Chromosomal radiosensitivity in G2-phase lymphocytes identifies breast cancer patients with distinctive tumour characteristics

A substantial proportion of women with breast cancer exhibit an abnormally high radiosensitivity as measured by the frequency of chromatid breaks induced in G2-phase, PHA stimulated lymphocytes. Chromatid break frequencies were compared for a cohort of previously untreated sporadic breast cancer patients and hospital outpatient controls. In the breast cancer group 46% showed high radiosensitivity compared to 14% of controls (P< 0.001). Comparison of those breast cancer patients with a high G2 radiosensitivity (G2RS) versus those with a low G2RS showed no difference in menopausal status or age but the high G2RS group had on average a lower score on the Nottingham Prognostic Index. Predicted survival in the high G2RS group at 15 years was 55% compared to 36% for the low G2RS group. Furthermore, 81% of tumours from the high G2RS were oestrogen receptor positive compared to 45% from the low G2RS group. Thus high G2RS identifies a sub-population of patients with distinctive tumour characteristics and with a predicted improved prognosis as compared with those in the low G2RS group. Our findings imply that besides influencing risk of breast cancer the genetic factors determining G2 radiosensitivity also influence the tumour characteristics and prognosis in these patients.

The microbiology of primary dental caries in humans

A systematic literature review from 1966 to 2000 revealed 2,730 English-language publications on the role of bacteria in human primary dental caries in vivo. The most pertinent 313 papers were analyzed in evidence tables accessible online (http://www.nidcr.nih.gov). The search targeted all bacterial types implicated previously in caries and asked two questions. First, what is the association of specific bacteria with tooth decay and can causation be attributed to any of those bacteria? Retrieved studies were categorized as randomized-blinded-interventional, longitudinal, case-control, and cross-sectional and were weighted in descending order in terms of significance. Although many studies, due to ethical requirements, had confounding variables, they still indicate strongly: 1) the central role of the mutans streptococci in initiation of caries of smooth surfaces and fissures of crowns of teeth and suggests their potent role in induction of root surface caries; and 2) that lactobacilli are implicated as important contributory bacteria in tooth decay, but their role in induction of lesions is not well supported. Second, what is the source of infection by cariogenic bacteria? Molecular/genetic studies of implicated bacteria isolated from humans, randomized-blinded-interventional, and longitudinal studies indicate that mutans streptococci are spread vertically among humans, mostly from mothers to their children. Implications of these conclusions are briefly discussed. The most significant problems of literature interpretation include the benefits/shortcomings of salivary and plaque monitoring of the flora, the role of sugar(s) in decay as it influences the flora, and modeling strategies to predict lesion score increments as distinct from determination of the etiological role of specific bacteria. Future directions for microbiological clinical caries research are suggested, and the use of the term "caries" to describe the disease, not its lesions, is urged.

Differential p53 protein expression in breast cancer fine needle aspirates: the potential for in vivo monitoring

Fine needle aspiration (FNA) biopsy is the least invasive method of sampling breast cancer in vivo and provides material for breast cancer diagnosis. FNA has also been used to examine cellular markers to predict and monitor the effects of therapy. The aim of this study was to assess the accuracy of using FNA material compared with resected cancer for Western blotting studies of the p53 pathway, a key to tumour response to radiotherapy and chemotherapy. Paired samples of breast cancer FNAs collected pre-operatively and post-operatively were compared with tissue samples obtained at the time of surgical resection. Western blots were probed for p53 using the antibodies DO12 and DO1, and for levels of downstream proteins p21/WAF1 and p27. The protein extracted by FNA was sufficient for up to 5 Western blot studies. p53 expression and phosphorylation did not differ significantly pre- and post-operatively, indicating that intra-operative manipulation does not affect p53 expression or downstream activation in breast cancer. However, expression of p53, p21 and p27 varied between individual patients suggesting a range of p53 pathway activation in breast cancer. Immunohistochemistry confirmed that the cancer cells accounted for the protein expression detected on Western blots. FNA yields adequate protein for Western blotting studies and could be used as a method to monitor p53 activity in vivo before and during anti-cancer treatment possibly providing early evidence of tumour response to therapy.

