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The regulation of chloride efflux from cystic fibrosis pancreatic adenocarcinoma cells (CFPAC-1) and wild-type CFTR-transfected CFPAC-1 cells (TPAC) was compared. Forskolin (10 microM) stimulated chloride efflux from the corrected TPAC cells but not from CFPAC-1 cells. Chloride efflux from both cell types was activated by thapsigargin (0.5 microM). The nucleotides ATP and UTP and the non-hydrolyzable ATP analogue, adenosine 5'-O-(3-thio) triphosphate (ATPgammaS), stimulated chloride efflux from both cell types. None of the other P2 purinoceptor agonists investigated elicited a response. The order of potency was ATP > or = UTP > or = ATPgammaS. Adenosine (10-100 microM) activated choride efflux from the TPAC but not the CFPAC cell line with no increase in intracellular cyclic AMP. Small but statistically significant inhibitions of the adenosine-(50 microM)-stimulated increase in chloride efflux were elicited by the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (CPX, 100 nM) and the A2 receptor antagonist 3,7-dimethyl-1-propylargylxanthine (DMPX, 10 microM). The A2A receptor antagonist 8-(3-chlorostyryl)caffeine (CSC, 100 nM) had no significant effect. These results provide evidence for the regulation of chloride efflux by P2Y2 purinoceptors in genetically-corrected and CF pancreatic cell lines. Studies with adenosine receptor antagonists indicate some possible involvement of A1 and A2 (but not A2A) receptors in the adenosine stimulation of chloride efflux, but the relatively small effects of the inhibitors coupled with lack of increase in cyclic AMP and a response only in the CFTR-transfected cells also suggests a possible direct effect of adenosine on CFTR.

Objective: To evaluate the impact of a 6 month group therapy program on the treatment of patients with fibromyalgia (FM). Since FM is a common problem in rheumatology practice, a program was designed to treat patients in a group setting using allied health professionals., Methods: The FM group (15 to 25 patients) met once a week for 6 months. The average session lasted 90 min and consisted of formal lectures, group sessions emphasizing behavior modification, stress reduction techniques, strategies to improve fitness and flexibility and support sessions for spouses/significant others. The 2 major outcome measures were the fibromyalgia impact questionnaire (FIQ) and the total tender point score. Secondary outcome measures were the quality of life scale, questionnaires to assess coping strategies and attitudes to illness, an index of aerobic conditioning, flexibility, distance walked in 6 min., Beck depression and Beck anxiety questionnaires. Patients were followed 2 years and compared to a group of patients outside the program., Results: Between 1989 and 1993 170 patients were evaluated and 104 patients completed the program. At the end of the 6 months 73 (70%) of patients had <11 tender points and FIQ improved 25%. Having a pain profile on MMPI or having major depression, did not predict poorer outcome. Thirty-three patients followed for 2 years after the program continue to show improvement. A control group of 29 patients who never entered the program showed no significant improvement., Conclusion: The group treatment of patients with FM in an outpatient setting shows promise; a more formal controlled study is needed to confirm this impression.

The filamentous fungus Fusarium lateritium is cyanide tolerant, due partly to the induction of the enzyme cyanide hydratase in the presence of cyanide. This enzyme catalyses the hydration of cyanide to formamide. The expression in Escherichia coli of a cDNA clone encoding cyanide hydratase is described. The cDNA cloned was expressed as a transcriptional fusion in the expression vector pKK233-2 and a high level of activity of cyanide hydratase was detected in E. coli. Site-directed mutagenesis of the cys-163 residue inactivated the enzyme.

