Shared reaction in solid-phase immunoassay for estriol determination

In the search of factors responsible for the experimental difficulties in developing accurate and sensitive solid-phase immunoassay of steroids, an experimental model has been set up for the study of nonspecific interaction of the steroid analyte with the coating protein. Along with the development of a highly sensitive enzyme-linked, solid-phase immunoassay for estriol measurement, we observed evidence of shared reactions. This property, to our knowledge not previously described for monomeric, low-molecular-weight antigens like estrogens, has been attributed to the presence of bovine serum albumin, which is capable of binding estrogens through hydrophobic interactions. The addition of estriol in solution in large excess did not reach a complete inhibition of the binding, so the possibility was excluded that the antibody simply binds to the adsorbed estrogen. The simplest explanation for the occurrence of the reaction is the hypothesis that a family of antigen determinants arises when the estriol is conjugated to a protein carrier. The corresponding antibodies are revealed only when the estrogen participates to the actual analytical system in the form of a steroid-protein conjugate. In the experiment, the estriol has been recognized as being coupled with one or more amino acid side chains present around its site of covalent linkage to the immunogen protein. The discussed results may be of help in developing a solid-phase immunoassay of small antigens as steroids, but also in applying the hybridoma and phage display technologies, the screening methods of which are based on sensitized solid phases.

Production of murine monoclonal antibodies against sulcofuron and flucofuron by in vitro immunisation

Monoclonal murine anti-pesticide antibodies were produced by in vitro immunisation (IVI) of cultured splenocytes with the pesticides sulcofuron and flucofuron. The majority of both anti-flucofuron and anti-sulcofuron antibodies obtained were of the IgM isotype, rather than IgG. When used in an indirect enzyme-linked immunosorbent assay (ELISA), the antibodies bound to plate coating antigens which incorporated haptens that mimicked moieties present within the immunising pesticide. The antibodies exhibited a high degree of specificity, with the degree of cross-reactivity related to the structural similarity between the hapten present in the plate coating antigen and the moieties present within the immunising pesticide. These results indicated that antibodies specific to both sulcofuron and flucofuron had been produced by IVI. Synthesis of both hapten analogues and immunogens as required for methods based on in vivo immunisation was avoided, whilst antibody production was also comparatively more rapid than traditional methods and minimised animal discomfort.

Human urine mutagenicity study comparing cigarettes which burn or primarily heat tobacco

Cigarette smokers have been reported to void urine which is more mutagenic, as measured in the Ames assay, than urine voided by non-smokers. Condensate from the mainstream smoke of a cigarette which primarily heats tobacco (test cigarette) has shown significantly reduced mutagenicity in a battery of in vitro genotoxicity assays compared with tobacco-burning cigarettes. The objective of this study was to determine whether the reduction in mutagenic activity observed in the in vitro assays would be reflected in the urine of smokers of the test cigarette. Twenty smokers were enrolled in a 4-week crossover study, with each smoker consuming test cigarettes ad libitum for a week and their usual brand of tobacco-burning cigarettes the other 3 weeks. Diet was strictly controlled throughout the study, and broiled and pan-fried meat was not served to minimize ingestion of mutagenic protein pyrolysis products. There was no statistically significant difference (p = 0.06) in consumption of tobacco-heating and tobacco-burning cigarettes. There were no statistically significant differences (p = 0.22) in salivary cotinine concentrations for smokers when smoking either tobacco-burning or tobacco-heating cigarettes. Urinary nicotine (ng/mg creatinine) was not different (p = 0.31) for smokers when smoking either tobacco-burning or tobacco-heating cigarettes. Urinary cotinine (ng/mg creatinine) was 32% lower (p = 0.0004) when smoking tobacco-heating cigarettes as compared with smoking tobacco-burning cigarettes. Twenty-four-hour urine samples were collected twice weekly, concentrated using XAD-2 resin and tested in Ames strains TA98 and YG1024 with metabolic activation. Tobacco-burning cigarette smokers experienced a 79% reduction in urinary mutagenicity as measured in strain YG1024 and a 72% reduction as measured in strain TA98 during the week that they smoked the tobacco-heating cigarette while maintaining a fixed dietary regimen. The results of this study indicate that smokers of tobacco-heating cigarettes void urine which is significantly less mutagenic than urine voided by smokers of tobacco-burning cigarettes.

Loss of nitric oxide production in the coronary circulation after the development of dilated cardiomyopathy: a specific defect in the neural regulation of coronary blood flow

1. The aims of our study were to determine the role of nitric oxide (NO) in cholinergic reflex dilation of the coronary circulation in normal healthy conscious dogs and after the development of pacing-induced dilated cardiac myopathy and overt congestive heart failure. 2. Dogs were instrumented using sterile surgical techniques under general anaesthesia and allowed to fully recover. The Bezold-Jarisch reflex was stimulated by the intra-atrial injection of veratrine or the intravenous injection of PGI2, while the carotid chemoreflex was stimulated by the intracarotid injection of nicotine. Experiments were performed before and after the development of overt congestive heart failure (HF) caused by rapid left ventricular pacing for 4 weeks. 3. The release of NO, or NO-mediated vascular relaxation following administration of acetylcholine (ACh) may have little physiological significance since as ACh is released from nerve endings in vivo. Stimulation of the Bezold-Jarisch or carotid chemoreflex resulted in typical vagal cholinergic reflex coronary vasodilation, an increase in coronary blood flow and a decrease in coronary vascular resistance, which was substantially reduced following NO synthesis inhibition with nitro-L-arginine. 4. After the development of severe congestive HF, the production of NO by sieved coronary microvessels from the heart was markedly reduced accompanied by a 60-80% reduction in both the mRNA (northern blot) and protein (western blot) for endothelial NO synthase in the aorta. 5. After the development of severe pacing-induced HF, activation of the Bezold-Jarisch or carotid chemoreflex no longer resulted in coronary vasodilation due to the disappearance of NO production from the coronary circulation. 6. Therefore, cholinergic reflex coronary vasodilation is mediated by NO. Because coronary blood vessels lose the ability to produce NO after the development of HF, reflex cholinergic coronary vasodilation is markedly altered, uncovering a previously undiscovered specific defect in the integrated control of the coronary circulation in the failing heart.

Survey of the diet of Pima Indians using quantitative food frequency assessment and 24-hour recall. Diabetic Renal Disease Study

OBJECTIVE

A dietary survey was conducted in the Gila River Indian Community in Arizona using two methods of dietary assessment--24-hour recall and quantitative food frequency (QFF) assessment--to determine the usual intake of the population.

DESIGN

Interviews were conducted by Pima women who were trained and monitored by a research dietitian. Energy and nutrient intake were calculated using a computerized dietary database that included specific Pima foods.

SUBJECTS

An age- and sex-stratified sample of 575 Pima Indians (273 men, 302 women) aged 18 to 74 years participated in the study.

STATISTICAL ANALYSES

Spearman correlations were used to compare the results of the two survey methods for energy and each nutrient. Intraclass correlations were used to measure reproducibility.

RESULTS

According to the 24-hour recall, mean reported energy intakes within decades of age were 95% to 112% of those in the US population for Pima women, and 76% to 94% of those in the US population for Pima men. Total energy intake assessed using QFF was 30% higher in men and 33% higher in women than the intake assessed using the 24-hour recall method.