Chromosomal imbalances in gastric and esophageal adenocarcinoma: specific comparative genomic hybridization-detected abnormalities segregate with junctional adenocarcinomas

The incidence of adenocarcinoma arising at the esophagogastric junction (EGJ) is increasing at a rate greater than that for any other form of solid malignancy. Commensurate with this, the incidence of histologically similar tumors arising in the gastric body and antral mucosa is declining. The increased incidence of the proximal group of tumors may reflect, in part, the higher prevalence of Barrett esophagus. These epidemiological features suggest that histologically similar tumors arising at the EGJ and from the distal stomach are different, which may be reflected in the genetic abnormalities that characterize the two groups of tumors. The purpose of this study was to screen genomic DNA from adenocarcinomas of the esophagus and stomach for regions of chromosomal imbalance, using comparative genomic hybridization to determine whether tumors at the EGJ (junctional tumors) have a different profile compared with tumors of the distal stomach. Tumor samples were derived from a series of 48 gastroesophageal adenocarcinomas (20 junctional and 28 distal) that were acquired prospectively from patients undergoing esophagogastrectomy. These tumors are characterized by several regions of chromosomal imbalance with no obvious correlation between most regions of abnormal copy number and tumor type. However, our study shows for the first time cytogenetic abnormalities (5p+ and 18q-) that identify statistically significant differences (P < 0.02 and < 0.05, respectively) between junctional and distal gastric tumors. These differences are gain of 5p (55% [11/20] of junctional tumors vs. 21% [6/28] of distal gastric tumors) and loss of 18q (25% [5/20] cases of junctional tumors vs. 4% [1/28] of distal tumors) segregating with tumors of the EGJ. These abnormalities may distinguish distinct tumor subtypes that are recognized in epidemiological and clinical studies but that are otherwise histologically identical.

Serotonin projection patterns to the cochlear nucleus

The cochlear nucleus is well known as an obligatory relay center for primary auditory nerve fibers. Perhaps not so well known is the neural input to the cochlear nucleus from cells containing serotonin that reside near the midline in the midbrain raphe region. Although the specific locations of the main, if not sole, sources of serotonin within the dorsal cochlear nucleus subdivision are known to be the dorsal and median raphe nuclei, sources of serotonin located within other cochlear nucleus subdivisions are not currently known. Anterograde tract tracing was used to label fibers originating from the dorsal and median raphe nuclei while fluorescence immunohistochemistry was used to simultaneously label specific serotonin fibers in cat. Biotinylated dextran amine was injected into the dorsal and median raphe nuclei and was visualized with Texas Red, while serotonin was visualized with fluorescein. Thus, double-labeled fibers were unequivocally identified as serotoninergic and originating from one of the labeled neurons within the dorsal and median raphe nuclei. Double-labeled fiber segments, typically of fine caliber with oval varicosities, were observed in many areas of the cochlear nucleus. They were found in the molecular layer of the dorsal cochlear nucleus, in the small cell cap region, and in the granule cell and external regions of the cochlear nuclei, bilaterally, of all cats. However, the density of these double-labeled fiber segments varied considerably depending upon the exact region in which they were found. Fiber segments were most dense in the dorsal cochlear nucleus (especially in the molecular layer) and the large spherical cell area of the anteroventral cochlear nucleus; they were moderately dense in the small cell cap region; and fiber segments were least dense in the octopus and multipolar cell regions of the posteroventral cochlear nucleus. Because of the presence of labeled fiber segments in subdivisions of the cochlear nucleus other than the dorsal cochlear nucleus, we concluded that the serotoninergic projection pattern to the cochlear nucleus is divergent and non-specific. Double-labeled fiber segments were also present, but sparse, in the superior olive, localized mainly in periolivary regions; this indicated that the divergence of dorsal and median raphe neurons that extends throughout regions of the cochlear nucleus also extended well beyond the cochlear nucleus to include at least the superior olivary complex as well.

Tropical tropospheric ozone and biomass burning

New methods for retrieving tropospheric ozone column depth and absorbing aerosol (smoke and dust) from the Earth Probe-Total Ozone Mapping Spectrometer (EP/TOMS) are used to follow pollution and to determine interannual variability and trends. During intense fires over Indonesia (August to November 1997), ozone plumes, decoupled from the smoke below, extended as far as India. This ozone overlay a regional ozone increase triggered by atmospheric responses to the El Niño and Indian Ocean Dipole. Tropospheric ozone and smoke aerosol measurements from the Nimbus 7 TOMS instrument show El Niño signals but no tropospheric ozone trend in the 1980s. Offsets between smoke and ozone seasonal maxima point to multiple factors determining tropical tropospheric ozone variability.

