Autoradiographic comparison of cholinergic and other transmitter receptors in the normal human hippocampus

The vulnerability of the human hippocampal complex to disease, trauma, and aging indicates the necessity to target this area therapeutically. The distribution and density of transmitter receptors provide a rational basis for this approach, and in this study the topography of 11 different pharmacological sites is compared with the cholinergic innervation, which is particularly vulnerable in dementia. The regional distribution of cholinergic innervation to the normal adult human hippocampus and adjacent cortex, marked by acetylcholinesterase (AChE) fiber and terminal reactivity, is notable for its concentration in CA2/3 of Ammon's horn and the dentate fascia. Neither nicotinic (high-affinity nicotine binding) nor muscarinic ("M1" or "M2") cholinergic receptor binding paralleled this distribution. In Ammon's horn, 5-HT2 and kainate receptor binding more closely resembled the pattern of AChE, being concentrated in CA2-4 compared with CA1. By contrast, muscarinic M1 and M2, 5-HT1A, benzodiazepine (including zolpidem-insensitive binding), NMDA (MK801), and AMPA/QUIS receptors were higher in CA1 and/or subiculum. Kainate binding, like AChE, was high in CA4. 5-HT2 and nicotinic binding partially mimicked the pattern of AChE around the granule layer. In the subicular complex and parahippocampal gyrus, where cholinergic activity is relatively lower, muscarinic, 5-HT1A, and benzodiazepine binding were relatively high and the nicotinic receptor was remarkable for its highest density compared to other areas examined. In stratum lacunosum-moleculare of CA1, which was relatively low in AChE activity, there was a dense band of nicotinic, M2, and benzodiazepine receptor binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence that generation of inositol 1,4,5-trisphosphate and hydrolysis of phosphatidylinositol 4,5-bisphosphate are rapid responses following addition of fungal elicitor which induces phytoalexin synthesis in lucerne (Medicago sativa) suspension culture cells

Treatment of lucerne suspension culture cells with glycoprotein elicitor from the phytopathogenic fungus Verticillium albo-atrum R & B triggers Ca(2+)-mediated induction of antimicrobial secondary metabolites termed phytoalexins. The present study investigated the possible role of polyphosphoinositide signal transduction in phytoalexin elicitation. Within 1 min of addition of elicitor to lucerne suspension culture cells we found a 100-160% (15-25 pmol/g fresh wt) increase in the level of compound with chromatographic and electrophoretic properties expected for an inositol trisphosphate (InsP3) and which was strongly bound by an inositol 1,4,5-trisphosphate (Ins(1,4,5)P3)-specific binding protein; after 3 min the level of this compound had fallen below that observed prior to elicitor challenge. In 32P-prelabelled cells, the relative proportion of radioactivity which cochromatographed with phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) was found to have decreased by 48% 1 min after elicitor addition and that rapid depletion of membrane lipid radioactivity was specific to this lipid fraction. The rapid, transient increase in level of Ins(1,4,5)P3 and concomitant fall in PtdIns(4,5)P2 suggests that Ins(1,4,5)P3 generated by hydrolysis of PtdIns(4,5)P2 may provide a Ca(2+)-mobilizing signal in phytoalexin elicitation in lucerne.

Genetic and biochemical analysis of a novel Ambler class A beta-lactamase responsible for cefoxitin resistance in Bacteroides species