CONCLUSIONS

A large dietary survey conducted using lay interviewers in a Native-American community was as reproducible as studies conducted in the general US population. The Pima diet was distributed among the major nutrients in a proportion similar to the US diet.

Ventricular enlargement associated with linkage marker for schizophrenia-related disorders in one pedigree

We previously obtained evidence indicating a genetic linkage marker for schizophrenia and related disorders (two-point lod score = 3.72, P = 0.01) on the short arm of chromosome 5(5p14.1-13.1) in one large pedigree. Automated computer algorithms were used to edge the brain and measure the volume of the ventricles, regional sulcal atrophy, and skull size and shape in the original nuclear family members. Of the 11 subjects who underwent computed tomography, six (three schizophrenic, two with schizotypal personality disorder, and one unaffected) carried the marker allele that co-segregated with schizophrenia-related disorders, while five (all unaffected) did not. The family members with the marker allele linked to schizophrenia-related disorders (n = 6) had significantly (P < 0.05) larger ventricle-brain ratios (VBRs) and more fronto-parietal atrophy (controlling for age) than the family members lacking the schizophrenia-related marker allele (n = 5). The three individuals with the largest VBRs all carried the marker, although they received diagnoses of no schizophrenia-related disorder, schizotypal personality disorder, and schizophrenia. Regional cortical values indicative of cerebrospinal fluid content were higher in the frontal and parietal regions of family members carrying the marker. The hypothesis that genetic linkage is associated with structural brain pathology is difficult to test because of all the potential compounding factors. Our findings suggest the possibility that, in this family, relatively enlarged VBR and fronto-parietal atrophy, as determined by computed tomograph, may be associated with a schizophrenia-related gene and present susceptibility to schizophrenia-related disorders. In addition to a replication of these findings in other similarly linked families yet to be identified, further studies using higher resolution structural and functional neuroimaging techniques will be required.

Determination of prothrombin activation fragments in young patients with inflammatory bowel disease

OBJECTIVE

To assess coagulation cascade activation as a potential index of thromboembolic risk in inflammatory bowel disease (IBD).

STUDY DESIGN

Fifty plasma samples were obtained during consecutive outpatient encounters with 29 patients (male:female = 20:9) with either Crohn's disease (CD) (n = 23) or ulcerative colitis (UC) (n = 6). Disease activity for CD was determined using the Pediatric Crohn's Disease Activity Index (PCDAI) and for UC using signs/symptoms and mucosal histology. Patients were grouped as active, recently active (not currently active but had been active within the previous 2 months), or inactive. Prothrombin fragment 1.2 (F1.2) was determined by enzyme-linked immunosorbent assay on plasma samples. Lab parameters were compared using the Kruskal-Wallis test with pairwise comparisons made using Wilcoxian rank sum test.

RESULTS

Forty-three percent of samples taken during active phases of disease (13 of 30) had elevated prothrombin cleavage byproduct F1.2. Similarly, five of eight encounters (63%) with recently active IBD had elevated F1.2 values. In contrast, none of the patients with inactive disease exhibited F1.2 elevation. Median F1.2 levels in both the active (0.85 nM/L) and recently active (1.4 nM/L) patient groups were greater than that of the inactive group (0.6 nM/L; p < 0.05).

CONCLUSIONS

Evidence of coagulation cascade activation in patients with active and recently active IBD suggests an increased risk of thrombogenesis during active disease that extends for a period of time after commencement of medications to induce remission in their disease process. It may be prudent to counsel patients to avoid risk factors associated with thrombotic phenomenon around the time of active IBD.

Correlation of hematologic markers of inflammation and lung function: a comparison of asymptomatic smokers and nonsmokers

Increased inflammation of the peripheral airways has been implicated as a cause of pulmonary function impairment. However, little information is available on the correlation between subclinical decrements of pulmonary function and inflammation in asymptomatic individuals. A relationship between markers of inflammation and lung function may be useful in predicting the early onset of lung function impairment. The purpose of this study was to investigate the correlation of hematologic markers of inflammation and spirometry in asymptomatic smokers and nonsmokers. The specific objectives of this study were twofold. The first objective was to quantify and compare the spirometric measures of lung function in smokers and nonsmokers having similar demographic and lifestyle characteristics. The second objective was to define the correlation between these spirometric measurements and hematologic markers of inflammation (white blood cells, monocytes, basophils, PGE1, IgG, and IgE). Systemic blood samples and spirometric measurements were obtained from 61 age-matched (33 +/- 9 years) healthy, asymptomatic smokers and nonsmokers, with similar self reported lifestyles (i.e., food, alcohol, vitamin consumption and exercise). Both male and female smokers self reported a higher coffee consumption (P < 0.05) compared to nonsmokers. Male smokers self-reported a trend toward current blue-collar versus white-collar occupation when compared with the nonsmokers. Body weight (77.6 +/- 16.6 kg) did not differ between the smokers and nonsmokers. The male nonsmokers were taller than the male smokers (P < 0.05). All subjects were asymptomatic and had clinically normal spirometry. Compared to male nonsmokers, the male smokers had lower FEF25-75% and FEF75-45% values (P < 0.05). No additional spirometric measurements, including FEV1/FVC, FEV1 and FVC were significantly different. The female smokers did not differ from the female nonsmokers (P < 0.05) in any of the spirometric endpoints measured. Thirteen statistically significant (P < 0.05) correlations involving inflammatory (white blood cells, monocytes, basophils, and PGE1) or immunologic endpoints (IgE) and spirometric measurements were observed in female smokers, female nonsmokers and male nonsmokers. No statistically significant correlations involving immunologic or inflammatory endpoints were observed in the male smokers. A better mechanistic understanding of the observed relationship between elevated hematologic inflammatory endpoints and reduced lung function may provide valuable insight into the clinical significance of these correlations.

A gene product related to Tral is required for the mobilization of Bacteroides mobilizable transposons and plasmids

The antibiotic-resistance transposon Tn4555 from Bacteroides can be transferred between strains by conjugation. The transposon is not self-transmissible and must be mobilized by resident chromosomal tetracycline-resistance elements. In the present report, the mechanism of transfer was examined at the genetic level by deletion analysis and nucleotide sequencing of clones that conferred a transmissible phenotype on a non-mobilizable plasmid. The results suggested that the product of mobATn was required for mobilization and it worked in concert with a cis-acting oriT-like sequence. This mechanism was compared with the mobilization system of a cryptic Bacteroides plasmid, pBI143, and the two systems were found to share a common transfer strategy. The mobA gene products from both genetic elements were related and they had limited homology to the broad group of mobilization proteins (relaxases) typified by Tral of RP4. Phylogenetic analysis of MobA and several other mobilization proteins from commensal gastro-intestinal tract organisms suggested that they formed a new subgroup of the Tral superfamily. The mobilization regions of both Tn4555 and pBI143 were located on discrete segments of DNA within the parent genetic element. These segments were delineated by regions of secondary structure, suggesting that they could be defined mobilization cassettes.

