and the overall maximum IMT (T(max)). This paper reports the cross-sectional reproducibility of ultrasound measurements at baseline.

METHOD

To evaluate measurement reliability, each patient is scanned twice at baseline and again at four annual visits, with 80% of the replicate scans performed by the same sonographer and 20% by a different sonographer; 50% of the replicate scans are read by the same reader and the other 50% by different readers.

RESULTS

The overall coefficient of reliability (R) was 0.859 for CBM(max), 0.872 for M(max) and 0.794 for T(max). The reliability for CBM(max) was stable during the 1 3/4-year baseline period (R = 0.848 to 0.953) and was uniform among the 23 field centres (R = 0.798 to 0.926). Intra- and inter-reader reliability were 0.915 and 0.872 respectively, and intra-sonographer reliability was 0.866.

CONCLUSION

The results demonstrate that by implementing standardized protocols and strict quality control procedures, highly reliable ultrasonic measurements of carotid artery IMT can be achieved in large multi-national trials.

Cloning, expression, and characterization of a human inosine triphosphate pyrophosphatase encoded by the itpa gene

ITP and dITP exist in all cells. dITP is potentially mutagenic, and the levels of these nucleotides are controlled by inosine triphosphate pyrophosphatase (EC ). Here we report the cloning, expression, and characterization of a 21.5-kDa human inosine triphosphate pyrophosphatase (hITPase), an enzyme whose activity has been reported in many animal tissues and studied in populations but whose protein sequence has not been determined before. At the optimal pH of 10.0, recombinant hITPase hydrolyzed ITP, dITP, and xanthosine 5'-triphosphate to their respective monophosphates whereas activity with other nucleoside triphosphates was low. K(m) values for ITP, dITP, and xanthosine 5'-triphosphate were 0.51, 0.31, and 0.57 mm, respectively, and k(cat) values were 580, 360, and 640 s(-1), respectively. A divalent cation was absolutely required for activity. The gene encoding the hITPase cDNA sequence was localized by radiation hybrid mapping to chromosome 20p in the interval D20S113-D20S97, the same interval in which the ITPA inosine triphosphatase gene was previously localized. A BLAST search revealed the existence of many similar sequences in organisms ranging from bacteria to mammals. The function of this ubiquitous protein family is proposed to be the elimination of minor potentially mutagenic or clastogenic purine nucleoside triphosphates from the cell.

Increased expression of adenylylcyclase type VI proportionately increases beta-adrenergic receptor-stimulated production of cAMP in neonatal rat cardiac myocytes

Cellular content of cAMP generated by activation of adenylylcyclase (AC; EC 4.6.1.1) is a key determinant of functional responsiveness in the heart and other tissues. We have tested two hypotheses regarding the relationship between AC content and beta-adrenergic receptor (betaAR)-mediated signal transduction in cardiac myocytes. First, that AC content limits adrenergic signal transduction, and, second, that increased AC, independent of (betaAR) number and G-protein content, yields a proportional increase in betaAR-mediated transmembrane signaling. We used recombinant adenovirus to increase AC isoform VI (ACVI) expression in neonatal cardiac myocytes. Cells that overexpressed ACVI responded to agonist stimulation with marked increases in cAMP production in proportion to protein expressed. In parallel experiments performed on cells transfected with lacZ (control) or ACVI, [3H]forskolin binding, used to assess AC protein expression, was amplified 6-fold, while betaAR-stimulated cAMP production from these cells was increased 7-fold. No changes in betaAR number, or in the heterotrimeric GTP-binding proteins, Galphas or Galphai2, were observed. Previous studies indicate that increased cardiac expression of betaAR or Galphas does not yield proportional increases in transmembrane adrenergic signaling. In contrast, the current data demonstrate that increased ACVI expression provides a proportional increase in beta-adrenergic signal transduction. Our results show that the amount of AC sets a limit on transmembrane beta-adrenergic signaling. We speculate that similar functional responses are possible in other cell types in which AC plays an important physiological role.