A clinical isolate of Bacteroides vulgatus was resistant to tetracycline, clindamycin, ampicillin, cephaloridine, cefoxitin, and other beta-lactam antibiotics except imipenem. beta-Lactam resistance was mediated by a membrane-associated, clavulanate-sensitive cephalosporinase capable of degrading cephalosporins and penicillins. Cefoxitin also was degraded but at a slow rate. The cefoxitin resistance (Fxr) determinant was cloned from B. vulgatus genomic libraries that were prepared in Escherichia coli and then mated with Bacteroides fragilis for the identification of Fxr strains. Analysis of B. fragilis strains with the cloned Fxr determinant revealed the presence of a new beta-lactamase protein with the physical and enzymatic properties of the beta-lactamase found in the original B. vulgatus isolate. The beta-lactamase gene (cfxA) was subcloned on a 2.2-kb DraI-HindIII fragment, and the nucleotide sequence was determined. These results showed that cfxA encoded a protein of 321 amino acids and 35,375 molecular weight. Mutant strains in which the cfxA structural gene was disrupted by insertional inactivation lost both Fxr and beta-lactamase activity. Comparison of CfxA with other beta-lactamases showed a relationship with the active-site serine beta-lactamases in the Ambler molecular class A, although CfxA had apparently diverged significantly. This was exemplified by the substitution in CfxA at 13 of 25 amino acid residues previously identified as being invariant in class A beta-lactamases. These results suggest that CfxA may represent a new class A homology group which diverged very early.

Identification of a circular intermediate in the transfer and transposition of Tn4555, a mobilizable transposon from Bacteroides spp

Transmissible cefoxitin (FX) resistance in Bacteroides vulgatus CLA341 was associated with the 12.5-kb, mobilizable transposon, Tn4555, which encoded the beta-lactamase gene cfxA. Transfer occurred by a conjugation-like mechanism, was stimulated by growth of donor cells with tetracycline (TC), and required the presence of a Bacteroides chromosomal Tcr element. Transconjugants resistant to either FX, TC, or both drugs were obtained, but only Fxr Tcr isolates could act as donors of Fxr in subsequent matings. Transfer of Fxr could be restored in Fxr Tcs strains by the introduction of a conjugal Tcr element from Bacteroides fragilis V479-1. A covalently closed circular DNA form of Tn4555 was observed in donor cells by Southern hybridization, and the levels of this circular transposon increased significantly in cells grown with TC. Both the cfxA gene and the Tn4555 mobilization region hybridized to the circular DNA, suggesting that this was a structurally intact transposon unit. Circular transposon DNA purified by CsCl-ethidium bromide density gradient centrifugation was used to transform Tcs B. fragilis 638, and Fxr transformants were obtained. Both the circular form and the integrated Tn4555 were observed in transformants, but the circular form was present at less than one copy per chromosomal equivalent. Examination of genomic DNA from Fxr transformants and transconjugants revealed that Tn4555 could insert at a wide variety of chromosomal sites. Multiple transposon insertions were present in many of the transconjugants, indicating that there was no specific barrier to the introduction of a second transposon copy.

Differentiation of monocytoid THP-1 cells with phorbol ester induces expression of prostaglandin endoperoxide synthase-1 (COX-1)

Prostaglandin endoperoxide synthase (PGH synthase) is responsible for converting arachidonic acid to PGH2, the common precursor of prostaglandins. It has been shown previously that phorbol ester-induced differentiation of the THP-1 human monocytic leukemia cell line is accompanied by induction of PGH synthase enzyme and enhanced capacity to produce prostaglandins. However, the identity of the isoform of PGH synthase that is induced under these conditions has not been established. Northern and Western analyses revealed a dramatic increase in levels of PGH synthase-1 mRNA and protein levels within 24 hr after treatment of THP-1 cells with phorbol ester. No significant increase in PGH synthase-2 mRNA or protein was observed. The increases in PGH synthase-1 were accompanied by enhanced capacity of the cells to produce PGE2. These findings indicate that expression of PGH synthase-1 is greatly enhanced in THP-1 cells by treatment with an agent that induces differentiation.