Opioid-mediated facilitation of long-term depression in rat hippocampus

Previous studies have demonstrated that opioid substances are often inhibitors of the gamma-aminobutyric acid (GABA) transmitter system in the hippocampal formation, and that GABA-mediated inhibition is a potent modulator of synaptic plasticity. Field excitatory postsynaptic potentials were recorded from the CA1 region of rat hippocampal slices in response to stimulation of the Schaffer collateral fibers to monitor the effects of acute opioid exposure on the induction of long-term depression (LTD) at excitatory synapses in the stratum radiatum. Exogenous application of a selective mu-opioid agonist resulted in a greater than 2-fold enhancement of LTD, whereas kappa- and delta-agonists did not significantly affect LTD magnitude. Costimulation of the opioid peptide-containing stratum lacunosum-moleculare during LTD induction also resulted in a facilitation of LTD in the stratum radiatum, an effect prevented by prior administration of an opioid antagonist. These results suggest that both exogenously applied and endogenously released opioids can act to facilitate LTD of the Schaffer collateral input to CA1 pyramidal neurons.

Inhibiting mutations in the transforming growth factor beta type 2 receptor in recurrent human breast cancer

Members of the transforming growth factor beta (TGF-beta) family are potent inhibitors of the growth of many epithelial cell types. Transmembrane signaling by TGF-beta occurs via a complex of the serine/threonine kinases TGF-beta type 1 receptor and TGF-beta type 2 receptor (TGFBR2), and inactivating mutations in the latter have recently been detected in some primary tumors and in several types of tumor-derived cell lines. The most common mutations that have been identified in TGFBR2 are frameshifts in a repetitive polyadenine region in replication error-positive colorectal carcinomas that result in a truncated protein and absence of receptor expression at the cell surface. A number of point mutations in the highly conserved serine/threonine kinase domain of TGFBR2 have also been reported, some of which have been correlated with either loss of trans-phosphorylation of TGF-beta type 1 receptor or constitutive activation of trans-phosphorylation. No TGFBR2 mutations have been reported in human breast tumors, but anomalous expression of TGF-beta in breast carcinomas suggests that TGF-beta signaling may be defective. We have therefore systematically examined unmatched sets of 17 primary and 17 recurrent breast tumor samples for mutations in TGFBR2, restricted to those regions of the gene in which mutations have previously been reported. None of the previously reported mutations was detected, but four novel mutations (V387M, N435S, V447A, and L452M) were found in the kinase domain in recurrent tumors. No mutations were detected in primary tumors. TGF-beta signaling was significantly inhibited by each of the N435S, V447A, and L452M mutations.

Serotonergic innervation of the auditory brainstem of the Mexican free-tailed bat,Tadarida brasiliensis

Anatomical and electrophysiological evidence suggests that serotonin alters the processing of sound in the auditory brainstem of many mammalian species. The Mexican free-tailed bat is a hearing specialist, like other microchiropteran bats. At the same time, many aspects of its auditory brainstem are similar to those in other mammals. This dichotomy raises an interesting question regarding the serotonergic innervation of the bat auditory brainstem: Is the serotonergic input to the auditory brainstem similar in bats and other mammals, or are there specializations in the serotonergic innervation of bats that may be related to their exceptional hearing capabilities? To address this question, we immunocytochemically labeled serotonergic fibers in the brainstem of the Mexican free-tailed bat, Tadarida brasiliensis. We found many similarities in the pattern of serotonergic innervation of the auditory brainstem in Tadarida compared with other mammals, but we also found two striking differences. Similarities to staining patterns in other mammals included a higher density of serotonergic fibers in the dorsal cochlear nucleus and in granule cell regions than in the ventral cochlear nucleus, a high density of fibers in some periolivary nuclei of the superior olive, and a higher density of fibers in peripheral regions of the inferior colliculus compared with its core. The two novel features of serotonergic innervation in Tadarida were a high density of fibers in the fusiform layer of the dorsal cochlear nucleus relative to surrounding layers and a relatively high density of serotonergic fibers in the low-frequency regions of the lateral and medial superior olive.