Evidence of a locus for schizophrenia and related disorders on the short arm of chromosome 5 in a large pedigree

We attempted to identify a locus for schizophrenia and related disorders in 24 nuclear families of schizophrenic probands using a predefined classification system for affected cases that included those disorders most clearly identified as sharing a genetic relationship with schizophrenia--schizoaffective disorder and schizotypal personality disorder. Initially, we evaluated 8 markers on chromosome 5 on the first 12 families with available genotyping and diagnostic assessments and, assuming autosomal dominant transmission, found a lod score of 2.67 for the D5S111 locus (5p14.1-13.1) in one large nuclear family (no. 17; sibship: n = 12; schizophrenia: n = 3; schizotypal personality disorder: n = 2); the other 11 families were much smaller, less complete, and provided little additional information. Other branches of no. 17 were then assessed and the 2-point lod score for family 17 rose to 3.72; using multipoint analysis the lod score in 17 was 4.37. When only schizophrenia was used to define affectedness, the positive evidence for linkage to D5S111 was greatly reduced. Sensitivity analysis indicated that the lod score is heavily dependent upon the predefined diagnostic criteria. Our studies of other families of schizophrenic probands eventually totalled 23, but linkage to D5S111 in these yielded a -2.41 lod score. The results provide evidence for genetic linkage of the D5S111 locus to schizophrenia and related disorders in one family. It may be of interest that over several generations, almost all the ancestors of family 17 could be traced back to a small, relatively isolated, hill region of Puerto Rico.

Oral white lesions with special reference to precancerous and tobacco- related lesions: conclusions of an international symposium held in Uppsala, Sweden, May 18-21 1994. International Collaborative Group on Oral White Lesions

An international group of epidemiologists, clinicians and pathologists with a special interest in oral white lesions and their precancerous significance has reviewed earlier work on this topic and identified some of the problems associated with previous definitions, descriptions and classifications. Modifications to these definitions, descriptions and classifications have been proposed, accompanied by explanations of the reasons for identifying the need for changes to be made. Leukoplakia may be a provisional or definitive diagnosis dependent upon the circumstances of oral examination and the availability of other information. Guidelines are provided to assist in the application of the definitions of oral leukoplakia and illustrations depict the homogeneous and non-homogeneous clinical variants. Consideration is also given to the importance of a red component in a white lesion, or a lesion that is entirely red (erythroplakia). A new clinical staging procedure for oral leukoplakia is also proposed.

Reduced gene expression of vascular endothelial NO synthase and cyclooxygenase-1 in heart failure

Endothelium-dependent responses are depressed in coronary and peripheral blood vessels after the onset of pacing-induced heart failure in dogs and heart failure of various etiologies in humans. The present study was designed to examine whether these responses were due to decreases in the expression of endothelial cell NO synthase (ecNOS) and cyclooxygenase-1 (COX-1). After 1 month of left ventricular pacing, 8 mongrel dogs were monitored for heart failure as defined by clinical signs and left ventricular end diastolic pressures > 25 mm Hg. Total RNA and protein were isolated from endothelial cells scraped from the thoracic aorta and analyzed by Northern and Western blotting, respectively. Blots probed with 32P-labeled cDNAs for ecNOS and COX-1 were quantified densitometrically, and results were normalized against GAPDH or von Willebrand factor (vWF). In arbitrary units, the ratios of ecNOS to GAPDH were 2.66 +/- 0.77 (mean +/- SEM, n = 17) and 1.12 +/- 0.37 (n = 6 and the ratios of COX-1 to GAPDH were 1.52 +/- 0.52 and 0.56 +/- 0.15 before and after heart failure, respectively. These represent 56% to 64% (P < .05) reductions in ecNOS and COX-1 gene expression. There was no change in the ratios of either COX-1 or ecNOS to vWF. There was also a marked reduction in ecNOS protein after heart failure, estimated at 70%. A marked reduction in nitrite production, a measure of enzyme activity, from thoracic aortas in response to stimulation by either acetylcholine or bradykinin also occurred. To determine whether ecNOS and COX-1 could be independently regulated, an orally active NO-releasing agent, CAS 936, was given to 7 normal dogs for 7 days, and aortic ecNOS and COX-1 mRNAs were analyzed. The ratio of ecNOS to GAPDH was depressed by 52% (P < .05) in aortas from these dogs, whereas the ratio of COX-1 to GAPDH was unchanged. Similar results were found when data were normalized to vWF. These results suggest that at least two endothelial vasodilator gene products are reduced in heart failure, as opposed to a selective defect in NO synthase gene expression.

Accumulation of Cr, Pb, Cu, Ni, Zn and Cd in soil following irrigation with treated urban effluent in Australia

The effect of irrigation with secondary treated municipal effluent on the accumulation of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) was investigated by monitoring sites that had been irrigated with effluent for 4 and 17 years. At Wodonga, seven tree species were sprinkler irrigated with effluent at an average application rate of 1347 mm per annum from 1980 to 1984. The other site at Canberra was a large grass playing field (9 ha), half of which had been effluent irrigated since 1977. The non-effluent irrigated area served as the control area and provided reference 'background' concentration to assess the extent of contamination due to 17 years of effluent irrigation. Archived soil samples collected before the commencement of effluent irrigation were compared with those taken in 1984 at Wodonga to assess the extent of contamination. The concentration of labile metals was determined by extraction with EDTA because this method provides a quantitative measure of bioavailable metals. Irrigation with effluent did not increase the EDTA-extractable metals concentration at either site. Furthermore, the EDTA-extractable metal values were within the natural 'back-ground' range reported for Australian soils. These data suggest that it may take between 50 and 100 years for heavy metal levels (mainly Cd) in effluent-irrigated soil to reach the currently proposed threshold values for environmental concern. The potentially harmful effects of long-term accumulation of heavy metals on plant growth cannot be ignored and could affect the sustainability of land-based disposal of effluent.

Tansley Review No. 86 Accumulation of phytoalexins: defence mechanism and stimulus response system

Phytoalexin synthesis is a defence-response- that is characterized by a requirement for a number of distinct elements, all of which must be present for the response to be expressed fully. These same elements: a signal, a cellular receptor, a signal transduction system and a responsive metabolic system, are also used to describe a stimulus-response system. A number of molecular species can function as signal molecules or elicitors of phytoalexin synthesis, including poly- and oligosaccharides, proteins and polypeptides, and fatty acids. Few receptors for elicitors have been identified but those that have been are proteins located on the plasma membrane of the plant. Induction of phytoalexin synthesis involves selective and co-ordinated activation of specific defence response genes, including those encoding the enzymes of phytoalexin synthesis, and these genes constitute the responsive metabolic system. The separate, and distant, locations of the receptor and the responsive genes means that the event in which the signal is perceived by the receptor must be relayed to the genes by means of a second messenger system. Several second messengers are candidates for such a coupling- or signal transduction-system, including udenosine-3',5'-cyclic monophosphate, Ca²⁺ , diacylglycerol and inositol 1,4,5-trisphosphate, active oxygen species and jasmonic acid. Each has been examined as a possible component of the signal transduction system mediating between the elicitor receptor interaction and the phytoalexin synthesis it induces. Analysis of the signalling events is made complex by the simultaneous solicitation by the invading micro-organism of several defence responses, each of which might involve elements of a different signal system. The same complexity is evident which the role of phytoalexin accumulation in resistance is analysed. Evaluation of the contribution made by phytoalexin accumulation towards resistance has been attempted by the use of various inhibitors and enhancers of the process. Transgenic and mutant plants with specific alterations in one or more ot those elements necessary for the plant to respond to the signals for phytoalexin synthesis and other defence responses, are beginning to aid resolution of the complex pattern ot signalling events and the respective roles of the inducible defence mechanisms in resistance. CONTENTS Summary 1 I. Introduction 2 II. Chemistry of phytoalexins 3 III. Phytoalexin accumulation as a determinant of resistance 6 IV. Elicitation of phytoalexin accumulation 11 References 34.