1. The dentate gyrus fails to develop epileptiform activity in many experimental models of epilepsy, including the in vitro low-Ca2+ model. Although manipulating the K+ concentration or osmolality of normal low-Ca2+ perfusion mediums can enhance the propensity of the dentate gyrus to develop seizure activity, the specific mechanisms contributing to this change are still under investigation. Identification of these mechanisms should improve our understanding of epileptogenesis and of the factors contributing to the propensity for seizure discharge in other tissues. 2. In the present experiments we used externally generated electric fields to depolarize the somata of large populations of dentate granule cells during exposure to a perfusion medium with no added Ca2+ (low-Ca2+ medium). Uniform electric fields were generated across an individual slice by passing current between two parallel AgCl-coated silver wires placed on the surface of the artificial cerebral spinal fluid. The wires were positioned to straddle the slice such that the current flow was parallel to the dendrosomatic axis of the cell population under investigation. 3. Under control conditions (low-Ca2+ medium, no applied field), stimulation of the dentate hilus evoked a single antidromic population spike in 89% of the slices studied (n = 27). During application of electric fields the same stimulus evoked epileptiform activity in all trials. Well-formed bursts first occurred at an average field intensity of +22.9 +/- 2.5 (SE) mV/mm (n = 24). The amplitude of individual spikes and the total number of spikes, within a burst increased in a graded fashion as the magnitude of the applied field was increased. 4. High field intensities evoked epileptiform activity in the absence of a synchronizing antidromic stimulus. These field-induced bursts occurred after a progressive buildup of rhythmic activity recorded in the extrasomatic space and could persist for the entire duration of an applied field, lasting for several seconds. The average field intensity required to produce a threshold burst was +84.6 +/- 3.6 mV/mm (n = 24). 5. In 11% of trials (3 of 27) the dentate gyrus exhibited poorly developed antidromic bursting without the application of depolarizing electric fields. These bursts were completely suppressed by hyperpolarizing fields in the range of -10 to -20 mV/mm. 6. The results of this investigation support the hypothesis that granule cell sensitivity to nonsynaptic interactions is adequate to support bursting in a normal low-Ca2+ medium, but bursting fails to occur because these cells are normally too hyperpolarized relative to their action potential threshold.(ABSTRACT TRUNCATED AT 400 WORDS)

It is now generally accepted that particulates in the nano-range (< 1 micron) can and do cross the intestinal mucosa. However, the issue is less well resolved for particles in the micro-range (> 1 micron) and this is discussed in relation to the variety of experimental designs present in the literature. Emphasis is placed on the relative contributions of quantitative bulk tissue analysis with respect to qualitative and quantitative morphological analysis. The discussion is extended to observations on factors influencing the particle translocation process including variation in particle uptake in relation to intestinal region and time post-dose administration based on data for uptake of -2 microns latex particles by rat Peyer's patch tissue. Although a significant body of data now identifies the intestinal processus of particle translocation it is underlined that discrepancies may arise as a consequence of different analytical approaches and that this is an issue to be addressed for valid comparisons of data.

Pseudomonas thermocarboxydovorans strain C2 is capable of using carbon monoxide as the sole source of carbon and energy. The key enzyme for CO utilisation is the molybdenum containing iron-flavoprotein carbon monoxide dehydrogenase (CODH). This paper reports the DNA sequencing of a 4.7 kb region of the C2 genome which appears to encode the CODH enzyme. The genes for the three subunits of CODH, which we have named cut A, B and C, have been identified and they appear to form an operon. The predicted protein sequences of the three subunits have homology to the structurally related protein, xanthine dehydrogenase, from Drosophila melanogaster. By comparison with xanthine dehydrogenase it can be predicted that the molybdenum cofactor binds to the large subunit of CODH, the small subunit of CODH contains the iron-sulphur centers and the medium subunit binds FAD/NAD+.

Purpose: This study investigated the relationships among four methods of detecting depression in patients with fibromyalgia., Methods: Data were obtained from 100 women (mean age 43 years) who had been diagnosed with fibromyalgia. Instruments included a computerized Diagnostic Interview Schedule (C-DIS), Beck Depression Inventory (BDI), an adjusted "disease-free" BDI (BDI-A), and Minnesota Multiphasic Personality Inventory depression subscale (MMPI-D). Chance-corrected concordance, sensitivity, specificity, and accuracy among the four methods were calculated., Results: The C-DIS detected 22% and BDI-A 29% with current major depression. The BDI and MMPI-D yielded higher estimates of 55% of the 44%, respectively. Agreement on the diagnosis among the four methods was significantly greater than chance. When compared with the C-DIS, the BDI was the most sensitive instrument and the BDI-A most specific.