Afferent projections of the superior olivary complex

Based on current literature, the afferents of the superior olivary complex (SOC) are described including those from the cochlear nucleus, inferior colliculus, thalamus, and auditory cortex. Intrinsic SOC afferents and non-auditory afferents from the serotoninergic and noradrenergic systems are also described. New data are provided that show a differential distribution of serotoninergic afferents within the SOC: serotoninergic fibers were relatively sparse in the lateral and medial superior olives and the medial nucleus of the trapezoid body and were most numerous in periolivary regions. There are variations in the density of serotoninergic fibers within periolivary regions themselves. New data is also provided on auditory and non-auditory afferents to SOC neurons, which have known targets. These include: cochlear nucleus afferents to periolivary (lateral nucleus of the trapezoid body, LNTB) cells that project to the inferior colliculus; cortical afferents to periolivary (ventral nucleus of the trapezoid body, VNTB) cells that project to the cochlear nucleus; and serotoninergic and noradrenergic afferents to periolivary (LNTB and VNTB) cells that project to the cochlear nucleus. The relationships between other types of afferents and SOC neurons with known projections are also described as functional circuits. The circuits include those that are part of the ascending auditory system (to the inferior and superior colliculi, lateral lemniscus, and medial geniculate nucleus), the descending auditory system (to the cochlea and cochlear nucleus), and the middle ear reflex circuits.

3-(3,5-Dimethoxyphenyl)-1,6-naphthyridine-2,7-diamines and related 2-urea derivatives are potent and selective inhibitors of the FGF receptor-1 tyrosine kinase

A series of 3-aryl-1,6-naphthyridine-2,7-diamines and related 2-ureas were prepared and evaluated as inhibitors of the FGF receptor-1 tyrosine kinase. Condensation of 4,6-diaminonicotinaldehyde and substituted phenylacetonitriles gave intermediate naphthyridine-2,7-diamines, and direct reaction of the monoanion of these (NaH/DMF) with alkyl or aryl isocyanates selectively gave the 2-ureas in varying yields (23-93%). For the preparation of more soluble 7-alkylamino-2-ureas, a number of protecting groups for the 2-amine were evaluated (phthaloyl, 4-methoxybenzyl) following selective blocking of the 7-amine (trityl), but these were not superior to the (required) 2-tert-Bu-urea group itself. Direct alkylation of the anion of the (unprotected) 7-amino group with excess 4-(3-chloropropyl)morpholine in DMF gave low (10%) yields of the desired product, but alkylation of the 7-acetamido anion, followed by mild alkaline hydrolysis, raised this to 64%. 3-Phenyl analogues were nonspecific inhibitors of isolated c-Src, FGFR, and PDGFR tyrosine kinases, whereas 3-(2,6-dichlorophenyl) analogues were most effective against c-Src and FGFR, and 3-(3,5-dimethoxyphenyl) derivatives showed high selectivity for FGFR alone. A water-soluble (7-morpholinylpropylamino) analogue retained high FGFR potency (IC(50) 31 nM) and selectivity. Pairwise comparison of the 1, 6-naphthyridines and the corresponding known pyrido[2,3-d]pyrimidine analogues showed little differences in potency or patterns of selectivity, suggesting that the 1-aza atom of the latter is not important for activity. A 7-acetamide derivative inhibited the growth of FGFR-expressing tumor cell lines and was particularly potent against HUVECs (IC(50) 4 nM). This compound was also a very potent inhibitor of HUVEC microcapillary formation (IC(50) 0.01 nM) and Matrigel invasion (IC(50) 7 nM) and showed significant in vivo antitumor effects in a highly vascularized mammary adenocarcinoma 16/c model at nontoxic doses. The compounds are worthy of further evaluation as antiangiogenesis agents.

Synthesis and structure-activity relationships of 7-substituted 3-(2, 6-dichlorophenyl)-1,6-naphthyridin-2(1H)-ones as selective inhibitors of pp60(c-src)