The energetics and cooperativity of protein folding: a simple experimental analysis based upon the solvation of internal residues

The reversible unfolding of two dissimilar proteins, phosphoglycerate kinase from Bacillus stearothermophilus (PGK) and Staphylococcus aureus nuclease (SAN), was induced with two denaturants, urea and guanidinium chloride (GuHCl). For each protein, structural transitions were monitored by intrinsic fluorescence intensity changes arising from a unique tryptophan residue. In the case of SAN the single, native tryptophan residue was used, whereas for PGK two versions, one with a tryptophan at position 315 and one at 379, were constructed genetically. The resultant folding curves were analyzed by considering the change in the solvation free energy of internal amino acid residues as the denaturant concentration was varied. We derive the following simple relationship: -RT ln K = delta Gw + n delta Gs,m[D]/Kden. + [D]) where K is the equilibrium constant describing the distribution of folded and unfolded forms at a given denaturant concentration [D], delta Gw is the free energy change for the transition in the absence of denaturant, and n is the number of internal side chains becoming exposed. delta Gs,m and Kden. are constants derived empirically from the solvation energies of model compounds and represent the behavior of an average internal side chain between 0 and 6 M GuHCl and 0 and 8 M urea. For proteins of known structure these values can easily be derived, and for others, average values in guanidinium chloride (delta Gs,m = 0.775 kcal/mol and Kden. = 5.4 M) or urea (delta Gs,m = 1.198 kcal/mol and Kden. = 25.25 M) can be used in the analysis. Results show that the parameters n and delta Gw are independent of the denaturant used for all 12 transitions studied. This supports the hypothesis that the unfolding activity of urea and GuHCl can be accounted for by their effect on the solvation energy of amino acid side chains which are buried in the folded but exposed in the unfolded protein. This simple analytical treatment allows the "cooperativity" of protein folding to be interpreted in terms of the number of side chains becoming exposed to the solvent in a given step and allows accurate estimation of the free energy irrespective of the denaturant concentration needed to induce the transition.

Heat Shock Protein and the Double Insult Theory for the Development of Insulin Dependent Diabetes

Heat shock proteins (HSP) are the most widely conserved group of proteins in phylogeny and play an important role in infection and autoimmunity. HSP65 has been suggested as the primary antigen in insulin dependent diabetes while an alternative antigen glutamic acid decarboxylase (GAD), has similar amino acid sequences. A ‘double insult theory’ for the development of insulin dependent diabetes is suggested whereby a bacterial infection leads to the production of HSP antibody. If during a ‘window of opportunity’ this is followed by a viral infection of the islet cells this could, in certain histocompatibility locus antigen (HLA) groups only, lead to the production of HSPs on the cell surface and a destructive autoimmune reaction.

NGF deprivation and neuronal degeneration trigger altered beta-amyloid precursor protein gene expression in the rat superior cervical ganglia in vivo and in vitro

In order to study the expression of beta-amyloid precursor protein (APP) isoforms during neuronal degeneration we have used the rat superior cervical ganglia (SCG) as an experimental model. In the neonate these sympathetic ganglia are nerve growth factor (NGF) dependent and in vivo administration of anti-NGF antiserum results in exaggerated neuronal degeneration. Analysis of APP mRNA transcripts in the SCG, following NGF deprivation, revealed a coincident decrease in APP695 and augmentation of APP751/770. These changes were specific to the SCG and were not seen in sensory ganglia. Subsequent in vitro studies, using primary dissociated cultures of sympathetic or cortical neurones, confirmed these changes in APP gene expression during neuronal degeneration. These observations may have important implications for the generation of beta-amyloid in Alzheimer's disease.

The atherogenic potential of carbon monoxide

This paper reviews the available evidence concerning the atherogenic potential of carbon monoxide. The evidence comes from two different types of studies--epidemiology studies on populations of humans chronically exposed to carbon monoxide, and animal studies conducted under conditions of controlled exposure to carbon monoxide. Data from both epidemiology and animal studies suggest that carbon monoxide is not atherogenic. Therefore, the increased levels of atherosclerosis associated with smoking as reported in epidemiology studies of human smokers probably cannot be attributed to CO exposure.