Objective: Indices of ovarian function and potential fertility have been studied in fully lactating women from the sixth week post-partum to the start of the second menstrual period., Patients: Thirty-four women entered the study and 17 (50%) continued until the first menses. Of these, 16 continued until the second menses. The median time from delivery to day 1 of the first menses was 202 days (range, 85 to 668 days)., Methods: The concentrations of estrone glucuronide (EG) and pregnanediol glucuronide in daily samples of early morning urine were measured by time-resolved fluoroimmunoassay and LH by an immunoradiometric assay. Algorithms were used retrospectively to determine the rise and peak days of all three metabolites., Results: Three cycles were studied relative to day 1 of first menses: (1) premenstrual (days -60 to -31), (2) menstrual (days -30 to -1), and (3) postmenstrual (days 1 to 56). Follicular development occurred in 53%, 100% and 100% of the dated cycles respectively. A peak of LH occurred in 6%, 75% and 80% of cycles, respectively. A period of potential fertility occurred in 11/17 (65%) and 13/16 (81%) of cycles (2) and (3), respectively. The proportion of potentially fertile cycles was higher after the first menses, and after 6 months had elapsed postpartum., Conclusion: A test based on the measurement of EG and used prospectively predicted 13/15 (85%) of the periods of potential fertility during the postmenstrual cycle.

We studied excyclotorsion prospectively in 12 non-strabismic normal patients, 24 patients with unilateral superior oblique paresis (SOP), and 14 patients with bilateral SOP to determine which test and position, and what amount of torsion best discriminates between bilateral and unilateral SOP. For each patient, we measured torsion at near in primary position and in 20 degrees downgaze, using both the double Maddox rod (DMR) and Bagolini lens (BL) tests. We calculated the average of three measurements for each test in each position and the differences in mean excyclotorsion between downgaze and primary position for each patient for each test. To discriminate between unilateral SOP and normal, and bilateral and unilateral SOP patients, the best test and position combination was the DMR in downgaze (P = .0001). The probability of a torsion measurement indicating a unilateral SOP rather than a normal value was 95% at 6 degrees of excyclotorsion; of bilateral rather than unilateral SOP, 90% at 20 degrees. The range in the three torsion readings within patients with either DMR or BL in either position varied up to 7 degrees.

The filamentous fungus Fusarium lateritium is cyanide tolerant, due, at least in part, to the induction by cyanide of the enzyme formamide hydrolyase (EC 4.2.1.66). This enzyme, more commonly known as cyanide hydratase, catalyses the hydration of cyanide to formamide. The enzyme was purified from F. lateritium and showed a subunit molecular mass of 43 kDa (as judged by SDS-PAGE), while the native protein appeared to form aggregates of up to 1217 kDa (as judged by gel-filtration and non-denaturing PAGE). mRNA samples from cultures grown with and without cyanide were in vitro translated and immunoprecipitated. This demonstrated that, in this species, the gene encoding the enzyme designated chy1, is cyanide inducible. Differential screening was used to isolate a cyanide hydratase cDNA clone which was subsequently used to obtain the corresponding genomic clone. A fragment of the cDNA clone encoding all but the first seven amino acids of the protein was expressed in E. coli using the expression vector pGEX-2T. Features of F. lateritium cyanide hydratase together with an analysis of the nucleotide sequence encoding this enzyme are presented.