Valproic acid inhibits proliferation and induces apoptosis in acute myeloid leukemia cells expressing P-gp and MRP1

The multidrug resistance (MDR) phenotype, induced by the overexpression of several ABC transporters or by antiapoptotic mechanisms, has been identified as the major cause of drug resistance in the treatment of patients with acute myeloid leukemia (AML). In this study, we have shown that valproic acid (VPA) (a histone deacetylase inhibitor) can inhibit the proliferation of both P-glycoprotein (P-gp)- and MDR-associated protein 1 (MRP1)-positive and -negative cells. VPA also induced apoptosis of P-gp-positive cells. VPA induced apoptosis in K562 cells led to decrease in Flip (FLICE/caspase-8 inhibitory protein) expression with Flip cleavage, which could not be observed in HL60 cells. In HL60/MRP cell line, which proved to be resistant to apoptosis by VPA, we observed an abnormal expression of apoptotic regulatory proteins, overexpression of Bcl-2 and absence of Bax. Also, the Bcl-2 antagonist HA14-1 rapidly restored apoptosis in this cell line. Cotreatment with cytosine arabinoside induced very strong apoptosis in both K562/DOX and HL60/DNR cell lines. VPA also induced apoptosis in AML patient cells expressing P-gp and/or MRP1. Our findings show VPA as an interesting drug that should be tested in clinical trials for overcoming the MDR phenotype in AML patients.

Cholesterol efflux via ATP-binding cassette transporter A1 (ABCA1) and cholesterol uptake via the LDL receptor influences cholesterol-induced impairment of beta cell function in mice

AIMS/HYPOTHESIS

Cellular cholesterol accumulation is an emerging mechanism for beta cell dysfunction in type 2 diabetes. Absence of the cholesterol transporter ATP-binding cassette transporter A1 (ABCA1) results in increased islet cholesterol and impaired insulin secretion, indicating that impaired cholesterol efflux leads to beta cell dysfunction. In this study, we aimed to determine the role of the LDL receptor (LDLr) in islet cholesterol uptake and to assess the contributions of cholesterol uptake compared with efflux to islet cholesterol levels.

METHODS

Islet cholesterol and beta cell function were assessed in mice lacking LDLr (Ldlr(-/-)), or apolipoprotein E (Apoe(-/-)), as well as in mice with beta-cell-specific deficiency of Abca1 crossed to Ldlr(-/-) mice.

RESULTS

Hypercholesterolaemia resulted in increased islet cholesterol levels and decreased beta cell function in Apoe(-/-) mice but not in Ldlr(-/-) mice, suggesting that the LDL receptor is required for cholesterol uptake leading to cholesterol-induced beta cell dysfunction. Interestingly, when wild-type islets with functional LDL receptors were transplanted into diabetic, hypercholesterolaemic mice, islet graft function was normal compared with Ldlr(-/-) islets, suggesting that compensatory mechanisms can maintain islet cholesterol homeostasis in a hypercholesterolaemic environment. Indeed, transplanted wild-type islets had increased Abca1 expression. However, lack of the Ldlr did not protect Abca1(-/-) mice from islet cholesterol accumulation, suggesting that cholesterol efflux is the critical regulator of cholesterol levels in islets.

CONCLUSIONS/INTERPRETATION

Our data indicate that islet cholesterol levels and beta cell function are strongly influenced by LDLr-mediated uptake of cholesterol into beta cells. Cholesterol efflux mediated by ABCA1, however, can compensate in hypercholesterolaemia to regulate islet cholesterol levels in vivo.

Value of carcinoembryonic antigen in the management of colorectal cancer

PURPOSE

The practical value of carcinoembryonic antigen (CEA) assay in the management of colorectal cancer after surgery is controversial. The value of CEA in the management of colorectal cancer was reviewed and discussed to justify the use of CEA assay in the management of colorectal cancer.

METHODS

A retrospective study was performed on 318 patients who underwent resection by one surgeon (JYW) between 1981 and 1986 and who were followed for a minimum of 5 years or until death.