Tau isoform expression and phosphorylation state during differentiation of cultured neuronal cells

The axonal microtubule-associated protein, tau, is thought to play an important role in axonal growth and in the establishment of neuronal polarity. In adult human brain there are six alternatively spliced tau isoforms, which have different microtubule binding affinities in vitro. The tubulin-tau interaction is further modified by phosphorylation of tau and, compared to adult brain tau, both foetal brain tau and paired helical filament (PHF) tau, characteristic of Alzheimer's disease, are hyperphosphorylated. In vivo both the expression of tau isoforms and their phosphorylation states are developmentally regulated. In order to establish the correlation between the expression of tau isoforms and their pattern of phosphorylation, we have characterised these two features in several in vitro models of neuronal differentiation, including the human neuroblastoma cell lines, SK-N-SH, SH-SY5Y and IMR32 cells, rat PC12 cells and primary rat cortical neurones. Sensitive RT-PCR analysis revealed a different complement of tau isoforms in the different cell lines and neuritogenesis was associated mainly with an increase in the overall tau protein level with no apparent phosphorylation changes. A switch in tau isoform expression occurred only at the terminal stages of neuronal development, when it may be important in reinforcing the previously established axonal cytoarchitecture.

Estimation of nitrification rates in flooded soils

Three techniques for estimating nitrification rates in flooded soils were evaluated in short-term incubation experiments using three soils. The techniques were based on inhibition of either ammonium or nitrite oxidation and (13)N isotope dilution. Of four inhibitors of ammonium oxidation evaluated, one (allylthiourea) was ineffective and two (2-ethynylpyridine or phenyl acetylene dissolved in ethanol) promoted immobilization of ammonium. Emulsified 2-ethynylpyridine and acetylene were equally effective inhibitors of ammonium oxidation and had little or no effect on gross rates of N mineralization and immobilization. Four inhibitors of nitrite oxidation were evaluated, but this approach was compromised by the nonspecificity of three of the compounds-potassium cyanide, 2-ethylamino-4-isopropylamino-6-methylthio-s-triazine (ametryne) and 3-(3,4-dichlorophenyl)-1-methylurea (DMU)-and by the partial effectiveness of another (potassium chlorate). Two methods based on isotope dilution gave similar estimates of nitrification rates. These rates were similar to those estimated by inhibition of ammonium oxidation in one soil but were lower in the other two soils. In the latter two soils, nitrification of labeled ammonium derived from dissimilatory nitrate reduction resulted in underestimation of nitrification rates by isotope dilution.

Nucleotide sequence determination and genetic analysis of the Bacteroides plasmid, pBI143

The nucleotide sequence and genetic organization of the Bacteroides plasmid pBI143 were determined. The plasmid was 2747 base pairs (bp) and had a G+C content of 41% (GenBank Accession No. U30316). There were two open reading frames greater than 50 codons and these were designated mobA and repA. A 56-bp inverted repeat divided pBI143 into modules with repA and mobA in separate regions. There was a marked difference in the G+C content and codon usage for the two regions; repA had 33% G+C and mobA was 44% G+C. MobA had homology to other Bacteroides mobilization proteins and RepA shared homology to a replication protein from Zymomonas mobilis plasmid pZM2. These two putative replication proteins formed a subgroup of the rolling-circle replication.proteins belonging to the pSN2 family of gram-positive plasmids. Consistent with this finding, single-stranded pBI143 DNA was detected in plasmid containing Bacteroides fragilis cultures. Availability of the pBI143 sequence allowed the elucidation of the complete nucleotide sequence for pFD288 an 8.9-kb Bacteroides shuttle vector (GenBank Accession No. U30830).

Intestinal mucin inhibits adhesion of human enteropathogenic Escherichia coli to HEp-2 cells

Mucins are complex glycoproteins that cover the intestinal mucosal surface and are thought to provide protection against enteropathogenic infections by preventing bacterial adherence and subsequent colonization, invasion and toxin delivery. The aims of this study was to evaluate the capacity of intestinal mucin to inhibit epithelial cell adhesion by human enteropathogenic Escherichia colI (EPEC). EPEC strain E2348/69 (serotype O127:H6), known to produce a 94-kd epithelia cell-adhesion-mediating outer membrane protein called intimin and known to contain an EPEC adherence factor (EAF) plasmid, and three of its mutants were studied. Crude mucus was obtained from rabbit small-ubtestinal mucosal scrapings. Purified mucins were isolated by serial cesium chloride density gradient ultracentrifugation. Bacterial adhesion to HEp-2 epithelial cell monolayers in the presence of purified intestinal mucins was quantified by recovery of live viable bacteria as colony-forming units. EPEC strain E2348/69 adhesion was inhibited in a concentration-dependent manner by increasing amounts of mucin (adhesion suppressed to <1% by 150 microgram mucin). The relative magnitudes of inhibition of adhesion of E2348/69 and its mutants [JPN15 (EAF plasmid negative), JPN15.96(pMAR7) (intimin negative), and JPN15.96 (intimin negative, EAF plasmid negative)] were similar in the presence of equal amounts of mucin. The presence of the intimin protein and EAF plasmid are not necessary to the proficiency of mucin to inhibit HEp-2 epithelial cell adhesion.

Axillary sampling and radiotherapy does not compromise the patient with early breast cancer: Trafford database experience

Local recurrence has been studied in a selected group of 379 patients, 39% of whom underwent simple mastectomy and 61% lumpectomy. The axilla was sampled in 52%, cleared in 8% and untreated in 40%. Axillary recurrence occurred in 16% of patients with a median follow-up of 54 months. Ninety-one per cent of these patients with lymph node recurrence had no surgery or sampling to the axilla, and a third received radiotherapy. Local recurrence was satisfactorily controlled by various modalities of treatment in all but 29 patients. Death related to distant metastasis in all but six of these 29 patients. Analysis suggests that patients with locally uncontrolled disease had aggressive tumours at diagnosis which were larger than average, most often grade 3 histologically and more frequently required mastectomy. Our results support previous studies indicating that survival would not be influenced by more radical surgery but that sampling followed by radiotherapy would have prevented the majority of our lymph node recurrences.