The authors present a new method for plotting and quantitating the field of binocular single vision (BSV). They modified a Goldmann perimeter to project a fusion target in the form of a cross (+). Unlike previous methods that used a spot, which is a poor fusion target that cannot detect cyclotorsion, the authors' method permits a single tester to plot BSV fields in patients who have any combination of horizontal, vertical, and cyclotorsional diplopia. The BSV fields were plotted in 23 patients with acquired diplopia using both the fusion target and the spot. Scoring was performed using a new scoring template weighted to the functionally important areas around primary and reading positions. Nine patients (39%) had scores for the two targets that differed by more than 10%. The authors' method yields BSV scores that are reproducible and easy to perform and that can be used for preoperative and postoperative assessments, serial monitoring of changes over time, and disability evaluations.

Carbon monoxide dehydrogenase (CODH) from Pseudomonas thermocarboxydovorans strain C2 is composed of three non-identical subunits. A gene library of C2 DNA in lambda vector L47.1 was generated and screened using anti-CODH serum. Western blotting experiments revealed a protein which co-migrated with and had the same immunological reaction as the large subunit of CODH in some of the clones isolated from the library. The coding region was pinpointed to a 4 kb fragment which was subcloned into plasmid. Western blotting experiments showed that all three subunits of CODH were coded for by the subclone. However, no CODH activity was detected.

[3H]Serotonin uptake into mouse cerebrocortical synaptosomes was decreased by the K+ ionophore valinomycin, the K+ and Na+ ionophore gramicidin, and the proton ionophore carbonylcyanide m-chlorophenylhydrazone. The Na+/H+ exchanger monensin reduced uptake at non-depolarizing concentrations. Uptake was also decreased by inhibition of the Na+, K(+)-ATPase with ouabain and by tetrodotoxin-sensitive activation of voltage-dependent sodium channels with veratridine, batrachotoxin and scorpion venom. In contrast, the Ca2+ channel agents BAY K8644 and nimodipine were ineffective. The effect of reducing the Na+ gradient depended upon whether the internal Na+ concentration was raised (i.e. by scorpion venom, monensin) or the external Na+ concentration was lowered (37 mM NaCl in the medium).

Thirty patients requiring surgery for true Brown's syndrome were examined postoperatively. Follow-up ranged from three months to 20 years. Eight-five percent of patients demonstrated some degree of superior oblique palsy, with 54% having a decompensated condition and 30% requiring a second surgical procedure. Patients with marked preoperative restriction appear to be at increased risk for developing a decompensated superior oblique palsy postoperatively. Solutions to this problem are suggested: 1) perform tenotomy at insertion and preserve the adjacent intermuscular septum so a less crippling effect is seen; 2) combine tenotomy with inferior oblique weakening initially in those patients with marked preoperative restriction.

Genes have been cloned from Salmonella typhimurium which when present on the multicopy plasmid pBR322 in the E. coli strain NT31 confer a Gua+ phenotype on this strain. NT31 is a purE gpt double mutant and it was expected that a Gua+ phenotype could be conferred on it by the cloning of either gpt or purE. It was, however found that in addition to these two loci the molecular cloning of another gene, which has been identified as hpt, in pBR322 confers a Gua+ phenotype on NT31. This result is explained by the overproduction of the hpt gene product, hypoxanthine phosphoribosyl transferase, which compensates for the lack of the gpt product guanine-xanthine phosphoribosyl transferase. Restriction analysis of the three loci, gpt, hpt and purE is also presented.

Relocation of professional staff in a community mental health center provided a setting in which to evaluate the effects of physical environment on job satisfaction. Two mental health teams moved from an old, drab central clinic building to new satellite clinics while a third team remained in the old building. Relocated staff reported significant increase in satisfaction with physical surroundings as compared to staff that did not move. Furthermore, satisfaction with physical surroundings had some impact on overall satisfaction ratings. Physical surroundings in a community mental health center may be a mediating variable for staff morale and effectiveness.

An intervention activity commensurate with specific organizational goals, directed to short-term change efforts to alter employee perceptions about their satisfaction, about such work activitiesas communication, and about opportunities to make job-related innovations was implemented for emergency room personnel in a large West Coast metropolitan hospital. When evaluated, using a research design which reduced validity threats in interpreting results, perceptions about some aspects of work were found to be more susceptible to change through short interventions than were others.