RESULTS

The incidence of preoperative CEA levels > 5 ng/ml in Dukes Stages A, B, C, and D were 0, 32, 48, and 79 percent, respectively. Five-year survival rates for groups with CEA levels < or = 5 ng/ml and > 5 ng/ml were 85 percent and 55 percent (P < 0.05), respectively, in Dukes Stage B patients and 64 percent and 37 percent (P < 0.05) in Stage C patients. The sensitivity and specificity of postoperative CEA monitoring in detecting recurrent diseases were 66 percent and 94 percent, respectively, for patients with a preoperative CEA value < or = 5 ng/ml and 97 percent and 88 percent for patients with a higher preoperative CEA value.

CONCLUSION

CEA is still the best tumor marker available to be used as an independent prognostic factor and as a monitor for recurrence of disease after primary tumor resection.

Endothelin-1 in the human prostate: tissue levels, source of production and isometric tension studies

Endothelins mediate contractile responses in many types of vascular and nonvascular smooth muscle. The present study represents the first detailed characterization of endothelins in the human prostate. The objectives of this study were to determine the tissue levels and source of endogenous endothelin-1 (ET1) in the human prostate. The contractile effects of ET1 were also investigated using in vitro isometric tension studies. The mean tissue level of ET1 was 0.58 +/- 0.08 pg./mg. tissue wet weight. Endothelin-like activity was markedly prominent in the glandular epithelium of the human prostate, whereas minimal endothelin-like activity was observed in the prostatic stroma. Strips of human prostatic tissue were suspended in isolated tissue chambers and challenged to a concentration response of ET1. The mean EC50 and Emax for ET1 was 3.2 x 10(-8) M. and 0.12 +/- 0.02 gm. force per mm.2 cross-sectional area (CSA), respectively. Preincubation with indomethacin, terazosin, or nifedipine did not alter the concentration-dependent response to ET1. A calcium-free buffer abolished the contractile response to ET1. Thus, ET1 mediates a potent contraction of human prostatic smooth muscle that is not mediated via alpha 1 adrenergic or dihydropyridine sensitive calcium channels or prostaglandin synthesis. The presence of marked endothelin-like immunoreactivity strongly suggests a biological significance for endogenous endothelins in the human prostate.

The alpha-adrenoceptor subtype mediating the tension of human prostatic smooth muscle

We have characterized the alpha 1 adrenoceptor subtypes in the human prostate using radioligand receptor binding studies. The objective of the present study was to determine the alpha 1 subtype mediating the tension of prostatic smooth muscle. Fresh human tissue was obtained from 9 males between 50 and 80 years of age undergoing prostatectomy for BPH. The incubation of prostatic tissue with the irreversible antagonist chlorethyclonidine (CEC) resulted in an 80% reduction of the maximal contractile response produced by phenylephrine. However, the alpha 1A-selective antagonists WB-4101 and 5-methylurapidil (5-MU) competitively inhibited the contractile response induced by phenylephrine, with KB = 2.64 and 4.46 nM, respectively, consistent with their affinity at the alpha 1A receptor subtype. The pharmacological profile of the alpha 1-receptor-mediated contractile response of prostate smooth muscle is inconsistent with their classification as either an alpha 1A or alpha 1B subtype. Alternatively, when compared with the properties of the cloned alpha 1 receptors, our results suggest that the alpha 1 receptors involved in the contraction of prostate smooth muscle have some pharmacological properties similar to those encoded by the gene of the bovine alpha 1C receptor subtype. The findings of the present study suggest that efforts should be made to confirm the identity of the alpha 1-receptor subtype expressed by prostate smooth muscle, in order to develop subtype-selective alpha 1 antagonists, and to evaluate their safety and efficacy in benign prostatic hyperplasia (BPH).