7-substituted 3-(2,6-dichlorophenyl)-1,6-naphthyridin-2(1H)-ones are potent inhibitors of protein tyrosine kinases, with some selectivity for c-Src. The compounds were prepared by condensing 4, 6-diaminonicotinaldehyde with 2,6-dichlorophenylacetonitrile and selectively converting the 2- and 7-amino groups of the product to hydroxy and fluoro groups, respectively, by prolonged diazotization in 50% aqueous fluoboric acid. N-Methylation, followed by treatment with aliphatic diamines, aromatic amines, or their derived lithium anions, gave the desired compounds. Selected isomeric 1, 8-naphthyridin-2(1H)-ones were also prepared in order to evaluate the relative contributions of both ring A aza atoms of the related pyrido[2,3-d]pyrimidin-7(8H)-ones to the inhibitory activity. The compounds were evaluated for their ability to prevent phosphorylation of a model substrate by c-Src, FGF-1 receptor, and PDGF-beta receptor enzymes. Overall, there was a high degree of correlation of the activities against the different kinases, with c-Src being generally the most sensitive to structural changes. 1, 6-Naphthyridin-2(1H)-one analogues bearing basic aliphatic side chains [7-NH(CH(2))(n)()NRR, 7-NHPhO(CH(2))(n)()NRR, or 7-NHPhN(CH(2))(4)NMe] were the most potent against c-Src (IC(50)s of 10-80 nM), showing good selectivity with respect to PDGFR (10-300-fold) but less with respect to FGFR. The 1, 6-naphthyridin-2(1H)-ones showed broadly similar activity to the analogous pyrido[2,3-d]pyrimidin-7(8H)-ones, whereas the 1, 8-naphthyridin-2(1H)-ones were at least 10(3)-fold less potent. These results, indicating that the 3-aza atom in the pyrido[2, 3-d]pyrimidin-7(8H)-ones is mandatory, whereas the 1-aza atom is not, support the published binding model for these compounds to c-Src (J. Med. Chem. 1998, 41, 1752), where the 3-aza and 2-NH atoms form a bidentate H-bond donor-acceptor motif that interacts with Met341 and the 1-aza atom is not involved in specific binding interactions.

Deaths following hernia surgery: room for improvement

BACKGROUND

Abdominal wall herniae are common and may well lead to death. The aim of this study was to examine the deaths of patients with an inguinal, femoral or incisional hernia to identify aspects of management which could be improved upon.

METHOD

Data collected by the Scottish Audit of Surgical Mortality 1994-1997 was analysed by interrogation of the database for all deaths on a surgical ward or within 30 days of surgery where the principle diagnosis was inguinal, fermoral or incisional hernia.

RESULTS

There were 133 deaths out of 31,525 operations over the 4-year period. Mortality was highest among femoral hernia operations in women (37 deaths/1184 operations; 3.1%) and 59% of femoral hernia surgery was performed outwith normal working hours. The 133 patients were elderly (mean age 79 years) and unfit, but less than half the operations involved consultant anaesthetists or consultant surgeons. Delay in referral contributed to death in 15/133 patients and adverse factors in management, particularly in the perioperative period, caused the death of 2 patients and contributed to the death of a further 29/133.

CONCLUSIONS

Herniae carry a significant mortality in elderly, unfit patients who require close attention to perioperative management. These patients should be anaesthetised and operated upon by consultant staff during the normal working day.

Dephosphorylation of p53 at Ser20 after cellular exposure to low levels of non-ionizing radiation

Induction of the transactivation function of p53 after cellular irradiation was studied under conditions in which upstream signaling events modulating p53 activation were uncoupled from those regulating stabilization. This investigation prompted the discovery of a novel radiation-responsive kinase pathway targeting Ser20 that results in the masking of the DO-1 epitope in undamaged cells. Unmasking of the DO-1 epitope via dephosphorylation occurs in response to low doses of non-ionizing radiation. Our data show that phosphorylation at Ser20 reduces binding of the mdm2 protein, suggesting that a function of the Ser20-kinase pathway may be to produce a stable pool of inactive p53 in undamaged cells which can be readily activated after cellular injury. Phospho-specific monoclonal antibodies were used to determine whether the Ser20 signaling pathway is coupled to the Ser15 and Ser392 radiation-responsive kinase pathways. These results demonstrated that: (1) dephosphorylation at Ser20 is co-ordinated with an increased steady-state phosphorylation at Ser392 after irradiation, without p53 protein stabilization, and (2) stabilization of p53 protein can occur without Ser15 phosphorylation at higher doses of radiation. These data show that the Ser20 and Ser392 phosphorylation sites are both targeted by an integrated network of signaling pathways which is acutely sensitive to radiation injury.

Completion of the journey of care: Scottish Audit of Surgical Mortality (SASM)

The ideal must be to audit all deaths as part of routine surgical and anaesthetic practice. We have examined the level of compliance of surgeons and anaesthetists participating in the Scottish Audit of Surgical Mortality (SASM) for the audit's first three years. The audit has achieved more than 92% compliance, unchanged over a three year period. As a consequence it can be regarded as a truly routine part of surgical and anaesthetic practice within Scotland.