Heat shock protein studies in type 1 and type 2 diabetes and human islet cell culture

Heat shock proteins (HSP) play an important role in auto-immunity and infection. Glutamic acid decarboxylase (GAD) the prime antigen in Type 1 diabetes has similar amino acid sequences to HSP65. An ELISA was developed using a plant-derived HSP65 antibody. HSP65 antibody was present in the serum of all normal subjects (median 1.64 AU, IQ range 1.49-1.74). Lower levels were found in established Type 1 diabetes (1.41 AU, 1.32-1.61, p < 0.001) and Type 2 diabetes (1.45 AU, 1.35-1.59, p < 0.006). In Type 1 HSP antibody levels fell with age (p = 0.007) and with duration (p = 0.008) and women with Type 1 had lower levels than men (p = 0.009). Human islet cell culture subjected to heat shock revealed an approximate four fold increase in heat shock protein antigen in the surrounding medium. The release of HSP antigen from stressed islet cells together with the finding of HSP antibody in the serum of all subjects suggest that HSP65 should not be completely discarded as having a possible role in the development of Type 1 diabetes. Low levels of HSP antibody in patients with established diabetes is probably a manifestation of impaired immunity induced by the diabetic state.

Enhanced responses to L-arginine in aortic rings from rats with angiotensin-dependent hypertension

We contrasted, in normotensive and hypertensive rats, the effect of L-arginine on isometric tension of phenylephrine-contracted rings of aorta bathed in Krebs' bicarbonate buffer on cyclic guanosine monophosphate content of aortic rings and on blood pressure. L-Arginine had no effect on isometric tension or cyclic guanosine monophosphate content of aortic rings from normotensive controls. Conversely, L-arginine (10(-5)-10(-3) mol/l) induced concentration-dependent relaxation of unrubbed and rubbed rings of thoracic and abdominal aorta and, as well, L-arginine (10(-3) mol/l) increased cyclic guanosine monophosphate in unrubbed and rubbed rings of thoracic aorta taken from hypertensive rats 7 to 14 days after aortic coarctation. Similar relaxations to L-arginine were seen in rings of thoracic and abdominal aorta from rats made hypertensive by infusion of angiotensin II for 7 to 8 days but not in rings of thoracic aorta from rats with aortic coarctation-induced hypertension of 28 to 42 days. Relaxant responses to L-arginine in rings of thoracic aorta from hypertensive rats 7 to 14 days after aortic coarctation were unaffected by pretreatment of rings with dexamethasone (10(-7) mol/l) or L-arginine (10(-4) mol/l) but were blunted by NG-nitro-L-arginine methylester (3 x 10(-4) mol/l) or methylene blue (10(-5) mol/l). Our results suggest that the vasorelaxant effects of L-arginine in aortic rings from hypertensive rats 7 to 14 days after aortic coarctation and 7 to 8 days after commencing angiotensin II infusion are mediated by nitric oxide.(ABSTRACT TRUNCATED AT 250 WORDS)

Immediate-early gene expression in human saphenous veins harvested during coronary artery bypass graft operations

Saphenous vein graft occlusion is a common late complication of coronary bypass grafting. Intimal smooth muscle cell hyperplasia is a component of this pathobiology, but the underlying molecular events are poorly understood. Immediate-early genes are activated shortly after growth stimulation and subserve cellular functions, which may contribute to intimal smooth muscle cell accumulation. In the present study, human saphenous vein grafts were harvested with minimal manipulation during coronary bypass and processed for isolation of total ribonucleic acid to examine change in immediate-early gene expression of messenger ribonucleic acid by Northern blotting techniques. Thirty saphenous vein grafts were incubated at 4 degrees C in Dulbecco's modified Eagle media from 30 minutes to 10 hours. The messenger ribonucleic acids for immediate-early genes c-fos and c-myc were weak or undetectable in controls but were increased (> 10 times controls) within 1 hour (c-fos) and persisted for at least 6 hours (c-myc) after harvest. Our results demonstrate, for the first time in human vascular tissue, incipient immediate-early gene induction. This information may lead to molecular therapies to control saphenous vein graft disease.

Biochemical and genetic analyses of a catalase from the anaerobic bacterium Bacteroides fragilis

A single catalase enzyme was produced by the anaerobic bacterium Bacteroides fragilis when cultures at late log phase were shifted to aerobic conditions. In anaerobic conditions, catalase activity was detected in stationary-phase cultures, indicating that not only oxygen exposure but also starvation may affect the production of this antioxidant enzyme. The purified enzyme showed a peroxidatic activity when pyrogallol was used as an electron donor. It is a hemoprotein containing one heme molecule per holomer and has an estimated molecular weight of 124,000 to 130,000. The catalase gene was cloned by screening a B. fragilis library for complementation of catalase activity in an Escherichia coli catalase mutant (katE katG) strain. The cloned gene, designated katB, encoded a catalase enzyme with electrophoretic mobility identical to that of the purified protein from the B. fragilis parental strain. The nucleotide sequence of katB revealed a 1,461-bp open reading frame for a protein with 486 amino acids and a predicted molecular weight of 55,905. This result was very close to the 60,000 Da determined by denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified catalase and indicates that the native enzyme is composed of two identical subunits. The N-terminal amino acid sequence of the purified catalase obtained by Edman degradation confirmed that it is a product of katB. The amino acid sequence of KatB showed high similarity to Haemophilus influenzae HktE (71.6% identity, 66% nucleotide identity), as well as to gram-positive bacterial and mammalian catalases. No similarities to bacterial catalase-peroxidase-type enzymes were found. The active-site residues, proximal and distal hemebinding ligands, and NADPH-binding residues of the bovine liver catalase-type enzyme were highly conserved in B. fragilis KatB.

High levels of ripening-specific reporter gene expression directed by tomato fruit polygalacturonase gene-flanking regions

The 1.4 kb 5' polygalacturonase (PG) gene-flanking region has previously been demonstrated to direct ripening-specific chloramphenicol acetyl transferase (CAT) expression in transgenic tomato plants. The steady state level of CAT mRNA in these plants was estimated to be less than 1% of the endogenous PG mRNA. Further constructs containing larger PG gene-flanking regions were generated and tested for their ability to direct higher levels of reporter gene expression. A 4.8 kb 5'-flanking region greatly increased levels of ripening-specific reporter gene activity, while a 1.8 kb 3' region was only shown to have a positive regulatory role in the presence of the extended 5' region. Transgenic plants containing the CAT gene flanked by both of these regions showed the same temporal pattern of accumulation of CAT and PG mRNA, and steady-state levels of the transgene mRNA were equivalent to 60% of the endogenous PG mRNA on a per gene basis. The proximal 150 bp of the PG promoter gave no detectable CAT activity. However, the distal 3.4 kb of the 4.8 kb 5' PG promoter was shown to confer high levels of ripening-specific gene expression when placed in either orientation upstream of the 150 bp minimal promoter. The DNA sequence of the 3.4 kb region revealed a 400 bp imperfect reverse repeat, and sequences which showed similarity to functionally significant sequences from the ripening-related, ethylene-regulated tomato E8 and E4 gene promoters. The possible roles of the flanking regions in regulating PG gene expression are discussed.

