An anaphase calcium signal controls chromosome disjunction in early sea urchin embryos.

A transient increase in intracellular calcium concentration [Ca2+]i occurs throughout the cell as sea urchin embryos enter anaphase of the first cell cycle. The transient just precedes chromatid disjunction and spindle elongation. Microinjection of calcium chelators or heparin, an InsP3 receptor antagonist, blocks chromosome separation.

Transepithelial transport of the fluoroquinolone ciprofloxacin by human airway epithelial Calu-3 cells.

Although fluoroquinolone antibiotics such as ciprofloxacin are able to gain access to lung tissue and both pleural and bronchial secretions, the characteristics of transport and cellular uptake of ciprofloxacin in human epithelial lung tissue remain obscure. We have chosen human airway epithelial (Calu-3) cells, reconstituted as functional epithelial layers grown on permeable filter supports, as a model with which to assess both transepithelial transport and cellular uptake of ciprofloxacin. Transepithelial ciprofloxacin fluxes in absorptive (apical-to-basal) and secretory (basal-to-apical) directions were similar throughout the concentration range studied (1.

Connexin 32 of gap junctions contains two cytoplasmic calmodulin-binding domains.

A fluorescent calmodulin derivative, 2-chloro-[4-(epsilon-amino-Lys75)]-[6-(4- diethylaminophenyl)-1,3,5-triazin-4-yl]-calmodulin (TA-calmodulin) [Török and Trentham (1994) Biochemistry 33, 12807-12820], and equilibrium fluorescence methods were used to identify calmodulin-binding domains of connexin subunits of gap junctions. Synthetic peptides corresponding to six extramembrane regions of connexin 32, a major component of rat liver gap junctions, and peptides derived from connexin 43 and 26, were tested. Two cytoplasmically oriented peptides that correspond to an N-terminal 21-amino-acid sequence and a 15-amino-acid sequence at the C-terminal tail of connexin 32 bound TA-calmodulin in a Ca2+-dependent manner.

Targeting to intestinal M cells.

The specialised, antigen-transporting, epithelial M cells in the follicle-associated epithelium (FAE) overlying gut-associated lymphoid tissues constitute the primary target for oral delivery of vaccines. Our studies have shown that polystyrene microspheres selectively bind to, and are efficiently transcytosed by, rabbit Peyer's patch M cells in closed intestinal loops. Binding of biodegradable poly(DL-lactide-co-glycolide) microspheres to rabbit Peyer's patch FAE is an order of magnitude lower than that of polystyrene microspheres.

The topographical organization of descending projections from the central nucleus of the inferior colliculus in guinea pig.

We describe the descending projections from the central nucleus of the inferior colliculus (CNIC) in guinea pig. Focal injections of the tracer biocytin, made in physiologically defined frequency regions of the CNIC, labelled laminated axonal terminal fields in the ipsilateral dorsal nucleus of the lateral lemniscus, and bilaterally in the ventral nucleus of the trapezoid body and the dorsal cochlear nucleus. Labelling was also present in the rostral periolivary nucleus, but we could not distinguish a clear border between the terminal fields in this nucleus and those in the ventral nucleus of the trapezoid body.

Prognostic significance of the c-erbB-2 oncogene product in childhood medulloblastoma.

The expression and prognostic significance of the c-erbB-2 oncogene product was studied in 55 cases of childhood medulloblastoma. Forty-six of the 55 tumours (83.6%) expressed the c-erbB-2 product.

The basis of autoimmunity: an overview.

Autoimmune diseases represent a failure of control in the immune system. In recent years, our understanding of the mechanisms of action of both the innate and the specific immune responses has increased greatly. In particular, we now know much more about the nature of antigens recognized by lymphocytes, as well as how diversity of antigen receptors is generated, antigens and antigen receptors interact, and the cells of the immune system communicate.

Cytochalisin D exerts stimulatory and inhibitory effects on insulin-induced glucokinase mRNA expression in hepatocytes.

The microfilament cytoskeleton is postulated to have a role in the localization, transport and anchorage of certain specific mRNAs. We investigated the effects of cytochalasin D, a fungal metabolite that binds to actin and disrupts the microfilament structure, on insulin-induced expression of glucokinase mRNA in rat hepatocyte cultures. Cytochalasin-D significantly potentiates insulin-induced glucokinase mRNA expression at 100 nM concentration but counteracts glucokinase expression at 2-20 microM.

Junctional uvomorulin/E-cadherin and phosphotyrosine-modified protein content are correlated with paracellular permeability in Madin-Darby canine kidney (MDCK) epithelia.

Strains I and II of Madin-Darby canine kidney (MDCK) cells, which differ markedly in transepithelial resistance (RT) and paracellular permeability, have been used to investigate whether differences in the cellular content of uvomorulin/E-cadherin and phosphotyrosine may be correlated with junctional properties. Using immunocytochemistry, the strain I "tight" epithelia showed significantly stronger uvomorulin staining at regions of cell-cell contact compared with strain II "leaky" MDCK epithelia. In contrast, strain I MDCK cells showed a relatively faint phosphotyrosine staining, distributed evenly throughout the cytoplasm, while strain II MDCK cells displayed intense staining for phosphotyrosine residues in the junctional region and the lateral cell membrane with additional labelling of the cytoplasm.

Horizontal gene transfer in the evolution of group A streptococcal emm-like genes: gene mosaics and variation in Vir regulons.