Enamel demineralization in primary and permanent teeth

Although enamel demineralization is important for our understanding of caries formation, no consensus has been reached regarding the possible differences in susceptibility of primary and permanent enamel. We used the constant composition (CC) technique to investigate the acid-induced demineralization of these tissues at a relative undersaturation with respect to hydroxyapatite (HAP) of 0.902, pH = 4.5, and ionic strength = 0.15 mol L(-1). The demineralization rates showed significant differences, primary enamel having the greater susceptibility to dissolution during an initial linear stage: 1.5 +/- 0.5 x 10(-10) mol mm(-2) min(-1) compared with 2.6 +/- 0.5 x 10(-11) mol mm(-2) min(-1) for permanent enamel. During the reactions, we observed nanosized crystallites which attached to the enamel surfaces or escaped into the bulk solution. These nanosized crystallites were kinetically protected against further dissolution, even though the solutions remained undersaturated. It is hypothesized that they may contribute to the remarkable mechanical and dynamic characteristics of enamel.

Functional categories of TP53 mutation in colorectal cancer: results of an International Collaborative Study

BACKGROUND

Loss of TP53 function through gene mutation is a critical event in the development and progression of many tumour types including colorectal cancer (CRC). In vitro studies have found considerable heterogeneity amongst different TP53 mutants in terms of their transactivating abilities. The aim of this work was to evaluate whether TP53 mutations classified as functionally inactive (< or=20% of wildtype transactivation ability) had different prognostic and predictive values in CRC compared with mutations that retained significant activity.

MATERIALS AND METHODS

TP53 mutations within a large, international database of CRC (n = 3583) were classified according to functional status for transactivation.

RESULTS

Inactive TP53 mutations were found in 29% of all CRCs and were more frequent in rectal (32%) than proximal colon (22%) tumours (P < 0.001). Higher frequencies of inactive TP53 mutations were also seen in advanced stage tumours (P = 0.0003) and in tumours with the poor prognostic features of vascular (P = 0.006) and lymphatic invasion (P = 0.002). Inactive TP53 mutations were associated with significantly worse outcome only in patients with Dukes' stage D tumours (RR = 1.71, 95%CI 1.25-2.33, P < 0.001). Patients with Dukes' C stage tumours appeared to gain a survival benefit from 5-fluorouracil-based chemotherapy regardless of TP53 functional status for transactivation ability.

CONCLUSIONS

Mutations that inactivate the transactivational ability of TP53 are more frequent in advanced CRC and are associated with worse prognosis in this stage of disease.

Selective, high affinity peptide antagonists of alpha-melanotropin action at human melanocortin receptor 4: their synthesis and biological evaluation in vitro

Peptide Ac-Nle(4)-cyclo(5beta-->10epsilon)(Asp(5)-His(6)-D-(2')Nal(7)-Arg(8)-Trp(9)-Lys(10))-NH(2), compound 1, a cyclic derivative of alpha-melanotropin, is a nonselective high affinity antagonist at human melanocortin receptors 3 and 4, and an agonist at melanocortin receptors 1 and 5. To differentiate between the physiological functions of these receptors, antagonists with improved receptor selectivity are needed. In this study, analogues of compound 1 without Ac-Nle(4) or His(6) and/or the amino group of Asp(5) were prepared and tested in binding assays and in functional assays on CHO cells expressing hMC3-5R. Several of these peptides were to be selective, high affinity hMC-4R antagonists. The most interesting was compound 10, named MBP10, cyclo(6beta-->10epsilon)(succinyl(6)-D-(2')Nal(7)-Arg(8)-Trp(9)-Lys(10))-NH(2), an antagonist (IC(50) = 0.5 nM) with 125-fold selectivity over hMC-3R (and of >300-fold selectivity over MC-1RB). This compound had no agonist activity at hMC-3R or hMC-4R and only weak agonist activity at hMC-5R. Examination of the sequences of these new peptides revealed that the D-(2')Nal(7)-Arg(8)-Trp(9) segment of peptide 1 forms the "essential core" required for high affinity and high selectivity of analogues of peptide 1 at hMC-4R, but the "extended core", His(6)-D-(2')Nal(7)-Arg(8)-Trp(9), is necessary for the maximum affinity for hMC-3R and hMC-5R.