Blood parameters associated with atherogenic and thrombogenic risk in smokers and nonsmokers with similar life-styles

Current evidence indicates that life-style factors can affect the risk of developing cardiovascular disease. The life-style of cigarette smokers, as a group, differs in many ways from that of nonsmokers. Most studies that compare clinical pathologic findings related to atherogenic and thrombogenic risk in smokers and nonsmokers do not adequately control for most of the life-style differences between these two groups. In this study, a number of atherogenic risk factors (cholesterol, low-density lipoprotein, high-density lipoprotein, very low-density lipoprotein, high-density lipoprotein/cholesterol, triglycerides, and glucose) and thrombogenic risk factors (total white blood cell count, total red blood cell count; percent of monocytes, lymphocytes, neutrophils, basophils, and eosinophils; interleukin-1, leukotriene B4, hematocrit, hemoglobin, bilirubin, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, mean corpuscular volume, platelet count, prothrombin time, partial thromboplastin time, and fibrinogen) were compared in male and female cigarette smokers and non-smokers who were selected to have approximately similar self-reported life-styles (i.e., food, alcohol, and vitamin consumption and exercise level). However, the smokers (male and female) consumed more coffee (P < 0.05) than the nonsmokers. A trend toward blue-collar versus white collar occupational status was also observed in the male smokers relative to male nonsmokers. Cigarette consumption and urinary cotinine and carboxyhemoglobin levels did not differ between male and female smokers. Atherogenic and thrombogenic values were determined from venous blood samples. No statistically significant (P > 0.05) differences in clinical pathologic findings related to atherogenic risk were observed between the smokers and nonsmokers.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for the key role of the adipocyte cGMP-inhibited cAMP phosphodiesterase in the antilipolytic action of insulin

Enhancement of cAMP degradation by increased cGMP-inhibited cAMP phosphodiesterase (cGI-PDE) activity is thought to be an important component of the mechanism whereby insulin counteracts catecholamine-induced lipolysis in adipocytes. In this study the selective cGI-PDE inhibitor OPC3911 was used to evaluate this role of cGI-PDE activation in intact rat adipocytes with special reference to changes in cAMP levels measured as cAMP-dependent protein kinase (cAMP-PK) activity ratios. OPC3911 completely blocked (IC50 = 0.3 microM) the maximal inhibitory effect of insulin on noradrenaline-induced lipolysis and the net dephosphorylation of hormone-sensitive lipase and other intracellular target proteins for insulin action, whereas insulin-induced lipogenesis was not changed. The effect of OPC3911 on cAMP-PK activity ratios at different levels of lipolysis achieved by noradrenaline stimulation revealed that the reduction of cAMP-PK caused by 1 nM insulin was completely blocked by 3 microM OPC3911. The effect of OPC3911 was not due to an excessive increase in cellular cAMP resulting in 'supramaximal' lipolysis unresponsive to insulin. These data demonstrate that reduction in cAMP levels by the activation of cGI-PDE may be sufficient to account for the antilipolytic action of insulin.

Fast stress and rest acquisitions for technetium-99m-sestamibi separate-day SPECT

Abbreviated acquisition protocols were designed for stress and rest to decrease stress and rest SPECT image acquisition times but maintain the high count density of 99mTc-sestamibi separate-day cardiac images.

METHODS

Scan findings were compared visually and quantitatively with standard SPECT for 12 rest and 32 stress patient studies.

RESULTS

Of 29 stress defects detected by standard SPECT, 27 were present with the fast technique; of 8 resting SPECT defects, all were detected with fast SPECT. Two stress and no resting false-positive defects occurred with fast SPECT. Linear correlations (r) between standard and fast quantitative defect extent and severity were 0.76 and 0.86, respectively for stress SPECT, and 0.88 and 0.96 for rest SPECT. Stress fast defects were slightly less severe (p = 0.02) than those observed using standard acquisition.

CONCLUSION

We conclude that these fast protocols for separate-day 99mTc-MIBI SPECT accurately detect and characterize perfusion defects and provide a means to improve patient tolerance and increase laboratory throughput.

Age at onset and familial risk in Alzheimer's disease

OBJECTIVE

The authors investigated the relationship between probands' age at onset of Alzheimer's disease with the risk of primary progressive dementia in the probands' first-degree relatives.

METHOD

Two hundred probands with clinically diagnosed Alzheimer's disease and 179 nondemented elderly probands were recruited from the Mount Sinai Alzheimer's Disease Research Center, located at Mount Sinai Hospital and the Bronx Veterans Affairs Medical Center. Demographic and diagnostic data were collected on 1,398 of the first-degree relatives of the probands with Alzheimer's disease and 955 first-degree relatives of the nondemented probands.

RESULTS

Cox proportional hazards regression analysis showed a significant inverse relationship between age at onset of Alzheimer's disease in probands and greater familial risk in their relatives. Follow-up analyses indicated that the most commonly used age at onset cutoff point--65 years--was one of the points where an association with familial aggregation is least likely to be revealed; other onset cutoff ages (e.g., 55, 70, and 75) better identified Alzheimer's disease groups with differing familial/genetic risks.

CONCLUSIONS

The authors conclude that patients with an earlier age at onset of Alzheimer's disease are more likely to have relatives with Alzheimer's disease than are patients with a later age at onset of the disease. An onset age of 70 best differentiated probands whose relatives were at higher risk from those whose relatives were at lower risk.

Dosimetric effects of matching electron fields with cobalt 60 fields in the management of head and neck cancer

The dose distributions in a blocked Co 60 beam with the area under the block irradiated with a 9-MeV electron beam at a nominal source to surface distance (SSD) of 100 cm and at an extended SSD of 115 cm were determined. The photon block was simulating the spinal cord shielding used when treating the posterior neck. A hot spot of 10% appeared close to the junction on the side of the photon field when electron treatment was given at a nominal SSD of 100 cm. At 115 cm SSD, the magnitude of the hot spot on the side of photon field increased to 20% and a cold spot on the order of 10% appeared in the distal area of the irradiated volume treated with electrons. A gap of 0.5 cm between the light field edges of the photon field and the electron field reduced the hot spot from 20% to 10% on the side of photon field. However, the magnitude of the cold spot on the side of electron field increased to 20%, and it appeared across the irradiated volume. Considering the limitation of the design of the electron applicators, which precludes the use of a nominal SSD of 100 cm for head and neck treatments, it is recommended that no gap should be allowed between the photon fields and the extended SSD electron fields. Clinically a limited hot spot of 20% is considered more acceptable than a cold spot of 20% extending from proximal to distal areas of the treatment volume.

Management of the hypertensive patient: a case report

Hypertension is a potentially life-threatening condition that can lead to heart failure, stroke, and kidney disease. Most patients with hypertension can be treated and controlled if they are diagnosed in a timely manner. This case report exemplifies how the dentist can play a key role in the detection of hypertension by simply taking vital signs on all patients. It is incumbent upon us as health-care professionals to understand the causes of hypertension, the therapeutic drugs used and associated side effects, and the potential for drug interactions. The dentist's ability to recognize and appropriately manage hypertension will greatly enhance the health and safety of our patients.