To evaluate further the association between myasthenia gravis and humoral immune deficiency, 92 sera from myasthenic patients were tested so as to determine titers against commensal E. coli, isohemagglutinin titers, and IgG and IgM concentrations. Results were compared with those obtained from normals, disease controls, and W27 positive arthropathy. On the basis of these three investigations it is concluded that subtle immunodeficiency is common in myasthenia gravis, and it is suggested that an immune defect might explain such diverse associations as thymic disease, HL-A antigens, and various autoimmune phenomena.

In collective bargaining, the nurses' definition of a situation might be quite different from that of health service management; thus, their reasons for striking and their assessment of the bargaining issues would not be congruent with those of management.

The authors describe a nonseparation, time-resolved fluoroimmunoassay involving the use of monoclonal antibodies for the measurement of estrone-3-glucuronide in urine. The method has appropriate sensitivity (12 nmol/l), better specificity than a conventional radioimmunoassay with polyclonal antibodies, and the advantages of speed, simplicity, less imprecision, and improved clinical effectiveness. The labeled antigen is a novel fluorescent europium chelate covalently linked to estrone glucuronide at carbon 6 of the glucuronide moiety. The antibodies were raised against estrone-3-glucuronyl-6-bovine serum albumin. The antibody binding reaction is performed in microtiter wells (or tubes) and involves the addition of labeled antigen in buffer (2 ng/100 microliters), a limited concentration of antibodies in buffer (100 microliters), and standard or urine sample (10 microliters). The mixture is incubated for 15 minutes at room temperature. Time-resolved fluorescence from the unbound label is proportional to the concentration of estrone glucuronide. The method may be used to monitor ovarian function and potential fertility in women.

A simple method for scoring the field of binocular single vision (BSV) is presented. The field is plotted on the Goldmann Perimeter using the III-4e target. The method gives greater weight to functionally important areas, especially the primary and reading positions. Several cases illustrate the application of the proposed scoring system by correlating patients' subjective disabilities with their diplopia scores. The method is more precise than any previous scheme and provides a quantitative measure that makes the examination of patients with diplopia more accessible to legal evaluation and numerical analysis.

Two techniques for performing the 10-diopter base-down fixation test were used in 44 patients, and the fixation-pattern responses were compared to determine whether they showed any significant differences. The two techniques elicited the same responses in most cases. A comparison of fixation pattern and visual acuity showed that for most of the patients with equal visual acuity or documented amblyopia an accurate diagnosis could be made with the 10-D base-down fixation test. However, for most of the patients with borderline amblyopia the test either overdiagnosed or underdiagnosed the visual status.

Injection of rats with cyclophosphamide (CY) after their consumption of a novel saccharin-flavored drinking solution resulted in a conditioned aversion to saccharin and a conditioned suppression of natural killer cell (NKC) cytotoxicity. In this study, male Sprague-Dawley rats were conditioned by pairing saccharin with 50 mg/kg CY, an immunosuppressive drug with noxious gastrointestinal side-effects. Twenty-two and 26 days later, re-exposure of conditioned animals to saccharin alone re-enlisted the immunosuppressive effects of CY when NKC cytotoxicity was measured on day 29. Although CY also suppressed spleen cell number, IgG antibody titers and interleukin 2 (IL2) production, these immune responses did not appear to be affected by the behavioral conditioning paradigm in this experiment. Unique aspects of this study include the ability to measure multiple immune responses in a single rat and the finding that previous reports of behaviorally conditioned immunosuppression can be extended to another parameter, NKC cytotoxicity. These findings could have significant implications to human medicine, especially in the area of autoimmunity and immunodeficiency, and intervention and treatment of cancer.