Cytosolic and sarcoplasmic reticulum-associated low Km, cGMP-inhibited cAMP phosphodiesterase in mammalian myocardium

The distribution and phosphoprotein band patterns of low Km, cGMP-inhibited cAMP phosphodiesterase (cGI PDE) activity were examined in cytosolic and microsomal fractions of human, canine, rabbit and guinea pig left ventricular myocardium following phosphorylation by cAMP-dependent protein kinase, immunoprecipitation with anti-cGI PDE antibodies and SDS-PAGE. The recovery of cGI PDE activity in cytosolic and microsomal fractions was comparable in all four species. Microsomal cGI PDE was comprised chiefly of a approximately 135 kDa phosphoprotein. Cytosolic cGI PDE was comprised solely of approximately 116 kDa and lower molecular weight phosphoproteins. The approximately 135 kDa phosphoprotein probably corresponds to the holoenzyme encoded by the recently cloned cDNA for human myocardial cGI PDE, whose predicted molecular weight is 126 kDa. The approximately 116 kDa phosphoprotein may result from deletion or removal of putative membrane-association domains from the N-terminal region of the holoenzyme. These results suggest that the cytosolic and sarcoplasmic reticulum-associated forms of mammalian myocardial cGI PDE are separate molecular species.

Detection of Epstein-Barr virus (EBV) DNA by the polymerase chain reaction (PCR) in oral smears from healthy individuals and patients with squamous cell carcinoma

To assess the presence of Epstein-Barr virus (EBV) DNA in normal oral mucosa, as well as its relationship to age, sex and different sites in the oral cavity, oral smears from healthy adults were investigated using the polymerase chain reaction (PCR). Smears taken from oral cancer patients were also examined using the same method. Sixty healthy volunteers (30 men and 30 women) were selected and divided equally into three age groups. Four cytologic samples were taken from each subject using a cytobrush. Smears from 20 patients with oral cancer were taken from similar sites and from the lesion. The Bam W region of EBV DNA was chosen as the specific genome for PCR amplification. Fifteen out of 60 healthy individuals (25%) showed EBV positivity. Of these, seven were men and eight were women. There were no significant differences between the three age groups nor between the four sites of oral mucosa. Our results also showed that EBV DNA could be identified in 10 out of 20 oral cancer patients (50%), though in only 7 (35%) of the lesions. Taken into account with the age of the patients, these findings indicate that EBV infection in the oral cavity does not appear to be directly associated with the pathogenesis of oral squamous cell carcinoma.

Legal aspects of impairment and disability in pneumoconiosis

This chapter analyzes and explains the meanings, under the federal Black Lung program, of the terms impairment, disability, and pneumoconiosis. To accomplish this objective, this chapter reviews the regulations and administrative and judicial decisions made under the Black Lung Act, and for comparison, it refers to definitions given to, or applications made of, those terms in other jurisdictions and programs.

Graded Work Exposure to Promote Work Return after Severe Hand Trauma

Fifty-one patients with posttraumatic stress disorder after work-related hand injuries were placed on a graded work exposure program to facilitate return to work. These patients consisted of an initial group of 25 patients and a replication group of 26 patients. The program returned 92% of the initial group and 88% of the replicated group to work with their previous employers. At 6-month follow-up, 88% of the initial group and 80.1% of the replication group were still working full-time at the jobs to which they had returned. All of the patients not working with their previous employer at follow-up had appraisal/projected flash-backs, which have previously been associated with a 90% failure to return to work. This intervention was successful with 73% of the patients experiencing such flashbacks. In conclusion, graded work exposure was an effective treatment to promote return to work for patients experiencing significant psychological symptomatology after severe hand injury.

Leucocyte migration: effects of in vitro exposure to anaesthetic agents: possible potentiation of effects by adrenaline

The effect on in vitro migration of leucocytes and lymphocytes of various drugs used in anaesthesia have been determined in the concentration range 10(-2) to 10(-6) M. The drugs included, thiopentone, bupivacaine, lignocaine, adrenaline, noradrenaline, hydrocortisone, morphine (with and without preservative), lorazepam, suxamethonium, pancuronium and atropine. Toxicity and effect on random mobility after incubation for 1 and 18 h were also determined. Thiopentone depressed leucocyte function at a concentration of 10(-5) M which is comparable to clinical plasma concentrations. Increasing the duration of exposure of the cells to the drugs significantly lowered the concentrations at which depression of function was observed. At concentrations used during local infiltration in clinical practice, bupivacaine and lignocaine were toxic to both leucocytes and lymphocytes. Adrenaline, whilst having no direct effect on cell function, potentiated the effect of lignocaine. Morphine showed no effect at 10(-4) M, a level 1,000 times greater than the reported toxic plasma levels. However, this level falls within the range reported for drug addicts. No effects were found for the other drugs.