Investigation of the role of cysteines in catalysis by prostaglandin endoperoxide synthase

The importance of cysteine residues in the cyclooxygenase activity of prostaglandin endoperoxide synthase (PGHS) was investigated using cysteine-specific reagents and site-directed mutagenesis. N-(7-Dimethyl-amino-4-methyl-3-coumarinyl)maleimide (DACM), a hydrophobic maleimide, inactivated both cyclooxygenase and peroxidase activities of apoPGHS in a time-dependent manner but did not affect holoPGHS. Heme titration experiments indicated that modification of apoPGHS with DACM prevented heme binding. Peptide mapping revealed that DACM modified Cys313, Cys512, and Cys540. N-Ethylmaleimide inactivated cyclooxygenase and peroxidase activities of holoPGHS in a time-dependent manner but did not affect apoPGHS. Peptide mapping demonstrated that N-ethylmaleimide reacted primarily with Cys313 in holoPGHS and with Cys540 in apoPGHS. Each of the 3 cysteines was changed to serine by site-directed mutagenesis, and the mutant proteins were expressed in COS-1 cells. The C512S mutant converted arachidonic acid to products to the same extent as wild-type PGHS. In contrast, the C313S and C540S mutants converted arachidonic acid to products to the extent of 10% of wild-type PGHS. These results indicate that Cys313, Cys512, and Cys540 are not essential for cyclooxygenase activity but that alteration of Cys540 or Cys313 dramatically decreases enzyme activity. Both residues are well removed from the cyclooxygenase and peroxidase active sites so our findings reveal that subtle changes, such as substitution of a single oxygen for sulfur atom as far as 30 A from the heme prosthetic group, can significantly alter enzyme activity.

Molecular and genetic analysis of the Bacteroides uniformis cephalosporinase gene, cblA, encoding the species-specific beta-lactamase

The gene, cblA, encoding the species-specific, clavulanate-susceptible, endogenous cephalosporinase was cloned from Bacteroides uniformis WAL-7088. The nucleotide sequence was determined, and the cblA structural gene was found to be 891 nucleotides, with a 48% G+C composition, which is similar to that of the B. uniformis genome. The cblA open reading frame encoded an Ambler class A beta-lactamase polypeptide precursor of 296 amino acid residues with a predicted molecular weight of 33,450. A beta-lactamase-deficient B. uniformis mutant with increased beta-lactam susceptibility was constructed by insertional inactivation of the chromosomal gene. This mutant was complemented by plasmids bearing the cblA gene, and the resulting strains were resistant to cephaloridine and had a beta-lactamase that comigrated with the parental beta-lactamase on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (30,500 Da) and in isoelectric focusing gels (pI 4.6), confirming a role for this beta-lactamase in resistance.

Prion protein is necessary for normal synaptic function

The prion diseases are neurodegenerative conditions, transmissible by inoculation, and in some cases inherited as an autosomal dominant disorder. They include Creutzfeldt-Jakob disease in humans and scrapie and bovine spongiform encephalopathy in animals. The prion consists principally of a post-translationally modified form of a host-encoded glycoprotein (PrPC), designated PrPSc (ref. 1); the normal cellular function of PrPC is, however, unknown. Although PrP is highly conserved among mammals and widely expressed in early embryogenesis, mice homozygous for disrupted PrP genes appear developmentally and behaviourally normal. PrP is a protein anchored to the neuronal surface by glycosylphosphatidylinositol, suggesting a role in cell signalling or adhesion. Here we report that hippocampal slices from PrP null mice have weakened GABAA (gamma-aminobutyric acid type A) receptor-mediated fast inhibition and impaired long-term potentiation. This impaired synaptic inhibition may be involved in the epileptiform activity seen in Creutzfeldt-Jakob disease and we argue that loss of function of PrPC may contribute to the early synaptic loss and neuronal degeneration seen in these diseases.

Insertional activation of cepA leads to high-level beta-lactamase expression in Bacteroides fragilis clinical isolates

Bacteroides fragilis is an important opportunistic pathogen of humans and is resistant to many drugs commonly used to treat anaerobic infections, including beta-lactams. A strain set comprised of B. fragilis isolates producing either low or high levels of the endogenous cephalosporinase activity, CepA, has been described previously (M. B. Rogers, A. C. Parker, and C. J. Smith, Antimicrob. Agents Chemother. 37:2391-2400, 1993). Clones containing cepA genes from each of seven representative strains were isolated, and the DNA sequences were determined. Nucleotide sequence comparisons revealed that there were few differences between the cepA coding sequences of the low- and high-activity strains. The cepA coding sequences were cloned into an expression vector, pFD340, and analyzed in a B. fragilis 638 cepA mutant. The results of beta-lactamase assays and ampicillin MICs showed that there was no significant difference in the enzymatic activity of structural genes from the high- or low-activity strains. Comparison of sequences upstream of the cepA coding region revealed that 50 bp prior to the translation start codon, the sequence for high-activity strains change dramatically. This region of the high-activity strains shared extensive homology with IS21, suggesting that an insertion was responsible for the increased expression of cepA in these isolates. Northern (RNA) blot analysis of total RNA by using cepA-specific DNA probes supported the idea that differential cepA expression in low- and high-activity strains was controlled at the level of transcription. However, the insertion did not alter the cepA transcription start site, which occurred 27 bp upstream of the ATG translation start codon in both expression classes. Possible mechanisms of cepA activation are discussed.

Patterns of risk in first-degree relatives of patients with Alzheimer's disease

BACKGROUND

Although an increased cumulative risk for primary progressive dementia (PPD) has been repeatedly demonstrated in relatives of probands with Alzheimer's disease (AD), an examination of their rates of illness at different ages has not been previously undertaken. Such an examination might reveal possible age-related characteristics associated with a more familial variety of AD.

METHODS

Using family history interviews and survival analysis, the cumulative risk for and 5-year age-specific hazard rates of PPD were assessed in the first-degree relatives of 200 probands with AD and two nondemented control groups--179 elderly ascertained through the Alzheimer's Disease Research Center (ADRC-derived controls) and 427 elderly ascertained from community senior centers (community controls).

RESULTS

The PPD risk curve for the relatives of probands with AD rose to about 30% and was significantly higher than the curves for the relatives of the ADRC-derived and community controls, where comparable rates were observed (approximately 12%). The age-specific hazard rates of PPD were calculated in three groups of relatives for each 5-year interval from ages 45 to 49 years through ages 85 to 89 years. The age-specific relative risk (RRi) for PPD in the relatives of probands with AD began to steadily diminish from the 75- to 79-year age interval (RRi = 13.49) through the 85- to 89-year age interval (RRi = 0.96) compared with the relatives of ADRC-derived controls and from the 60- to 64-year age interval (RRi = 16.15) through the 85- to 89-year age interval (RRi = 2.03) compared with the relatives of the community controls.

CONCLUSIONS

These data indicate that, for relatives of probands with AD, while the lifetime risk for PPD is greater than in relatives of controls, the familial contribution to the risk for PPD decreases with increasing age. The higher risk for PPD in relatives of probands with AD may be substantially diminished or even eliminated by the latter half of the ninth decade.