Plasma membrane vesicle preparations from mouse cerebral cortex actively accumulated [3H]serotonin upon the imposition of a K+ gradient (in greater than out), a Na+ gradient (out greater than in), and the presence of external Cl-. Maximal stimulation of uptake by internal K+ occurred at 15 mM and half-maximal stimulation at 2 mM. Internal K+ did not enhance uptake merely via generation of a membrane potential because simultaneous parallel increases in internal and external K+ concentration also stimulated uptake. External Cl- increased serotonin uptake with a Km of 18 mM and a Hill number of 1.0, suggesting a requirement for one chloride ion for transport. Uptake could not be driven by internal H+ instead of K+. Estimation of the membrane potential by the distribution of triphenylmethylphosphonium ion showed a modest effect of valinomycin (1-20 microM) in increasing the potential from -19 to -31 mV accompanied by an increase in serotonin uptake. Proton ionophores prevented this effect of valinomycin and, by themselves, reduced the potential to -6 mV, but did not affect serotonin transport. A model is proposed for serotonin transport in brain plasma membrane vesicles that is similar to the model for porcine blood platelet vesicles as far as electroneutrality and stimulation by K+, Na+, and Cl- are concerned, but that is different in substitution of internal H+ for K+.

A model for assessing immunotoxicologic effects of chemicals and drugs was developed in the Sprague-Dawley rat whereby multiple concomitant immunoassays were performed in a single animal. The multiple parameters of immunity assessed in each rat included T cell-dependent IgG antibody production, delayed hypersensitivity, natural killer cell cytotoxicity, and production of three potent immune regulating immunocytokines: macrophage-derived interleukin 1 and prostaglandin E2, and lymphocyte-derived interleukin 2. Splenocyte and resident peritoneal macrophage numbers were also quantitated and spleen and thymus weights recorded. The sensitivity of this animal model was tested by treating rats with the immune-potentiating drugs, NPT 15392 (erythro-9-[2-hydroxy,3-nonyl]hypoxanthine) and avridine (N,N-dioctadecyl-N',N'-bis-[2-hydroxyethyl]propanediamine, or the immune-suppressive drugs, cyclophosphamide (N,N-bis[2-chloroethyl]tetrahydro-2H-1,3,2-oxazaphosphorin-2-amine -2-oxide) and dexamethasone. Rats treated with NPT 15392 or avridine generally had enhanced immune responses, while those treated with cyclophosphamide or dexamethasone had decreased immune responses. Differential responsiveness of various immunocyte populations within individual rats to different drugs, or to doses of the same drug, indicates the efficacy of measuring multiple responses within the same animal. The multiassay-single animal approach represents an economical, versatile, sensitive, and relatively comprehensive paradigm for assessing immunotoxicologic/pharmacologic properties of chemicals and drugs. The approach is extremely economical since multiple immune responses are evaluated in each animal. The approach is versatile because it is amenable to incorporation of a variety of in vitro and in vivo assays and could be applied to almost any species. The model is relatively comprehensive because major types of immune responses/immunocyte populations and immunoregulatory pathways are tested. Finally, the model is sensitive for detecting immunosuppression as well as immunoenhancement, as validated by the use of known immune response modifiers in this study.

We have molecularly cloned the rDt transposon, one component of the classic "Dotted" two-element system of controlling elements. The rDt transposon was identified as a DNA insertion in each of two independent mutation events of the maize A1 gene, a gene necessary for the biosynthesis of anthocyanin pigment. Both mutant alleles result in a stable, anthocyaninless phenotype in all plant tissues. When the transposon "Dotted", (Dt), is present in the genome each allele exhibits a characteristic mutable phenotype (spots of anthocyanin pigmentation). The DNA insertion has been designated rDt, for it responds to or is regulated by the Dt element to allow expression of the otherwise mutated gene, and it had not been named in earlier genetic studies. Sequence analysis revealed the rDt element to be an identical 704 bp insertion within the two mutable alleles, but in opposite orientation and in different exons of the gene. rDt contains an imperfect terminal inverted repeat with similarity to transposable elements of various species. A duplication of 8 bp of the target host site is formed upon integration of the element, and the element is excised from the locus in a germinal revertant. The difference in phenotype of the two unstable alleles, a1 and am-1:Cache, is discussed.