The development of enzyme-linked immunosorbent assays (ELISA) for the catecholamines adrenalin and noradrenalin

Monoclonal antibodies have been raised against adrenalin and noradrenalin and used as the basis of enzyme-linked immunosorbent assays (ELISA) to detect and estimate the concentrations of these catecholamines. Inhibition assays are described, with sensitive quantification in the range from 1 mg/ml to 100 pg/ml. Cross-reactivity assays reveal that neither assay is subject to interference by catecholamine metabolites at concentrations less than 100 ng/ml and 1 micrograms/ml respectively. Isolation and quantification of both catecholamines from clinical samples is discussed and the potential application of these ELISAs in a clinical setting is proposed.

Gender influence on specialists' ratings of residency program candidates

Sexism has been perceived at all levels of medical education. Although specialty training has been scrutinized from various perspectives, there have been few objective assessments of sexual discrimination in the selection of candidates. This study evaluates the responses of board-certified physicians to fictional residency applicants' personal statements, which were identical except for gender. Male and female physicians from six specialties in which women were overrepresented and six specialties in which women were underrepresented all favored female candidates. Female physicians in both groups rated male candidates as less hardworking than did male physicians. Implications of these and other findings are discussed.

Activation of a cryptic streptomycin-resistance gene in the Bacteroides erm transposon, Tn4551

Bacteroides compound transposons encoding erm resistance are highly homologous but previous studies have shown some divergence of Tn4551. Results presented here describe a novel Tn4551 streptomycin-resistance gene, aadS, that was phenotypically silent in wild-type Bacteroides. However, aadS expression could be activated by a trans-acting chromosomal mutation. The aadS-encoded peptide displayed significant homology to Gram-positive streptomycin-dependent adenyltransferases, and enzymatic analysis confirmed the production of this activity. Examination of the nucleotide sequence showed that 200 bp upstream of aadS, the DNA base composition changed abruptly from 31% G+C to 48% G+C. These two regions were demarcated by a DNA sequence with homology to the recombination hot spots reported for Tn21 and the Bacteroides ermFU gene and to sequences at the ends of the chromosomal Bacteroides conjugal element, XBU4422.

Molecular cloning and expression of human myocardial cGMP-inhibited cAMP phosphodiesterase

We have cloned a cDNA for a myocardial cGMP-inhibited cAMP phosphodiesterase (cGI PDE) from a human heart cDNA library in lambda Zap II. The open reading frame [3.5 kilobases (kb)] of cDNA clone n.13.2 (7.7 kb) encodes a protein of 125 kDa. In Northern blots of total human ventricle RNA, a single mRNA species (8.3 kb) hybridized with a 4-kb EcoRI restriction fragment of clone n.13.2 cDNA (containing the entire open reading frame). The carboxyl-terminal region of the deduced amino acid sequence of the cGI PDE contains the putative catalytic domain conserved among mammalian PDE families. A partial cDNA clone, n.2, encoding a truncated, 54-kDa cGI PDE containing the conserved domain was expressed as a catalytically active fusion protein in Escherichia coli. cAMP hydrolytic activity was inhibited by cGMP and OPC 3911 but not by rolipram. Thus, this report provides direct proof that the conserved domain contains the catalytic core of cGI PDEs.