M-CSF (monocyte colony stimulating factor) and M-CSF receptor expression by breast tumour cells: M-CSF mediated recruitment of tumour infiltrating monocytes?

Infiltrating immune cells in 30 primary human epithelial breast tumours were studied using specific anti-CD3 (T cells), anti-CD68 (macrophages), anti-CD57 (NK cells), and an anti-pan-B cell antibody (L26). The majority of tumour infiltrating inflammatory cells are T cells (40-50%) and monocytes/macrophages (15-35%). The macrophage specific chemo-attractant and growth factor CSF-1 is detected by immunohistochemical techniques (IHC) at the level of invasive breast cancer cells in 46/50 tumours but not at the level of in-situ (pre-invasive) cancer. A mosaic staining pattern was usually observed, with a very high expression in areas of obvious stromal invasion (90% cells positive) and absent or trace staining in intraductal carcinoma. Macrophages and plasma cells are equally intensely positive. In-situ hybridisation experiments confirm the production of CSF-1 (mRNA) by tumour cells and show the same pattern of expression. Expression of the CSF-1 receptor protein (fms) was also observed by IHC in 41/48 invasive tumours, albeit at weaker intensities than in tumour infiltrating monocytes/macrophages. A concomitant expression of both CSF-1 and fms in in-situ carcinoma was never seen (n = 14). It is therefore proposed that the associated expression of CSF-1 and its receptor may be linked to the invasive potential of breast cancer, the monocytic infiltrate being an indication of the quantitative importance of CSF-1 production by the tumour.

Continuous positive airway pressure by nasal prongs in bronchiolitis

Ten infants with evidence of impending respiratory failure from severe bronchiolitis were successfully treated with continuous positive airway pressure (NCPAP) with double nasal prongs. Their mean (SD) age was 6.7 (3.8) months and mean (SD) body weight was 7.1 (2.1) kg. Respiratory assessments were made immediately before and 2 hours after application of NCPAP. Clinical symptoms, signs, and arterial blood gases improved in all patients, with a significant fall in mean (SD) respiratory rate [71 (6) vs. 54 (9) per minute], mean (SD) heart rate (178(9) vs. 154(15) per minute], and mean (SD) partial pressure of arterial carbon dioxide [Paco2; 48.0 (13.9) vs. 42.4 (12.9) mmHg]. There was a significant rise in mean (SD) arterial blood pH [7.33 (0.05) vs. 7.37 (0.05)] and mean (SD) oxygenation ratio [Fio2/Pao2, 155 (25) vs. 175 (22)]. We believe NCPAP is an effective method, with numerous advantages in the treatment of severe bronchiolitis. Early application of NCPAP is suggested to avoid the need for mechanical ventilation.

Butyrate inhibits colon carcinoma cell growth through two distinct pathways

BACKGROUND

Dietary fiber and the resultant increase in colonic butyrate levels protect against colon carcinogenesis. Previous studies have shown that p21 and histone hyperacetylation are important in basal growth inhibition by butyrate. This study was designed to elucidate other mechanism underlying the butyrate effects on cell growth.

METHODS

HT-29 colon carcinoma cells (standard medium or medium lacking serum) were treated with sodium butyrate (NaBu), epidermal growth factor (EGF), or both. Northern blot analyses were performed with cDNA probes specific for c-fos, c-jun, and actin. Cell growth was measured by 3H-thymidine incorporation. Enzyme-linked immunosorbent assay (ELISA) was used to quantify EGF receptor levels.

RESULTS

Butyrate and serum starvation (SS) both induced a cell cycle withdrawal by 24 hours. In response to EGF treatment, SS cells exhibited a growth spurt and induced c-fos and c-jun proto-oncogene expression, whereas butyrate-treated cells exhibited minimal growth response to EGF. This relative unresponsiveness to EGF in butyrate-treated cells corresponded to a dramatic decline in EGF receptor levels when compared to untreated controls.

CONCLUSIONS

Butyrate appears to inhibit colon cancer cell growth by two mechanisms, one involving histone hyperacetylation and p21 induction and the other related to impaired EGF-responsiveness.