Male Sprague-Dawley rats were exposed to chlorine-based disinfectants in the drinking water from weaning to 12 weeks of age, at which time they were terminated and assessed for immune competence. Chlorine-based drinking water disinfectants used were sodium hypochlorite (5, 15 and 30 ppm) and monochloramine (9, 19 and 38 ppm). Parameters of immunity measured were spleen and thymus weights, antibody production, delayed-type hypersensitivity (DTH) reactions, natural killer cell (NKC) cytotoxicity, oxidative metabolism response (i.e chemiluminescence-CL) and phagocytosis by macrophages, and production of 2 immunoregulatory cytokines, interleukin 2 (IL2) and prostaglandin E2 (PGE2). Significant (P less than or equal to 0.05) reductions of spleen weight, DTH reactions, and oxidative metabolism by macrophages were observed only in groups of rats exposed to high levels (30 ppm) of sodium hypochlorite, while PGE2 production was elevated. Rats exposed to the higher doses of monochloramine had reduced spleen weights (38 ppm), decreased antibody synthesis (9 and 19 ppm) and augmented PGE2 production (19 and 38 ppm). These results extend the earlier observations of others that macrophage function of laboratory rodents may be impaired by exposure to high concentrations of chlorinated drinking water. Furthermore, the function of other major populations of immunocytes and types of immune responses may also be altered following subchronic exposure to high concentrations of chlorinated drinking water. These types of effects on the immune system are a previously unrecognized potential side-effect of the ubiquitous practice of disinfection of water with chlorine compounds. Alteration of immune function of chlorine-based disinfectant-exposed rats in this study was only evident at relatively high doses, and only selected immune responses were altered. It appears, therefore, that these chlorine-based disinfectants are not particularly strong immunodepressants. However, further studies in different species may be warranted in order to better extrapolate to implications to human health following chronic low-level exposure.

Dentine of the enamel-free areas (EFA) of first mandibular molar teeth of rats aged between 20-150 days was examined by scanning electron microscopy. Demineralized sections were stained with Gram-Twort's stain and examined for dental caries. In newly erupted teeth, a few dentinal tubules opened on the EFA surface. As teeth became worn down, extensive areas of EFA showed numerous patent tubules. In primary dentine, no occlusion or partial occlusion of tubules was apparent at any age except at the occlusal surface. It is postulated that this surface narrowing was caused either by dentine debris or salivary deposits. The only other covering of tubule openings appeared to be a thin salivary pellicle which in older animals was plaque-like. Patent tubules in primary dentine contained odontoblast processes which even in worn teeth extended to EFA surfaces. Processes in adjacent enamel-covered dentine also extended to the enamel-dentine junction. Only a few examples of bacterial invasion of EFA dentine were seen: in younger animals bacteria occupied cracks in the EFA surface, but in older animals they also occupied tubules. The EFA dentine does not appear to respond to attrition by infilling of the tubules; the persistence of vital odontoblast processes in worn teeth suggests that dead tract formation is not extensive. Continuous occlusal wear may restrict the progress of caries in EFA but odontoblasts in the rat may be also physiologically and immunologically involved in restricting the ingress of bacteria into otherwise poorly protected EFA.

The a1 locus of Zea mays has been cloned using transposable elements as gene tags. The strategy was to make genomic libraries from maize stocks with a1 mutations induced either by En(Spm) or by Robertson's Mutator-system. These libraries were then screened with either Spm-I8 and En1, for the En-containing mutant, or with Mu1 for the Mu-induced mutation. There are many En and Mu1 hybridizing sequences present in the maize genome, however, by a process of cross-screening of the positives from the two libraries and by molecular analysis of the En-positive clones it was possible to identify clones in both libraries carrying all or part of the a1 gene.