Most M type 5 group A streptococcal strains were found to contain a single emm-like gene between virR and scpA (the Vir regulon), but two distinct emm-like genes were identified in the Vir regulon of the M5 strain NCTC8193. The complete sequences of both of these genes were determined. One, called emm5.

Identification of bovine glutamate dehydrogenase as an RNA-binding protein.

Two RNA binding activities were demonstrated in bovine liver homogenate. One binding protein was isolated by a simple ion exchange and gel filtration protocol and was shown by N-terminal protein sequence analysis to be glutamate dehydrogenase. Using identical RNA substrate and assay conditions, no detectable RNA binding was observed with equimolar amounts of other representative dehydrogenases and proteins.

Na(+)-independent, H(+)-coupled transepithelial beta-alanine absorption by human intestinal Caco-2 cell monolayers.

beta-Alanine transport across intact human intestinal epithelial (Caco-2) cell layers has been investigated. In Na(+)-containing solutions, net absorptive flux of beta-alanine from apical-to-basal surfaces is small or absent, despite Na(+)-dependent intracellular beta-alanine accumulation across both apical and basal surfaces. Upon apical acidification (apical pH 6.

Transepithelial glycylsarcosine transport in intestinal Caco-2 cells mediated by expression of H(+)-coupled carriers at both apical and basal membranes.

Glycylsarcosine (Gly-Sar) transport in human intestinal epithelial (Caco-2) cells has been investigated. Gly-Sar transport, from apical to basal surfaces (Ja-b), and intracellular accumulation are greatest when the apical medium is acidified (apical pH 6.0, basal pH 7.

MSH receptors and function in amelanotic B16 melanoma cells.

The possible mechanisms for the reduced melanin content and poor melanogenic response to MSH was investigated in B16-F10DD differentiation deficient melanoma cells. In particular, the MSH receptor status and associated signal transduction pathway linking to tyrosinase activity in these cells was studied for evidence of any defects. F10DD cells contained high-affinity binding sites for alpha-MSH, with KD values similar to those previously reported for other variants of the B16 melanoma.

Bradykinin stimulation of electrogenic ion transport in epithelial layers of cultured human endometrium.

Primary cultures of glandular endometrial epithelial cells grown on permeable supports formed monolayers with a high transepithelial electrical resistance [1096 +/- 83 omega.cm2 (n = 34)] and displayed electrogenic ion transport as demonstrated by an inward short circuit current (Isc; 20 +/- 2 microA/cm2). Bradykinin, 10(-8)-10(-6) M, added to either the basolateral or apical solutions enhanced the inward ISC.

Genomic instability and metastatic progression.

Recently, there has been a growing body of opinion that tumour cells progress from a less malignant to a more malignant (metastatic) phenotype, due to an inherent instability within the genome. It has also been suggested that genomic instability and the rate of generation of metastatic variants both increase as the tumour cells achieve a higher state of malignancy. In this review, several different aspects of genomic instability have been discussed with particular reference to the low (F1) and high (BL6, ML8) metastatic variants of a B16 murine melanoma.

The role of pharmacogenetics in chemotherapy: modulation of tumour response and host toxicity.

What may appear to be a strategy for investigating pharmacogenetic variation must be seen in the context of an evolving understanding of the molecular biology of drug metabolism. New biochemical and analytical techniques permit the determination of mechanisms of drug action and the molecular biology of host and tumour factors influencing that action. However, the only example of the application of pharmacogenetics in cancer chemotherapy is that of 6MP in the treatment of ALL.

Long term use of transcutaneous electrical nerve stimulation at Newcastle Pain Relief Clinic.

This retrospective study of long-term use of transcutaneous electrical nerve stimulation (TENS) at Newcastle Pain Relief Clinic indicates that TENS has been a successful analgesic treatment for 58.6% of 1582 patients attending the clinic over a period of 10 years. A wide range of pain conditions were found to respond to TENS and many patients continued to use the treatment for several years.

MSH receptor expression and the relationship to melanogenesis and metastatic activity in B16 melanoma.

In this study we have compared the effects of different pro-opiomelanocortin (POMC) peptides on melanogenesis and metastasis and their relationship to MSH receptor expression in B16F1 melanoma cells. All peptides, apart from beta-endorphin, increased melanogenesis and the order of potency was Nle4DPhe7-alpha-MSH greater than alpha-MSH greater than ACTH[1-39] greater than des-acetyl alpha-MSH greater than ACTH[1-24]. A similar order of potency was found for metastasis, except for ACTH [1-24], which had a relatively greater effect on metastasis.

Investigation of adrenal function in women with oligomenorrhoea and hirsutism (clinical PCOS) from the north-east of England using an adrenal stimulation test.

Objective: To determine the prevalence of adrenal enzyme dysfunction in women presenting with oligomenorrhoea and hirsutism, two clinical features of polycystic ovary syndrome (PCOS).

Design: A prospective study of women attending outpatient clinics with these complaints. Androstenedione, dehydroepiandrosterone (DHEA), 17-hydroxyprogesterone (17-OHP), 11-deoxycortisol and cortisol were measured before and after overnight dexamethasone suppression and at 60 minutes after adrenal stimulation by ACTH injection.

Prostaglandin protects against bile salt induced increases in proton permeation of duodenal brush border membrane.

A direct protective action of prostaglandin on luminal cell membranes was investigated by preincubating rabbit duodenal brush border membrane vesicles with prostaglandin E2 (PGE2) before incubation with bile salts. Membrane perturbation was assessed by measuring the net proton permeability (Pnet). Bile salts (deoxycholate, glycodeoxycholate, and taurodeoxycholate; 0.