Restraint inhibits luteinizing hormone and testosterone secretion in intact male rhesus macaques: effects of concurrent naloxone administration

The present study investigates how restraint affects the hypothalamo-hypophysial adreno-cortical axis and the hypothalamo-hypophysial gonadal axis in intact, adult male rhesus macaques. Restraint was chosen because it is not physically painful or harmful to the animal, but rather serves both as a physical and psychological stressor. Blood samples were collected from a remote site at 15-min intervals beginning at 07.00 h from tethered adult male rhesus macaques. Each of 4 animals was subjected to 6 h of chair restraint after a 3-hour control period in the animals' home cage. Samples were collected for an additional 6 h at the end of the restraint period when the animal was returned to its home cage. Brief anesthesia with ketamine (administered through the indwelling catheter) facilitated transfer of the animals to and from the chair. Blood samples were collected from 4 undisturbed males to document LH and testosterone secretion throughout the day. Plasma ACTH and cortisol, measured as indexes of stress, were elevated within 15 min after initiation of restraint and remained elevated for most of the restraint period. Conversely, LH and testosterone began to fall immediately after restraint and remained suppressed for several hours after the animals were removed from restraint and returned to their home cage. Testosterone levels were more consistently inhibited than were LH levels, a reflection of the fact that in some animals, testosterone remained low after the return of pulsatile LH secretion. In studies with naloxone (Nx), the opiate receptor antagonist (5 mg bolus plus 5 mg/h) was given beginning either at the initiation of restraint (n = 2) or 2 h thereafter (n = 2), and continued until the end of the restraint period. With Nx treatment of the restrained animals, both ACTH and cortisol were elevated as in the controls and LH and testosterone secretion were significantly increased within 1-2 h. However, after the Nx treatment was terminated and the animals were returned to their home cages, plasma levels of LH and testosterone were not different from levels in restrained animals and were significantly less than levels in untreated animals. These data show that restraint is a potent stimulus for activation of the HPAC axis and inhibits both LH and testosterone release. The pathway through which restraint inhibits LH release probably includes endogenous opiate suppression of hypothalamic GnRH release since Nx partially blocks the effect of stress.

Analysis of rRNA restriction fragment length polymorphisms from Bacteroides spp. and Bacteroides fragilis isolates associated with diarrhea in humans and animals

The Escherichia coli rRNA operon rrnB was used as a 32P-labeled hybridization probe in Southern blots of genomic DNAs from representative strains of the saccharolytic, gram-negative, obligate anaerobes of the genus Bacteroides. Control experiments with the B. fragilis type strain ATCC 25285 established that nearly identical rRNA fragment patterns were produced when either the E. coli rrnB gene probe or homologous rRNA isolated from B. fragilis was used as the probe. In addition, it was shown that a specific 16S or 23S rrnB gene probe also could be used to produce fragment patterns suitable for analysis. Thirty-one strains from 8 of the 10 recognized Bacteroides species were then examined. The resulting autoradiographs revealed specific fragment patterns for all but one (B. ovatus) of the species tested. Restriction fragment length polymorphisms were observed for many of the strains tested, but these differences did not hinder species classification. The five B. ovatus strains examined did not form a distinct group, and their rRNA fragment patterns displayed a marked heterogeneity. The same approach was applied to a unique set of enterotoxin-producing B. fragilis strains isolated from animals and humans with diarrhea. The results demonstrated that these strains were in fact B. fragilis and that they produce rRNA fragment patterns closely related to those of the type strain ATCC 25285. This set of strains did not appear to form a separate subgroup or genotype within the B. fragilis species, and there were no distinguishable restriction fragment length polymorphisms that could be used to specifically separate enterotoxin-producing strains from nonenterotoxigenic strains.

Insulin and isoproterenol induce phosphorylation of the particulate cyclic GMP-inhibited, low Km cyclic AMP phosphodiesterase (cGI PDE) in 3T3-L1 adipocytes

The cGI PDE in particulate fractions of differentiated adipocytes (but not control 3T3-L1 fibroblasts) was cross-reactive with a polyclonal antibody raised against the bovine adipose cGI PDE. The 3T3-L1 adipocyte cGI PDE is a 135 kDa protein which is phosphorylated in 32P-labeled cells in response to beta-agonist or insulin. These results indicate that the 3T3-L1 cGI PDE is similar in structure and hormonal regulation to the analogous enzyme in the rat adipocyte.