The effect of intraperitoneal N-methyl-N-nitrosourea on hamster palatal gingiva and intermolar mucosa

Fifty 4- to 6-week-old male random-bred golden hamsters were injected intraperitoneally with a weight-related dose (12.5 mg/kg body weight) of N-methyl-N-nitrosourea (NMU) three times a week for 4 weeks. Groups of seven animals were killed 10, 16 and 22 weeks after the first injection. The palatal gingiva from six animals and the intermolar mucosa from 21 animals was examined. Seven male age-matched untreated control animals were killed at each period. Although all NMU-treated hamsters showed dysplastic and neoplastic changes similar to those in human oral squamous-cell carcinoma, other changes such as acantholytic dyskeratosis, invading cysts, duct-like structures and basaloid islands and cords were not. The extent and severity of the changes increased with time so that by 22 weeks there was extensive involvement of the palatal bone and marrow spaces, the molar periodontal ligament and the greater palatine neurovascular bundle by neoplastic epithelium. The invading epithelium was derived from the junctional, crevicular and palatal gingival and intermolar epithelium. The latent period for the crevicular and junctional epithelia was shorter than that for the palatal gingival and intermolar epithelium. The invasive changes from the latter epithelium were often preceded by exophytic changes such as epithelial projections, papillae and papillomas. Such changes were infrequent for the gingival, crevicular and junctional epithelia. The study shows that intraperitoneal NMU acts as a complete carcinogen on the palatal gingival and intermolar epithelium in hamsters.

Identification of the phosphorylation site in vitro for cAMP-dependent protein kinase on the rat adipocyte cGMP-inhibited cAMP phosphodiesterase

Rat adipocyte cGMP-inhibited cAMP phosphodiesterase (cGI-PDE) appears to be dually regulated in intact cells by serine phosphorylations induced by isoprenaline and insulin, respectively (Degerman, E., Smith, C. J., Tornqvist, H., Vasta, V., Belfrage, P., and Manganiello, V. C. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 533-537; Smith, C. J., Vasta, V., Degerman, E., Belfrage, P., and Manganiello, V. C. (1991) J. Biol. Chem. 266, 13385-13390). Since cAMP-dependent protein kinase (cAMP-PK) catalyzes the beta-adrenergic effects, the site in the isolated cGI-PDE phosphorylated by this kinase was explored. A peptide, LRRSSGASGLLTSEHHSR (P18), corresponding to the amino acid sequence Leu423-Arg440 in the putative regulatory domain of the rat adipocyte cGI-PDE was synthesized. It contains a consensus substrate sequence -RRXS- for cAMP-PK within two tryptic cleavage sites and was readily phosphorylated by cAMP-PK. Two phosphopeptides, identified as RS-[32P]SGASGLLTSEHHSR and S-[32P]SGASGLLTSEHHSR, were obtained after stoichiometric phosphorylation and trypsinization of the peptide. These two peptides and the two main tryptic phosphopeptides obtained from immunoisolated [32P]cGI-PDE phosphorylated with cAMP-PK in a solubilized crude adipocyte membrane fraction were immuno-precipitated by an affinity-purified polyclonal antibody raised against P18 and exhibited the same chromatographic and electrophoretic profiles in three different separation systems. Similar radiosequencing profiles indicated that the second most N-terminal serine, corresponding to Ser-427 in the intact cGI-PDE, was phosphorylated by cAMP-PK in both P18 and authentic cGI-PDE. It is concluded that serine 427 is the target for cAMP-PK phosphorylation of the rat adipocyte cGI-PDE in vitro.

Single-step affinity purification, partial structure and properties of human platelet cGMP inhibited cAMP phosphodiesterase

The human platelet cilostamide- and cGMP-inhibited cAMP phosphodiesterase (cGI-PDE) was rapidly purified approximately 19,000-fold to apparent homogeneity using single step affinity chromatography on the isothiocyanate derivative of cilostamide coupled to aminoethyl agarose. Within 24 h, 30 micrograms of enzyme protein was obtained from 20 ml of packed platelets. Vmax for cAMP and cGMP was 6.1 and 0.9 mumol/min per mg protein, respectively. Several polypeptides (110/105, 79, 62, 55/53 kDa) were identified after SDS-PAGE, all of which were immunologically related to cGI-PDE and represented approx. 5, 20, 50 and 20% of the total protein, respectively. Limited proteolysis of the cGI-PDE with chymotrypsin produced a major fragment of approximately 47 kDa (and at least two smaller peptides) with catalytic activity and sensitivity to cGMP and OPC 3911 similar to controls. Phosphorylation of the cGI-PDE by cAMP-dependent protein kinase (A-kinase) resulted in maximal incorporation of 0.6-1.8 mol of 32P/mol 110/105 and 79 kDa polypeptides; much lower and variable amounts of phosphate were incorporated into the 62 and 55/53 kDa polypeptides. After digestion of cGI-PDE with several proteinases a number of peptides were isolated and sequenced. Most of the peptide sequences obtained could be aligned within the carboxy terminal domain of the deduced sequence of the human cardiac cGI-PDE. These and other results suggest that the subunit size of the intact platelet cGI-PDE is 110 kDa and that proteolytic fragments of 79, 62 and 55/53 kDa are produced during purification. The smaller fragments (62 and 55/53 kDa) contain the catalytic domain; the larger fragments (110 and 79 kDa) also contain the regulatory domain with phosphorylation sites for A-kinase.

A lesson in ethics

In arriving at an ethical decision, concern for the patient must come first. Recompense, inconvenience or embarrassment for the dentist are of secondary importance. Finally, the DSSNY Code of Ethics is at the essence of our profession. It encompasses the very image of how we wish to be viewed by society and indeed how we view ourselves. Uphold and guard it well.

Restraint inhibits luteinizing hormone secretion in the follicular phase of the menstrual cycle in rhesus macaques

The present study investigated the question of how restraint affects the hypothalamo-pituitary adrenocortical axis and the hypothalamo-pituitary gonadal axis in intact, adult female rhesus macaques in both the follicular and luteal phases of the menstrual cycle. Restraint was chosen because it is not physically harmful to the animal but rather serves primarily as a psychological stressor. Blood samples were collected from a remote site at 15-min intervals beginning at 0700 h from tethered adult female rhesus macaques. Each animal was subjected to 6 h of chair restraint after a 3-h control period in the animal's home cage. Samples were collected for an additional 6 h after the end of the restraint period, when each animal was returned to its home cage. Brief anesthesia with ketamine (administered through indwelling catheter) facilitated transfer of the animals to and from the chair. Blood samples were also collected from undisturbed females in both the follicular and luteal phases to document LH, cortisol, and progesterone secretion throughout the day. Plasma ACTH and cortisol, measured as indices of stress, were elevated within 15 min after initiation of restraint and remained elevated after the animals were returned to their cages. In animals sampled in the follicular phase, mean plasma LH levels were lower during restraint and remained suppressed for several hours after the animals were removed from restraint. LH levels were not significantly inhibited by restraint in the luteal phase. When the opiate receptor antagonist naloxone (Nx; 5 mg bolus plus 5 mg/h) was given beginning 2 h after the initiation of restraint, LH levels were elevated compared to prerestraint levels in both phases of the menstrual cycle. These data indicate that restraint is a potent activator of the pituitary-adrenal axis and that at least in the follicular phase of the menstrual cycle, restraint inhibits pituitary LH release. This inhibition of gonadotropin release may involve endogenous opiate suppression of GnRH release, since Nx reversed the effect of restraint.